deps: github.com/hashicorp/terraform@sdk-v0.11-with-go-modules

Updated via: go get github.com/hashicorp/terraform@sdk-v0.11-with-go-modules and go mod tidy

62 files changed, 14518 insertions, 0 deletions

diff --git a/vendor/google.golang.org/genproto/LICENSE b/vendor/google.golang.org/genproto/LICENSE
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/vendor/google.golang.org/genproto/LICENSE
@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
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+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
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+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
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+      Licensor for the purpose of discussing and improving the Work, but
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+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
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+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+      Work and such Derivative Works in Source or Object form.
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+   3. Grant of Patent License. Subject to the terms and conditions of
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
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+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
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+   4. Redistribution. You may reproduce and distribute copies of the
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+      meet the following conditions:
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+      (a) You must give any other recipients of the Work or
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+      (d) If the Work includes a "NOTICE" text file as part of its
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+          of the NOTICE file are for informational purposes only and
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+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
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+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
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+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
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+      whether in tort (including negligence), contract, or otherwise,
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+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
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+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
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+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/vendor/google.golang.org/genproto/googleapis/rpc/status/status.pb.go b/vendor/google.golang.org/genproto/googleapis/rpc/status/status.pb.go
new file mode 100644
index 0000000..8867ae7
--- /dev/null
+++ b/vendor/google.golang.org/genproto/googleapis/rpc/status/status.pb.go
@@ -0,0 +1,143 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: google/rpc/status.proto
+
+/*
+Package status is a generated protocol buffer package.
+
+It is generated from these files:
+        google/rpc/status.proto
+
+It has these top-level messages:
+        Status
+*/
+package status
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+import google_protobuf "github.com/golang/protobuf/ptypes/any"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+// The `Status` type defines a logical error model that is suitable for different
+// programming environments, including REST APIs and RPC APIs. It is used by
+// [gRPC](https://github.com/grpc). The error model is designed to be:
+//
+// - Simple to use and understand for most users
+// - Flexible enough to meet unexpected needs
+//
+// # Overview
+//
+// The `Status` message contains three pieces of data: error code, error message,
+// and error details. The error code should be an enum value of
+// [google.rpc.Code][google.rpc.Code], but it may accept additional error codes if needed.  The
+// error message should be a developer-facing English message that helps
+// developers *understand* and *resolve* the error. If a localized user-facing
+// error message is needed, put the localized message in the error details or
+// localize it in the client. The optional error details may contain arbitrary
+// information about the error. There is a predefined set of error detail types
+// in the package `google.rpc` that can be used for common error conditions.
+//
+// # Language mapping
+//
+// The `Status` message is the logical representation of the error model, but it
+// is not necessarily the actual wire format. When the `Status` message is
+// exposed in different client libraries and different wire protocols, it can be
+// mapped differently. For example, it will likely be mapped to some exceptions
+// in Java, but more likely mapped to some error codes in C.
+//
+// # Other uses
+//
+// The error model and the `Status` message can be used in a variety of
+// environments, either with or without APIs, to provide a
+// consistent developer experience across different environments.
+//
+// Example uses of this error model include:
+//
+// - Partial errors. If a service needs to return partial errors to the client,
+//     it may embed the `Status` in the normal response to indicate the partial
+//     errors.
+//
+// - Workflow errors. A typical workflow has multiple steps. Each step may
+//     have a `Status` message for error reporting.
+//
+// - Batch operations. If a client uses batch request and batch response, the
+//     `Status` message should be used directly inside batch response, one for
+//     each error sub-response.
+//
+// - Asynchronous operations. If an API call embeds asynchronous operation
+//     results in its response, the status of those operations should be
+//     represented directly using the `Status` message.
+//
+// - Logging. If some API errors are stored in logs, the message `Status` could
+//     be used directly after any stripping needed for security/privacy reasons.
+type Status struct {
+        // The status code, which should be an enum value of [google.rpc.Code][google.rpc.Code].
+        Code int32 `protobuf:"varint,1,opt,name=code" json:"code,omitempty"`
+        // A developer-facing error message, which should be in English. Any
+        // user-facing error message should be localized and sent in the
+        // [google.rpc.Status.details][google.rpc.Status.details] field, or localized by the client.
+        Message string `protobuf:"bytes,2,opt,name=message" json:"message,omitempty"`
+        // A list of messages that carry the error details.  There is a common set of
+        // message types for APIs to use.
+        Details []*google_protobuf.Any `protobuf:"bytes,3,rep,name=details" json:"details,omitempty"`
+}
+
+func (m *Status) Reset()                    { *m = Status{} }
+func (m *Status) String() string            { return proto.CompactTextString(m) }
+func (*Status) ProtoMessage()               {}
+func (*Status) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+func (m *Status) GetCode() int32 {
+        if m != nil {
+                return m.Code
+        }
+        return 0
+}
+
+func (m *Status) GetMessage() string {
+        if m != nil {
+                return m.Message
+        }
+        return ""
+}
+
+func (m *Status) GetDetails() []*google_protobuf.Any {
+        if m != nil {
+                return m.Details
+        }
+        return nil
+}
+
+func init() {
+        proto.RegisterType((*Status)(nil), "google.rpc.Status")
+}
+
+func init() { proto.RegisterFile("google/rpc/status.proto", fileDescriptor0) }
+
+var fileDescriptor0 = []byte{
+        // 209 bytes of a gzipped FileDescriptorProto
+        0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x12, 0x4f, 0xcf, 0xcf, 0x4f,
+        0xcf, 0x49, 0xd5, 0x2f, 0x2a, 0x48, 0xd6, 0x2f, 0x2e, 0x49, 0x2c, 0x29, 0x2d, 0xd6, 0x2b, 0x28,
+        0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x82, 0x48, 0xe8, 0x15, 0x15, 0x24, 0x4b, 0x49, 0x42, 0x15, 0x81,
+        0x65, 0x92, 0x4a, 0xd3, 0xf4, 0x13, 0xf3, 0x2a, 0x21, 0xca, 0x94, 0xd2, 0xb8, 0xd8, 0x82, 0xc1,
+        0xda, 0x84, 0x84, 0xb8, 0x58, 0x92, 0xf3, 0x53, 0x52, 0x25, 0x18, 0x15, 0x18, 0x35, 0x58, 0x83,
+        0xc0, 0x6c, 0x21, 0x09, 0x2e, 0xf6, 0xdc, 0xd4, 0xe2, 0xe2, 0xc4, 0xf4, 0x54, 0x09, 0x26, 0x05,
+        0x46, 0x0d, 0xce, 0x20, 0x18, 0x57, 0x48, 0x8f, 0x8b, 0x3d, 0x25, 0xb5, 0x24, 0x31, 0x33, 0xa7,
+        0x58, 0x82, 0x59, 0x81, 0x59, 0x83, 0xdb, 0x48, 0x44, 0x0f, 0x6a, 0x21, 0xcc, 0x12, 0x3d, 0xc7,
+        0xbc, 0xca, 0x20, 0x98, 0x22, 0xa7, 0x38, 0x2e, 0xbe, 0xe4, 0xfc, 0x5c, 0x3d, 0x84, 0xa3, 0x9c,
+        0xb8, 0x21, 0xf6, 0x06, 0x80, 0x94, 0x07, 0x30, 0x46, 0x99, 0x43, 0xa5, 0xd2, 0xf3, 0x73, 0x12,
+        0xf3, 0xd2, 0xf5, 0xf2, 0x8b, 0xd2, 0xf5, 0xd3, 0x53, 0xf3, 0xc0, 0x86, 0xe9, 0x43, 0xa4, 0x12,
+        0x0b, 0x32, 0x8b, 0x91, 0xfc, 0x69, 0x0d, 0xa1, 0x16, 0x31, 0x31, 0x07, 0x05, 0x38, 0x27, 0xb1,
+        0x81, 0x55, 0x1a, 0x03, 0x02, 0x00, 0x00, 0xff, 0xff, 0xa4, 0x53, 0xf0, 0x7c, 0x10, 0x01, 0x00,
+        0x00,
+}
diff --git a/vendor/google.golang.org/grpc/.travis.yml b/vendor/google.golang.org/grpc/.travis.yml
new file mode 100644
index 0000000..88a785d
--- /dev/null
+++ b/vendor/google.golang.org/grpc/.travis.yml
@@ -0,0 +1,21 @@
+language: go
+
+go:
+  - 1.6.x
+  - 1.7.x
+  - 1.8.x
+
+go_import_path: google.golang.org/grpc
+
+before_install:
+  - if [[ $TRAVIS_GO_VERSION = 1.8* ]]; then go get -u github.com/golang/lint/golint honnef.co/go/tools/cmd/staticcheck; fi
+  - go get -u golang.org/x/tools/cmd/goimports github.com/axw/gocov/gocov github.com/mattn/goveralls golang.org/x/tools/cmd/cover
+
+script:
+  - 'set -o pipefail && git ls-files "*.go" | xargs grep -L "\(Copyright [0-9]\{4,\} gRPC authors\)\|DO NOT EDIT" 2>&1 | tee /dev/stderr | (! read)'
+  - 'set -o pipefail && gofmt -s -d -l . 2>&1 | tee /dev/stderr | (! read)'
+  - 'set -o pipefail && goimports -l . 2>&1 | tee /dev/stderr | (! read)'
+  - 'if [[ $TRAVIS_GO_VERSION = 1.8* ]]; then ! golint ./... | grep -vE "(_mock|_string|\.pb)\.go:"; fi'
+  - 'if [[ $TRAVIS_GO_VERSION = 1.8* ]]; then ! go tool vet -all . 2>&1 | grep -vF .pb.go:; fi' # https://github.com/golang/protobuf/issues/214
+  - make test testrace
+  - 'if [[ $TRAVIS_GO_VERSION = 1.8* ]]; then staticcheck -ignore google.golang.org/grpc/transport/transport_test.go:SA2002 ./...; fi' # TODO(menghanl): fix these
diff --git a/vendor/google.golang.org/grpc/AUTHORS b/vendor/google.golang.org/grpc/AUTHORS
new file mode 100644
index 0000000..e491a9e
--- /dev/null
+++ b/vendor/google.golang.org/grpc/AUTHORS
@@ -0,0 +1 @@
+Google Inc.
diff --git a/vendor/google.golang.org/grpc/CONTRIBUTING.md b/vendor/google.golang.org/grpc/CONTRIBUTING.md
new file mode 100644
index 0000000..a5c6e06
--- /dev/null
+++ b/vendor/google.golang.org/grpc/CONTRIBUTING.md
@@ -0,0 +1,32 @@
+# How to contribute
+
+We definitely welcome your patches and contributions to gRPC!
+
+If you are new to github, please start by reading [Pull Request howto](https://help.github.com/articles/about-pull-requests/)
+
+## Legal requirements
+
+In order to protect both you and ourselves, you will need to sign the
+[Contributor License Agreement](https://cla.developers.google.com/clas).
+
+## Guidelines for Pull Requests
+How to get your contributions merged smoothly and quickly.
+ 
+- Create **small PRs** that are narrowly focused on **addressing a single concern**. We often times receive PRs that are trying to fix several things at a time, but only one fix is considered acceptable, nothing gets merged and both author's & review's time is wasted. Create more PRs to address different concerns and everyone will be happy.
+ 
+- For speculative changes, consider opening an issue and discussing it first. If you are suggesting a behavioral or API change, consider starting with a [gRFC proposal](https://github.com/grpc/proposal). 
+ 
+- Provide a good **PR description** as a record of **what** change is being made and **why** it was made. Link to a github issue if it exists.
+ 
+- Don't fix code style and formatting unless you are already changing that line to address an issue. PRs with irrelevant changes won't be merged. If you do want to fix formatting or style, do that in a separate PR.
+ 
+- Unless your PR is trivial, you should expect there will be reviewer comments that you'll need to address before merging. We expect you to be reasonably responsive to those comments, otherwise the PR will be closed after 2-3 weeks of inactivity.
+ 
+- Maintain **clean commit history** and use **meaningful commit messages**. PRs with messy commit history are difficult to review and won't be merged. Use `rebase -i upstream/master` to curate your commit history and/or to bring in latest changes from master (but avoid rebasing in the middle of a code review).
+ 
+- Keep your PR up to date with upstream/master (if there are merge conflicts, we can't really merge your change).
+ 
+- **All tests need to be passing** before your change can be merged. We recommend you **run tests locally** before creating your PR to catch breakages early on.
+
+- Exceptions to the rules can be made if there's a compelling reason for doing so.
+ 
diff --git a/vendor/google.golang.org/grpc/LICENSE b/vendor/google.golang.org/grpc/LICENSE
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/vendor/google.golang.org/grpc/LICENSE
@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/vendor/google.golang.org/grpc/Makefile b/vendor/google.golang.org/grpc/Makefile
new file mode 100644
index 0000000..03bb01f
--- /dev/null
+++ b/vendor/google.golang.org/grpc/Makefile
@@ -0,0 +1,52 @@
+all: test testrace
+
+deps:
+        go get -d -v google.golang.org/grpc/...
+
+updatedeps:
+        go get -d -v -u -f google.golang.org/grpc/...
+
+testdeps:
+        go get -d -v -t google.golang.org/grpc/...
+
+updatetestdeps:
+        go get -d -v -t -u -f google.golang.org/grpc/...
+
+build: deps
+        go build google.golang.org/grpc/...
+
+proto:
+        @ if ! which protoc > /dev/null; then \
+                echo "error: protoc not installed" >&2; \
+                exit 1; \
+        fi
+        go get -u -v github.com/golang/protobuf/protoc-gen-go
+        # use $$dir as the root for all proto files in the same directory
+        for dir in $$(git ls-files '*.proto' | xargs -n1 dirname | uniq); do \
+                protoc -I $$dir --go_out=plugins=grpc:$$dir $$dir/*.proto; \
+        done
+
+test: testdeps
+        go test -v -cpu 1,4 google.golang.org/grpc/...
+
+testrace: testdeps
+        go test -v -race -cpu 1,4 google.golang.org/grpc/...
+
+clean:
+        go clean -i google.golang.org/grpc/...
+
+coverage: testdeps
+        ./coverage.sh --coveralls
+
+.PHONY: \
+        all \
+        deps \
+        updatedeps \
+        testdeps \
+        updatetestdeps \
+        build \
+        proto \
+        test \
+        testrace \
+        clean \
+        coverage
diff --git a/vendor/google.golang.org/grpc/README.md b/vendor/google.golang.org/grpc/README.md
new file mode 100644
index 0000000..72c7325
--- /dev/null
+++ b/vendor/google.golang.org/grpc/README.md
@@ -0,0 +1,45 @@
+# gRPC-Go
+
+[![Build Status](https://travis-ci.org/grpc/grpc-go.svg)](https://travis-ci.org/grpc/grpc-go) [![GoDoc](https://godoc.org/google.golang.org/grpc?status.svg)](https://godoc.org/google.golang.org/grpc)
+
+The Go implementation of [gRPC](https://grpc.io/): A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the [gRPC Quick Start: Go](https://grpc.io/docs/quickstart/go.html) guide.
+
+Installation
+------------
+
+To install this package, you need to install Go and setup your Go workspace on your computer. The simplest way to install the library is to run:
+
+```
+$ go get google.golang.org/grpc
+```
+
+Prerequisites
+-------------
+
+This requires Go 1.6 or later.
+
+Constraints
+-----------
+The grpc package should only depend on standard Go packages and a small number of exceptions. If your contribution introduces new dependencies which are NOT in the [list](http://godoc.org/google.golang.org/grpc?imports), you need a discussion with gRPC-Go authors and consultants.
+
+Documentation
+-------------
+See [API documentation](https://godoc.org/google.golang.org/grpc) for package and API descriptions and find examples in the [examples directory](examples/).
+
+Performance
+-----------
+See the current benchmarks for some of the languages supported in [this dashboard](https://performance-dot-grpc-testing.appspot.com/explore?dashboard=5652536396611584&widget=490377658&container=1286539696).
+
+Status
+------
+General Availability [Google Cloud Platform Launch Stages](https://cloud.google.com/terms/launch-stages).
+
+FAQ
+---
+
+#### Compiling error, undefined: grpc.SupportPackageIsVersion
+
+Please update proto package, gRPC package and rebuild the proto files:
+ - `go get -u github.com/golang/protobuf/{proto,protoc-gen-go}`
+ - `go get -u google.golang.org/grpc`
+ - `protoc --go_out=plugins=grpc:. *.proto`
diff --git a/vendor/google.golang.org/grpc/backoff.go b/vendor/google.golang.org/grpc/backoff.go
new file mode 100644
index 0000000..090fbe8
--- /dev/null
+++ b/vendor/google.golang.org/grpc/backoff.go
@@ -0,0 +1,98 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "math/rand"
+        "time"
+)
+
+// DefaultBackoffConfig uses values specified for backoff in
+// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
+var (
+        DefaultBackoffConfig = BackoffConfig{
+                MaxDelay:  120 * time.Second,
+                baseDelay: 1.0 * time.Second,
+                factor:    1.6,
+                jitter:    0.2,
+        }
+)
+
+// backoffStrategy defines the methodology for backing off after a grpc
+// connection failure.
+//
+// This is unexported until the gRPC project decides whether or not to allow
+// alternative backoff strategies. Once a decision is made, this type and its
+// method may be exported.
+type backoffStrategy interface {
+        // backoff returns the amount of time to wait before the next retry given
+        // the number of consecutive failures.
+        backoff(retries int) time.Duration
+}
+
+// BackoffConfig defines the parameters for the default gRPC backoff strategy.
+type BackoffConfig struct {
+        // MaxDelay is the upper bound of backoff delay.
+        MaxDelay time.Duration
+
+        // TODO(stevvooe): The following fields are not exported, as allowing
+        // changes would violate the current gRPC specification for backoff. If
+        // gRPC decides to allow more interesting backoff strategies, these fields
+        // may be opened up in the future.
+
+        // baseDelay is the amount of time to wait before retrying after the first
+        // failure.
+        baseDelay time.Duration
+
+        // factor is applied to the backoff after each retry.
+        factor float64
+
+        // jitter provides a range to randomize backoff delays.
+        jitter float64
+}
+
+func setDefaults(bc *BackoffConfig) {
+        md := bc.MaxDelay
+        *bc = DefaultBackoffConfig
+
+        if md > 0 {
+                bc.MaxDelay = md
+        }
+}
+
+func (bc BackoffConfig) backoff(retries int) time.Duration {
+        if retries == 0 {
+                return bc.baseDelay
+        }
+        backoff, max := float64(bc.baseDelay), float64(bc.MaxDelay)
+        for backoff < max && retries > 0 {
+                backoff *= bc.factor
+                retries--
+        }
+        if backoff > max {
+                backoff = max
+        }
+        // Randomize backoff delays so that if a cluster of requests start at
+        // the same time, they won't operate in lockstep.
+        backoff *= 1 + bc.jitter*(rand.Float64()*2-1)
+        if backoff < 0 {
+                return 0
+        }
+        return time.Duration(backoff)
+}
diff --git a/vendor/google.golang.org/grpc/balancer.go b/vendor/google.golang.org/grpc/balancer.go
new file mode 100644
index 0000000..cde472c
--- /dev/null
+++ b/vendor/google.golang.org/grpc/balancer.go
@@ -0,0 +1,397 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "fmt"
+        "net"
+        "sync"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/grpclog"
+        "google.golang.org/grpc/naming"
+)
+
+// Address represents a server the client connects to.
+// This is the EXPERIMENTAL API and may be changed or extended in the future.
+type Address struct {
+        // Addr is the server address on which a connection will be established.
+        Addr string
+        // Metadata is the information associated with Addr, which may be used
+        // to make load balancing decision.
+        Metadata interface{}
+}
+
+// BalancerConfig specifies the configurations for Balancer.
+type BalancerConfig struct {
+        // DialCreds is the transport credential the Balancer implementation can
+        // use to dial to a remote load balancer server. The Balancer implementations
+        // can ignore this if it does not need to talk to another party securely.
+        DialCreds credentials.TransportCredentials
+        // Dialer is the custom dialer the Balancer implementation can use to dial
+        // to a remote load balancer server. The Balancer implementations
+        // can ignore this if it doesn't need to talk to remote balancer.
+        Dialer func(context.Context, string) (net.Conn, error)
+}
+
+// BalancerGetOptions configures a Get call.
+// This is the EXPERIMENTAL API and may be changed or extended in the future.
+type BalancerGetOptions struct {
+        // BlockingWait specifies whether Get should block when there is no
+        // connected address.
+        BlockingWait bool
+}
+
+// Balancer chooses network addresses for RPCs.
+// This is the EXPERIMENTAL API and may be changed or extended in the future.
+type Balancer interface {
+        // Start does the initialization work to bootstrap a Balancer. For example,
+        // this function may start the name resolution and watch the updates. It will
+        // be called when dialing.
+        Start(target string, config BalancerConfig) error
+        // Up informs the Balancer that gRPC has a connection to the server at
+        // addr. It returns down which is called once the connection to addr gets
+        // lost or closed.
+        // TODO: It is not clear how to construct and take advantage of the meaningful error
+        // parameter for down. Need realistic demands to guide.
+        Up(addr Address) (down func(error))
+        // Get gets the address of a server for the RPC corresponding to ctx.
+        // i) If it returns a connected address, gRPC internals issues the RPC on the
+        // connection to this address;
+        // ii) If it returns an address on which the connection is under construction
+        // (initiated by Notify(...)) but not connected, gRPC internals
+        //  * fails RPC if the RPC is fail-fast and connection is in the TransientFailure or
+        //  Shutdown state;
+        //  or
+        //  * issues RPC on the connection otherwise.
+        // iii) If it returns an address on which the connection does not exist, gRPC
+        // internals treats it as an error and will fail the corresponding RPC.
+        //
+        // Therefore, the following is the recommended rule when writing a custom Balancer.
+        // If opts.BlockingWait is true, it should return a connected address or
+        // block if there is no connected address. It should respect the timeout or
+        // cancellation of ctx when blocking. If opts.BlockingWait is false (for fail-fast
+        // RPCs), it should return an address it has notified via Notify(...) immediately
+        // instead of blocking.
+        //
+        // The function returns put which is called once the rpc has completed or failed.
+        // put can collect and report RPC stats to a remote load balancer.
+        //
+        // This function should only return the errors Balancer cannot recover by itself.
+        // gRPC internals will fail the RPC if an error is returned.
+        Get(ctx context.Context, opts BalancerGetOptions) (addr Address, put func(), err error)
+        // Notify returns a channel that is used by gRPC internals to watch the addresses
+        // gRPC needs to connect. The addresses might be from a name resolver or remote
+        // load balancer. gRPC internals will compare it with the existing connected
+        // addresses. If the address Balancer notified is not in the existing connected
+        // addresses, gRPC starts to connect the address. If an address in the existing
+        // connected addresses is not in the notification list, the corresponding connection
+        // is shutdown gracefully. Otherwise, there are no operations to take. Note that
+        // the Address slice must be the full list of the Addresses which should be connected.
+        // It is NOT delta.
+        Notify() <-chan []Address
+        // Close shuts down the balancer.
+        Close() error
+}
+
+// downErr implements net.Error. It is constructed by gRPC internals and passed to the down
+// call of Balancer.
+type downErr struct {
+        timeout   bool
+        temporary bool
+        desc      string
+}
+
+func (e downErr) Error() string   { return e.desc }
+func (e downErr) Timeout() bool   { return e.timeout }
+func (e downErr) Temporary() bool { return e.temporary }
+
+func downErrorf(timeout, temporary bool, format string, a ...interface{}) downErr {
+        return downErr{
+                timeout:   timeout,
+                temporary: temporary,
+                desc:      fmt.Sprintf(format, a...),
+        }
+}
+
+// RoundRobin returns a Balancer that selects addresses round-robin. It uses r to watch
+// the name resolution updates and updates the addresses available correspondingly.
+func RoundRobin(r naming.Resolver) Balancer {
+        return &roundRobin{r: r}
+}
+
+type addrInfo struct {
+        addr      Address
+        connected bool
+}
+
+type roundRobin struct {
+        r      naming.Resolver
+        w      naming.Watcher
+        addrs  []*addrInfo // all the addresses the client should potentially connect
+        mu     sync.Mutex
+        addrCh chan []Address // the channel to notify gRPC internals the list of addresses the client should connect to.
+        next   int            // index of the next address to return for Get()
+        waitCh chan struct{}  // the channel to block when there is no connected address available
+        done   bool           // The Balancer is closed.
+}
+
+func (rr *roundRobin) watchAddrUpdates() error {
+        updates, err := rr.w.Next()
+        if err != nil {
+                grpclog.Warningf("grpc: the naming watcher stops working due to %v.", err)
+                return err
+        }
+        rr.mu.Lock()
+        defer rr.mu.Unlock()
+        for _, update := range updates {
+                addr := Address{
+                        Addr:     update.Addr,
+                        Metadata: update.Metadata,
+                }
+                switch update.Op {
+                case naming.Add:
+                        var exist bool
+                        for _, v := range rr.addrs {
+                                if addr == v.addr {
+                                        exist = true
+                                        grpclog.Infoln("grpc: The name resolver wanted to add an existing address: ", addr)
+                                        break
+                                }
+                        }
+                        if exist {
+                                continue
+                        }
+                        rr.addrs = append(rr.addrs, &addrInfo{addr: addr})
+                case naming.Delete:
+                        for i, v := range rr.addrs {
+                                if addr == v.addr {
+                                        copy(rr.addrs[i:], rr.addrs[i+1:])
+                                        rr.addrs = rr.addrs[:len(rr.addrs)-1]
+                                        break
+                                }
+                        }
+                default:
+                        grpclog.Errorln("Unknown update.Op ", update.Op)
+                }
+        }
+        // Make a copy of rr.addrs and write it onto rr.addrCh so that gRPC internals gets notified.
+        open := make([]Address, len(rr.addrs))
+        for i, v := range rr.addrs {
+                open[i] = v.addr
+        }
+        if rr.done {
+                return ErrClientConnClosing
+        }
+        select {
+        case <-rr.addrCh:
+        default:
+        }
+        rr.addrCh <- open
+        return nil
+}
+
+func (rr *roundRobin) Start(target string, config BalancerConfig) error {
+        rr.mu.Lock()
+        defer rr.mu.Unlock()
+        if rr.done {
+                return ErrClientConnClosing
+        }
+        if rr.r == nil {
+                // If there is no name resolver installed, it is not needed to
+                // do name resolution. In this case, target is added into rr.addrs
+                // as the only address available and rr.addrCh stays nil.
+                rr.addrs = append(rr.addrs, &addrInfo{addr: Address{Addr: target}})
+                return nil
+        }
+        w, err := rr.r.Resolve(target)
+        if err != nil {
+                return err
+        }
+        rr.w = w
+        rr.addrCh = make(chan []Address, 1)
+        go func() {
+                for {
+                        if err := rr.watchAddrUpdates(); err != nil {
+                                return
+                        }
+                }
+        }()
+        return nil
+}
+
+// Up sets the connected state of addr and sends notification if there are pending
+// Get() calls.
+func (rr *roundRobin) Up(addr Address) func(error) {
+        rr.mu.Lock()
+        defer rr.mu.Unlock()
+        var cnt int
+        for _, a := range rr.addrs {
+                if a.addr == addr {
+                        if a.connected {
+                                return nil
+                        }
+                        a.connected = true
+                }
+                if a.connected {
+                        cnt++
+                }
+        }
+        // addr is only one which is connected. Notify the Get() callers who are blocking.
+        if cnt == 1 && rr.waitCh != nil {
+                close(rr.waitCh)
+                rr.waitCh = nil
+        }
+        return func(err error) {
+                rr.down(addr, err)
+        }
+}
+
+// down unsets the connected state of addr.
+func (rr *roundRobin) down(addr Address, err error) {
+        rr.mu.Lock()
+        defer rr.mu.Unlock()
+        for _, a := range rr.addrs {
+                if addr == a.addr {
+                        a.connected = false
+                        break
+                }
+        }
+}
+
+// Get returns the next addr in the rotation.
+func (rr *roundRobin) Get(ctx context.Context, opts BalancerGetOptions) (addr Address, put func(), err error) {
+        var ch chan struct{}
+        rr.mu.Lock()
+        if rr.done {
+                rr.mu.Unlock()
+                err = ErrClientConnClosing
+                return
+        }
+
+        if len(rr.addrs) > 0 {
+                if rr.next >= len(rr.addrs) {
+                        rr.next = 0
+                }
+                next := rr.next
+                for {
+                        a := rr.addrs[next]
+                        next = (next + 1) % len(rr.addrs)
+                        if a.connected {
+                                addr = a.addr
+                                rr.next = next
+                                rr.mu.Unlock()
+                                return
+                        }
+                        if next == rr.next {
+                                // Has iterated all the possible address but none is connected.
+                                break
+                        }
+                }
+        }
+        if !opts.BlockingWait {
+                if len(rr.addrs) == 0 {
+                        rr.mu.Unlock()
+                        err = Errorf(codes.Unavailable, "there is no address available")
+                        return
+                }
+                // Returns the next addr on rr.addrs for failfast RPCs.
+                addr = rr.addrs[rr.next].addr
+                rr.next++
+                rr.mu.Unlock()
+                return
+        }
+        // Wait on rr.waitCh for non-failfast RPCs.
+        if rr.waitCh == nil {
+                ch = make(chan struct{})
+                rr.waitCh = ch
+        } else {
+                ch = rr.waitCh
+        }
+        rr.mu.Unlock()
+        for {
+                select {
+                case <-ctx.Done():
+                        err = ctx.Err()
+                        return
+                case <-ch:
+                        rr.mu.Lock()
+                        if rr.done {
+                                rr.mu.Unlock()
+                                err = ErrClientConnClosing
+                                return
+                        }
+
+                        if len(rr.addrs) > 0 {
+                                if rr.next >= len(rr.addrs) {
+                                        rr.next = 0
+                                }
+                                next := rr.next
+                                for {
+                                        a := rr.addrs[next]
+                                        next = (next + 1) % len(rr.addrs)
+                                        if a.connected {
+                                                addr = a.addr
+                                                rr.next = next
+                                                rr.mu.Unlock()
+                                                return
+                                        }
+                                        if next == rr.next {
+                                                // Has iterated all the possible address but none is connected.
+                                                break
+                                        }
+                                }
+                        }
+                        // The newly added addr got removed by Down() again.
+                        if rr.waitCh == nil {
+                                ch = make(chan struct{})
+                                rr.waitCh = ch
+                        } else {
+                                ch = rr.waitCh
+                        }
+                        rr.mu.Unlock()
+                }
+        }
+}
+
+func (rr *roundRobin) Notify() <-chan []Address {
+        return rr.addrCh
+}
+
+func (rr *roundRobin) Close() error {
+        rr.mu.Lock()
+        defer rr.mu.Unlock()
+        if rr.done {
+                return errBalancerClosed
+        }
+        rr.done = true
+        if rr.w != nil {
+                rr.w.Close()
+        }
+        if rr.waitCh != nil {
+                close(rr.waitCh)
+                rr.waitCh = nil
+        }
+        if rr.addrCh != nil {
+                close(rr.addrCh)
+        }
+        return nil
+}
diff --git a/vendor/google.golang.org/grpc/call.go b/vendor/google.golang.org/grpc/call.go
new file mode 100644
index 0000000..797190f
--- /dev/null
+++ b/vendor/google.golang.org/grpc/call.go
@@ -0,0 +1,309 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "bytes"
+        "io"
+        "time"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/trace"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/peer"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/transport"
+)
+
+// recvResponse receives and parses an RPC response.
+// On error, it returns the error and indicates whether the call should be retried.
+//
+// TODO(zhaoq): Check whether the received message sequence is valid.
+// TODO ctx is used for stats collection and processing. It is the context passed from the application.
+func recvResponse(ctx context.Context, dopts dialOptions, t transport.ClientTransport, c *callInfo, stream *transport.Stream, reply interface{}) (err error) {
+        // Try to acquire header metadata from the server if there is any.
+        defer func() {
+                if err != nil {
+                        if _, ok := err.(transport.ConnectionError); !ok {
+                                t.CloseStream(stream, err)
+                        }
+                }
+        }()
+        c.headerMD, err = stream.Header()
+        if err != nil {
+                return
+        }
+        p := &parser{r: stream}
+        var inPayload *stats.InPayload
+        if dopts.copts.StatsHandler != nil {
+                inPayload = &stats.InPayload{
+                        Client: true,
+                }
+        }
+        for {
+                if c.maxReceiveMessageSize == nil {
+                        return Errorf(codes.Internal, "callInfo maxReceiveMessageSize field uninitialized(nil)")
+                }
+                if err = recv(p, dopts.codec, stream, dopts.dc, reply, *c.maxReceiveMessageSize, inPayload); err != nil {
+                        if err == io.EOF {
+                                break
+                        }
+                        return
+                }
+        }
+        if inPayload != nil && err == io.EOF && stream.Status().Code() == codes.OK {
+                // TODO in the current implementation, inTrailer may be handled before inPayload in some cases.
+                // Fix the order if necessary.
+                dopts.copts.StatsHandler.HandleRPC(ctx, inPayload)
+        }
+        c.trailerMD = stream.Trailer()
+        return nil
+}
+
+// sendRequest writes out various information of an RPC such as Context and Message.
+func sendRequest(ctx context.Context, dopts dialOptions, compressor Compressor, c *callInfo, callHdr *transport.CallHdr, stream *transport.Stream, t transport.ClientTransport, args interface{}, opts *transport.Options) (err error) {
+        defer func() {
+                if err != nil {
+                        // If err is connection error, t will be closed, no need to close stream here.
+                        if _, ok := err.(transport.ConnectionError); !ok {
+                                t.CloseStream(stream, err)
+                        }
+                }
+        }()
+        var (
+                cbuf       *bytes.Buffer
+                outPayload *stats.OutPayload
+        )
+        if compressor != nil {
+                cbuf = new(bytes.Buffer)
+        }
+        if dopts.copts.StatsHandler != nil {
+                outPayload = &stats.OutPayload{
+                        Client: true,
+                }
+        }
+        outBuf, err := encode(dopts.codec, args, compressor, cbuf, outPayload)
+        if err != nil {
+                return err
+        }
+        if c.maxSendMessageSize == nil {
+                return Errorf(codes.Internal, "callInfo maxSendMessageSize field uninitialized(nil)")
+        }
+        if len(outBuf) > *c.maxSendMessageSize {
+                return Errorf(codes.ResourceExhausted, "grpc: trying to send message larger than max (%d vs. %d)", len(outBuf), *c.maxSendMessageSize)
+        }
+        err = t.Write(stream, outBuf, opts)
+        if err == nil && outPayload != nil {
+                outPayload.SentTime = time.Now()
+                dopts.copts.StatsHandler.HandleRPC(ctx, outPayload)
+        }
+        // t.NewStream(...) could lead to an early rejection of the RPC (e.g., the service/method
+        // does not exist.) so that t.Write could get io.EOF from wait(...). Leave the following
+        // recvResponse to get the final status.
+        if err != nil && err != io.EOF {
+                return err
+        }
+        // Sent successfully.
+        return nil
+}
+
+// Invoke sends the RPC request on the wire and returns after response is received.
+// Invoke is called by generated code. Also users can call Invoke directly when it
+// is really needed in their use cases.
+func Invoke(ctx context.Context, method string, args, reply interface{}, cc *ClientConn, opts ...CallOption) error {
+        if cc.dopts.unaryInt != nil {
+                return cc.dopts.unaryInt(ctx, method, args, reply, cc, invoke, opts...)
+        }
+        return invoke(ctx, method, args, reply, cc, opts...)
+}
+
+func invoke(ctx context.Context, method string, args, reply interface{}, cc *ClientConn, opts ...CallOption) (e error) {
+        c := defaultCallInfo
+        mc := cc.GetMethodConfig(method)
+        if mc.WaitForReady != nil {
+                c.failFast = !*mc.WaitForReady
+        }
+
+        if mc.Timeout != nil && *mc.Timeout >= 0 {
+                var cancel context.CancelFunc
+                ctx, cancel = context.WithTimeout(ctx, *mc.Timeout)
+                defer cancel()
+        }
+
+        opts = append(cc.dopts.callOptions, opts...)
+        for _, o := range opts {
+                if err := o.before(&c); err != nil {
+                        return toRPCErr(err)
+                }
+        }
+        defer func() {
+                for _, o := range opts {
+                        o.after(&c)
+                }
+        }()
+
+        c.maxSendMessageSize = getMaxSize(mc.MaxReqSize, c.maxSendMessageSize, defaultClientMaxSendMessageSize)
+        c.maxReceiveMessageSize = getMaxSize(mc.MaxRespSize, c.maxReceiveMessageSize, defaultClientMaxReceiveMessageSize)
+
+        if EnableTracing {
+                c.traceInfo.tr = trace.New("grpc.Sent."+methodFamily(method), method)
+                defer c.traceInfo.tr.Finish()
+                c.traceInfo.firstLine.client = true
+                if deadline, ok := ctx.Deadline(); ok {
+                        c.traceInfo.firstLine.deadline = deadline.Sub(time.Now())
+                }
+                c.traceInfo.tr.LazyLog(&c.traceInfo.firstLine, false)
+                // TODO(dsymonds): Arrange for c.traceInfo.firstLine.remoteAddr to be set.
+                defer func() {
+                        if e != nil {
+                                c.traceInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{e}}, true)
+                                c.traceInfo.tr.SetError()
+                        }
+                }()
+        }
+        ctx = newContextWithRPCInfo(ctx)
+        sh := cc.dopts.copts.StatsHandler
+        if sh != nil {
+                ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: method, FailFast: c.failFast})
+                begin := &stats.Begin{
+                        Client:    true,
+                        BeginTime: time.Now(),
+                        FailFast:  c.failFast,
+                }
+                sh.HandleRPC(ctx, begin)
+                defer func() {
+                        end := &stats.End{
+                                Client:  true,
+                                EndTime: time.Now(),
+                                Error:   e,
+                        }
+                        sh.HandleRPC(ctx, end)
+                }()
+        }
+        topts := &transport.Options{
+                Last:  true,
+                Delay: false,
+        }
+        for {
+                var (
+                        err    error
+                        t      transport.ClientTransport
+                        stream *transport.Stream
+                        // Record the put handler from Balancer.Get(...). It is called once the
+                        // RPC has completed or failed.
+                        put func()
+                )
+                // TODO(zhaoq): Need a formal spec of fail-fast.
+                callHdr := &transport.CallHdr{
+                        Host:   cc.authority,
+                        Method: method,
+                }
+                if cc.dopts.cp != nil {
+                        callHdr.SendCompress = cc.dopts.cp.Type()
+                }
+                if c.creds != nil {
+                        callHdr.Creds = c.creds
+                }
+
+                gopts := BalancerGetOptions{
+                        BlockingWait: !c.failFast,
+                }
+                t, put, err = cc.getTransport(ctx, gopts)
+                if err != nil {
+                        // TODO(zhaoq): Probably revisit the error handling.
+                        if _, ok := status.FromError(err); ok {
+                                return err
+                        }
+                        if err == errConnClosing || err == errConnUnavailable {
+                                if c.failFast {
+                                        return Errorf(codes.Unavailable, "%v", err)
+                                }
+                                continue
+                        }
+                        // All the other errors are treated as Internal errors.
+                        return Errorf(codes.Internal, "%v", err)
+                }
+                if c.traceInfo.tr != nil {
+                        c.traceInfo.tr.LazyLog(&payload{sent: true, msg: args}, true)
+                }
+                stream, err = t.NewStream(ctx, callHdr)
+                if err != nil {
+                        if put != nil {
+                                if _, ok := err.(transport.ConnectionError); ok {
+                                        // If error is connection error, transport was sending data on wire,
+                                        // and we are not sure if anything has been sent on wire.
+                                        // If error is not connection error, we are sure nothing has been sent.
+                                        updateRPCInfoInContext(ctx, rpcInfo{bytesSent: true, bytesReceived: false})
+                                }
+                                put()
+                        }
+                        if _, ok := err.(transport.ConnectionError); (ok || err == transport.ErrStreamDrain) && !c.failFast {
+                                continue
+                        }
+                        return toRPCErr(err)
+                }
+                if peer, ok := peer.FromContext(stream.Context()); ok {
+                        c.peer = peer
+                }
+                err = sendRequest(ctx, cc.dopts, cc.dopts.cp, &c, callHdr, stream, t, args, topts)
+                if err != nil {
+                        if put != nil {
+                                updateRPCInfoInContext(ctx, rpcInfo{
+                                        bytesSent:     stream.BytesSent(),
+                                        bytesReceived: stream.BytesReceived(),
+                                })
+                                put()
+                        }
+                        // Retry a non-failfast RPC when
+                        // i) there is a connection error; or
+                        // ii) the server started to drain before this RPC was initiated.
+                        if _, ok := err.(transport.ConnectionError); (ok || err == transport.ErrStreamDrain) && !c.failFast {
+                                continue
+                        }
+                        return toRPCErr(err)
+                }
+                err = recvResponse(ctx, cc.dopts, t, &c, stream, reply)
+                if err != nil {
+                        if put != nil {
+                                updateRPCInfoInContext(ctx, rpcInfo{
+                                        bytesSent:     stream.BytesSent(),
+                                        bytesReceived: stream.BytesReceived(),
+                                })
+                                put()
+                        }
+                        if _, ok := err.(transport.ConnectionError); (ok || err == transport.ErrStreamDrain) && !c.failFast {
+                                continue
+                        }
+                        return toRPCErr(err)
+                }
+                if c.traceInfo.tr != nil {
+                        c.traceInfo.tr.LazyLog(&payload{sent: false, msg: reply}, true)
+                }
+                t.CloseStream(stream, nil)
+                if put != nil {
+                        updateRPCInfoInContext(ctx, rpcInfo{
+                                bytesSent:     stream.BytesSent(),
+                                bytesReceived: stream.BytesReceived(),
+                        })
+                        put()
+                }
+                return stream.Status().Err()
+        }
+}
diff --git a/vendor/google.golang.org/grpc/clientconn.go b/vendor/google.golang.org/grpc/clientconn.go
new file mode 100644
index 0000000..e3f6cb1
--- /dev/null
+++ b/vendor/google.golang.org/grpc/clientconn.go
@@ -0,0 +1,1158 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "errors"
+        "net"
+        "strings"
+        "sync"
+        "time"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/trace"
+        "google.golang.org/grpc/connectivity"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/grpclog"
+        "google.golang.org/grpc/keepalive"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/transport"
+)
+
+var (
+        // ErrClientConnClosing indicates that the operation is illegal because
+        // the ClientConn is closing.
+        ErrClientConnClosing = errors.New("grpc: the client connection is closing")
+        // ErrClientConnTimeout indicates that the ClientConn cannot establish the
+        // underlying connections within the specified timeout.
+        // DEPRECATED: Please use context.DeadlineExceeded instead.
+        ErrClientConnTimeout = errors.New("grpc: timed out when dialing")
+
+        // errNoTransportSecurity indicates that there is no transport security
+        // being set for ClientConn. Users should either set one or explicitly
+        // call WithInsecure DialOption to disable security.
+        errNoTransportSecurity = errors.New("grpc: no transport security set (use grpc.WithInsecure() explicitly or set credentials)")
+        // errTransportCredentialsMissing indicates that users want to transmit security
+        // information (e.g., oauth2 token) which requires secure connection on an insecure
+        // connection.
+        errTransportCredentialsMissing = errors.New("grpc: the credentials require transport level security (use grpc.WithTransportCredentials() to set)")
+        // errCredentialsConflict indicates that grpc.WithTransportCredentials()
+        // and grpc.WithInsecure() are both called for a connection.
+        errCredentialsConflict = errors.New("grpc: transport credentials are set for an insecure connection (grpc.WithTransportCredentials() and grpc.WithInsecure() are both called)")
+        // errNetworkIO indicates that the connection is down due to some network I/O error.
+        errNetworkIO = errors.New("grpc: failed with network I/O error")
+        // errConnDrain indicates that the connection starts to be drained and does not accept any new RPCs.
+        errConnDrain = errors.New("grpc: the connection is drained")
+        // errConnClosing indicates that the connection is closing.
+        errConnClosing = errors.New("grpc: the connection is closing")
+        // errConnUnavailable indicates that the connection is unavailable.
+        errConnUnavailable = errors.New("grpc: the connection is unavailable")
+        // errBalancerClosed indicates that the balancer is closed.
+        errBalancerClosed = errors.New("grpc: balancer is closed")
+        // minimum time to give a connection to complete
+        minConnectTimeout = 20 * time.Second
+)
+
+// dialOptions configure a Dial call. dialOptions are set by the DialOption
+// values passed to Dial.
+type dialOptions struct {
+        unaryInt    UnaryClientInterceptor
+        streamInt   StreamClientInterceptor
+        codec       Codec
+        cp          Compressor
+        dc          Decompressor
+        bs          backoffStrategy
+        balancer    Balancer
+        block       bool
+        insecure    bool
+        timeout     time.Duration
+        scChan      <-chan ServiceConfig
+        copts       transport.ConnectOptions
+        callOptions []CallOption
+}
+
+const (
+        defaultClientMaxReceiveMessageSize = 1024 * 1024 * 4
+        defaultClientMaxSendMessageSize    = 1024 * 1024 * 4
+)
+
+// DialOption configures how we set up the connection.
+type DialOption func(*dialOptions)
+
+// WithInitialWindowSize returns a DialOption which sets the value for initial window size on a stream.
+// The lower bound for window size is 64K and any value smaller than that will be ignored.
+func WithInitialWindowSize(s int32) DialOption {
+        return func(o *dialOptions) {
+                o.copts.InitialWindowSize = s
+        }
+}
+
+// WithInitialConnWindowSize returns a DialOption which sets the value for initial window size on a connection.
+// The lower bound for window size is 64K and any value smaller than that will be ignored.
+func WithInitialConnWindowSize(s int32) DialOption {
+        return func(o *dialOptions) {
+                o.copts.InitialConnWindowSize = s
+        }
+}
+
+// WithMaxMsgSize returns a DialOption which sets the maximum message size the client can receive. Deprecated: use WithDefaultCallOptions(MaxCallRecvMsgSize(s)) instead.
+func WithMaxMsgSize(s int) DialOption {
+        return WithDefaultCallOptions(MaxCallRecvMsgSize(s))
+}
+
+// WithDefaultCallOptions returns a DialOption which sets the default CallOptions for calls over the connection.
+func WithDefaultCallOptions(cos ...CallOption) DialOption {
+        return func(o *dialOptions) {
+                o.callOptions = append(o.callOptions, cos...)
+        }
+}
+
+// WithCodec returns a DialOption which sets a codec for message marshaling and unmarshaling.
+func WithCodec(c Codec) DialOption {
+        return func(o *dialOptions) {
+                o.codec = c
+        }
+}
+
+// WithCompressor returns a DialOption which sets a CompressorGenerator for generating message
+// compressor.
+func WithCompressor(cp Compressor) DialOption {
+        return func(o *dialOptions) {
+                o.cp = cp
+        }
+}
+
+// WithDecompressor returns a DialOption which sets a DecompressorGenerator for generating
+// message decompressor.
+func WithDecompressor(dc Decompressor) DialOption {
+        return func(o *dialOptions) {
+                o.dc = dc
+        }
+}
+
+// WithBalancer returns a DialOption which sets a load balancer.
+func WithBalancer(b Balancer) DialOption {
+        return func(o *dialOptions) {
+                o.balancer = b
+        }
+}
+
+// WithServiceConfig returns a DialOption which has a channel to read the service configuration.
+func WithServiceConfig(c <-chan ServiceConfig) DialOption {
+        return func(o *dialOptions) {
+                o.scChan = c
+        }
+}
+
+// WithBackoffMaxDelay configures the dialer to use the provided maximum delay
+// when backing off after failed connection attempts.
+func WithBackoffMaxDelay(md time.Duration) DialOption {
+        return WithBackoffConfig(BackoffConfig{MaxDelay: md})
+}
+
+// WithBackoffConfig configures the dialer to use the provided backoff
+// parameters after connection failures.
+//
+// Use WithBackoffMaxDelay until more parameters on BackoffConfig are opened up
+// for use.
+func WithBackoffConfig(b BackoffConfig) DialOption {
+        // Set defaults to ensure that provided BackoffConfig is valid and
+        // unexported fields get default values.
+        setDefaults(&b)
+        return withBackoff(b)
+}
+
+// withBackoff sets the backoff strategy used for retries after a
+// failed connection attempt.
+//
+// This can be exported if arbitrary backoff strategies are allowed by gRPC.
+func withBackoff(bs backoffStrategy) DialOption {
+        return func(o *dialOptions) {
+                o.bs = bs
+        }
+}
+
+// WithBlock returns a DialOption which makes caller of Dial blocks until the underlying
+// connection is up. Without this, Dial returns immediately and connecting the server
+// happens in background.
+func WithBlock() DialOption {
+        return func(o *dialOptions) {
+                o.block = true
+        }
+}
+
+// WithInsecure returns a DialOption which disables transport security for this ClientConn.
+// Note that transport security is required unless WithInsecure is set.
+func WithInsecure() DialOption {
+        return func(o *dialOptions) {
+                o.insecure = true
+        }
+}
+
+// WithTransportCredentials returns a DialOption which configures a
+// connection level security credentials (e.g., TLS/SSL).
+func WithTransportCredentials(creds credentials.TransportCredentials) DialOption {
+        return func(o *dialOptions) {
+                o.copts.TransportCredentials = creds
+        }
+}
+
+// WithPerRPCCredentials returns a DialOption which sets
+// credentials and places auth state on each outbound RPC.
+func WithPerRPCCredentials(creds credentials.PerRPCCredentials) DialOption {
+        return func(o *dialOptions) {
+                o.copts.PerRPCCredentials = append(o.copts.PerRPCCredentials, creds)
+        }
+}
+
+// WithTimeout returns a DialOption that configures a timeout for dialing a ClientConn
+// initially. This is valid if and only if WithBlock() is present.
+// Deprecated: use DialContext and context.WithTimeout instead.
+func WithTimeout(d time.Duration) DialOption {
+        return func(o *dialOptions) {
+                o.timeout = d
+        }
+}
+
+// WithDialer returns a DialOption that specifies a function to use for dialing network addresses.
+// If FailOnNonTempDialError() is set to true, and an error is returned by f, gRPC checks the error's
+// Temporary() method to decide if it should try to reconnect to the network address.
+func WithDialer(f func(string, time.Duration) (net.Conn, error)) DialOption {
+        return func(o *dialOptions) {
+                o.copts.Dialer = func(ctx context.Context, addr string) (net.Conn, error) {
+                        if deadline, ok := ctx.Deadline(); ok {
+                                return f(addr, deadline.Sub(time.Now()))
+                        }
+                        return f(addr, 0)
+                }
+        }
+}
+
+// WithStatsHandler returns a DialOption that specifies the stats handler
+// for all the RPCs and underlying network connections in this ClientConn.
+func WithStatsHandler(h stats.Handler) DialOption {
+        return func(o *dialOptions) {
+                o.copts.StatsHandler = h
+        }
+}
+
+// FailOnNonTempDialError returns a DialOption that specifies if gRPC fails on non-temporary dial errors.
+// If f is true, and dialer returns a non-temporary error, gRPC will fail the connection to the network
+// address and won't try to reconnect.
+// The default value of FailOnNonTempDialError is false.
+// This is an EXPERIMENTAL API.
+func FailOnNonTempDialError(f bool) DialOption {
+        return func(o *dialOptions) {
+                o.copts.FailOnNonTempDialError = f
+        }
+}
+
+// WithUserAgent returns a DialOption that specifies a user agent string for all the RPCs.
+func WithUserAgent(s string) DialOption {
+        return func(o *dialOptions) {
+                o.copts.UserAgent = s
+        }
+}
+
+// WithKeepaliveParams returns a DialOption that specifies keepalive paramaters for the client transport.
+func WithKeepaliveParams(kp keepalive.ClientParameters) DialOption {
+        return func(o *dialOptions) {
+                o.copts.KeepaliveParams = kp
+        }
+}
+
+// WithUnaryInterceptor returns a DialOption that specifies the interceptor for unary RPCs.
+func WithUnaryInterceptor(f UnaryClientInterceptor) DialOption {
+        return func(o *dialOptions) {
+                o.unaryInt = f
+        }
+}
+
+// WithStreamInterceptor returns a DialOption that specifies the interceptor for streaming RPCs.
+func WithStreamInterceptor(f StreamClientInterceptor) DialOption {
+        return func(o *dialOptions) {
+                o.streamInt = f
+        }
+}
+
+// WithAuthority returns a DialOption that specifies the value to be used as
+// the :authority pseudo-header. This value only works with WithInsecure and
+// has no effect if TransportCredentials are present.
+func WithAuthority(a string) DialOption {
+        return func(o *dialOptions) {
+                o.copts.Authority = a
+        }
+}
+
+// Dial creates a client connection to the given target.
+func Dial(target string, opts ...DialOption) (*ClientConn, error) {
+        return DialContext(context.Background(), target, opts...)
+}
+
+// DialContext creates a client connection to the given target. ctx can be used to
+// cancel or expire the pending connection. Once this function returns, the
+// cancellation and expiration of ctx will be noop. Users should call ClientConn.Close
+// to terminate all the pending operations after this function returns.
+func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *ClientConn, err error) {
+        cc := &ClientConn{
+                target: target,
+                csMgr:  &connectivityStateManager{},
+                conns:  make(map[Address]*addrConn),
+        }
+        cc.csEvltr = &connectivityStateEvaluator{csMgr: cc.csMgr}
+        cc.ctx, cc.cancel = context.WithCancel(context.Background())
+
+        for _, opt := range opts {
+                opt(&cc.dopts)
+        }
+        cc.mkp = cc.dopts.copts.KeepaliveParams
+
+        if cc.dopts.copts.Dialer == nil {
+                cc.dopts.copts.Dialer = newProxyDialer(
+                        func(ctx context.Context, addr string) (net.Conn, error) {
+                                return dialContext(ctx, "tcp", addr)
+                        },
+                )
+        }
+
+        if cc.dopts.copts.UserAgent != "" {
+                cc.dopts.copts.UserAgent += " " + grpcUA
+        } else {
+                cc.dopts.copts.UserAgent = grpcUA
+        }
+
+        if cc.dopts.timeout > 0 {
+                var cancel context.CancelFunc
+                ctx, cancel = context.WithTimeout(ctx, cc.dopts.timeout)
+                defer cancel()
+        }
+
+        defer func() {
+                select {
+                case <-ctx.Done():
+                        conn, err = nil, ctx.Err()
+                default:
+                }
+
+                if err != nil {
+                        cc.Close()
+                }
+        }()
+
+        scSet := false
+        if cc.dopts.scChan != nil {
+                // Try to get an initial service config.
+                select {
+                case sc, ok := <-cc.dopts.scChan:
+                        if ok {
+                                cc.sc = sc
+                                scSet = true
+                        }
+                default:
+                }
+        }
+        // Set defaults.
+        if cc.dopts.codec == nil {
+                cc.dopts.codec = protoCodec{}
+        }
+        if cc.dopts.bs == nil {
+                cc.dopts.bs = DefaultBackoffConfig
+        }
+        creds := cc.dopts.copts.TransportCredentials
+        if creds != nil && creds.Info().ServerName != "" {
+                cc.authority = creds.Info().ServerName
+        } else if cc.dopts.insecure && cc.dopts.copts.Authority != "" {
+                cc.authority = cc.dopts.copts.Authority
+        } else {
+                cc.authority = target
+        }
+        waitC := make(chan error, 1)
+        go func() {
+                defer close(waitC)
+                if cc.dopts.balancer == nil && cc.sc.LB != nil {
+                        cc.dopts.balancer = cc.sc.LB
+                }
+                if cc.dopts.balancer != nil {
+                        var credsClone credentials.TransportCredentials
+                        if creds != nil {
+                                credsClone = creds.Clone()
+                        }
+                        config := BalancerConfig{
+                                DialCreds: credsClone,
+                                Dialer:    cc.dopts.copts.Dialer,
+                        }
+                        if err := cc.dopts.balancer.Start(target, config); err != nil {
+                                waitC <- err
+                                return
+                        }
+                        ch := cc.dopts.balancer.Notify()
+                        if ch != nil {
+                                if cc.dopts.block {
+                                        doneChan := make(chan struct{})
+                                        go cc.lbWatcher(doneChan)
+                                        <-doneChan
+                                } else {
+                                        go cc.lbWatcher(nil)
+                                }
+                                return
+                        }
+                }
+                // No balancer, or no resolver within the balancer.  Connect directly.
+                if err := cc.resetAddrConn(Address{Addr: target}, cc.dopts.block, nil); err != nil {
+                        waitC <- err
+                        return
+                }
+        }()
+        select {
+        case <-ctx.Done():
+                return nil, ctx.Err()
+        case err := <-waitC:
+                if err != nil {
+                        return nil, err
+                }
+        }
+        if cc.dopts.scChan != nil && !scSet {
+                // Blocking wait for the initial service config.
+                select {
+                case sc, ok := <-cc.dopts.scChan:
+                        if ok {
+                                cc.sc = sc
+                        }
+                case <-ctx.Done():
+                        return nil, ctx.Err()
+                }
+        }
+        if cc.dopts.scChan != nil {
+                go cc.scWatcher()
+        }
+
+        return cc, nil
+}
+
+// connectivityStateEvaluator gets updated by addrConns when their
+// states transition, based on which it evaluates the state of
+// ClientConn.
+// Note: This code will eventually sit in the balancer in the new design.
+type connectivityStateEvaluator struct {
+        csMgr               *connectivityStateManager
+        mu                  sync.Mutex
+        numReady            uint64 // Number of addrConns in ready state.
+        numConnecting       uint64 // Number of addrConns in connecting state.
+        numTransientFailure uint64 // Number of addrConns in transientFailure.
+}
+
+// recordTransition records state change happening in every addrConn and based on
+// that it evaluates what state the ClientConn is in.
+// It can only transition between connectivity.Ready, connectivity.Connecting and connectivity.TransientFailure. Other states,
+// Idle and connectivity.Shutdown are transitioned into by ClientConn; in the begining of the connection
+// before any addrConn is created ClientConn is in idle state. In the end when ClientConn
+// closes it is in connectivity.Shutdown state.
+// TODO Note that in later releases, a ClientConn with no activity will be put into an Idle state.
+func (cse *connectivityStateEvaluator) recordTransition(oldState, newState connectivity.State) {
+        cse.mu.Lock()
+        defer cse.mu.Unlock()
+
+        // Update counters.
+        for idx, state := range []connectivity.State{oldState, newState} {
+                updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
+                switch state {
+                case connectivity.Ready:
+                        cse.numReady += updateVal
+                case connectivity.Connecting:
+                        cse.numConnecting += updateVal
+                case connectivity.TransientFailure:
+                        cse.numTransientFailure += updateVal
+                }
+        }
+
+        // Evaluate.
+        if cse.numReady > 0 {
+                cse.csMgr.updateState(connectivity.Ready)
+                return
+        }
+        if cse.numConnecting > 0 {
+                cse.csMgr.updateState(connectivity.Connecting)
+                return
+        }
+        cse.csMgr.updateState(connectivity.TransientFailure)
+}
+
+// connectivityStateManager keeps the connectivity.State of ClientConn.
+// This struct will eventually be exported so the balancers can access it.
+type connectivityStateManager struct {
+        mu         sync.Mutex
+        state      connectivity.State
+        notifyChan chan struct{}
+}
+
+// updateState updates the connectivity.State of ClientConn.
+// If there's a change it notifies goroutines waiting on state change to
+// happen.
+func (csm *connectivityStateManager) updateState(state connectivity.State) {
+        csm.mu.Lock()
+        defer csm.mu.Unlock()
+        if csm.state == connectivity.Shutdown {
+                return
+        }
+        if csm.state == state {
+                return
+        }
+        csm.state = state
+        if csm.notifyChan != nil {
+                // There are other goroutines waiting on this channel.
+                close(csm.notifyChan)
+                csm.notifyChan = nil
+        }
+}
+
+func (csm *connectivityStateManager) getState() connectivity.State {
+        csm.mu.Lock()
+        defer csm.mu.Unlock()
+        return csm.state
+}
+
+func (csm *connectivityStateManager) getNotifyChan() <-chan struct{} {
+        csm.mu.Lock()
+        defer csm.mu.Unlock()
+        if csm.notifyChan == nil {
+                csm.notifyChan = make(chan struct{})
+        }
+        return csm.notifyChan
+}
+
+// ClientConn represents a client connection to an RPC server.
+type ClientConn struct {
+        ctx    context.Context
+        cancel context.CancelFunc
+
+        target    string
+        authority string
+        dopts     dialOptions
+        csMgr     *connectivityStateManager
+        csEvltr   *connectivityStateEvaluator // This will eventually be part of balancer.
+
+        mu    sync.RWMutex
+        sc    ServiceConfig
+        conns map[Address]*addrConn
+        // Keepalive parameter can be updated if a GoAway is received.
+        mkp keepalive.ClientParameters
+}
+
+// WaitForStateChange waits until the connectivity.State of ClientConn changes from sourceState or
+// ctx expires. A true value is returned in former case and false in latter.
+// This is an EXPERIMENTAL API.
+func (cc *ClientConn) WaitForStateChange(ctx context.Context, sourceState connectivity.State) bool {
+        ch := cc.csMgr.getNotifyChan()
+        if cc.csMgr.getState() != sourceState {
+                return true
+        }
+        select {
+        case <-ctx.Done():
+                return false
+        case <-ch:
+                return true
+        }
+}
+
+// GetState returns the connectivity.State of ClientConn.
+// This is an EXPERIMENTAL API.
+func (cc *ClientConn) GetState() connectivity.State {
+        return cc.csMgr.getState()
+}
+
+// lbWatcher watches the Notify channel of the balancer in cc and manages
+// connections accordingly.  If doneChan is not nil, it is closed after the
+// first successfull connection is made.
+func (cc *ClientConn) lbWatcher(doneChan chan struct{}) {
+        defer func() {
+                // In case channel from cc.dopts.balancer.Notify() gets closed before a
+                // successful connection gets established, don't forget to notify the
+                // caller.
+                if doneChan != nil {
+                        close(doneChan)
+                }
+        }()
+
+        for addrs := range cc.dopts.balancer.Notify() {
+                var (
+                        add []Address   // Addresses need to setup connections.
+                        del []*addrConn // Connections need to tear down.
+                )
+                cc.mu.Lock()
+                for _, a := range addrs {
+                        if _, ok := cc.conns[a]; !ok {
+                                add = append(add, a)
+                        }
+                }
+                for k, c := range cc.conns {
+                        var keep bool
+                        for _, a := range addrs {
+                                if k == a {
+                                        keep = true
+                                        break
+                                }
+                        }
+                        if !keep {
+                                del = append(del, c)
+                                delete(cc.conns, c.addr)
+                        }
+                }
+                cc.mu.Unlock()
+                for _, a := range add {
+                        var err error
+                        if doneChan != nil {
+                                err = cc.resetAddrConn(a, true, nil)
+                                if err == nil {
+                                        close(doneChan)
+                                        doneChan = nil
+                                }
+                        } else {
+                                err = cc.resetAddrConn(a, false, nil)
+                        }
+                        if err != nil {
+                                grpclog.Warningf("Error creating connection to %v. Err: %v", a, err)
+                        }
+                }
+                for _, c := range del {
+                        c.tearDown(errConnDrain)
+                }
+        }
+}
+
+func (cc *ClientConn) scWatcher() {
+        for {
+                select {
+                case sc, ok := <-cc.dopts.scChan:
+                        if !ok {
+                                return
+                        }
+                        cc.mu.Lock()
+                        // TODO: load balance policy runtime change is ignored.
+                        // We may revist this decision in the future.
+                        cc.sc = sc
+                        cc.mu.Unlock()
+                case <-cc.ctx.Done():
+                        return
+                }
+        }
+}
+
+// resetAddrConn creates an addrConn for addr and adds it to cc.conns.
+// If there is an old addrConn for addr, it will be torn down, using tearDownErr as the reason.
+// If tearDownErr is nil, errConnDrain will be used instead.
+//
+// We should never need to replace an addrConn with a new one. This function is only used
+// as newAddrConn to create new addrConn.
+// TODO rename this function and clean up the code.
+func (cc *ClientConn) resetAddrConn(addr Address, block bool, tearDownErr error) error {
+        ac := &addrConn{
+                cc:    cc,
+                addr:  addr,
+                dopts: cc.dopts,
+        }
+        ac.ctx, ac.cancel = context.WithCancel(cc.ctx)
+        ac.csEvltr = cc.csEvltr
+        if EnableTracing {
+                ac.events = trace.NewEventLog("grpc.ClientConn", ac.addr.Addr)
+        }
+        if !ac.dopts.insecure {
+                if ac.dopts.copts.TransportCredentials == nil {
+                        return errNoTransportSecurity
+                }
+        } else {
+                if ac.dopts.copts.TransportCredentials != nil {
+                        return errCredentialsConflict
+                }
+                for _, cd := range ac.dopts.copts.PerRPCCredentials {
+                        if cd.RequireTransportSecurity() {
+                                return errTransportCredentialsMissing
+                        }
+                }
+        }
+        // Track ac in cc. This needs to be done before any getTransport(...) is called.
+        cc.mu.Lock()
+        if cc.conns == nil {
+                cc.mu.Unlock()
+                return ErrClientConnClosing
+        }
+        stale := cc.conns[ac.addr]
+        cc.conns[ac.addr] = ac
+        cc.mu.Unlock()
+        if stale != nil {
+                // There is an addrConn alive on ac.addr already. This could be due to
+                // a buggy Balancer that reports duplicated Addresses.
+                if tearDownErr == nil {
+                        // tearDownErr is nil if resetAddrConn is called by
+                        // 1) Dial
+                        // 2) lbWatcher
+                        // In both cases, the stale ac should drain, not close.
+                        stale.tearDown(errConnDrain)
+                } else {
+                        stale.tearDown(tearDownErr)
+                }
+        }
+        if block {
+                if err := ac.resetTransport(false); err != nil {
+                        if err != errConnClosing {
+                                // Tear down ac and delete it from cc.conns.
+                                cc.mu.Lock()
+                                delete(cc.conns, ac.addr)
+                                cc.mu.Unlock()
+                                ac.tearDown(err)
+                        }
+                        if e, ok := err.(transport.ConnectionError); ok && !e.Temporary() {
+                                return e.Origin()
+                        }
+                        return err
+                }
+                // Start to monitor the error status of transport.
+                go ac.transportMonitor()
+        } else {
+                // Start a goroutine connecting to the server asynchronously.
+                go func() {
+                        if err := ac.resetTransport(false); err != nil {
+                                grpclog.Warningf("Failed to dial %s: %v; please retry.", ac.addr.Addr, err)
+                                if err != errConnClosing {
+                                        // Keep this ac in cc.conns, to get the reason it's torn down.
+                                        ac.tearDown(err)
+                                }
+                                return
+                        }
+                        ac.transportMonitor()
+                }()
+        }
+        return nil
+}
+
+// GetMethodConfig gets the method config of the input method.
+// If there's an exact match for input method (i.e. /service/method), we return
+// the corresponding MethodConfig.
+// If there isn't an exact match for the input method, we look for the default config
+// under the service (i.e /service/). If there is a default MethodConfig for
+// the serivce, we return it.
+// Otherwise, we return an empty MethodConfig.
+func (cc *ClientConn) GetMethodConfig(method string) MethodConfig {
+        // TODO: Avoid the locking here.
+        cc.mu.RLock()
+        defer cc.mu.RUnlock()
+        m, ok := cc.sc.Methods[method]
+        if !ok {
+                i := strings.LastIndex(method, "/")
+                m, _ = cc.sc.Methods[method[:i+1]]
+        }
+        return m
+}
+
+func (cc *ClientConn) getTransport(ctx context.Context, opts BalancerGetOptions) (transport.ClientTransport, func(), error) {
+        var (
+                ac  *addrConn
+                ok  bool
+                put func()
+        )
+        if cc.dopts.balancer == nil {
+                // If balancer is nil, there should be only one addrConn available.
+                cc.mu.RLock()
+                if cc.conns == nil {
+                        cc.mu.RUnlock()
+                        return nil, nil, toRPCErr(ErrClientConnClosing)
+                }
+                for _, ac = range cc.conns {
+                        // Break after the first iteration to get the first addrConn.
+                        ok = true
+                        break
+                }
+                cc.mu.RUnlock()
+        } else {
+                var (
+                        addr Address
+                        err  error
+                )
+                addr, put, err = cc.dopts.balancer.Get(ctx, opts)
+                if err != nil {
+                        return nil, nil, toRPCErr(err)
+                }
+                cc.mu.RLock()
+                if cc.conns == nil {
+                        cc.mu.RUnlock()
+                        return nil, nil, toRPCErr(ErrClientConnClosing)
+                }
+                ac, ok = cc.conns[addr]
+                cc.mu.RUnlock()
+        }
+        if !ok {
+                if put != nil {
+                        updateRPCInfoInContext(ctx, rpcInfo{bytesSent: false, bytesReceived: false})
+                        put()
+                }
+                return nil, nil, errConnClosing
+        }
+        t, err := ac.wait(ctx, cc.dopts.balancer != nil, !opts.BlockingWait)
+        if err != nil {
+                if put != nil {
+                        updateRPCInfoInContext(ctx, rpcInfo{bytesSent: false, bytesReceived: false})
+                        put()
+                }
+                return nil, nil, err
+        }
+        return t, put, nil
+}
+
+// Close tears down the ClientConn and all underlying connections.
+func (cc *ClientConn) Close() error {
+        cc.cancel()
+
+        cc.mu.Lock()
+        if cc.conns == nil {
+                cc.mu.Unlock()
+                return ErrClientConnClosing
+        }
+        conns := cc.conns
+        cc.conns = nil
+        cc.csMgr.updateState(connectivity.Shutdown)
+        cc.mu.Unlock()
+        if cc.dopts.balancer != nil {
+                cc.dopts.balancer.Close()
+        }
+        for _, ac := range conns {
+                ac.tearDown(ErrClientConnClosing)
+        }
+        return nil
+}
+
+// addrConn is a network connection to a given address.
+type addrConn struct {
+        ctx    context.Context
+        cancel context.CancelFunc
+
+        cc     *ClientConn
+        addr   Address
+        dopts  dialOptions
+        events trace.EventLog
+
+        csEvltr *connectivityStateEvaluator
+
+        mu    sync.Mutex
+        state connectivity.State
+        down  func(error) // the handler called when a connection is down.
+        // ready is closed and becomes nil when a new transport is up or failed
+        // due to timeout.
+        ready     chan struct{}
+        transport transport.ClientTransport
+
+        // The reason this addrConn is torn down.
+        tearDownErr error
+}
+
+// adjustParams updates parameters used to create transports upon
+// receiving a GoAway.
+func (ac *addrConn) adjustParams(r transport.GoAwayReason) {
+        switch r {
+        case transport.TooManyPings:
+                v := 2 * ac.dopts.copts.KeepaliveParams.Time
+                ac.cc.mu.Lock()
+                if v > ac.cc.mkp.Time {
+                        ac.cc.mkp.Time = v
+                }
+                ac.cc.mu.Unlock()
+        }
+}
+
+// printf records an event in ac's event log, unless ac has been closed.
+// REQUIRES ac.mu is held.
+func (ac *addrConn) printf(format string, a ...interface{}) {
+        if ac.events != nil {
+                ac.events.Printf(format, a...)
+        }
+}
+
+// errorf records an error in ac's event log, unless ac has been closed.
+// REQUIRES ac.mu is held.
+func (ac *addrConn) errorf(format string, a ...interface{}) {
+        if ac.events != nil {
+                ac.events.Errorf(format, a...)
+        }
+}
+
+// resetTransport recreates a transport to the address for ac.
+// For the old transport:
+// - if drain is true, it will be gracefully closed.
+// - otherwise, it will be closed.
+func (ac *addrConn) resetTransport(drain bool) error {
+        ac.mu.Lock()
+        if ac.state == connectivity.Shutdown {
+                ac.mu.Unlock()
+                return errConnClosing
+        }
+        ac.printf("connecting")
+        if ac.down != nil {
+                ac.down(downErrorf(false, true, "%v", errNetworkIO))
+                ac.down = nil
+        }
+        oldState := ac.state
+        ac.state = connectivity.Connecting
+        ac.csEvltr.recordTransition(oldState, ac.state)
+        t := ac.transport
+        ac.transport = nil
+        ac.mu.Unlock()
+        if t != nil && !drain {
+                t.Close()
+        }
+        ac.cc.mu.RLock()
+        ac.dopts.copts.KeepaliveParams = ac.cc.mkp
+        ac.cc.mu.RUnlock()
+        for retries := 0; ; retries++ {
+                ac.mu.Lock()
+                if ac.state == connectivity.Shutdown {
+                        // ac.tearDown(...) has been invoked.
+                        ac.mu.Unlock()
+                        return errConnClosing
+                }
+                ac.mu.Unlock()
+                sleepTime := ac.dopts.bs.backoff(retries)
+                timeout := minConnectTimeout
+                if timeout < sleepTime {
+                        timeout = sleepTime
+                }
+                ctx, cancel := context.WithTimeout(ac.ctx, timeout)
+                connectTime := time.Now()
+                sinfo := transport.TargetInfo{
+                        Addr:     ac.addr.Addr,
+                        Metadata: ac.addr.Metadata,
+                }
+                newTransport, err := transport.NewClientTransport(ctx, sinfo, ac.dopts.copts)
+                // Don't call cancel in success path due to a race in Go 1.6:
+                // https://github.com/golang/go/issues/15078.
+                if err != nil {
+                        cancel()
+
+                        if e, ok := err.(transport.ConnectionError); ok && !e.Temporary() {
+                                return err
+                        }
+                        grpclog.Warningf("grpc: addrConn.resetTransport failed to create client transport: %v; Reconnecting to %v", err, ac.addr)
+                        ac.mu.Lock()
+                        if ac.state == connectivity.Shutdown {
+                                // ac.tearDown(...) has been invoked.
+                                ac.mu.Unlock()
+                                return errConnClosing
+                        }
+                        ac.errorf("transient failure: %v", err)
+                        oldState = ac.state
+                        ac.state = connectivity.TransientFailure
+                        ac.csEvltr.recordTransition(oldState, ac.state)
+                        if ac.ready != nil {
+                                close(ac.ready)
+                                ac.ready = nil
+                        }
+                        ac.mu.Unlock()
+                        timer := time.NewTimer(sleepTime - time.Since(connectTime))
+                        select {
+                        case <-timer.C:
+                        case <-ac.ctx.Done():
+                                timer.Stop()
+                                return ac.ctx.Err()
+                        }
+                        timer.Stop()
+                        continue
+                }
+                ac.mu.Lock()
+                ac.printf("ready")
+                if ac.state == connectivity.Shutdown {
+                        // ac.tearDown(...) has been invoked.
+                        ac.mu.Unlock()
+                        newTransport.Close()
+                        return errConnClosing
+                }
+                oldState = ac.state
+                ac.state = connectivity.Ready
+                ac.csEvltr.recordTransition(oldState, ac.state)
+                ac.transport = newTransport
+                if ac.ready != nil {
+                        close(ac.ready)
+                        ac.ready = nil
+                }
+                if ac.cc.dopts.balancer != nil {
+                        ac.down = ac.cc.dopts.balancer.Up(ac.addr)
+                }
+                ac.mu.Unlock()
+                return nil
+        }
+}
+
+// Run in a goroutine to track the error in transport and create the
+// new transport if an error happens. It returns when the channel is closing.
+func (ac *addrConn) transportMonitor() {
+        for {
+                ac.mu.Lock()
+                t := ac.transport
+                ac.mu.Unlock()
+                select {
+                // This is needed to detect the teardown when
+                // the addrConn is idle (i.e., no RPC in flight).
+                case <-ac.ctx.Done():
+                        select {
+                        case <-t.Error():
+                                t.Close()
+                        default:
+                        }
+                        return
+                case <-t.GoAway():
+                        ac.adjustParams(t.GetGoAwayReason())
+                        // If GoAway happens without any network I/O error, the underlying transport
+                        // will be gracefully closed, and a new transport will be created.
+                        // (The transport will be closed when all the pending RPCs finished or failed.)
+                        // If GoAway and some network I/O error happen concurrently, the underlying transport
+                        // will be closed, and a new transport will be created.
+                        var drain bool
+                        select {
+                        case <-t.Error():
+                        default:
+                                drain = true
+                        }
+                        if err := ac.resetTransport(drain); err != nil {
+                                grpclog.Infof("get error from resetTransport %v, transportMonitor returning", err)
+                                if err != errConnClosing {
+                                        // Keep this ac in cc.conns, to get the reason it's torn down.
+                                        ac.tearDown(err)
+                                }
+                                return
+                        }
+                case <-t.Error():
+                        select {
+                        case <-ac.ctx.Done():
+                                t.Close()
+                                return
+                        case <-t.GoAway():
+                                ac.adjustParams(t.GetGoAwayReason())
+                                if err := ac.resetTransport(false); err != nil {
+                                        grpclog.Infof("get error from resetTransport %v, transportMonitor returning", err)
+                                        if err != errConnClosing {
+                                                // Keep this ac in cc.conns, to get the reason it's torn down.
+                                                ac.tearDown(err)
+                                        }
+                                        return
+                                }
+                        default:
+                        }
+                        ac.mu.Lock()
+                        if ac.state == connectivity.Shutdown {
+                                // ac has been shutdown.
+                                ac.mu.Unlock()
+                                return
+                        }
+                        oldState := ac.state
+                        ac.state = connectivity.TransientFailure
+                        ac.csEvltr.recordTransition(oldState, ac.state)
+                        ac.mu.Unlock()
+                        if err := ac.resetTransport(false); err != nil {
+                                grpclog.Infof("get error from resetTransport %v, transportMonitor returning", err)
+                                ac.mu.Lock()
+                                ac.printf("transport exiting: %v", err)
+                                ac.mu.Unlock()
+                                grpclog.Warningf("grpc: addrConn.transportMonitor exits due to: %v", err)
+                                if err != errConnClosing {
+                                        // Keep this ac in cc.conns, to get the reason it's torn down.
+                                        ac.tearDown(err)
+                                }
+                                return
+                        }
+                }
+        }
+}
+
+// wait blocks until i) the new transport is up or ii) ctx is done or iii) ac is closed or
+// iv) transport is in connectivity.TransientFailure and there is a balancer/failfast is true.
+func (ac *addrConn) wait(ctx context.Context, hasBalancer, failfast bool) (transport.ClientTransport, error) {
+        for {
+                ac.mu.Lock()
+                switch {
+                case ac.state == connectivity.Shutdown:
+                        if failfast || !hasBalancer {
+                                // RPC is failfast or balancer is nil. This RPC should fail with ac.tearDownErr.
+                                err := ac.tearDownErr
+                                ac.mu.Unlock()
+                                return nil, err
+                        }
+                        ac.mu.Unlock()
+                        return nil, errConnClosing
+                case ac.state == connectivity.Ready:
+                        ct := ac.transport
+                        ac.mu.Unlock()
+                        return ct, nil
+                case ac.state == connectivity.TransientFailure:
+                        if failfast || hasBalancer {
+                                ac.mu.Unlock()
+                                return nil, errConnUnavailable
+                        }
+                }
+                ready := ac.ready
+                if ready == nil {
+                        ready = make(chan struct{})
+                        ac.ready = ready
+                }
+                ac.mu.Unlock()
+                select {
+                case <-ctx.Done():
+                        return nil, toRPCErr(ctx.Err())
+                // Wait until the new transport is ready or failed.
+                case <-ready:
+                }
+        }
+}
+
+// tearDown starts to tear down the addrConn.
+// TODO(zhaoq): Make this synchronous to avoid unbounded memory consumption in
+// some edge cases (e.g., the caller opens and closes many addrConn's in a
+// tight loop.
+// tearDown doesn't remove ac from ac.cc.conns.
+func (ac *addrConn) tearDown(err error) {
+        ac.cancel()
+
+        ac.mu.Lock()
+        defer ac.mu.Unlock()
+        if ac.down != nil {
+                ac.down(downErrorf(false, false, "%v", err))
+                ac.down = nil
+        }
+        if err == errConnDrain && ac.transport != nil {
+                // GracefulClose(...) may be executed multiple times when
+                // i) receiving multiple GoAway frames from the server; or
+                // ii) there are concurrent name resolver/Balancer triggered
+                // address removal and GoAway.
+                ac.transport.GracefulClose()
+        }
+        if ac.state == connectivity.Shutdown {
+                return
+        }
+        oldState := ac.state
+        ac.state = connectivity.Shutdown
+        ac.tearDownErr = err
+        ac.csEvltr.recordTransition(oldState, ac.state)
+        if ac.events != nil {
+                ac.events.Finish()
+                ac.events = nil
+        }
+        if ac.ready != nil {
+                close(ac.ready)
+                ac.ready = nil
+        }
+        if ac.transport != nil && err != errConnDrain {
+                ac.transport.Close()
+        }
+        return
+}
diff --git a/vendor/google.golang.org/grpc/codec.go b/vendor/google.golang.org/grpc/codec.go
new file mode 100644
index 0000000..905b048
--- /dev/null
+++ b/vendor/google.golang.org/grpc/codec.go
@@ -0,0 +1,104 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "math"
+        "sync"
+
+        "github.com/golang/protobuf/proto"
+)
+
+// Codec defines the interface gRPC uses to encode and decode messages.
+// Note that implementations of this interface must be thread safe;
+// a Codec's methods can be called from concurrent goroutines.
+type Codec interface {
+        // Marshal returns the wire format of v.
+        Marshal(v interface{}) ([]byte, error)
+        // Unmarshal parses the wire format into v.
+        Unmarshal(data []byte, v interface{}) error
+        // String returns the name of the Codec implementation. The returned
+        // string will be used as part of content type in transmission.
+        String() string
+}
+
+// protoCodec is a Codec implementation with protobuf. It is the default codec for gRPC.
+type protoCodec struct {
+}
+
+type cachedProtoBuffer struct {
+        lastMarshaledSize uint32
+        proto.Buffer
+}
+
+func capToMaxInt32(val int) uint32 {
+        if val > math.MaxInt32 {
+                return uint32(math.MaxInt32)
+        }
+        return uint32(val)
+}
+
+func (p protoCodec) marshal(v interface{}, cb *cachedProtoBuffer) ([]byte, error) {
+        protoMsg := v.(proto.Message)
+        newSlice := make([]byte, 0, cb.lastMarshaledSize)
+
+        cb.SetBuf(newSlice)
+        cb.Reset()
+        if err := cb.Marshal(protoMsg); err != nil {
+                return nil, err
+        }
+        out := cb.Bytes()
+        cb.lastMarshaledSize = capToMaxInt32(len(out))
+        return out, nil
+}
+
+func (p protoCodec) Marshal(v interface{}) ([]byte, error) {
+        cb := protoBufferPool.Get().(*cachedProtoBuffer)
+        out, err := p.marshal(v, cb)
+
+        // put back buffer and lose the ref to the slice
+        cb.SetBuf(nil)
+        protoBufferPool.Put(cb)
+        return out, err
+}
+
+func (p protoCodec) Unmarshal(data []byte, v interface{}) error {
+        cb := protoBufferPool.Get().(*cachedProtoBuffer)
+        cb.SetBuf(data)
+        v.(proto.Message).Reset()
+        err := cb.Unmarshal(v.(proto.Message))
+        cb.SetBuf(nil)
+        protoBufferPool.Put(cb)
+        return err
+}
+
+func (protoCodec) String() string {
+        return "proto"
+}
+
+var (
+        protoBufferPool = &sync.Pool{
+                New: func() interface{} {
+                        return &cachedProtoBuffer{
+                                Buffer:            proto.Buffer{},
+                                lastMarshaledSize: 16,
+                        }
+                },
+        }
+)
diff --git a/vendor/google.golang.org/grpc/codegen.sh b/vendor/google.golang.org/grpc/codegen.sh
new file mode 100644
index 0000000..4cdc6ba
--- /dev/null
+++ b/vendor/google.golang.org/grpc/codegen.sh
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+# This script serves as an example to demonstrate how to generate the gRPC-Go
+# interface and the related messages from .proto file.
+#
+# It assumes the installation of i) Google proto buffer compiler at
+# https://github.com/google/protobuf (after v2.6.1) and ii) the Go codegen
+# plugin at https://github.com/golang/protobuf (after 2015-02-20). If you have
+# not, please install them first.
+#
+# We recommend running this script at $GOPATH/src.
+#
+# If this is not what you need, feel free to make your own scripts. Again, this
+# script is for demonstration purpose.
+#
+proto=$1
+protoc --go_out=plugins=grpc:. $proto
diff --git a/vendor/google.golang.org/grpc/codes/code_string.go b/vendor/google.golang.org/grpc/codes/code_string.go
new file mode 100644
index 0000000..e6762d0
--- /dev/null
+++ b/vendor/google.golang.org/grpc/codes/code_string.go
@@ -0,0 +1,16 @@
+// generated by stringer -type=Code; DO NOT EDIT
+
+package codes
+
+import "fmt"
+
+const _Code_name = "OKCanceledUnknownInvalidArgumentDeadlineExceededNotFoundAlreadyExistsPermissionDeniedResourceExhaustedFailedPreconditionAbortedOutOfRangeUnimplementedInternalUnavailableDataLossUnauthenticated"
+
+var _Code_index = [...]uint8{0, 2, 10, 17, 32, 48, 56, 69, 85, 102, 120, 127, 137, 150, 158, 169, 177, 192}
+
+func (i Code) String() string {
+        if i+1 >= Code(len(_Code_index)) {
+                return fmt.Sprintf("Code(%d)", i)
+        }
+        return _Code_name[_Code_index[i]:_Code_index[i+1]]
+}
diff --git a/vendor/google.golang.org/grpc/codes/codes.go b/vendor/google.golang.org/grpc/codes/codes.go
new file mode 100644
index 0000000..21e7733
--- /dev/null
+++ b/vendor/google.golang.org/grpc/codes/codes.go
@@ -0,0 +1,144 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package codes defines the canonical error codes used by gRPC. It is
+// consistent across various languages.
+package codes // import "google.golang.org/grpc/codes"
+
+// A Code is an unsigned 32-bit error code as defined in the gRPC spec.
+type Code uint32
+
+//go:generate stringer -type=Code
+
+const (
+        // OK is returned on success.
+        OK Code = 0
+
+        // Canceled indicates the operation was canceled (typically by the caller).
+        Canceled Code = 1
+
+        // Unknown error.  An example of where this error may be returned is
+        // if a Status value received from another address space belongs to
+        // an error-space that is not known in this address space.  Also
+        // errors raised by APIs that do not return enough error information
+        // may be converted to this error.
+        Unknown Code = 2
+
+        // InvalidArgument indicates client specified an invalid argument.
+        // Note that this differs from FailedPrecondition. It indicates arguments
+        // that are problematic regardless of the state of the system
+        // (e.g., a malformed file name).
+        InvalidArgument Code = 3
+
+        // DeadlineExceeded means operation expired before completion.
+        // For operations that change the state of the system, this error may be
+        // returned even if the operation has completed successfully. For
+        // example, a successful response from a server could have been delayed
+        // long enough for the deadline to expire.
+        DeadlineExceeded Code = 4
+
+        // NotFound means some requested entity (e.g., file or directory) was
+        // not found.
+        NotFound Code = 5
+
+        // AlreadyExists means an attempt to create an entity failed because one
+        // already exists.
+        AlreadyExists Code = 6
+
+        // PermissionDenied indicates the caller does not have permission to
+        // execute the specified operation. It must not be used for rejections
+        // caused by exhausting some resource (use ResourceExhausted
+        // instead for those errors).  It must not be
+        // used if the caller cannot be identified (use Unauthenticated
+        // instead for those errors).
+        PermissionDenied Code = 7
+
+        // Unauthenticated indicates the request does not have valid
+        // authentication credentials for the operation.
+        Unauthenticated Code = 16
+
+        // ResourceExhausted indicates some resource has been exhausted, perhaps
+        // a per-user quota, or perhaps the entire file system is out of space.
+        ResourceExhausted Code = 8
+
+        // FailedPrecondition indicates operation was rejected because the
+        // system is not in a state required for the operation's execution.
+        // For example, directory to be deleted may be non-empty, an rmdir
+        // operation is applied to a non-directory, etc.
+        //
+        // A litmus test that may help a service implementor in deciding
+        // between FailedPrecondition, Aborted, and Unavailable:
+        //  (a) Use Unavailable if the client can retry just the failing call.
+        //  (b) Use Aborted if the client should retry at a higher-level
+        //      (e.g., restarting a read-modify-write sequence).
+        //  (c) Use FailedPrecondition if the client should not retry until
+        //      the system state has been explicitly fixed.  E.g., if an "rmdir"
+        //      fails because the directory is non-empty, FailedPrecondition
+        //      should be returned since the client should not retry unless
+        //      they have first fixed up the directory by deleting files from it.
+        //  (d) Use FailedPrecondition if the client performs conditional
+        //      REST Get/Update/Delete on a resource and the resource on the
+        //      server does not match the condition. E.g., conflicting
+        //      read-modify-write on the same resource.
+        FailedPrecondition Code = 9
+
+        // Aborted indicates the operation was aborted, typically due to a
+        // concurrency issue like sequencer check failures, transaction aborts,
+        // etc.
+        //
+        // See litmus test above for deciding between FailedPrecondition,
+        // Aborted, and Unavailable.
+        Aborted Code = 10
+
+        // OutOfRange means operation was attempted past the valid range.
+        // E.g., seeking or reading past end of file.
+        //
+        // Unlike InvalidArgument, this error indicates a problem that may
+        // be fixed if the system state changes. For example, a 32-bit file
+        // system will generate InvalidArgument if asked to read at an
+        // offset that is not in the range [0,2^32-1], but it will generate
+        // OutOfRange if asked to read from an offset past the current
+        // file size.
+        //
+        // There is a fair bit of overlap between FailedPrecondition and
+        // OutOfRange.  We recommend using OutOfRange (the more specific
+        // error) when it applies so that callers who are iterating through
+        // a space can easily look for an OutOfRange error to detect when
+        // they are done.
+        OutOfRange Code = 11
+
+        // Unimplemented indicates operation is not implemented or not
+        // supported/enabled in this service.
+        Unimplemented Code = 12
+
+        // Internal errors.  Means some invariants expected by underlying
+        // system has been broken.  If you see one of these errors,
+        // something is very broken.
+        Internal Code = 13
+
+        // Unavailable indicates the service is currently unavailable.
+        // This is a most likely a transient condition and may be corrected
+        // by retrying with a backoff.
+        //
+        // See litmus test above for deciding between FailedPrecondition,
+        // Aborted, and Unavailable.
+        Unavailable Code = 14
+
+        // DataLoss indicates unrecoverable data loss or corruption.
+        DataLoss Code = 15
+)
diff --git a/vendor/google.golang.org/grpc/connectivity/connectivity.go b/vendor/google.golang.org/grpc/connectivity/connectivity.go
new file mode 100644
index 0000000..568ef5d
--- /dev/null
+++ b/vendor/google.golang.org/grpc/connectivity/connectivity.go
@@ -0,0 +1,72 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package connectivity defines connectivity semantics.
+// For details, see https://github.com/grpc/grpc/blob/master/doc/connectivity-semantics-and-api.md.
+// All APIs in this package are experimental.
+package connectivity
+
+import (
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/grpclog"
+)
+
+// State indicates the state of connectivity.
+// It can be the state of a ClientConn or SubConn.
+type State int
+
+func (s State) String() string {
+        switch s {
+        case Idle:
+                return "IDLE"
+        case Connecting:
+                return "CONNECTING"
+        case Ready:
+                return "READY"
+        case TransientFailure:
+                return "TRANSIENT_FAILURE"
+        case Shutdown:
+                return "SHUTDOWN"
+        default:
+                grpclog.Errorf("unknown connectivity state: %d", s)
+                return "Invalid-State"
+        }
+}
+
+const (
+        // Idle indicates the ClientConn is idle.
+        Idle State = iota
+        // Connecting indicates the ClienConn is connecting.
+        Connecting
+        // Ready indicates the ClientConn is ready for work.
+        Ready
+        // TransientFailure indicates the ClientConn has seen a failure but expects to recover.
+        TransientFailure
+        // Shutdown indicates the ClientConn has started shutting down.
+        Shutdown
+)
+
+// Reporter reports the connectivity states.
+type Reporter interface {
+        // CurrentState returns the current state of the reporter.
+        CurrentState() State
+        // WaitForStateChange blocks until the reporter's state is different from the given state,
+        // and returns true.
+        // It returns false if <-ctx.Done() can proceed (ctx got timeout or got canceled).
+        WaitForStateChange(context.Context, State) bool
+}
diff --git a/vendor/google.golang.org/grpc/coverage.sh b/vendor/google.golang.org/grpc/coverage.sh
new file mode 100644
index 0000000..b85f918
--- /dev/null
+++ b/vendor/google.golang.org/grpc/coverage.sh
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+
+
+set -e
+
+workdir=.cover
+profile="$workdir/cover.out"
+mode=set
+end2endtest="google.golang.org/grpc/test"
+
+generate_cover_data() {
+    rm -rf "$workdir"
+    mkdir "$workdir"
+
+    for pkg in "$@"; do
+        if [ $pkg == "google.golang.org/grpc" -o $pkg == "google.golang.org/grpc/transport" -o $pkg == "google.golang.org/grpc/metadata" -o $pkg == "google.golang.org/grpc/credentials" ]
+            then
+                f="$workdir/$(echo $pkg | tr / -)"
+                go test -covermode="$mode" -coverprofile="$f.cover" "$pkg"
+                go test -covermode="$mode" -coverpkg "$pkg" -coverprofile="$f.e2e.cover" "$end2endtest"
+        fi
+    done
+
+    echo "mode: $mode" >"$profile"
+    grep -h -v "^mode:" "$workdir"/*.cover >>"$profile"
+}
+
+show_cover_report() {
+    go tool cover -${1}="$profile"
+}
+
+push_to_coveralls() {
+    goveralls -coverprofile="$profile"
+}
+
+generate_cover_data $(go list ./...)
+show_cover_report func
+case "$1" in
+"")
+    ;;
+--html)
+    show_cover_report html ;;
+--coveralls)
+    push_to_coveralls ;;
+*)
+    echo >&2 "error: invalid option: $1" ;;
+esac
+rm -rf "$workdir"
diff --git a/vendor/google.golang.org/grpc/credentials/credentials.go b/vendor/google.golang.org/grpc/credentials/credentials.go
new file mode 100644
index 0000000..2475fe8
--- /dev/null
+++ b/vendor/google.golang.org/grpc/credentials/credentials.go
@@ -0,0 +1,219 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package credentials implements various credentials supported by gRPC library,
+// which encapsulate all the state needed by a client to authenticate with a
+// server and make various assertions, e.g., about the client's identity, role,
+// or whether it is authorized to make a particular call.
+package credentials // import "google.golang.org/grpc/credentials"
+
+import (
+        "crypto/tls"
+        "crypto/x509"
+        "errors"
+        "fmt"
+        "io/ioutil"
+        "net"
+        "strings"
+
+        "golang.org/x/net/context"
+)
+
+var (
+        // alpnProtoStr are the specified application level protocols for gRPC.
+        alpnProtoStr = []string{"h2"}
+)
+
+// PerRPCCredentials defines the common interface for the credentials which need to
+// attach security information to every RPC (e.g., oauth2).
+type PerRPCCredentials interface {
+        // GetRequestMetadata gets the current request metadata, refreshing
+        // tokens if required. This should be called by the transport layer on
+        // each request, and the data should be populated in headers or other
+        // context. uri is the URI of the entry point for the request. When
+        // supported by the underlying implementation, ctx can be used for
+        // timeout and cancellation.
+        // TODO(zhaoq): Define the set of the qualified keys instead of leaving
+        // it as an arbitrary string.
+        GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error)
+        // RequireTransportSecurity indicates whether the credentials requires
+        // transport security.
+        RequireTransportSecurity() bool
+}
+
+// ProtocolInfo provides information regarding the gRPC wire protocol version,
+// security protocol, security protocol version in use, server name, etc.
+type ProtocolInfo struct {
+        // ProtocolVersion is the gRPC wire protocol version.
+        ProtocolVersion string
+        // SecurityProtocol is the security protocol in use.
+        SecurityProtocol string
+        // SecurityVersion is the security protocol version.
+        SecurityVersion string
+        // ServerName is the user-configured server name.
+        ServerName string
+}
+
+// AuthInfo defines the common interface for the auth information the users are interested in.
+type AuthInfo interface {
+        AuthType() string
+}
+
+var (
+        // ErrConnDispatched indicates that rawConn has been dispatched out of gRPC
+        // and the caller should not close rawConn.
+        ErrConnDispatched = errors.New("credentials: rawConn is dispatched out of gRPC")
+)
+
+// TransportCredentials defines the common interface for all the live gRPC wire
+// protocols and supported transport security protocols (e.g., TLS, SSL).
+type TransportCredentials interface {
+        // ClientHandshake does the authentication handshake specified by the corresponding
+        // authentication protocol on rawConn for clients. It returns the authenticated
+        // connection and the corresponding auth information about the connection.
+        // Implementations must use the provided context to implement timely cancellation.
+        // gRPC will try to reconnect if the error returned is a temporary error
+        // (io.EOF, context.DeadlineExceeded or err.Temporary() == true).
+        // If the returned error is a wrapper error, implementations should make sure that
+        // the error implements Temporary() to have the correct retry behaviors.
+        ClientHandshake(context.Context, string, net.Conn) (net.Conn, AuthInfo, error)
+        // ServerHandshake does the authentication handshake for servers. It returns
+        // the authenticated connection and the corresponding auth information about
+        // the connection.
+        ServerHandshake(net.Conn) (net.Conn, AuthInfo, error)
+        // Info provides the ProtocolInfo of this TransportCredentials.
+        Info() ProtocolInfo
+        // Clone makes a copy of this TransportCredentials.
+        Clone() TransportCredentials
+        // OverrideServerName overrides the server name used to verify the hostname on the returned certificates from the server.
+        // gRPC internals also use it to override the virtual hosting name if it is set.
+        // It must be called before dialing. Currently, this is only used by grpclb.
+        OverrideServerName(string) error
+}
+
+// TLSInfo contains the auth information for a TLS authenticated connection.
+// It implements the AuthInfo interface.
+type TLSInfo struct {
+        State tls.ConnectionState
+}
+
+// AuthType returns the type of TLSInfo as a string.
+func (t TLSInfo) AuthType() string {
+        return "tls"
+}
+
+// tlsCreds is the credentials required for authenticating a connection using TLS.
+type tlsCreds struct {
+        // TLS configuration
+        config *tls.Config
+}
+
+func (c tlsCreds) Info() ProtocolInfo {
+        return ProtocolInfo{
+                SecurityProtocol: "tls",
+                SecurityVersion:  "1.2",
+                ServerName:       c.config.ServerName,
+        }
+}
+
+func (c *tlsCreds) ClientHandshake(ctx context.Context, addr string, rawConn net.Conn) (_ net.Conn, _ AuthInfo, err error) {
+        // use local cfg to avoid clobbering ServerName if using multiple endpoints
+        cfg := cloneTLSConfig(c.config)
+        if cfg.ServerName == "" {
+                colonPos := strings.LastIndex(addr, ":")
+                if colonPos == -1 {
+                        colonPos = len(addr)
+                }
+                cfg.ServerName = addr[:colonPos]
+        }
+        conn := tls.Client(rawConn, cfg)
+        errChannel := make(chan error, 1)
+        go func() {
+                errChannel <- conn.Handshake()
+        }()
+        select {
+        case err := <-errChannel:
+                if err != nil {
+                        return nil, nil, err
+                }
+        case <-ctx.Done():
+                return nil, nil, ctx.Err()
+        }
+        return conn, TLSInfo{conn.ConnectionState()}, nil
+}
+
+func (c *tlsCreds) ServerHandshake(rawConn net.Conn) (net.Conn, AuthInfo, error) {
+        conn := tls.Server(rawConn, c.config)
+        if err := conn.Handshake(); err != nil {
+                return nil, nil, err
+        }
+        return conn, TLSInfo{conn.ConnectionState()}, nil
+}
+
+func (c *tlsCreds) Clone() TransportCredentials {
+        return NewTLS(c.config)
+}
+
+func (c *tlsCreds) OverrideServerName(serverNameOverride string) error {
+        c.config.ServerName = serverNameOverride
+        return nil
+}
+
+// NewTLS uses c to construct a TransportCredentials based on TLS.
+func NewTLS(c *tls.Config) TransportCredentials {
+        tc := &tlsCreds{cloneTLSConfig(c)}
+        tc.config.NextProtos = alpnProtoStr
+        return tc
+}
+
+// NewClientTLSFromCert constructs TLS credentials from the input certificate for client.
+// serverNameOverride is for testing only. If set to a non empty string,
+// it will override the virtual host name of authority (e.g. :authority header field) in requests.
+func NewClientTLSFromCert(cp *x509.CertPool, serverNameOverride string) TransportCredentials {
+        return NewTLS(&tls.Config{ServerName: serverNameOverride, RootCAs: cp})
+}
+
+// NewClientTLSFromFile constructs TLS credentials from the input certificate file for client.
+// serverNameOverride is for testing only. If set to a non empty string,
+// it will override the virtual host name of authority (e.g. :authority header field) in requests.
+func NewClientTLSFromFile(certFile, serverNameOverride string) (TransportCredentials, error) {
+        b, err := ioutil.ReadFile(certFile)
+        if err != nil {
+                return nil, err
+        }
+        cp := x509.NewCertPool()
+        if !cp.AppendCertsFromPEM(b) {
+                return nil, fmt.Errorf("credentials: failed to append certificates")
+        }
+        return NewTLS(&tls.Config{ServerName: serverNameOverride, RootCAs: cp}), nil
+}
+
+// NewServerTLSFromCert constructs TLS credentials from the input certificate for server.
+func NewServerTLSFromCert(cert *tls.Certificate) TransportCredentials {
+        return NewTLS(&tls.Config{Certificates: []tls.Certificate{*cert}})
+}
+
+// NewServerTLSFromFile constructs TLS credentials from the input certificate file and key
+// file for server.
+func NewServerTLSFromFile(certFile, keyFile string) (TransportCredentials, error) {
+        cert, err := tls.LoadX509KeyPair(certFile, keyFile)
+        if err != nil {
+                return nil, err
+        }
+        return NewTLS(&tls.Config{Certificates: []tls.Certificate{cert}}), nil
+}
diff --git a/vendor/google.golang.org/grpc/credentials/credentials_util_go17.go b/vendor/google.golang.org/grpc/credentials/credentials_util_go17.go
new file mode 100644
index 0000000..60409aa
--- /dev/null
+++ b/vendor/google.golang.org/grpc/credentials/credentials_util_go17.go
@@ -0,0 +1,60 @@
+// +build go1.7
+// +build !go1.8
+
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package credentials
+
+import (
+        "crypto/tls"
+)
+
+// cloneTLSConfig returns a shallow clone of the exported
+// fields of cfg, ignoring the unexported sync.Once, which
+// contains a mutex and must not be copied.
+//
+// If cfg is nil, a new zero tls.Config is returned.
+func cloneTLSConfig(cfg *tls.Config) *tls.Config {
+        if cfg == nil {
+                return &tls.Config{}
+        }
+        return &tls.Config{
+                Rand:                        cfg.Rand,
+                Time:                        cfg.Time,
+                Certificates:                cfg.Certificates,
+                NameToCertificate:           cfg.NameToCertificate,
+                GetCertificate:              cfg.GetCertificate,
+                RootCAs:                     cfg.RootCAs,
+                NextProtos:                  cfg.NextProtos,
+                ServerName:                  cfg.ServerName,
+                ClientAuth:                  cfg.ClientAuth,
+                ClientCAs:                   cfg.ClientCAs,
+                InsecureSkipVerify:          cfg.InsecureSkipVerify,
+                CipherSuites:                cfg.CipherSuites,
+                PreferServerCipherSuites:    cfg.PreferServerCipherSuites,
+                SessionTicketsDisabled:      cfg.SessionTicketsDisabled,
+                SessionTicketKey:            cfg.SessionTicketKey,
+                ClientSessionCache:          cfg.ClientSessionCache,
+                MinVersion:                  cfg.MinVersion,
+                MaxVersion:                  cfg.MaxVersion,
+                CurvePreferences:            cfg.CurvePreferences,
+                DynamicRecordSizingDisabled: cfg.DynamicRecordSizingDisabled,
+                Renegotiation:               cfg.Renegotiation,
+        }
+}
diff --git a/vendor/google.golang.org/grpc/credentials/credentials_util_go18.go b/vendor/google.golang.org/grpc/credentials/credentials_util_go18.go
new file mode 100644
index 0000000..93f0e1d
--- /dev/null
+++ b/vendor/google.golang.org/grpc/credentials/credentials_util_go18.go
@@ -0,0 +1,38 @@
+// +build go1.8
+
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package credentials
+
+import (
+        "crypto/tls"
+)
+
+// cloneTLSConfig returns a shallow clone of the exported
+// fields of cfg, ignoring the unexported sync.Once, which
+// contains a mutex and must not be copied.
+//
+// If cfg is nil, a new zero tls.Config is returned.
+func cloneTLSConfig(cfg *tls.Config) *tls.Config {
+        if cfg == nil {
+                return &tls.Config{}
+        }
+
+        return cfg.Clone()
+}
diff --git a/vendor/google.golang.org/grpc/credentials/credentials_util_pre_go17.go b/vendor/google.golang.org/grpc/credentials/credentials_util_pre_go17.go
new file mode 100644
index 0000000..d6bbcc9
--- /dev/null
+++ b/vendor/google.golang.org/grpc/credentials/credentials_util_pre_go17.go
@@ -0,0 +1,57 @@
+// +build !go1.7
+
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package credentials
+
+import (
+        "crypto/tls"
+)
+
+// cloneTLSConfig returns a shallow clone of the exported
+// fields of cfg, ignoring the unexported sync.Once, which
+// contains a mutex and must not be copied.
+//
+// If cfg is nil, a new zero tls.Config is returned.
+func cloneTLSConfig(cfg *tls.Config) *tls.Config {
+        if cfg == nil {
+                return &tls.Config{}
+        }
+        return &tls.Config{
+                Rand:                     cfg.Rand,
+                Time:                     cfg.Time,
+                Certificates:             cfg.Certificates,
+                NameToCertificate:        cfg.NameToCertificate,
+                GetCertificate:           cfg.GetCertificate,
+                RootCAs:                  cfg.RootCAs,
+                NextProtos:               cfg.NextProtos,
+                ServerName:               cfg.ServerName,
+                ClientAuth:               cfg.ClientAuth,
+                ClientCAs:                cfg.ClientCAs,
+                InsecureSkipVerify:       cfg.InsecureSkipVerify,
+                CipherSuites:             cfg.CipherSuites,
+                PreferServerCipherSuites: cfg.PreferServerCipherSuites,
+                SessionTicketsDisabled:   cfg.SessionTicketsDisabled,
+                SessionTicketKey:         cfg.SessionTicketKey,
+                ClientSessionCache:       cfg.ClientSessionCache,
+                MinVersion:               cfg.MinVersion,
+                MaxVersion:               cfg.MaxVersion,
+                CurvePreferences:         cfg.CurvePreferences,
+        }
+}
diff --git a/vendor/google.golang.org/grpc/doc.go b/vendor/google.golang.org/grpc/doc.go
new file mode 100644
index 0000000..187adbb
--- /dev/null
+++ b/vendor/google.golang.org/grpc/doc.go
@@ -0,0 +1,24 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/*
+Package grpc implements an RPC system called gRPC.
+
+See grpc.io for more information about gRPC.
+*/
+package grpc // import "google.golang.org/grpc"
diff --git a/vendor/google.golang.org/grpc/go16.go b/vendor/google.golang.org/grpc/go16.go
new file mode 100644
index 0000000..f3dbf21
--- /dev/null
+++ b/vendor/google.golang.org/grpc/go16.go
@@ -0,0 +1,98 @@
+// +build go1.6,!go1.7
+
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "fmt"
+        "io"
+        "net"
+        "net/http"
+        "os"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/transport"
+)
+
+// dialContext connects to the address on the named network.
+func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
+        return (&net.Dialer{Cancel: ctx.Done()}).Dial(network, address)
+}
+
+func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {
+        req.Cancel = ctx.Done()
+        if err := req.Write(conn); err != nil {
+                return fmt.Errorf("failed to write the HTTP request: %v", err)
+        }
+        return nil
+}
+
+// toRPCErr converts an error into an error from the status package.
+func toRPCErr(err error) error {
+        if _, ok := status.FromError(err); ok {
+                return err
+        }
+        switch e := err.(type) {
+        case transport.StreamError:
+                return status.Error(e.Code, e.Desc)
+        case transport.ConnectionError:
+                return status.Error(codes.Unavailable, e.Desc)
+        default:
+                switch err {
+                case context.DeadlineExceeded:
+                        return status.Error(codes.DeadlineExceeded, err.Error())
+                case context.Canceled:
+                        return status.Error(codes.Canceled, err.Error())
+                case ErrClientConnClosing:
+                        return status.Error(codes.FailedPrecondition, err.Error())
+                }
+        }
+        return status.Error(codes.Unknown, err.Error())
+}
+
+// convertCode converts a standard Go error into its canonical code. Note that
+// this is only used to translate the error returned by the server applications.
+func convertCode(err error) codes.Code {
+        switch err {
+        case nil:
+                return codes.OK
+        case io.EOF:
+                return codes.OutOfRange
+        case io.ErrClosedPipe, io.ErrNoProgress, io.ErrShortBuffer, io.ErrShortWrite, io.ErrUnexpectedEOF:
+                return codes.FailedPrecondition
+        case os.ErrInvalid:
+                return codes.InvalidArgument
+        case context.Canceled:
+                return codes.Canceled
+        case context.DeadlineExceeded:
+                return codes.DeadlineExceeded
+        }
+        switch {
+        case os.IsExist(err):
+                return codes.AlreadyExists
+        case os.IsNotExist(err):
+                return codes.NotFound
+        case os.IsPermission(err):
+                return codes.PermissionDenied
+        }
+        return codes.Unknown
+}
diff --git a/vendor/google.golang.org/grpc/go17.go b/vendor/google.golang.org/grpc/go17.go
new file mode 100644
index 0000000..a3421d9
--- /dev/null
+++ b/vendor/google.golang.org/grpc/go17.go
@@ -0,0 +1,98 @@
+// +build go1.7
+
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "context"
+        "io"
+        "net"
+        "net/http"
+        "os"
+
+        netctx "golang.org/x/net/context"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/transport"
+)
+
+// dialContext connects to the address on the named network.
+func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
+        return (&net.Dialer{}).DialContext(ctx, network, address)
+}
+
+func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {
+        req = req.WithContext(ctx)
+        if err := req.Write(conn); err != nil {
+                return err
+        }
+        return nil
+}
+
+// toRPCErr converts an error into an error from the status package.
+func toRPCErr(err error) error {
+        if _, ok := status.FromError(err); ok {
+                return err
+        }
+        switch e := err.(type) {
+        case transport.StreamError:
+                return status.Error(e.Code, e.Desc)
+        case transport.ConnectionError:
+                return status.Error(codes.Unavailable, e.Desc)
+        default:
+                switch err {
+                case context.DeadlineExceeded, netctx.DeadlineExceeded:
+                        return status.Error(codes.DeadlineExceeded, err.Error())
+                case context.Canceled, netctx.Canceled:
+                        return status.Error(codes.Canceled, err.Error())
+                case ErrClientConnClosing:
+                        return status.Error(codes.FailedPrecondition, err.Error())
+                }
+        }
+        return status.Error(codes.Unknown, err.Error())
+}
+
+// convertCode converts a standard Go error into its canonical code. Note that
+// this is only used to translate the error returned by the server applications.
+func convertCode(err error) codes.Code {
+        switch err {
+        case nil:
+                return codes.OK
+        case io.EOF:
+                return codes.OutOfRange
+        case io.ErrClosedPipe, io.ErrNoProgress, io.ErrShortBuffer, io.ErrShortWrite, io.ErrUnexpectedEOF:
+                return codes.FailedPrecondition
+        case os.ErrInvalid:
+                return codes.InvalidArgument
+        case context.Canceled, netctx.Canceled:
+                return codes.Canceled
+        case context.DeadlineExceeded, netctx.DeadlineExceeded:
+                return codes.DeadlineExceeded
+        }
+        switch {
+        case os.IsExist(err):
+                return codes.AlreadyExists
+        case os.IsNotExist(err):
+                return codes.NotFound
+        case os.IsPermission(err):
+                return codes.PermissionDenied
+        }
+        return codes.Unknown
+}
diff --git a/vendor/google.golang.org/grpc/grpclb.go b/vendor/google.golang.org/grpc/grpclb.go
new file mode 100644
index 0000000..f7b6b7d
--- /dev/null
+++ b/vendor/google.golang.org/grpc/grpclb.go
@@ -0,0 +1,737 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "errors"
+        "fmt"
+        "math/rand"
+        "net"
+        "sync"
+        "time"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/codes"
+        lbpb "google.golang.org/grpc/grpclb/grpc_lb_v1"
+        "google.golang.org/grpc/grpclog"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/naming"
+)
+
+// Client API for LoadBalancer service.
+// Mostly copied from generated pb.go file.
+// To avoid circular dependency.
+type loadBalancerClient struct {
+        cc *ClientConn
+}
+
+func (c *loadBalancerClient) BalanceLoad(ctx context.Context, opts ...CallOption) (*balanceLoadClientStream, error) {
+        desc := &StreamDesc{
+                StreamName:    "BalanceLoad",
+                ServerStreams: true,
+                ClientStreams: true,
+        }
+        stream, err := NewClientStream(ctx, desc, c.cc, "/grpc.lb.v1.LoadBalancer/BalanceLoad", opts...)
+        if err != nil {
+                return nil, err
+        }
+        x := &balanceLoadClientStream{stream}
+        return x, nil
+}
+
+type balanceLoadClientStream struct {
+        ClientStream
+}
+
+func (x *balanceLoadClientStream) Send(m *lbpb.LoadBalanceRequest) error {
+        return x.ClientStream.SendMsg(m)
+}
+
+func (x *balanceLoadClientStream) Recv() (*lbpb.LoadBalanceResponse, error) {
+        m := new(lbpb.LoadBalanceResponse)
+        if err := x.ClientStream.RecvMsg(m); err != nil {
+                return nil, err
+        }
+        return m, nil
+}
+
+// NewGRPCLBBalancer creates a grpclb load balancer.
+func NewGRPCLBBalancer(r naming.Resolver) Balancer {
+        return &balancer{
+                r: r,
+        }
+}
+
+type remoteBalancerInfo struct {
+        addr string
+        // the server name used for authentication with the remote LB server.
+        name string
+}
+
+// grpclbAddrInfo consists of the information of a backend server.
+type grpclbAddrInfo struct {
+        addr      Address
+        connected bool
+        // dropForRateLimiting indicates whether this particular request should be
+        // dropped by the client for rate limiting.
+        dropForRateLimiting bool
+        // dropForLoadBalancing indicates whether this particular request should be
+        // dropped by the client for load balancing.
+        dropForLoadBalancing bool
+}
+
+type balancer struct {
+        r        naming.Resolver
+        target   string
+        mu       sync.Mutex
+        seq      int // a sequence number to make sure addrCh does not get stale addresses.
+        w        naming.Watcher
+        addrCh   chan []Address
+        rbs      []remoteBalancerInfo
+        addrs    []*grpclbAddrInfo
+        next     int
+        waitCh   chan struct{}
+        done     bool
+        expTimer *time.Timer
+        rand     *rand.Rand
+
+        clientStats lbpb.ClientStats
+}
+
+func (b *balancer) watchAddrUpdates(w naming.Watcher, ch chan []remoteBalancerInfo) error {
+        updates, err := w.Next()
+        if err != nil {
+                grpclog.Warningf("grpclb: failed to get next addr update from watcher: %v", err)
+                return err
+        }
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if b.done {
+                return ErrClientConnClosing
+        }
+        for _, update := range updates {
+                switch update.Op {
+                case naming.Add:
+                        var exist bool
+                        for _, v := range b.rbs {
+                                // TODO: Is the same addr with different server name a different balancer?
+                                if update.Addr == v.addr {
+                                        exist = true
+                                        break
+                                }
+                        }
+                        if exist {
+                                continue
+                        }
+                        md, ok := update.Metadata.(*naming.AddrMetadataGRPCLB)
+                        if !ok {
+                                // TODO: Revisit the handling here and may introduce some fallback mechanism.
+                                grpclog.Errorf("The name resolution contains unexpected metadata %v", update.Metadata)
+                                continue
+                        }
+                        switch md.AddrType {
+                        case naming.Backend:
+                                // TODO: Revisit the handling here and may introduce some fallback mechanism.
+                                grpclog.Errorf("The name resolution does not give grpclb addresses")
+                                continue
+                        case naming.GRPCLB:
+                                b.rbs = append(b.rbs, remoteBalancerInfo{
+                                        addr: update.Addr,
+                                        name: md.ServerName,
+                                })
+                        default:
+                                grpclog.Errorf("Received unknow address type %d", md.AddrType)
+                                continue
+                        }
+                case naming.Delete:
+                        for i, v := range b.rbs {
+                                if update.Addr == v.addr {
+                                        copy(b.rbs[i:], b.rbs[i+1:])
+                                        b.rbs = b.rbs[:len(b.rbs)-1]
+                                        break
+                                }
+                        }
+                default:
+                        grpclog.Errorf("Unknown update.Op %v", update.Op)
+                }
+        }
+        // TODO: Fall back to the basic round-robin load balancing if the resulting address is
+        // not a load balancer.
+        select {
+        case <-ch:
+        default:
+        }
+        ch <- b.rbs
+        return nil
+}
+
+func (b *balancer) serverListExpire(seq int) {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        // TODO: gRPC interanls do not clear the connections when the server list is stale.
+        // This means RPCs will keep using the existing server list until b receives new
+        // server list even though the list is expired. Revisit this behavior later.
+        if b.done || seq < b.seq {
+                return
+        }
+        b.next = 0
+        b.addrs = nil
+        // Ask grpc internals to close all the corresponding connections.
+        b.addrCh <- nil
+}
+
+func convertDuration(d *lbpb.Duration) time.Duration {
+        if d == nil {
+                return 0
+        }
+        return time.Duration(d.Seconds)*time.Second + time.Duration(d.Nanos)*time.Nanosecond
+}
+
+func (b *balancer) processServerList(l *lbpb.ServerList, seq int) {
+        if l == nil {
+                return
+        }
+        servers := l.GetServers()
+        expiration := convertDuration(l.GetExpirationInterval())
+        var (
+                sl    []*grpclbAddrInfo
+                addrs []Address
+        )
+        for _, s := range servers {
+                md := metadata.Pairs("lb-token", s.LoadBalanceToken)
+                ip := net.IP(s.IpAddress)
+                ipStr := ip.String()
+                if ip.To4() == nil {
+                        // Add square brackets to ipv6 addresses, otherwise net.Dial() and
+                        // net.SplitHostPort() will return too many colons error.
+                        ipStr = fmt.Sprintf("[%s]", ipStr)
+                }
+                addr := Address{
+                        Addr:     fmt.Sprintf("%s:%d", ipStr, s.Port),
+                        Metadata: &md,
+                }
+                sl = append(sl, &grpclbAddrInfo{
+                        addr:                 addr,
+                        dropForRateLimiting:  s.DropForRateLimiting,
+                        dropForLoadBalancing: s.DropForLoadBalancing,
+                })
+                addrs = append(addrs, addr)
+        }
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if b.done || seq < b.seq {
+                return
+        }
+        if len(sl) > 0 {
+                // reset b.next to 0 when replacing the server list.
+                b.next = 0
+                b.addrs = sl
+                b.addrCh <- addrs
+                if b.expTimer != nil {
+                        b.expTimer.Stop()
+                        b.expTimer = nil
+                }
+                if expiration > 0 {
+                        b.expTimer = time.AfterFunc(expiration, func() {
+                                b.serverListExpire(seq)
+                        })
+                }
+        }
+        return
+}
+
+func (b *balancer) sendLoadReport(s *balanceLoadClientStream, interval time.Duration, done <-chan struct{}) {
+        ticker := time.NewTicker(interval)
+        defer ticker.Stop()
+        for {
+                select {
+                case <-ticker.C:
+                case <-done:
+                        return
+                }
+                b.mu.Lock()
+                stats := b.clientStats
+                b.clientStats = lbpb.ClientStats{} // Clear the stats.
+                b.mu.Unlock()
+                t := time.Now()
+                stats.Timestamp = &lbpb.Timestamp{
+                        Seconds: t.Unix(),
+                        Nanos:   int32(t.Nanosecond()),
+                }
+                if err := s.Send(&lbpb.LoadBalanceRequest{
+                        LoadBalanceRequestType: &lbpb.LoadBalanceRequest_ClientStats{
+                                ClientStats: &stats,
+                        },
+                }); err != nil {
+                        grpclog.Errorf("grpclb: failed to send load report: %v", err)
+                        return
+                }
+        }
+}
+
+func (b *balancer) callRemoteBalancer(lbc *loadBalancerClient, seq int) (retry bool) {
+        ctx, cancel := context.WithCancel(context.Background())
+        defer cancel()
+        stream, err := lbc.BalanceLoad(ctx)
+        if err != nil {
+                grpclog.Errorf("grpclb: failed to perform RPC to the remote balancer %v", err)
+                return
+        }
+        b.mu.Lock()
+        if b.done {
+                b.mu.Unlock()
+                return
+        }
+        b.mu.Unlock()
+        initReq := &lbpb.LoadBalanceRequest{
+                LoadBalanceRequestType: &lbpb.LoadBalanceRequest_InitialRequest{
+                        InitialRequest: &lbpb.InitialLoadBalanceRequest{
+                                Name: b.target,
+                        },
+                },
+        }
+        if err := stream.Send(initReq); err != nil {
+                grpclog.Errorf("grpclb: failed to send init request: %v", err)
+                // TODO: backoff on retry?
+                return true
+        }
+        reply, err := stream.Recv()
+        if err != nil {
+                grpclog.Errorf("grpclb: failed to recv init response: %v", err)
+                // TODO: backoff on retry?
+                return true
+        }
+        initResp := reply.GetInitialResponse()
+        if initResp == nil {
+                grpclog.Errorf("grpclb: reply from remote balancer did not include initial response.")
+                return
+        }
+        // TODO: Support delegation.
+        if initResp.LoadBalancerDelegate != "" {
+                // delegation
+                grpclog.Errorf("TODO: Delegation is not supported yet.")
+                return
+        }
+        streamDone := make(chan struct{})
+        defer close(streamDone)
+        b.mu.Lock()
+        b.clientStats = lbpb.ClientStats{} // Clear client stats.
+        b.mu.Unlock()
+        if d := convertDuration(initResp.ClientStatsReportInterval); d > 0 {
+                go b.sendLoadReport(stream, d, streamDone)
+        }
+        // Retrieve the server list.
+        for {
+                reply, err := stream.Recv()
+                if err != nil {
+                        grpclog.Errorf("grpclb: failed to recv server list: %v", err)
+                        break
+                }
+                b.mu.Lock()
+                if b.done || seq < b.seq {
+                        b.mu.Unlock()
+                        return
+                }
+                b.seq++ // tick when receiving a new list of servers.
+                seq = b.seq
+                b.mu.Unlock()
+                if serverList := reply.GetServerList(); serverList != nil {
+                        b.processServerList(serverList, seq)
+                }
+        }
+        return true
+}
+
+func (b *balancer) Start(target string, config BalancerConfig) error {
+        b.rand = rand.New(rand.NewSource(time.Now().Unix()))
+        // TODO: Fall back to the basic direct connection if there is no name resolver.
+        if b.r == nil {
+                return errors.New("there is no name resolver installed")
+        }
+        b.target = target
+        b.mu.Lock()
+        if b.done {
+                b.mu.Unlock()
+                return ErrClientConnClosing
+        }
+        b.addrCh = make(chan []Address)
+        w, err := b.r.Resolve(target)
+        if err != nil {
+                b.mu.Unlock()
+                grpclog.Errorf("grpclb: failed to resolve address: %v, err: %v", target, err)
+                return err
+        }
+        b.w = w
+        b.mu.Unlock()
+        balancerAddrsCh := make(chan []remoteBalancerInfo, 1)
+        // Spawn a goroutine to monitor the name resolution of remote load balancer.
+        go func() {
+                for {
+                        if err := b.watchAddrUpdates(w, balancerAddrsCh); err != nil {
+                                grpclog.Warningf("grpclb: the naming watcher stops working due to %v.\n", err)
+                                close(balancerAddrsCh)
+                                return
+                        }
+                }
+        }()
+        // Spawn a goroutine to talk to the remote load balancer.
+        go func() {
+                var (
+                        cc *ClientConn
+                        // ccError is closed when there is an error in the current cc.
+                        // A new rb should be picked from rbs and connected.
+                        ccError chan struct{}
+                        rb      *remoteBalancerInfo
+                        rbs     []remoteBalancerInfo
+                        rbIdx   int
+                )
+
+                defer func() {
+                        if ccError != nil {
+                                select {
+                                case <-ccError:
+                                default:
+                                        close(ccError)
+                                }
+                        }
+                        if cc != nil {
+                                cc.Close()
+                        }
+                }()
+
+                for {
+                        var ok bool
+                        select {
+                        case rbs, ok = <-balancerAddrsCh:
+                                if !ok {
+                                        return
+                                }
+                                foundIdx := -1
+                                if rb != nil {
+                                        for i, trb := range rbs {
+                                                if trb == *rb {
+                                                        foundIdx = i
+                                                        break
+                                                }
+                                        }
+                                }
+                                if foundIdx >= 0 {
+                                        if foundIdx >= 1 {
+                                                // Move the address in use to the beginning of the list.
+                                                b.rbs[0], b.rbs[foundIdx] = b.rbs[foundIdx], b.rbs[0]
+                                                rbIdx = 0
+                                        }
+                                        continue // If found, don't dial new cc.
+                                } else if len(rbs) > 0 {
+                                        // Pick a random one from the list, instead of always using the first one.
+                                        if l := len(rbs); l > 1 && rb != nil {
+                                                tmpIdx := b.rand.Intn(l - 1)
+                                                b.rbs[0], b.rbs[tmpIdx] = b.rbs[tmpIdx], b.rbs[0]
+                                        }
+                                        rbIdx = 0
+                                        rb = &rbs[0]
+                                } else {
+                                        // foundIdx < 0 && len(rbs) <= 0.
+                                        rb = nil
+                                }
+                        case <-ccError:
+                                ccError = nil
+                                if rbIdx < len(rbs)-1 {
+                                        rbIdx++
+                                        rb = &rbs[rbIdx]
+                                } else {
+                                        rb = nil
+                                }
+                        }
+
+                        if rb == nil {
+                                continue
+                        }
+
+                        if cc != nil {
+                                cc.Close()
+                        }
+                        // Talk to the remote load balancer to get the server list.
+                        var (
+                                err   error
+                                dopts []DialOption
+                        )
+                        if creds := config.DialCreds; creds != nil {
+                                if rb.name != "" {
+                                        if err := creds.OverrideServerName(rb.name); err != nil {
+                                                grpclog.Warningf("grpclb: failed to override the server name in the credentials: %v", err)
+                                                continue
+                                        }
+                                }
+                                dopts = append(dopts, WithTransportCredentials(creds))
+                        } else {
+                                dopts = append(dopts, WithInsecure())
+                        }
+                        if dialer := config.Dialer; dialer != nil {
+                                // WithDialer takes a different type of function, so we instead use a special DialOption here.
+                                dopts = append(dopts, func(o *dialOptions) { o.copts.Dialer = dialer })
+                        }
+                        ccError = make(chan struct{})
+                        cc, err = Dial(rb.addr, dopts...)
+                        if err != nil {
+                                grpclog.Warningf("grpclb: failed to setup a connection to the remote balancer %v: %v", rb.addr, err)
+                                close(ccError)
+                                continue
+                        }
+                        b.mu.Lock()
+                        b.seq++ // tick when getting a new balancer address
+                        seq := b.seq
+                        b.next = 0
+                        b.mu.Unlock()
+                        go func(cc *ClientConn, ccError chan struct{}) {
+                                lbc := &loadBalancerClient{cc}
+                                b.callRemoteBalancer(lbc, seq)
+                                cc.Close()
+                                select {
+                                case <-ccError:
+                                default:
+                                        close(ccError)
+                                }
+                        }(cc, ccError)
+                }
+        }()
+        return nil
+}
+
+func (b *balancer) down(addr Address, err error) {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        for _, a := range b.addrs {
+                if addr == a.addr {
+                        a.connected = false
+                        break
+                }
+        }
+}
+
+func (b *balancer) Up(addr Address) func(error) {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if b.done {
+                return nil
+        }
+        var cnt int
+        for _, a := range b.addrs {
+                if a.addr == addr {
+                        if a.connected {
+                                return nil
+                        }
+                        a.connected = true
+                }
+                if a.connected && !a.dropForRateLimiting && !a.dropForLoadBalancing {
+                        cnt++
+                }
+        }
+        // addr is the only one which is connected. Notify the Get() callers who are blocking.
+        if cnt == 1 && b.waitCh != nil {
+                close(b.waitCh)
+                b.waitCh = nil
+        }
+        return func(err error) {
+                b.down(addr, err)
+        }
+}
+
+func (b *balancer) Get(ctx context.Context, opts BalancerGetOptions) (addr Address, put func(), err error) {
+        var ch chan struct{}
+        b.mu.Lock()
+        if b.done {
+                b.mu.Unlock()
+                err = ErrClientConnClosing
+                return
+        }
+        seq := b.seq
+
+        defer func() {
+                if err != nil {
+                        return
+                }
+                put = func() {
+                        s, ok := rpcInfoFromContext(ctx)
+                        if !ok {
+                                return
+                        }
+                        b.mu.Lock()
+                        defer b.mu.Unlock()
+                        if b.done || seq < b.seq {
+                                return
+                        }
+                        b.clientStats.NumCallsFinished++
+                        if !s.bytesSent {
+                                b.clientStats.NumCallsFinishedWithClientFailedToSend++
+                        } else if s.bytesReceived {
+                                b.clientStats.NumCallsFinishedKnownReceived++
+                        }
+                }
+        }()
+
+        b.clientStats.NumCallsStarted++
+        if len(b.addrs) > 0 {
+                if b.next >= len(b.addrs) {
+                        b.next = 0
+                }
+                next := b.next
+                for {
+                        a := b.addrs[next]
+                        next = (next + 1) % len(b.addrs)
+                        if a.connected {
+                                if !a.dropForRateLimiting && !a.dropForLoadBalancing {
+                                        addr = a.addr
+                                        b.next = next
+                                        b.mu.Unlock()
+                                        return
+                                }
+                                if !opts.BlockingWait {
+                                        b.next = next
+                                        if a.dropForLoadBalancing {
+                                                b.clientStats.NumCallsFinished++
+                                                b.clientStats.NumCallsFinishedWithDropForLoadBalancing++
+                                        } else if a.dropForRateLimiting {
+                                                b.clientStats.NumCallsFinished++
+                                                b.clientStats.NumCallsFinishedWithDropForRateLimiting++
+                                        }
+                                        b.mu.Unlock()
+                                        err = Errorf(codes.Unavailable, "%s drops requests", a.addr.Addr)
+                                        return
+                                }
+                        }
+                        if next == b.next {
+                                // Has iterated all the possible address but none is connected.
+                                break
+                        }
+                }
+        }
+        if !opts.BlockingWait {
+                if len(b.addrs) == 0 {
+                        b.clientStats.NumCallsFinished++
+                        b.clientStats.NumCallsFinishedWithClientFailedToSend++
+                        b.mu.Unlock()
+                        err = Errorf(codes.Unavailable, "there is no address available")
+                        return
+                }
+                // Returns the next addr on b.addrs for a failfast RPC.
+                addr = b.addrs[b.next].addr
+                b.next++
+                b.mu.Unlock()
+                return
+        }
+        // Wait on b.waitCh for non-failfast RPCs.
+        if b.waitCh == nil {
+                ch = make(chan struct{})
+                b.waitCh = ch
+        } else {
+                ch = b.waitCh
+        }
+        b.mu.Unlock()
+        for {
+                select {
+                case <-ctx.Done():
+                        b.mu.Lock()
+                        b.clientStats.NumCallsFinished++
+                        b.clientStats.NumCallsFinishedWithClientFailedToSend++
+                        b.mu.Unlock()
+                        err = ctx.Err()
+                        return
+                case <-ch:
+                        b.mu.Lock()
+                        if b.done {
+                                b.clientStats.NumCallsFinished++
+                                b.clientStats.NumCallsFinishedWithClientFailedToSend++
+                                b.mu.Unlock()
+                                err = ErrClientConnClosing
+                                return
+                        }
+
+                        if len(b.addrs) > 0 {
+                                if b.next >= len(b.addrs) {
+                                        b.next = 0
+                                }
+                                next := b.next
+                                for {
+                                        a := b.addrs[next]
+                                        next = (next + 1) % len(b.addrs)
+                                        if a.connected {
+                                                if !a.dropForRateLimiting && !a.dropForLoadBalancing {
+                                                        addr = a.addr
+                                                        b.next = next
+                                                        b.mu.Unlock()
+                                                        return
+                                                }
+                                                if !opts.BlockingWait {
+                                                        b.next = next
+                                                        if a.dropForLoadBalancing {
+                                                                b.clientStats.NumCallsFinished++
+                                                                b.clientStats.NumCallsFinishedWithDropForLoadBalancing++
+                                                        } else if a.dropForRateLimiting {
+                                                                b.clientStats.NumCallsFinished++
+                                                                b.clientStats.NumCallsFinishedWithDropForRateLimiting++
+                                                        }
+                                                        b.mu.Unlock()
+                                                        err = Errorf(codes.Unavailable, "drop requests for the addreess %s", a.addr.Addr)
+                                                        return
+                                                }
+                                        }
+                                        if next == b.next {
+                                                // Has iterated all the possible address but none is connected.
+                                                break
+                                        }
+                                }
+                        }
+                        // The newly added addr got removed by Down() again.
+                        if b.waitCh == nil {
+                                ch = make(chan struct{})
+                                b.waitCh = ch
+                        } else {
+                                ch = b.waitCh
+                        }
+                        b.mu.Unlock()
+                }
+        }
+}
+
+func (b *balancer) Notify() <-chan []Address {
+        return b.addrCh
+}
+
+func (b *balancer) Close() error {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if b.done {
+                return errBalancerClosed
+        }
+        b.done = true
+        if b.expTimer != nil {
+                b.expTimer.Stop()
+        }
+        if b.waitCh != nil {
+                close(b.waitCh)
+        }
+        if b.addrCh != nil {
+                close(b.addrCh)
+        }
+        if b.w != nil {
+                b.w.Close()
+        }
+        return nil
+}
diff --git a/vendor/google.golang.org/grpc/grpclb/grpc_lb_v1/grpclb.pb.go b/vendor/google.golang.org/grpc/grpclb/grpc_lb_v1/grpclb.pb.go
new file mode 100644
index 0000000..f63941b
--- /dev/null
+++ b/vendor/google.golang.org/grpc/grpclb/grpc_lb_v1/grpclb.pb.go
@@ -0,0 +1,629 @@
+// Code generated by protoc-gen-go.
+// source: grpclb.proto
+// DO NOT EDIT!
+
+/*
+Package grpc_lb_v1 is a generated protocol buffer package.
+
+It is generated from these files:
+        grpclb.proto
+
+It has these top-level messages:
+        Duration
+        Timestamp
+        LoadBalanceRequest
+        InitialLoadBalanceRequest
+        ClientStats
+        LoadBalanceResponse
+        InitialLoadBalanceResponse
+        ServerList
+        Server
+*/
+package grpc_lb_v1
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type Duration struct {
+        // Signed seconds of the span of time. Must be from -315,576,000,000
+        // to +315,576,000,000 inclusive.
+        Seconds int64 `protobuf:"varint,1,opt,name=seconds" json:"seconds,omitempty"`
+        // Signed fractions of a second at nanosecond resolution of the span
+        // of time. Durations less than one second are represented with a 0
+        // `seconds` field and a positive or negative `nanos` field. For durations
+        // of one second or more, a non-zero value for the `nanos` field must be
+        // of the same sign as the `seconds` field. Must be from -999,999,999
+        // to +999,999,999 inclusive.
+        Nanos int32 `protobuf:"varint,2,opt,name=nanos" json:"nanos,omitempty"`
+}
+
+func (m *Duration) Reset()                    { *m = Duration{} }
+func (m *Duration) String() string            { return proto.CompactTextString(m) }
+func (*Duration) ProtoMessage()               {}
+func (*Duration) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+func (m *Duration) GetSeconds() int64 {
+        if m != nil {
+                return m.Seconds
+        }
+        return 0
+}
+
+func (m *Duration) GetNanos() int32 {
+        if m != nil {
+                return m.Nanos
+        }
+        return 0
+}
+
+type Timestamp struct {
+        // Represents seconds of UTC time since Unix epoch
+        // 1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
+        // 9999-12-31T23:59:59Z inclusive.
+        Seconds int64 `protobuf:"varint,1,opt,name=seconds" json:"seconds,omitempty"`
+        // Non-negative fractions of a second at nanosecond resolution. Negative
+        // second values with fractions must still have non-negative nanos values
+        // that count forward in time. Must be from 0 to 999,999,999
+        // inclusive.
+        Nanos int32 `protobuf:"varint,2,opt,name=nanos" json:"nanos,omitempty"`
+}
+
+func (m *Timestamp) Reset()                    { *m = Timestamp{} }
+func (m *Timestamp) String() string            { return proto.CompactTextString(m) }
+func (*Timestamp) ProtoMessage()               {}
+func (*Timestamp) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
+
+func (m *Timestamp) GetSeconds() int64 {
+        if m != nil {
+                return m.Seconds
+        }
+        return 0
+}
+
+func (m *Timestamp) GetNanos() int32 {
+        if m != nil {
+                return m.Nanos
+        }
+        return 0
+}
+
+type LoadBalanceRequest struct {
+        // Types that are valid to be assigned to LoadBalanceRequestType:
+        //      *LoadBalanceRequest_InitialRequest
+        //      *LoadBalanceRequest_ClientStats
+        LoadBalanceRequestType isLoadBalanceRequest_LoadBalanceRequestType `protobuf_oneof:"load_balance_request_type"`
+}
+
+func (m *LoadBalanceRequest) Reset()                    { *m = LoadBalanceRequest{} }
+func (m *LoadBalanceRequest) String() string            { return proto.CompactTextString(m) }
+func (*LoadBalanceRequest) ProtoMessage()               {}
+func (*LoadBalanceRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }
+
+type isLoadBalanceRequest_LoadBalanceRequestType interface {
+        isLoadBalanceRequest_LoadBalanceRequestType()
+}
+
+type LoadBalanceRequest_InitialRequest struct {
+        InitialRequest *InitialLoadBalanceRequest `protobuf:"bytes,1,opt,name=initial_request,json=initialRequest,oneof"`
+}
+type LoadBalanceRequest_ClientStats struct {
+        ClientStats *ClientStats `protobuf:"bytes,2,opt,name=client_stats,json=clientStats,oneof"`
+}
+
+func (*LoadBalanceRequest_InitialRequest) isLoadBalanceRequest_LoadBalanceRequestType() {}
+func (*LoadBalanceRequest_ClientStats) isLoadBalanceRequest_LoadBalanceRequestType()    {}
+
+func (m *LoadBalanceRequest) GetLoadBalanceRequestType() isLoadBalanceRequest_LoadBalanceRequestType {
+        if m != nil {
+                return m.LoadBalanceRequestType
+        }
+        return nil
+}
+
+func (m *LoadBalanceRequest) GetInitialRequest() *InitialLoadBalanceRequest {
+        if x, ok := m.GetLoadBalanceRequestType().(*LoadBalanceRequest_InitialRequest); ok {
+                return x.InitialRequest
+        }
+        return nil
+}
+
+func (m *LoadBalanceRequest) GetClientStats() *ClientStats {
+        if x, ok := m.GetLoadBalanceRequestType().(*LoadBalanceRequest_ClientStats); ok {
+                return x.ClientStats
+        }
+        return nil
+}
+
+// XXX_OneofFuncs is for the internal use of the proto package.
+func (*LoadBalanceRequest) XXX_OneofFuncs() (func(msg proto.Message, b *proto.Buffer) error, func(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error), func(msg proto.Message) (n int), []interface{}) {
+        return _LoadBalanceRequest_OneofMarshaler, _LoadBalanceRequest_OneofUnmarshaler, _LoadBalanceRequest_OneofSizer, []interface{}{
+                (*LoadBalanceRequest_InitialRequest)(nil),
+                (*LoadBalanceRequest_ClientStats)(nil),
+        }
+}
+
+func _LoadBalanceRequest_OneofMarshaler(msg proto.Message, b *proto.Buffer) error {
+        m := msg.(*LoadBalanceRequest)
+        // load_balance_request_type
+        switch x := m.LoadBalanceRequestType.(type) {
+        case *LoadBalanceRequest_InitialRequest:
+                b.EncodeVarint(1<<3 | proto.WireBytes)
+                if err := b.EncodeMessage(x.InitialRequest); err != nil {
+                        return err
+                }
+        case *LoadBalanceRequest_ClientStats:
+                b.EncodeVarint(2<<3 | proto.WireBytes)
+                if err := b.EncodeMessage(x.ClientStats); err != nil {
+                        return err
+                }
+        case nil:
+        default:
+                return fmt.Errorf("LoadBalanceRequest.LoadBalanceRequestType has unexpected type %T", x)
+        }
+        return nil
+}
+
+func _LoadBalanceRequest_OneofUnmarshaler(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error) {
+        m := msg.(*LoadBalanceRequest)
+        switch tag {
+        case 1: // load_balance_request_type.initial_request
+                if wire != proto.WireBytes {
+                        return true, proto.ErrInternalBadWireType
+                }
+                msg := new(InitialLoadBalanceRequest)
+                err := b.DecodeMessage(msg)
+                m.LoadBalanceRequestType = &LoadBalanceRequest_InitialRequest{msg}
+                return true, err
+        case 2: // load_balance_request_type.client_stats
+                if wire != proto.WireBytes {
+                        return true, proto.ErrInternalBadWireType
+                }
+                msg := new(ClientStats)
+                err := b.DecodeMessage(msg)
+                m.LoadBalanceRequestType = &LoadBalanceRequest_ClientStats{msg}
+                return true, err
+        default:
+                return false, nil
+        }
+}
+
+func _LoadBalanceRequest_OneofSizer(msg proto.Message) (n int) {
+        m := msg.(*LoadBalanceRequest)
+        // load_balance_request_type
+        switch x := m.LoadBalanceRequestType.(type) {
+        case *LoadBalanceRequest_InitialRequest:
+                s := proto.Size(x.InitialRequest)
+                n += proto.SizeVarint(1<<3 | proto.WireBytes)
+                n += proto.SizeVarint(uint64(s))
+                n += s
+        case *LoadBalanceRequest_ClientStats:
+                s := proto.Size(x.ClientStats)
+                n += proto.SizeVarint(2<<3 | proto.WireBytes)
+                n += proto.SizeVarint(uint64(s))
+                n += s
+        case nil:
+        default:
+                panic(fmt.Sprintf("proto: unexpected type %T in oneof", x))
+        }
+        return n
+}
+
+type InitialLoadBalanceRequest struct {
+        // Name of load balanced service (IE, balancer.service.com)
+        // length should be less than 256 bytes.
+        Name string `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
+}
+
+func (m *InitialLoadBalanceRequest) Reset()                    { *m = InitialLoadBalanceRequest{} }
+func (m *InitialLoadBalanceRequest) String() string            { return proto.CompactTextString(m) }
+func (*InitialLoadBalanceRequest) ProtoMessage()               {}
+func (*InitialLoadBalanceRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{3} }
+
+func (m *InitialLoadBalanceRequest) GetName() string {
+        if m != nil {
+                return m.Name
+        }
+        return ""
+}
+
+// Contains client level statistics that are useful to load balancing. Each
+// count except the timestamp should be reset to zero after reporting the stats.
+type ClientStats struct {
+        // The timestamp of generating the report.
+        Timestamp *Timestamp `protobuf:"bytes,1,opt,name=timestamp" json:"timestamp,omitempty"`
+        // The total number of RPCs that started.
+        NumCallsStarted int64 `protobuf:"varint,2,opt,name=num_calls_started,json=numCallsStarted" json:"num_calls_started,omitempty"`
+        // The total number of RPCs that finished.
+        NumCallsFinished int64 `protobuf:"varint,3,opt,name=num_calls_finished,json=numCallsFinished" json:"num_calls_finished,omitempty"`
+        // The total number of RPCs that were dropped by the client because of rate
+        // limiting.
+        NumCallsFinishedWithDropForRateLimiting int64 `protobuf:"varint,4,opt,name=num_calls_finished_with_drop_for_rate_limiting,json=numCallsFinishedWithDropForRateLimiting" json:"num_calls_finished_with_drop_for_rate_limiting,omitempty"`
+        // The total number of RPCs that were dropped by the client because of load
+        // balancing.
+        NumCallsFinishedWithDropForLoadBalancing int64 `protobuf:"varint,5,opt,name=num_calls_finished_with_drop_for_load_balancing,json=numCallsFinishedWithDropForLoadBalancing" json:"num_calls_finished_with_drop_for_load_balancing,omitempty"`
+        // The total number of RPCs that failed to reach a server except dropped RPCs.
+        NumCallsFinishedWithClientFailedToSend int64 `protobuf:"varint,6,opt,name=num_calls_finished_with_client_failed_to_send,json=numCallsFinishedWithClientFailedToSend" json:"num_calls_finished_with_client_failed_to_send,omitempty"`
+        // The total number of RPCs that finished and are known to have been received
+        // by a server.
+        NumCallsFinishedKnownReceived int64 `protobuf:"varint,7,opt,name=num_calls_finished_known_received,json=numCallsFinishedKnownReceived" json:"num_calls_finished_known_received,omitempty"`
+}
+
+func (m *ClientStats) Reset()                    { *m = ClientStats{} }
+func (m *ClientStats) String() string            { return proto.CompactTextString(m) }
+func (*ClientStats) ProtoMessage()               {}
+func (*ClientStats) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{4} }
+
+func (m *ClientStats) GetTimestamp() *Timestamp {
+        if m != nil {
+                return m.Timestamp
+        }
+        return nil
+}
+
+func (m *ClientStats) GetNumCallsStarted() int64 {
+        if m != nil {
+                return m.NumCallsStarted
+        }
+        return 0
+}
+
+func (m *ClientStats) GetNumCallsFinished() int64 {
+        if m != nil {
+                return m.NumCallsFinished
+        }
+        return 0
+}
+
+func (m *ClientStats) GetNumCallsFinishedWithDropForRateLimiting() int64 {
+        if m != nil {
+                return m.NumCallsFinishedWithDropForRateLimiting
+        }
+        return 0
+}
+
+func (m *ClientStats) GetNumCallsFinishedWithDropForLoadBalancing() int64 {
+        if m != nil {
+                return m.NumCallsFinishedWithDropForLoadBalancing
+        }
+        return 0
+}
+
+func (m *ClientStats) GetNumCallsFinishedWithClientFailedToSend() int64 {
+        if m != nil {
+                return m.NumCallsFinishedWithClientFailedToSend
+        }
+        return 0
+}
+
+func (m *ClientStats) GetNumCallsFinishedKnownReceived() int64 {
+        if m != nil {
+                return m.NumCallsFinishedKnownReceived
+        }
+        return 0
+}
+
+type LoadBalanceResponse struct {
+        // Types that are valid to be assigned to LoadBalanceResponseType:
+        //      *LoadBalanceResponse_InitialResponse
+        //      *LoadBalanceResponse_ServerList
+        LoadBalanceResponseType isLoadBalanceResponse_LoadBalanceResponseType `protobuf_oneof:"load_balance_response_type"`
+}
+
+func (m *LoadBalanceResponse) Reset()                    { *m = LoadBalanceResponse{} }
+func (m *LoadBalanceResponse) String() string            { return proto.CompactTextString(m) }
+func (*LoadBalanceResponse) ProtoMessage()               {}
+func (*LoadBalanceResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{5} }
+
+type isLoadBalanceResponse_LoadBalanceResponseType interface {
+        isLoadBalanceResponse_LoadBalanceResponseType()
+}
+
+type LoadBalanceResponse_InitialResponse struct {
+        InitialResponse *InitialLoadBalanceResponse `protobuf:"bytes,1,opt,name=initial_response,json=initialResponse,oneof"`
+}
+type LoadBalanceResponse_ServerList struct {
+        ServerList *ServerList `protobuf:"bytes,2,opt,name=server_list,json=serverList,oneof"`
+}
+
+func (*LoadBalanceResponse_InitialResponse) isLoadBalanceResponse_LoadBalanceResponseType() {}
+func (*LoadBalanceResponse_ServerList) isLoadBalanceResponse_LoadBalanceResponseType()      {}
+
+func (m *LoadBalanceResponse) GetLoadBalanceResponseType() isLoadBalanceResponse_LoadBalanceResponseType {
+        if m != nil {
+                return m.LoadBalanceResponseType
+        }
+        return nil
+}
+
+func (m *LoadBalanceResponse) GetInitialResponse() *InitialLoadBalanceResponse {
+        if x, ok := m.GetLoadBalanceResponseType().(*LoadBalanceResponse_InitialResponse); ok {
+                return x.InitialResponse
+        }
+        return nil
+}
+
+func (m *LoadBalanceResponse) GetServerList() *ServerList {
+        if x, ok := m.GetLoadBalanceResponseType().(*LoadBalanceResponse_ServerList); ok {
+                return x.ServerList
+        }
+        return nil
+}
+
+// XXX_OneofFuncs is for the internal use of the proto package.
+func (*LoadBalanceResponse) XXX_OneofFuncs() (func(msg proto.Message, b *proto.Buffer) error, func(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error), func(msg proto.Message) (n int), []interface{}) {
+        return _LoadBalanceResponse_OneofMarshaler, _LoadBalanceResponse_OneofUnmarshaler, _LoadBalanceResponse_OneofSizer, []interface{}{
+                (*LoadBalanceResponse_InitialResponse)(nil),
+                (*LoadBalanceResponse_ServerList)(nil),
+        }
+}
+
+func _LoadBalanceResponse_OneofMarshaler(msg proto.Message, b *proto.Buffer) error {
+        m := msg.(*LoadBalanceResponse)
+        // load_balance_response_type
+        switch x := m.LoadBalanceResponseType.(type) {
+        case *LoadBalanceResponse_InitialResponse:
+                b.EncodeVarint(1<<3 | proto.WireBytes)
+                if err := b.EncodeMessage(x.InitialResponse); err != nil {
+                        return err
+                }
+        case *LoadBalanceResponse_ServerList:
+                b.EncodeVarint(2<<3 | proto.WireBytes)
+                if err := b.EncodeMessage(x.ServerList); err != nil {
+                        return err
+                }
+        case nil:
+        default:
+                return fmt.Errorf("LoadBalanceResponse.LoadBalanceResponseType has unexpected type %T", x)
+        }
+        return nil
+}
+
+func _LoadBalanceResponse_OneofUnmarshaler(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error) {
+        m := msg.(*LoadBalanceResponse)
+        switch tag {
+        case 1: // load_balance_response_type.initial_response
+                if wire != proto.WireBytes {
+                        return true, proto.ErrInternalBadWireType
+                }
+                msg := new(InitialLoadBalanceResponse)
+                err := b.DecodeMessage(msg)
+                m.LoadBalanceResponseType = &LoadBalanceResponse_InitialResponse{msg}
+                return true, err
+        case 2: // load_balance_response_type.server_list
+                if wire != proto.WireBytes {
+                        return true, proto.ErrInternalBadWireType
+                }
+                msg := new(ServerList)
+                err := b.DecodeMessage(msg)
+                m.LoadBalanceResponseType = &LoadBalanceResponse_ServerList{msg}
+                return true, err
+        default:
+                return false, nil
+        }
+}
+
+func _LoadBalanceResponse_OneofSizer(msg proto.Message) (n int) {
+        m := msg.(*LoadBalanceResponse)
+        // load_balance_response_type
+        switch x := m.LoadBalanceResponseType.(type) {
+        case *LoadBalanceResponse_InitialResponse:
+                s := proto.Size(x.InitialResponse)
+                n += proto.SizeVarint(1<<3 | proto.WireBytes)
+                n += proto.SizeVarint(uint64(s))
+                n += s
+        case *LoadBalanceResponse_ServerList:
+                s := proto.Size(x.ServerList)
+                n += proto.SizeVarint(2<<3 | proto.WireBytes)
+                n += proto.SizeVarint(uint64(s))
+                n += s
+        case nil:
+        default:
+                panic(fmt.Sprintf("proto: unexpected type %T in oneof", x))
+        }
+        return n
+}
+
+type InitialLoadBalanceResponse struct {
+        // This is an application layer redirect that indicates the client should use
+        // the specified server for load balancing. When this field is non-empty in
+        // the response, the client should open a separate connection to the
+        // load_balancer_delegate and call the BalanceLoad method. Its length should
+        // be less than 64 bytes.
+        LoadBalancerDelegate string `protobuf:"bytes,1,opt,name=load_balancer_delegate,json=loadBalancerDelegate" json:"load_balancer_delegate,omitempty"`
+        // This interval defines how often the client should send the client stats
+        // to the load balancer. Stats should only be reported when the duration is
+        // positive.
+        ClientStatsReportInterval *Duration `protobuf:"bytes,2,opt,name=client_stats_report_interval,json=clientStatsReportInterval" json:"client_stats_report_interval,omitempty"`
+}
+
+func (m *InitialLoadBalanceResponse) Reset()                    { *m = InitialLoadBalanceResponse{} }
+func (m *InitialLoadBalanceResponse) String() string            { return proto.CompactTextString(m) }
+func (*InitialLoadBalanceResponse) ProtoMessage()               {}
+func (*InitialLoadBalanceResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{6} }
+
+func (m *InitialLoadBalanceResponse) GetLoadBalancerDelegate() string {
+        if m != nil {
+                return m.LoadBalancerDelegate
+        }
+        return ""
+}
+
+func (m *InitialLoadBalanceResponse) GetClientStatsReportInterval() *Duration {
+        if m != nil {
+                return m.ClientStatsReportInterval
+        }
+        return nil
+}
+
+type ServerList struct {
+        // Contains a list of servers selected by the load balancer. The list will
+        // be updated when server resolutions change or as needed to balance load
+        // across more servers. The client should consume the server list in order
+        // unless instructed otherwise via the client_config.
+        Servers []*Server `protobuf:"bytes,1,rep,name=servers" json:"servers,omitempty"`
+        // Indicates the amount of time that the client should consider this server
+        // list as valid. It may be considered stale after waiting this interval of
+        // time after receiving the list. If the interval is not positive, the
+        // client can assume the list is valid until the next list is received.
+        ExpirationInterval *Duration `protobuf:"bytes,3,opt,name=expiration_interval,json=expirationInterval" json:"expiration_interval,omitempty"`
+}
+
+func (m *ServerList) Reset()                    { *m = ServerList{} }
+func (m *ServerList) String() string            { return proto.CompactTextString(m) }
+func (*ServerList) ProtoMessage()               {}
+func (*ServerList) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{7} }
+
+func (m *ServerList) GetServers() []*Server {
+        if m != nil {
+                return m.Servers
+        }
+        return nil
+}
+
+func (m *ServerList) GetExpirationInterval() *Duration {
+        if m != nil {
+                return m.ExpirationInterval
+        }
+        return nil
+}
+
+// Contains server information. When none of the [drop_for_*] fields are true,
+// use the other fields. When drop_for_rate_limiting is true, ignore all other
+// fields. Use drop_for_load_balancing only when it is true and
+// drop_for_rate_limiting is false.
+type Server struct {
+        // A resolved address for the server, serialized in network-byte-order. It may
+        // either be an IPv4 or IPv6 address.
+        IpAddress []byte `protobuf:"bytes,1,opt,name=ip_address,json=ipAddress,proto3" json:"ip_address,omitempty"`
+        // A resolved port number for the server.
+        Port int32 `protobuf:"varint,2,opt,name=port" json:"port,omitempty"`
+        // An opaque but printable token given to the frontend for each pick. All
+        // frontend requests for that pick must include the token in its initial
+        // metadata. The token is used by the backend to verify the request and to
+        // allow the backend to report load to the gRPC LB system.
+        //
+        // Its length is variable but less than 50 bytes.
+        LoadBalanceToken string `protobuf:"bytes,3,opt,name=load_balance_token,json=loadBalanceToken" json:"load_balance_token,omitempty"`
+        // Indicates whether this particular request should be dropped by the client
+        // for rate limiting.
+        DropForRateLimiting bool `protobuf:"varint,4,opt,name=drop_for_rate_limiting,json=dropForRateLimiting" json:"drop_for_rate_limiting,omitempty"`
+        // Indicates whether this particular request should be dropped by the client
+        // for load balancing.
+        DropForLoadBalancing bool `protobuf:"varint,5,opt,name=drop_for_load_balancing,json=dropForLoadBalancing" json:"drop_for_load_balancing,omitempty"`
+}
+
+func (m *Server) Reset()                    { *m = Server{} }
+func (m *Server) String() string            { return proto.CompactTextString(m) }
+func (*Server) ProtoMessage()               {}
+func (*Server) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{8} }
+
+func (m *Server) GetIpAddress() []byte {
+        if m != nil {
+                return m.IpAddress
+        }
+        return nil
+}
+
+func (m *Server) GetPort() int32 {
+        if m != nil {
+                return m.Port
+        }
+        return 0
+}
+
+func (m *Server) GetLoadBalanceToken() string {
+        if m != nil {
+                return m.LoadBalanceToken
+        }
+        return ""
+}
+
+func (m *Server) GetDropForRateLimiting() bool {
+        if m != nil {
+                return m.DropForRateLimiting
+        }
+        return false
+}
+
+func (m *Server) GetDropForLoadBalancing() bool {
+        if m != nil {
+                return m.DropForLoadBalancing
+        }
+        return false
+}
+
+func init() {
+        proto.RegisterType((*Duration)(nil), "grpc.lb.v1.Duration")
+        proto.RegisterType((*Timestamp)(nil), "grpc.lb.v1.Timestamp")
+        proto.RegisterType((*LoadBalanceRequest)(nil), "grpc.lb.v1.LoadBalanceRequest")
+        proto.RegisterType((*InitialLoadBalanceRequest)(nil), "grpc.lb.v1.InitialLoadBalanceRequest")
+        proto.RegisterType((*ClientStats)(nil), "grpc.lb.v1.ClientStats")
+        proto.RegisterType((*LoadBalanceResponse)(nil), "grpc.lb.v1.LoadBalanceResponse")
+        proto.RegisterType((*InitialLoadBalanceResponse)(nil), "grpc.lb.v1.InitialLoadBalanceResponse")
+        proto.RegisterType((*ServerList)(nil), "grpc.lb.v1.ServerList")
+        proto.RegisterType((*Server)(nil), "grpc.lb.v1.Server")
+}
+
+func init() { proto.RegisterFile("grpclb.proto", fileDescriptor0) }
+
+var fileDescriptor0 = []byte{
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+        0x0d, 0x3d, 0x90, 0x90, 0x3e, 0x83, 0x92, 0x66, 0x6a, 0xc0, 0x14, 0x89, 0xb8, 0x36, 0x89, 0x07,
+        0x56, 0xf3, 0x7c, 0x6d, 0xb7, 0x7d, 0xca, 0x9d, 0x87, 0x40, 0x0f, 0x57, 0x07, 0x9b, 0xb0, 0x71,
+        0xcb, 0x01, 0x9e, 0xd3, 0x5b, 0xe0, 0x5b, 0x00, 0x1b, 0x93, 0xa5, 0xa0, 0x27, 0xb0, 0x9a, 0x4f,
+        0x56, 0x24, 0x64, 0x11, 0xbb, 0xa0, 0x26, 0xb5, 0x45, 0x25, 0xca, 0x92, 0xd4, 0x51, 0xb2, 0x87,
+        0xde, 0xc1, 0x66, 0xde, 0xb2, 0x44, 0xb1, 0x58, 0x2a, 0x43, 0xb8, 0x30, 0x4c, 0x0d, 0x68, 0x94,
+        0xc8, 0xaf, 0xe4, 0xe5, 0xa7, 0x43, 0x0c, 0xaf, 0xe7, 0xdc, 0x8b, 0x5d, 0xde, 0x49, 0x92, 0x56,
+        0xfb, 0x12, 0x00, 0x64, 0xc7, 0x44, 0xbb, 0x76, 0x62, 0xd9, 0x95, 0x9d, 0x58, 0x85, 0x7a, 0xa9,
+        0x89, 0x46, 0xfb, 0x81, 0x53, 0x08, 0x7a, 0x0d, 0x2b, 0xec, 0x53, 0xcc, 0x7d, 0x95, 0x4c, 0x4a,
+        0x61, 0x8a, 0x14, 0x94, 0x25, 0x0c, 0x35, 0xfc, 0x0c, 0x60, 0xde, 0x53, 0xa3, 0x2d, 0x00, 0x1e,
+        0x13, 0x1a, 0x86, 0x8a, 0x69, 0x3f, 0x34, 0xcb, 0xb8, 0xc8, 0xe3, 0x57, 0x3e, 0x60, 0xe7, 0x87,
+        0x55, 0x9f, 0x4c, 0x4d, 0xf7, 0x6d, 0xed, 0x7c, 0xe3, 0x2e, 0x8c, 0xbc, 0x62, 0xc2, 0x69, 0x28,
+        0xe2, 0xe5, 0x5c, 0x2b, 0xcf, 0x6c, 0x1c, 0xed, 0xc3, 0xea, 0x14, 0xdb, 0x2e, 0xe2, 0x95, 0x70,
+        0x8c, 0x45, 0x9f, 0xc2, 0xda, 0x34, 0x2b, 0x2e, 0xe2, 0x4a, 0x38, 0xc6, 0x76, 0xcd, 0x0e, 0x94,
+        0x73, 0xf7, 0xaf, 0x10, 0x86, 0x52, 0xf2, 0x6d, 0xc3, 0xe8, 0xdf, 0x7c, 0x83, 0x46, 0x87, 0xe5,
+        0xc6, 0x7f, 0x13, 0xf7, 0xfd, 0x43, 0xaa, 0x07, 0x8f, 0x82, 0xce, 0xbc, 0xfb, 0x7d, 0xed, 0xff,
+        0x0a, 0x00, 0x00, 0xff, 0xff, 0x64, 0xbf, 0xda, 0x5e, 0xce, 0x06, 0x00, 0x00,
+}
diff --git a/vendor/google.golang.org/grpc/grpclb/grpc_lb_v1/grpclb.proto b/vendor/google.golang.org/grpc/grpclb/grpc_lb_v1/grpclb.proto
new file mode 100644
index 0000000..b13b343
--- /dev/null
+++ b/vendor/google.golang.org/grpc/grpclb/grpc_lb_v1/grpclb.proto
@@ -0,0 +1,164 @@
+// Copyright 2016 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package grpc.lb.v1;
+
+message Duration {
+  // Signed seconds of the span of time. Must be from -315,576,000,000
+  // to +315,576,000,000 inclusive.
+  int64 seconds = 1;
+
+  // Signed fractions of a second at nanosecond resolution of the span
+  // of time. Durations less than one second are represented with a 0
+  // `seconds` field and a positive or negative `nanos` field. For durations
+  // of one second or more, a non-zero value for the `nanos` field must be
+  // of the same sign as the `seconds` field. Must be from -999,999,999
+  // to +999,999,999 inclusive.
+  int32 nanos = 2;
+}
+
+message Timestamp {
+
+  // Represents seconds of UTC time since Unix epoch
+  // 1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
+  // 9999-12-31T23:59:59Z inclusive.
+  int64 seconds = 1;
+
+  // Non-negative fractions of a second at nanosecond resolution. Negative
+  // second values with fractions must still have non-negative nanos values
+  // that count forward in time. Must be from 0 to 999,999,999
+  // inclusive.
+  int32 nanos = 2;
+}
+
+service LoadBalancer {
+  // Bidirectional rpc to get a list of servers.
+  rpc BalanceLoad(stream LoadBalanceRequest)
+      returns (stream LoadBalanceResponse);
+}
+
+message LoadBalanceRequest {
+  oneof load_balance_request_type {
+    // This message should be sent on the first request to the load balancer.
+    InitialLoadBalanceRequest initial_request = 1;
+
+    // The client stats should be periodically reported to the load balancer
+    // based on the duration defined in the InitialLoadBalanceResponse.
+    ClientStats client_stats = 2;
+  }
+}
+
+message InitialLoadBalanceRequest {
+  // Name of load balanced service (IE, balancer.service.com)
+  // length should be less than 256 bytes.
+  string name = 1;
+}
+
+// Contains client level statistics that are useful to load balancing. Each
+// count except the timestamp should be reset to zero after reporting the stats.
+message ClientStats {
+  // The timestamp of generating the report.
+  Timestamp timestamp = 1;
+
+  // The total number of RPCs that started.
+  int64 num_calls_started = 2;
+
+  // The total number of RPCs that finished.
+  int64 num_calls_finished = 3;
+
+  // The total number of RPCs that were dropped by the client because of rate
+  // limiting.
+  int64 num_calls_finished_with_drop_for_rate_limiting = 4;
+
+  // The total number of RPCs that were dropped by the client because of load
+  // balancing.
+  int64 num_calls_finished_with_drop_for_load_balancing = 5;
+
+  // The total number of RPCs that failed to reach a server except dropped RPCs.
+  int64 num_calls_finished_with_client_failed_to_send = 6;
+
+  // The total number of RPCs that finished and are known to have been received
+  // by a server.
+  int64 num_calls_finished_known_received = 7;
+}
+
+message LoadBalanceResponse {
+  oneof load_balance_response_type {
+    // This message should be sent on the first response to the client.
+    InitialLoadBalanceResponse initial_response = 1;
+
+    // Contains the list of servers selected by the load balancer. The client
+    // should send requests to these servers in the specified order.
+    ServerList server_list = 2;
+  }
+}
+
+message InitialLoadBalanceResponse {
+  // This is an application layer redirect that indicates the client should use
+  // the specified server for load balancing. When this field is non-empty in
+  // the response, the client should open a separate connection to the
+  // load_balancer_delegate and call the BalanceLoad method. Its length should
+  // be less than 64 bytes.
+  string load_balancer_delegate = 1;
+
+  // This interval defines how often the client should send the client stats
+  // to the load balancer. Stats should only be reported when the duration is
+  // positive.
+  Duration client_stats_report_interval = 2;
+}
+
+message ServerList {
+  // Contains a list of servers selected by the load balancer. The list will
+  // be updated when server resolutions change or as needed to balance load
+  // across more servers. The client should consume the server list in order
+  // unless instructed otherwise via the client_config.
+  repeated Server servers = 1;
+
+  // Indicates the amount of time that the client should consider this server
+  // list as valid. It may be considered stale after waiting this interval of
+  // time after receiving the list. If the interval is not positive, the
+  // client can assume the list is valid until the next list is received.
+  Duration expiration_interval = 3;
+}
+
+// Contains server information. When none of the [drop_for_*] fields are true,
+// use the other fields. When drop_for_rate_limiting is true, ignore all other
+// fields. Use drop_for_load_balancing only when it is true and
+// drop_for_rate_limiting is false.
+message Server {
+  // A resolved address for the server, serialized in network-byte-order. It may
+  // either be an IPv4 or IPv6 address.
+  bytes ip_address = 1;
+
+  // A resolved port number for the server.
+  int32 port = 2;
+
+  // An opaque but printable token given to the frontend for each pick. All
+  // frontend requests for that pick must include the token in its initial
+  // metadata. The token is used by the backend to verify the request and to
+  // allow the backend to report load to the gRPC LB system.
+  //
+  // Its length is variable but less than 50 bytes.
+  string load_balance_token = 3;
+
+  // Indicates whether this particular request should be dropped by the client
+  // for rate limiting.
+  bool drop_for_rate_limiting = 4;
+
+  // Indicates whether this particular request should be dropped by the client
+  // for load balancing.
+  bool drop_for_load_balancing = 5;
+}
diff --git a/vendor/google.golang.org/grpc/grpclog/grpclog.go b/vendor/google.golang.org/grpc/grpclog/grpclog.go
new file mode 100644
index 0000000..16a7d88
--- /dev/null
+++ b/vendor/google.golang.org/grpc/grpclog/grpclog.go
@@ -0,0 +1,123 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package grpclog defines logging for grpc.
+//
+// All logs in transport package only go to verbose level 2.
+// All logs in other packages in grpc are logged in spite of the verbosity level.
+//
+// In the default logger,
+// severity level can be set by environment variable GRPC_GO_LOG_SEVERITY_LEVEL,
+// verbosity level can be set by GRPC_GO_LOG_VERBOSITY_LEVEL.
+package grpclog // import "google.golang.org/grpc/grpclog"
+
+import "os"
+
+var logger = newLoggerV2()
+
+// V reports whether verbosity level l is at least the requested verbose level.
+func V(l int) bool {
+        return logger.V(l)
+}
+
+// Info logs to the INFO log.
+func Info(args ...interface{}) {
+        logger.Info(args...)
+}
+
+// Infof logs to the INFO log. Arguments are handled in the manner of fmt.Printf.
+func Infof(format string, args ...interface{}) {
+        logger.Infof(format, args...)
+}
+
+// Infoln logs to the INFO log. Arguments are handled in the manner of fmt.Println.
+func Infoln(args ...interface{}) {
+        logger.Infoln(args...)
+}
+
+// Warning logs to the WARNING log.
+func Warning(args ...interface{}) {
+        logger.Warning(args...)
+}
+
+// Warningf logs to the WARNING log. Arguments are handled in the manner of fmt.Printf.
+func Warningf(format string, args ...interface{}) {
+        logger.Warningf(format, args...)
+}
+
+// Warningln logs to the WARNING log. Arguments are handled in the manner of fmt.Println.
+func Warningln(args ...interface{}) {
+        logger.Warningln(args...)
+}
+
+// Error logs to the ERROR log.
+func Error(args ...interface{}) {
+        logger.Error(args...)
+}
+
+// Errorf logs to the ERROR log. Arguments are handled in the manner of fmt.Printf.
+func Errorf(format string, args ...interface{}) {
+        logger.Errorf(format, args...)
+}
+
+// Errorln logs to the ERROR log. Arguments are handled in the manner of fmt.Println.
+func Errorln(args ...interface{}) {
+        logger.Errorln(args...)
+}
+
+// Fatal logs to the FATAL log. Arguments are handled in the manner of fmt.Print.
+// It calls os.Exit() with exit code 1.
+func Fatal(args ...interface{}) {
+        logger.Fatal(args...)
+        // Make sure fatal logs will exit.
+        os.Exit(1)
+}
+
+// Fatalf logs to the FATAL log. Arguments are handled in the manner of fmt.Printf.
+// It calles os.Exit() with exit code 1.
+func Fatalf(format string, args ...interface{}) {
+        logger.Fatalf(format, args...)
+        // Make sure fatal logs will exit.
+        os.Exit(1)
+}
+
+// Fatalln logs to the FATAL log. Arguments are handled in the manner of fmt.Println.
+// It calle os.Exit()) with exit code 1.
+func Fatalln(args ...interface{}) {
+        logger.Fatalln(args...)
+        // Make sure fatal logs will exit.
+        os.Exit(1)
+}
+
+// Print prints to the logger. Arguments are handled in the manner of fmt.Print.
+// Deprecated: use Info.
+func Print(args ...interface{}) {
+        logger.Info(args...)
+}
+
+// Printf prints to the logger. Arguments are handled in the manner of fmt.Printf.
+// Deprecated: use Infof.
+func Printf(format string, args ...interface{}) {
+        logger.Infof(format, args...)
+}
+
+// Println prints to the logger. Arguments are handled in the manner of fmt.Println.
+// Deprecated: use Infoln.
+func Println(args ...interface{}) {
+        logger.Infoln(args...)
+}
diff --git a/vendor/google.golang.org/grpc/grpclog/logger.go b/vendor/google.golang.org/grpc/grpclog/logger.go
new file mode 100644
index 0000000..d03b239
--- /dev/null
+++ b/vendor/google.golang.org/grpc/grpclog/logger.go
@@ -0,0 +1,83 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpclog
+
+// Logger mimics golang's standard Logger as an interface.
+// Deprecated: use LoggerV2.
+type Logger interface {
+        Fatal(args ...interface{})
+        Fatalf(format string, args ...interface{})
+        Fatalln(args ...interface{})
+        Print(args ...interface{})
+        Printf(format string, args ...interface{})
+        Println(args ...interface{})
+}
+
+// SetLogger sets the logger that is used in grpc. Call only from
+// init() functions.
+// Deprecated: use SetLoggerV2.
+func SetLogger(l Logger) {
+        logger = &loggerWrapper{Logger: l}
+}
+
+// loggerWrapper wraps Logger into a LoggerV2.
+type loggerWrapper struct {
+        Logger
+}
+
+func (g *loggerWrapper) Info(args ...interface{}) {
+        g.Logger.Print(args...)
+}
+
+func (g *loggerWrapper) Infoln(args ...interface{}) {
+        g.Logger.Println(args...)
+}
+
+func (g *loggerWrapper) Infof(format string, args ...interface{}) {
+        g.Logger.Printf(format, args...)
+}
+
+func (g *loggerWrapper) Warning(args ...interface{}) {
+        g.Logger.Print(args...)
+}
+
+func (g *loggerWrapper) Warningln(args ...interface{}) {
+        g.Logger.Println(args...)
+}
+
+func (g *loggerWrapper) Warningf(format string, args ...interface{}) {
+        g.Logger.Printf(format, args...)
+}
+
+func (g *loggerWrapper) Error(args ...interface{}) {
+        g.Logger.Print(args...)
+}
+
+func (g *loggerWrapper) Errorln(args ...interface{}) {
+        g.Logger.Println(args...)
+}
+
+func (g *loggerWrapper) Errorf(format string, args ...interface{}) {
+        g.Logger.Printf(format, args...)
+}
+
+func (g *loggerWrapper) V(l int) bool {
+        // Returns true for all verbose level.
+        return true
+}
diff --git a/vendor/google.golang.org/grpc/grpclog/loggerv2.go b/vendor/google.golang.org/grpc/grpclog/loggerv2.go
new file mode 100644
index 0000000..d493257
--- /dev/null
+++ b/vendor/google.golang.org/grpc/grpclog/loggerv2.go
@@ -0,0 +1,195 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpclog
+
+import (
+        "io"
+        "io/ioutil"
+        "log"
+        "os"
+        "strconv"
+)
+
+// LoggerV2 does underlying logging work for grpclog.
+type LoggerV2 interface {
+        // Info logs to INFO log. Arguments are handled in the manner of fmt.Print.
+        Info(args ...interface{})
+        // Infoln logs to INFO log. Arguments are handled in the manner of fmt.Println.
+        Infoln(args ...interface{})
+        // Infof logs to INFO log. Arguments are handled in the manner of fmt.Printf.
+        Infof(format string, args ...interface{})
+        // Warning logs to WARNING log. Arguments are handled in the manner of fmt.Print.
+        Warning(args ...interface{})
+        // Warningln logs to WARNING log. Arguments are handled in the manner of fmt.Println.
+        Warningln(args ...interface{})
+        // Warningf logs to WARNING log. Arguments are handled in the manner of fmt.Printf.
+        Warningf(format string, args ...interface{})
+        // Error logs to ERROR log. Arguments are handled in the manner of fmt.Print.
+        Error(args ...interface{})
+        // Errorln logs to ERROR log. Arguments are handled in the manner of fmt.Println.
+        Errorln(args ...interface{})
+        // Errorf logs to ERROR log. Arguments are handled in the manner of fmt.Printf.
+        Errorf(format string, args ...interface{})
+        // Fatal logs to ERROR log. Arguments are handled in the manner of fmt.Print.
+        // gRPC ensures that all Fatal logs will exit with os.Exit(1).
+        // Implementations may also call os.Exit() with a non-zero exit code.
+        Fatal(args ...interface{})
+        // Fatalln logs to ERROR log. Arguments are handled in the manner of fmt.Println.
+        // gRPC ensures that all Fatal logs will exit with os.Exit(1).
+        // Implementations may also call os.Exit() with a non-zero exit code.
+        Fatalln(args ...interface{})
+        // Fatalf logs to ERROR log. Arguments are handled in the manner of fmt.Printf.
+        // gRPC ensures that all Fatal logs will exit with os.Exit(1).
+        // Implementations may also call os.Exit() with a non-zero exit code.
+        Fatalf(format string, args ...interface{})
+        // V reports whether verbosity level l is at least the requested verbose level.
+        V(l int) bool
+}
+
+// SetLoggerV2 sets logger that is used in grpc to a V2 logger.
+// Not mutex-protected, should be called before any gRPC functions.
+func SetLoggerV2(l LoggerV2) {
+        logger = l
+}
+
+const (
+        // infoLog indicates Info severity.
+        infoLog int = iota
+        // warningLog indicates Warning severity.
+        warningLog
+        // errorLog indicates Error severity.
+        errorLog
+        // fatalLog indicates Fatal severity.
+        fatalLog
+)
+
+// severityName contains the string representation of each severity.
+var severityName = []string{
+        infoLog:    "INFO",
+        warningLog: "WARNING",
+        errorLog:   "ERROR",
+        fatalLog:   "FATAL",
+}
+
+// loggerT is the default logger used by grpclog.
+type loggerT struct {
+        m []*log.Logger
+        v int
+}
+
+// NewLoggerV2 creates a loggerV2 with the provided writers.
+// Fatal logs will be written to errorW, warningW, infoW, followed by exit(1).
+// Error logs will be written to errorW, warningW and infoW.
+// Warning logs will be written to warningW and infoW.
+// Info logs will be written to infoW.
+func NewLoggerV2(infoW, warningW, errorW io.Writer) LoggerV2 {
+        return NewLoggerV2WithVerbosity(infoW, warningW, errorW, 0)
+}
+
+// NewLoggerV2WithVerbosity creates a loggerV2 with the provided writers and
+// verbosity level.
+func NewLoggerV2WithVerbosity(infoW, warningW, errorW io.Writer, v int) LoggerV2 {
+        var m []*log.Logger
+        m = append(m, log.New(infoW, severityName[infoLog]+": ", log.LstdFlags))
+        m = append(m, log.New(io.MultiWriter(infoW, warningW), severityName[warningLog]+": ", log.LstdFlags))
+        ew := io.MultiWriter(infoW, warningW, errorW) // ew will be used for error and fatal.
+        m = append(m, log.New(ew, severityName[errorLog]+": ", log.LstdFlags))
+        m = append(m, log.New(ew, severityName[fatalLog]+": ", log.LstdFlags))
+        return &loggerT{m: m, v: v}
+}
+
+// newLoggerV2 creates a loggerV2 to be used as default logger.
+// All logs are written to stderr.
+func newLoggerV2() LoggerV2 {
+        errorW := ioutil.Discard
+        warningW := ioutil.Discard
+        infoW := ioutil.Discard
+
+        logLevel := os.Getenv("GRPC_GO_LOG_SEVERITY_LEVEL")
+        switch logLevel {
+        case "", "ERROR", "error": // If env is unset, set level to ERROR.
+                errorW = os.Stderr
+        case "WARNING", "warning":
+                warningW = os.Stderr
+        case "INFO", "info":
+                infoW = os.Stderr
+        }
+
+        var v int
+        vLevel := os.Getenv("GRPC_GO_LOG_VERBOSITY_LEVEL")
+        if vl, err := strconv.Atoi(vLevel); err == nil {
+                v = vl
+        }
+        return NewLoggerV2WithVerbosity(infoW, warningW, errorW, v)
+}
+
+func (g *loggerT) Info(args ...interface{}) {
+        g.m[infoLog].Print(args...)
+}
+
+func (g *loggerT) Infoln(args ...interface{}) {
+        g.m[infoLog].Println(args...)
+}
+
+func (g *loggerT) Infof(format string, args ...interface{}) {
+        g.m[infoLog].Printf(format, args...)
+}
+
+func (g *loggerT) Warning(args ...interface{}) {
+        g.m[warningLog].Print(args...)
+}
+
+func (g *loggerT) Warningln(args ...interface{}) {
+        g.m[warningLog].Println(args...)
+}
+
+func (g *loggerT) Warningf(format string, args ...interface{}) {
+        g.m[warningLog].Printf(format, args...)
+}
+
+func (g *loggerT) Error(args ...interface{}) {
+        g.m[errorLog].Print(args...)
+}
+
+func (g *loggerT) Errorln(args ...interface{}) {
+        g.m[errorLog].Println(args...)
+}
+
+func (g *loggerT) Errorf(format string, args ...interface{}) {
+        g.m[errorLog].Printf(format, args...)
+}
+
+func (g *loggerT) Fatal(args ...interface{}) {
+        g.m[fatalLog].Fatal(args...)
+        // No need to call os.Exit() again because log.Logger.Fatal() calls os.Exit().
+}
+
+func (g *loggerT) Fatalln(args ...interface{}) {
+        g.m[fatalLog].Fatalln(args...)
+        // No need to call os.Exit() again because log.Logger.Fatal() calls os.Exit().
+}
+
+func (g *loggerT) Fatalf(format string, args ...interface{}) {
+        g.m[fatalLog].Fatalf(format, args...)
+        // No need to call os.Exit() again because log.Logger.Fatal() calls os.Exit().
+}
+
+func (g *loggerT) V(l int) bool {
+        return l <= g.v
+}
diff --git a/vendor/google.golang.org/grpc/health/grpc_health_v1/health.pb.go b/vendor/google.golang.org/grpc/health/grpc_health_v1/health.pb.go
new file mode 100644
index 0000000..89c4d45
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/grpc_health_v1/health.pb.go
@@ -0,0 +1,176 @@
+// Code generated by protoc-gen-go.
+// source: health.proto
+// DO NOT EDIT!
+
+/*
+Package grpc_health_v1 is a generated protocol buffer package.
+
+It is generated from these files:
+        health.proto
+
+It has these top-level messages:
+        HealthCheckRequest
+        HealthCheckResponse
+*/
+package grpc_health_v1
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+import (
+        context "golang.org/x/net/context"
+        grpc "google.golang.org/grpc"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type HealthCheckResponse_ServingStatus int32
+
+const (
+        HealthCheckResponse_UNKNOWN     HealthCheckResponse_ServingStatus = 0
+        HealthCheckResponse_SERVING     HealthCheckResponse_ServingStatus = 1
+        HealthCheckResponse_NOT_SERVING HealthCheckResponse_ServingStatus = 2
+)
+
+var HealthCheckResponse_ServingStatus_name = map[int32]string{
+        0: "UNKNOWN",
+        1: "SERVING",
+        2: "NOT_SERVING",
+}
+var HealthCheckResponse_ServingStatus_value = map[string]int32{
+        "UNKNOWN":     0,
+        "SERVING":     1,
+        "NOT_SERVING": 2,
+}
+
+func (x HealthCheckResponse_ServingStatus) String() string {
+        return proto.EnumName(HealthCheckResponse_ServingStatus_name, int32(x))
+}
+func (HealthCheckResponse_ServingStatus) EnumDescriptor() ([]byte, []int) {
+        return fileDescriptor0, []int{1, 0}
+}
+
+type HealthCheckRequest struct {
+        Service string `protobuf:"bytes,1,opt,name=service" json:"service,omitempty"`
+}
+
+func (m *HealthCheckRequest) Reset()                    { *m = HealthCheckRequest{} }
+func (m *HealthCheckRequest) String() string            { return proto.CompactTextString(m) }
+func (*HealthCheckRequest) ProtoMessage()               {}
+func (*HealthCheckRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+type HealthCheckResponse struct {
+        Status HealthCheckResponse_ServingStatus `protobuf:"varint,1,opt,name=status,enum=grpc.health.v1.HealthCheckResponse_ServingStatus" json:"status,omitempty"`
+}
+
+func (m *HealthCheckResponse) Reset()                    { *m = HealthCheckResponse{} }
+func (m *HealthCheckResponse) String() string            { return proto.CompactTextString(m) }
+func (*HealthCheckResponse) ProtoMessage()               {}
+func (*HealthCheckResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
+
+func init() {
+        proto.RegisterType((*HealthCheckRequest)(nil), "grpc.health.v1.HealthCheckRequest")
+        proto.RegisterType((*HealthCheckResponse)(nil), "grpc.health.v1.HealthCheckResponse")
+        proto.RegisterEnum("grpc.health.v1.HealthCheckResponse_ServingStatus", HealthCheckResponse_ServingStatus_name, HealthCheckResponse_ServingStatus_value)
+}
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ context.Context
+var _ grpc.ClientConn
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+const _ = grpc.SupportPackageIsVersion4
+
+// Client API for Health service
+
+type HealthClient interface {
+        Check(ctx context.Context, in *HealthCheckRequest, opts ...grpc.CallOption) (*HealthCheckResponse, error)
+}
+
+type healthClient struct {
+        cc *grpc.ClientConn
+}
+
+func NewHealthClient(cc *grpc.ClientConn) HealthClient {
+        return &healthClient{cc}
+}
+
+func (c *healthClient) Check(ctx context.Context, in *HealthCheckRequest, opts ...grpc.CallOption) (*HealthCheckResponse, error) {
+        out := new(HealthCheckResponse)
+        err := grpc.Invoke(ctx, "/grpc.health.v1.Health/Check", in, out, c.cc, opts...)
+        if err != nil {
+                return nil, err
+        }
+        return out, nil
+}
+
+// Server API for Health service
+
+type HealthServer interface {
+        Check(context.Context, *HealthCheckRequest) (*HealthCheckResponse, error)
+}
+
+func RegisterHealthServer(s *grpc.Server, srv HealthServer) {
+        s.RegisterService(&_Health_serviceDesc, srv)
+}
+
+func _Health_Check_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+        in := new(HealthCheckRequest)
+        if err := dec(in); err != nil {
+                return nil, err
+        }
+        if interceptor == nil {
+                return srv.(HealthServer).Check(ctx, in)
+        }
+        info := &grpc.UnaryServerInfo{
+                Server:     srv,
+                FullMethod: "/grpc.health.v1.Health/Check",
+        }
+        handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+                return srv.(HealthServer).Check(ctx, req.(*HealthCheckRequest))
+        }
+        return interceptor(ctx, in, info, handler)
+}
+
+var _Health_serviceDesc = grpc.ServiceDesc{
+        ServiceName: "grpc.health.v1.Health",
+        HandlerType: (*HealthServer)(nil),
+        Methods: []grpc.MethodDesc{
+                {
+                        MethodName: "Check",
+                        Handler:    _Health_Check_Handler,
+                },
+        },
+        Streams:  []grpc.StreamDesc{},
+        Metadata: "health.proto",
+}
+
+func init() { proto.RegisterFile("health.proto", fileDescriptor0) }
+
+var fileDescriptor0 = []byte{
+        // 204 bytes of a gzipped FileDescriptorProto
+        0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0xe2, 0xe2, 0xc9, 0x48, 0x4d, 0xcc,
+        0x29, 0xc9, 0xd0, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x4b, 0x2f, 0x2a, 0x48, 0xd6, 0x83,
+        0x0a, 0x95, 0x19, 0x2a, 0xe9, 0x71, 0x09, 0x79, 0x80, 0x39, 0xce, 0x19, 0xa9, 0xc9, 0xd9, 0x41,
+        0xa9, 0x85, 0xa5, 0xa9, 0xc5, 0x25, 0x42, 0x12, 0x5c, 0xec, 0xc5, 0xa9, 0x45, 0x65, 0x99, 0xc9,
+        0xa9, 0x12, 0x8c, 0x0a, 0x8c, 0x1a, 0x9c, 0x41, 0x30, 0xae, 0xd2, 0x1c, 0x46, 0x2e, 0x61, 0x14,
+        0x0d, 0xc5, 0x05, 0xf9, 0x79, 0xc5, 0xa9, 0x42, 0x9e, 0x5c, 0x6c, 0xc5, 0x25, 0x89, 0x25, 0xa5,
+        0xc5, 0x60, 0x0d, 0x7c, 0x46, 0x86, 0x7a, 0xa8, 0x16, 0xe9, 0x61, 0xd1, 0xa4, 0x17, 0x0c, 0x32,
+        0x34, 0x2f, 0x3d, 0x18, 0xac, 0x31, 0x08, 0x6a, 0x80, 0x92, 0x15, 0x17, 0x2f, 0x8a, 0x84, 0x10,
+        0x37, 0x17, 0x7b, 0xa8, 0x9f, 0xb7, 0x9f, 0x7f, 0xb8, 0x9f, 0x00, 0x03, 0x88, 0x13, 0xec, 0x1a,
+        0x14, 0xe6, 0xe9, 0xe7, 0x2e, 0xc0, 0x28, 0xc4, 0xcf, 0xc5, 0xed, 0xe7, 0x1f, 0x12, 0x0f, 0x13,
+        0x60, 0x32, 0x8a, 0xe2, 0x62, 0x83, 0x58, 0x24, 0x14, 0xc0, 0xc5, 0x0a, 0xb6, 0x4c, 0x48, 0x09,
+        0xaf, 0x4b, 0xc0, 0xfe, 0x95, 0x52, 0x26, 0xc2, 0xb5, 0x49, 0x6c, 0xe0, 0x10, 0x34, 0x06, 0x04,
+        0x00, 0x00, 0xff, 0xff, 0xac, 0x56, 0x2a, 0xcb, 0x51, 0x01, 0x00, 0x00,
+}
diff --git a/vendor/google.golang.org/grpc/health/grpc_health_v1/health.proto b/vendor/google.golang.org/grpc/health/grpc_health_v1/health.proto
new file mode 100644
index 0000000..6072fdc
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/grpc_health_v1/health.proto
@@ -0,0 +1,34 @@
+// Copyright 2017 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package grpc.health.v1;
+
+message HealthCheckRequest {
+  string service = 1;
+}
+
+message HealthCheckResponse {
+  enum ServingStatus {
+        UNKNOWN = 0;
+        SERVING = 1;
+        NOT_SERVING = 2;
+  }
+  ServingStatus status = 1;
+}
+
+service Health{
+  rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
+} 
diff --git a/vendor/google.golang.org/grpc/health/health.go b/vendor/google.golang.org/grpc/health/health.go
new file mode 100644
index 0000000..4dccbc7
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/health.go
@@ -0,0 +1,70 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package health provides some utility functions to health-check a server. The implementation
+// is based on protobuf. Users need to write their own implementations if other IDLs are used.
+package health
+
+import (
+        "sync"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc"
+        "google.golang.org/grpc/codes"
+        healthpb "google.golang.org/grpc/health/grpc_health_v1"
+)
+
+// Server implements `service Health`.
+type Server struct {
+        mu sync.Mutex
+        // statusMap stores the serving status of the services this Server monitors.
+        statusMap map[string]healthpb.HealthCheckResponse_ServingStatus
+}
+
+// NewServer returns a new Server.
+func NewServer() *Server {
+        return &Server{
+                statusMap: make(map[string]healthpb.HealthCheckResponse_ServingStatus),
+        }
+}
+
+// Check implements `service Health`.
+func (s *Server) Check(ctx context.Context, in *healthpb.HealthCheckRequest) (*healthpb.HealthCheckResponse, error) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if in.Service == "" {
+                // check the server overall health status.
+                return &healthpb.HealthCheckResponse{
+                        Status: healthpb.HealthCheckResponse_SERVING,
+                }, nil
+        }
+        if status, ok := s.statusMap[in.Service]; ok {
+                return &healthpb.HealthCheckResponse{
+                        Status: status,
+                }, nil
+        }
+        return nil, grpc.Errorf(codes.NotFound, "unknown service")
+}
+
+// SetServingStatus is called when need to reset the serving status of a service
+// or insert a new service entry into the statusMap.
+func (s *Server) SetServingStatus(service string, status healthpb.HealthCheckResponse_ServingStatus) {
+        s.mu.Lock()
+        s.statusMap[service] = status
+        s.mu.Unlock()
+}
diff --git a/vendor/google.golang.org/grpc/interceptor.go b/vendor/google.golang.org/grpc/interceptor.go
new file mode 100644
index 0000000..06dc825
--- /dev/null
+++ b/vendor/google.golang.org/grpc/interceptor.go
@@ -0,0 +1,75 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "golang.org/x/net/context"
+)
+
+// UnaryInvoker is called by UnaryClientInterceptor to complete RPCs.
+type UnaryInvoker func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, opts ...CallOption) error
+
+// UnaryClientInterceptor intercepts the execution of a unary RPC on the client. invoker is the handler to complete the RPC
+// and it is the responsibility of the interceptor to call it.
+// This is an EXPERIMENTAL API.
+type UnaryClientInterceptor func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, invoker UnaryInvoker, opts ...CallOption) error
+
+// Streamer is called by StreamClientInterceptor to create a ClientStream.
+type Streamer func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (ClientStream, error)
+
+// StreamClientInterceptor intercepts the creation of ClientStream. It may return a custom ClientStream to intercept all I/O
+// operations. streamer is the handler to create a ClientStream and it is the responsibility of the interceptor to call it.
+// This is an EXPERIMENTAL API.
+type StreamClientInterceptor func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, streamer Streamer, opts ...CallOption) (ClientStream, error)
+
+// UnaryServerInfo consists of various information about a unary RPC on
+// server side. All per-rpc information may be mutated by the interceptor.
+type UnaryServerInfo struct {
+        // Server is the service implementation the user provides. This is read-only.
+        Server interface{}
+        // FullMethod is the full RPC method string, i.e., /package.service/method.
+        FullMethod string
+}
+
+// UnaryHandler defines the handler invoked by UnaryServerInterceptor to complete the normal
+// execution of a unary RPC.
+type UnaryHandler func(ctx context.Context, req interface{}) (interface{}, error)
+
+// UnaryServerInterceptor provides a hook to intercept the execution of a unary RPC on the server. info
+// contains all the information of this RPC the interceptor can operate on. And handler is the wrapper
+// of the service method implementation. It is the responsibility of the interceptor to invoke handler
+// to complete the RPC.
+type UnaryServerInterceptor func(ctx context.Context, req interface{}, info *UnaryServerInfo, handler UnaryHandler) (resp interface{}, err error)
+
+// StreamServerInfo consists of various information about a streaming RPC on
+// server side. All per-rpc information may be mutated by the interceptor.
+type StreamServerInfo struct {
+        // FullMethod is the full RPC method string, i.e., /package.service/method.
+        FullMethod string
+        // IsClientStream indicates whether the RPC is a client streaming RPC.
+        IsClientStream bool
+        // IsServerStream indicates whether the RPC is a server streaming RPC.
+        IsServerStream bool
+}
+
+// StreamServerInterceptor provides a hook to intercept the execution of a streaming RPC on the server.
+// info contains all the information of this RPC the interceptor can operate on. And handler is the
+// service method implementation. It is the responsibility of the interceptor to invoke handler to
+// complete the RPC.
+type StreamServerInterceptor func(srv interface{}, ss ServerStream, info *StreamServerInfo, handler StreamHandler) error
diff --git a/vendor/google.golang.org/grpc/internal/internal.go b/vendor/google.golang.org/grpc/internal/internal.go
new file mode 100644
index 0000000..0708383
--- /dev/null
+++ b/vendor/google.golang.org/grpc/internal/internal.go
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package internal contains gRPC-internal code for testing, to avoid polluting
+// the godoc of the top-level grpc package.
+package internal
+
+// TestingCloseConns closes all existing transports but keeps
+// grpcServer.lis accepting new connections.
+//
+// The provided grpcServer must be of type *grpc.Server. It is untyped
+// for circular dependency reasons.
+var TestingCloseConns func(grpcServer interface{})
+
+// TestingUseHandlerImpl enables the http.Handler-based server implementation.
+// It must be called before Serve and requires TLS credentials.
+//
+// The provided grpcServer must be of type *grpc.Server. It is untyped
+// for circular dependency reasons.
+var TestingUseHandlerImpl func(grpcServer interface{})
diff --git a/vendor/google.golang.org/grpc/keepalive/keepalive.go b/vendor/google.golang.org/grpc/keepalive/keepalive.go
new file mode 100644
index 0000000..f8adc7e
--- /dev/null
+++ b/vendor/google.golang.org/grpc/keepalive/keepalive.go
@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package keepalive defines configurable parameters for point-to-point healthcheck.
+package keepalive
+
+import (
+        "time"
+)
+
+// ClientParameters is used to set keepalive parameters on the client-side.
+// These configure how the client will actively probe to notice when a connection is broken
+// and send pings so intermediaries will be aware of the liveness of the connection.
+// Make sure these parameters are set in coordination with the keepalive policy on the server,
+// as incompatible settings can result in closing of connection.
+type ClientParameters struct {
+        // After a duration of this time if the client doesn't see any activity it pings the server to see if the transport is still alive.
+        Time time.Duration // The current default value is infinity.
+        // After having pinged for keepalive check, the client waits for a duration of Timeout and if no activity is seen even after that
+        // the connection is closed.
+        Timeout time.Duration // The current default value is 20 seconds.
+        // If true, client runs keepalive checks even with no active RPCs.
+        PermitWithoutStream bool // false by default.
+}
+
+// ServerParameters is used to set keepalive and max-age parameters on the server-side.
+type ServerParameters struct {
+        // MaxConnectionIdle is a duration for the amount of time after which an idle connection would be closed by sending a GoAway.
+        // Idleness duration is defined since the most recent time the number of outstanding RPCs became zero or the connection establishment.
+        MaxConnectionIdle time.Duration // The current default value is infinity.
+        // MaxConnectionAge is a duration for the maximum amount of time a connection may exist before it will be closed by sending a GoAway.
+        // A random jitter of +/-10% will be added to MaxConnectionAge to spread out connection storms.
+        MaxConnectionAge time.Duration // The current default value is infinity.
+        // MaxConnectinoAgeGrace is an additive period after MaxConnectionAge after which the connection will be forcibly closed.
+        MaxConnectionAgeGrace time.Duration // The current default value is infinity.
+        // After a duration of this time if the server doesn't see any activity it pings the client to see if the transport is still alive.
+        Time time.Duration // The current default value is 2 hours.
+        // After having pinged for keepalive check, the server waits for a duration of Timeout and if no activity is seen even after that
+        // the connection is closed.
+        Timeout time.Duration // The current default value is 20 seconds.
+}
+
+// EnforcementPolicy is used to set keepalive enforcement policy on the server-side.
+// Server will close connection with a client that violates this policy.
+type EnforcementPolicy struct {
+        // MinTime is the minimum amount of time a client should wait before sending a keepalive ping.
+        MinTime time.Duration // The current default value is 5 minutes.
+        // If true, server expects keepalive pings even when there are no active streams(RPCs).
+        PermitWithoutStream bool // false by default.
+}
diff --git a/vendor/google.golang.org/grpc/metadata/metadata.go b/vendor/google.golang.org/grpc/metadata/metadata.go
new file mode 100644
index 0000000..be4f9e7
--- /dev/null
+++ b/vendor/google.golang.org/grpc/metadata/metadata.go
@@ -0,0 +1,141 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package metadata define the structure of the metadata supported by gRPC library.
+// Please refer to https://grpc.io/docs/guides/wire.html for more information about custom-metadata.
+package metadata // import "google.golang.org/grpc/metadata"
+
+import (
+        "fmt"
+        "strings"
+
+        "golang.org/x/net/context"
+)
+
+// DecodeKeyValue returns k, v, nil.  It is deprecated and should not be used.
+func DecodeKeyValue(k, v string) (string, string, error) {
+        return k, v, nil
+}
+
+// MD is a mapping from metadata keys to values. Users should use the following
+// two convenience functions New and Pairs to generate MD.
+type MD map[string][]string
+
+// New creates an MD from a given key-value map.
+//
+// Only the following ASCII characters are allowed in keys:
+//  - digits: 0-9
+//  - uppercase letters: A-Z (normalized to lower)
+//  - lowercase letters: a-z
+//  - special characters: -_.
+// Uppercase letters are automatically converted to lowercase.
+func New(m map[string]string) MD {
+        md := MD{}
+        for k, val := range m {
+                key := strings.ToLower(k)
+                md[key] = append(md[key], val)
+        }
+        return md
+}
+
+// Pairs returns an MD formed by the mapping of key, value ...
+// Pairs panics if len(kv) is odd.
+//
+// Only the following ASCII characters are allowed in keys:
+//  - digits: 0-9
+//  - uppercase letters: A-Z (normalized to lower)
+//  - lowercase letters: a-z
+//  - special characters: -_.
+// Uppercase letters are automatically converted to lowercase.
+func Pairs(kv ...string) MD {
+        if len(kv)%2 == 1 {
+                panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
+        }
+        md := MD{}
+        var key string
+        for i, s := range kv {
+                if i%2 == 0 {
+                        key = strings.ToLower(s)
+                        continue
+                }
+                md[key] = append(md[key], s)
+        }
+        return md
+}
+
+// Len returns the number of items in md.
+func (md MD) Len() int {
+        return len(md)
+}
+
+// Copy returns a copy of md.
+func (md MD) Copy() MD {
+        return Join(md)
+}
+
+// Join joins any number of mds into a single MD.
+// The order of values for each key is determined by the order in which
+// the mds containing those values are presented to Join.
+func Join(mds ...MD) MD {
+        out := MD{}
+        for _, md := range mds {
+                for k, v := range md {
+                        out[k] = append(out[k], v...)
+                }
+        }
+        return out
+}
+
+type mdIncomingKey struct{}
+type mdOutgoingKey struct{}
+
+// NewContext is a wrapper for NewOutgoingContext(ctx, md).  Deprecated.
+func NewContext(ctx context.Context, md MD) context.Context {
+        return NewOutgoingContext(ctx, md)
+}
+
+// NewIncomingContext creates a new context with incoming md attached.
+func NewIncomingContext(ctx context.Context, md MD) context.Context {
+        return context.WithValue(ctx, mdIncomingKey{}, md)
+}
+
+// NewOutgoingContext creates a new context with outgoing md attached.
+func NewOutgoingContext(ctx context.Context, md MD) context.Context {
+        return context.WithValue(ctx, mdOutgoingKey{}, md)
+}
+
+// FromContext is a wrapper for FromIncomingContext(ctx).  Deprecated.
+func FromContext(ctx context.Context) (md MD, ok bool) {
+        return FromIncomingContext(ctx)
+}
+
+// FromIncomingContext returns the incoming metadata in ctx if it exists.  The
+// returned MD should not be modified. Writing to it may cause races.
+// Modification should be made to copies of the returned MD.
+func FromIncomingContext(ctx context.Context) (md MD, ok bool) {
+        md, ok = ctx.Value(mdIncomingKey{}).(MD)
+        return
+}
+
+// FromOutgoingContext returns the outgoing metadata in ctx if it exists.  The
+// returned MD should not be modified. Writing to it may cause races.
+// Modification should be made to the copies of the returned MD.
+func FromOutgoingContext(ctx context.Context) (md MD, ok bool) {
+        md, ok = ctx.Value(mdOutgoingKey{}).(MD)
+        return
+}
diff --git a/vendor/google.golang.org/grpc/naming/dns_resolver.go b/vendor/google.golang.org/grpc/naming/dns_resolver.go
new file mode 100644
index 0000000..efd37e3
--- /dev/null
+++ b/vendor/google.golang.org/grpc/naming/dns_resolver.go
@@ -0,0 +1,292 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package naming
+
+import (
+        "errors"
+        "fmt"
+        "net"
+        "strconv"
+        "time"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/grpclog"
+)
+
+const (
+        defaultPort = "443"
+        defaultFreq = time.Minute * 30
+)
+
+var (
+        errMissingAddr  = errors.New("missing address")
+        errWatcherClose = errors.New("watcher has been closed")
+)
+
+// NewDNSResolverWithFreq creates a DNS Resolver that can resolve DNS names, and
+// create watchers that poll the DNS server using the frequency set by freq.
+func NewDNSResolverWithFreq(freq time.Duration) (Resolver, error) {
+        return &dnsResolver{freq: freq}, nil
+}
+
+// NewDNSResolver creates a DNS Resolver that can resolve DNS names, and create
+// watchers that poll the DNS server using the default frequency defined by defaultFreq.
+func NewDNSResolver() (Resolver, error) {
+        return NewDNSResolverWithFreq(defaultFreq)
+}
+
+// dnsResolver handles name resolution for names following the DNS scheme
+type dnsResolver struct {
+        // frequency of polling the DNS server that the watchers created by this resolver will use.
+        freq time.Duration
+}
+
+// formatIP returns ok = false if addr is not a valid textual representation of an IP address.
+// If addr is an IPv4 address, return the addr and ok = true.
+// If addr is an IPv6 address, return the addr enclosed in square brackets and ok = true.
+func formatIP(addr string) (addrIP string, ok bool) {
+        ip := net.ParseIP(addr)
+        if ip == nil {
+                return "", false
+        }
+        if ip.To4() != nil {
+                return addr, true
+        }
+        return "[" + addr + "]", true
+}
+
+// parseTarget takes the user input target string, returns formatted host and port info.
+// If target doesn't specify a port, set the port to be the defaultPort.
+// If target is in IPv6 format and host-name is enclosed in sqarue brackets, brackets
+// are strippd when setting the host.
+// examples:
+// target: "www.google.com" returns host: "www.google.com", port: "443"
+// target: "ipv4-host:80" returns host: "ipv4-host", port: "80"
+// target: "[ipv6-host]" returns host: "ipv6-host", port: "443"
+// target: ":80" returns host: "localhost", port: "80"
+// target: ":" returns host: "localhost", port: "443"
+func parseTarget(target string) (host, port string, err error) {
+        if target == "" {
+                return "", "", errMissingAddr
+        }
+
+        if ip := net.ParseIP(target); ip != nil {
+                // target is an IPv4 or IPv6(without brackets) address
+                return target, defaultPort, nil
+        }
+        if host, port, err := net.SplitHostPort(target); err == nil {
+                // target has port, i.e ipv4-host:port, [ipv6-host]:port, host-name:port
+                if host == "" {
+                        // Keep consistent with net.Dial(): If the host is empty, as in ":80", the local system is assumed.
+                        host = "localhost"
+                }
+                if port == "" {
+                        // If the port field is empty(target ends with colon), e.g. "[::1]:", defaultPort is used.
+                        port = defaultPort
+                }
+                return host, port, nil
+        }
+        if host, port, err := net.SplitHostPort(target + ":" + defaultPort); err == nil {
+                // target doesn't have port
+                return host, port, nil
+        }
+        return "", "", fmt.Errorf("invalid target address %v", target)
+}
+
+// Resolve creates a watcher that watches the name resolution of the target.
+func (r *dnsResolver) Resolve(target string) (Watcher, error) {
+        host, port, err := parseTarget(target)
+        if err != nil {
+                return nil, err
+        }
+
+        if net.ParseIP(host) != nil {
+                ipWatcher := &ipWatcher{
+                        updateChan: make(chan *Update, 1),
+                }
+                host, _ = formatIP(host)
+                ipWatcher.updateChan <- &Update{Op: Add, Addr: host + ":" + port}
+                return ipWatcher, nil
+        }
+
+        ctx, cancel := context.WithCancel(context.Background())
+        return &dnsWatcher{
+                r:      r,
+                host:   host,
+                port:   port,
+                ctx:    ctx,
+                cancel: cancel,
+                t:      time.NewTimer(0),
+        }, nil
+}
+
+// dnsWatcher watches for the name resolution update for a specific target
+type dnsWatcher struct {
+        r    *dnsResolver
+        host string
+        port string
+        // The latest resolved address list
+        curAddrs []*Update
+        ctx      context.Context
+        cancel   context.CancelFunc
+        t        *time.Timer
+}
+
+// ipWatcher watches for the name resolution update for an IP address.
+type ipWatcher struct {
+        updateChan chan *Update
+}
+
+// Next returns the adrress resolution Update for the target. For IP address,
+// the resolution is itself, thus polling name server is unncessary. Therefore,
+// Next() will return an Update the first time it is called, and will be blocked
+// for all following calls as no Update exisits until watcher is closed.
+func (i *ipWatcher) Next() ([]*Update, error) {
+        u, ok := <-i.updateChan
+        if !ok {
+                return nil, errWatcherClose
+        }
+        return []*Update{u}, nil
+}
+
+// Close closes the ipWatcher.
+func (i *ipWatcher) Close() {
+        close(i.updateChan)
+}
+
+// AddressType indicates the address type returned by name resolution.
+type AddressType uint8
+
+const (
+        // Backend indicates the server is a backend server.
+        Backend AddressType = iota
+        // GRPCLB indicates the server is a grpclb load balancer.
+        GRPCLB
+)
+
+// AddrMetadataGRPCLB contains the information the name resolver for grpclb should provide. The
+// name resolver used by the grpclb balancer is required to provide this type of metadata in
+// its address updates.
+type AddrMetadataGRPCLB struct {
+        // AddrType is the type of server (grpc load balancer or backend).
+        AddrType AddressType
+        // ServerName is the name of the grpc load balancer. Used for authentication.
+        ServerName string
+}
+
+// compileUpdate compares the old resolved addresses and newly resolved addresses,
+// and generates an update list
+func (w *dnsWatcher) compileUpdate(newAddrs []*Update) []*Update {
+        update := make(map[Update]bool)
+        for _, u := range newAddrs {
+                update[*u] = true
+        }
+        for _, u := range w.curAddrs {
+                if _, ok := update[*u]; ok {
+                        delete(update, *u)
+                        continue
+                }
+                update[Update{Addr: u.Addr, Op: Delete, Metadata: u.Metadata}] = true
+        }
+        res := make([]*Update, 0, len(update))
+        for k := range update {
+                tmp := k
+                res = append(res, &tmp)
+        }
+        return res
+}
+
+func (w *dnsWatcher) lookupSRV() []*Update {
+        var newAddrs []*Update
+        _, srvs, err := lookupSRV(w.ctx, "grpclb", "tcp", w.host)
+        if err != nil {
+                grpclog.Infof("grpc: failed dns SRV record lookup due to %v.\n", err)
+                return nil
+        }
+        for _, s := range srvs {
+                lbAddrs, err := lookupHost(w.ctx, s.Target)
+                if err != nil {
+                        grpclog.Warningf("grpc: failed load banlacer address dns lookup due to %v.\n", err)
+                        continue
+                }
+                for _, a := range lbAddrs {
+                        a, ok := formatIP(a)
+                        if !ok {
+                                grpclog.Errorf("grpc: failed IP parsing due to %v.\n", err)
+                                continue
+                        }
+                        newAddrs = append(newAddrs, &Update{Addr: a + ":" + strconv.Itoa(int(s.Port)),
+                                Metadata: AddrMetadataGRPCLB{AddrType: GRPCLB, ServerName: s.Target}})
+                }
+        }
+        return newAddrs
+}
+
+func (w *dnsWatcher) lookupHost() []*Update {
+        var newAddrs []*Update
+        addrs, err := lookupHost(w.ctx, w.host)
+        if err != nil {
+                grpclog.Warningf("grpc: failed dns A record lookup due to %v.\n", err)
+                return nil
+        }
+        for _, a := range addrs {
+                a, ok := formatIP(a)
+                if !ok {
+                        grpclog.Errorf("grpc: failed IP parsing due to %v.\n", err)
+                        continue
+                }
+                newAddrs = append(newAddrs, &Update{Addr: a + ":" + w.port})
+        }
+        return newAddrs
+}
+
+func (w *dnsWatcher) lookup() []*Update {
+        newAddrs := w.lookupSRV()
+        if newAddrs == nil {
+                // If failed to get any balancer address (either no corresponding SRV for the
+                // target, or caused by failure during resolution/parsing of the balancer target),
+                // return any A record info available.
+                newAddrs = w.lookupHost()
+        }
+        result := w.compileUpdate(newAddrs)
+        w.curAddrs = newAddrs
+        return result
+}
+
+// Next returns the resolved address update(delta) for the target. If there's no
+// change, it will sleep for 30 mins and try to resolve again after that.
+func (w *dnsWatcher) Next() ([]*Update, error) {
+        for {
+                select {
+                case <-w.ctx.Done():
+                        return nil, errWatcherClose
+                case <-w.t.C:
+                }
+                result := w.lookup()
+                // Next lookup should happen after an interval defined by w.r.freq.
+                w.t.Reset(w.r.freq)
+                if len(result) > 0 {
+                        return result, nil
+                }
+        }
+}
+
+func (w *dnsWatcher) Close() {
+        w.cancel()
+}
diff --git a/vendor/google.golang.org/grpc/naming/go17.go b/vendor/google.golang.org/grpc/naming/go17.go
new file mode 100644
index 0000000..a537b08
--- /dev/null
+++ b/vendor/google.golang.org/grpc/naming/go17.go
@@ -0,0 +1,34 @@
+// +build go1.6, !go1.8
+
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package naming
+
+import (
+        "net"
+
+        "golang.org/x/net/context"
+)
+
+var (
+        lookupHost = func(ctx context.Context, host string) ([]string, error) { return net.LookupHost(host) }
+        lookupSRV  = func(ctx context.Context, service, proto, name string) (string, []*net.SRV, error) {
+                return net.LookupSRV(service, proto, name)
+        }
+)
diff --git a/vendor/google.golang.org/grpc/naming/go18.go b/vendor/google.golang.org/grpc/naming/go18.go
new file mode 100644
index 0000000..b5a0f84
--- /dev/null
+++ b/vendor/google.golang.org/grpc/naming/go18.go
@@ -0,0 +1,28 @@
+// +build go1.8
+
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package naming
+
+import "net"
+
+var (
+        lookupHost = net.DefaultResolver.LookupHost
+        lookupSRV  = net.DefaultResolver.LookupSRV
+)
diff --git a/vendor/google.golang.org/grpc/naming/naming.go b/vendor/google.golang.org/grpc/naming/naming.go
new file mode 100644
index 0000000..1af7e32
--- /dev/null
+++ b/vendor/google.golang.org/grpc/naming/naming.go
@@ -0,0 +1,59 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package naming defines the naming API and related data structures for gRPC.
+// The interface is EXPERIMENTAL and may be suject to change.
+package naming
+
+// Operation defines the corresponding operations for a name resolution change.
+type Operation uint8
+
+const (
+        // Add indicates a new address is added.
+        Add Operation = iota
+        // Delete indicates an exisiting address is deleted.
+        Delete
+)
+
+// Update defines a name resolution update. Notice that it is not valid having both
+// empty string Addr and nil Metadata in an Update.
+type Update struct {
+        // Op indicates the operation of the update.
+        Op Operation
+        // Addr is the updated address. It is empty string if there is no address update.
+        Addr string
+        // Metadata is the updated metadata. It is nil if there is no metadata update.
+        // Metadata is not required for a custom naming implementation.
+        Metadata interface{}
+}
+
+// Resolver creates a Watcher for a target to track its resolution changes.
+type Resolver interface {
+        // Resolve creates a Watcher for target.
+        Resolve(target string) (Watcher, error)
+}
+
+// Watcher watches for the updates on the specified target.
+type Watcher interface {
+        // Next blocks until an update or error happens. It may return one or more
+        // updates. The first call should get the full set of the results. It should
+        // return an error if and only if Watcher cannot recover.
+        Next() ([]*Update, error)
+        // Close closes the Watcher.
+        Close()
+}
diff --git a/vendor/google.golang.org/grpc/peer/peer.go b/vendor/google.golang.org/grpc/peer/peer.go
new file mode 100644
index 0000000..317b8b9
--- /dev/null
+++ b/vendor/google.golang.org/grpc/peer/peer.go
@@ -0,0 +1,51 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package peer defines various peer information associated with RPCs and
+// corresponding utils.
+package peer
+
+import (
+        "net"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/credentials"
+)
+
+// Peer contains the information of the peer for an RPC, such as the address
+// and authentication information.
+type Peer struct {
+        // Addr is the peer address.
+        Addr net.Addr
+        // AuthInfo is the authentication information of the transport.
+        // It is nil if there is no transport security being used.
+        AuthInfo credentials.AuthInfo
+}
+
+type peerKey struct{}
+
+// NewContext creates a new context with peer information attached.
+func NewContext(ctx context.Context, p *Peer) context.Context {
+        return context.WithValue(ctx, peerKey{}, p)
+}
+
+// FromContext returns the peer information in ctx if it exists.
+func FromContext(ctx context.Context) (p *Peer, ok bool) {
+        p, ok = ctx.Value(peerKey{}).(*Peer)
+        return
+}
diff --git a/vendor/google.golang.org/grpc/proxy.go b/vendor/google.golang.org/grpc/proxy.go
new file mode 100644
index 0000000..2d40236
--- /dev/null
+++ b/vendor/google.golang.org/grpc/proxy.go
@@ -0,0 +1,130 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "bufio"
+        "errors"
+        "fmt"
+        "io"
+        "net"
+        "net/http"
+        "net/http/httputil"
+        "net/url"
+
+        "golang.org/x/net/context"
+)
+
+var (
+        // errDisabled indicates that proxy is disabled for the address.
+        errDisabled = errors.New("proxy is disabled for the address")
+        // The following variable will be overwritten in the tests.
+        httpProxyFromEnvironment = http.ProxyFromEnvironment
+)
+
+func mapAddress(ctx context.Context, address string) (string, error) {
+        req := &http.Request{
+                URL: &url.URL{
+                        Scheme: "https",
+                        Host:   address,
+                },
+        }
+        url, err := httpProxyFromEnvironment(req)
+        if err != nil {
+                return "", err
+        }
+        if url == nil {
+                return "", errDisabled
+        }
+        return url.Host, nil
+}
+
+// To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
+// It's possible that this reader reads more than what's need for the response and stores
+// those bytes in the buffer.
+// bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the
+// bytes in the buffer.
+type bufConn struct {
+        net.Conn
+        r io.Reader
+}
+
+func (c *bufConn) Read(b []byte) (int, error) {
+        return c.r.Read(b)
+}
+
+func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, addr string) (_ net.Conn, err error) {
+        defer func() {
+                if err != nil {
+                        conn.Close()
+                }
+        }()
+
+        req := (&http.Request{
+                Method: http.MethodConnect,
+                URL:    &url.URL{Host: addr},
+                Header: map[string][]string{"User-Agent": {grpcUA}},
+        })
+
+        if err := sendHTTPRequest(ctx, req, conn); err != nil {
+                return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
+        }
+
+        r := bufio.NewReader(conn)
+        resp, err := http.ReadResponse(r, req)
+        if err != nil {
+                return nil, fmt.Errorf("reading server HTTP response: %v", err)
+        }
+        defer resp.Body.Close()
+        if resp.StatusCode != http.StatusOK {
+                dump, err := httputil.DumpResponse(resp, true)
+                if err != nil {
+                        return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status)
+                }
+                return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
+        }
+
+        return &bufConn{Conn: conn, r: r}, nil
+}
+
+// newProxyDialer returns a dialer that connects to proxy first if necessary.
+// The returned dialer checks if a proxy is necessary, dial to the proxy with the
+// provided dialer, does HTTP CONNECT handshake and returns the connection.
+func newProxyDialer(dialer func(context.Context, string) (net.Conn, error)) func(context.Context, string) (net.Conn, error) {
+        return func(ctx context.Context, addr string) (conn net.Conn, err error) {
+                var skipHandshake bool
+                newAddr, err := mapAddress(ctx, addr)
+                if err != nil {
+                        if err != errDisabled {
+                                return nil, err
+                        }
+                        skipHandshake = true
+                        newAddr = addr
+                }
+
+                conn, err = dialer(ctx, newAddr)
+                if err != nil {
+                        return
+                }
+                if !skipHandshake {
+                        conn, err = doHTTPConnectHandshake(ctx, conn, addr)
+                }
+                return
+        }
+}
diff --git a/vendor/google.golang.org/grpc/rpc_util.go b/vendor/google.golang.org/grpc/rpc_util.go
new file mode 100644
index 0000000..9b9d388
--- /dev/null
+++ b/vendor/google.golang.org/grpc/rpc_util.go
@@ -0,0 +1,524 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "bytes"
+        "compress/gzip"
+        "encoding/binary"
+        "io"
+        "io/ioutil"
+        "math"
+        "sync"
+        "time"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/peer"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/transport"
+)
+
+// Compressor defines the interface gRPC uses to compress a message.
+type Compressor interface {
+        // Do compresses p into w.
+        Do(w io.Writer, p []byte) error
+        // Type returns the compression algorithm the Compressor uses.
+        Type() string
+}
+
+type gzipCompressor struct {
+        pool sync.Pool
+}
+
+// NewGZIPCompressor creates a Compressor based on GZIP.
+func NewGZIPCompressor() Compressor {
+        return &gzipCompressor{
+                pool: sync.Pool{
+                        New: func() interface{} {
+                                return gzip.NewWriter(ioutil.Discard)
+                        },
+                },
+        }
+}
+
+func (c *gzipCompressor) Do(w io.Writer, p []byte) error {
+        z := c.pool.Get().(*gzip.Writer)
+        z.Reset(w)
+        if _, err := z.Write(p); err != nil {
+                return err
+        }
+        return z.Close()
+}
+
+func (c *gzipCompressor) Type() string {
+        return "gzip"
+}
+
+// Decompressor defines the interface gRPC uses to decompress a message.
+type Decompressor interface {
+        // Do reads the data from r and uncompress them.
+        Do(r io.Reader) ([]byte, error)
+        // Type returns the compression algorithm the Decompressor uses.
+        Type() string
+}
+
+type gzipDecompressor struct {
+        pool sync.Pool
+}
+
+// NewGZIPDecompressor creates a Decompressor based on GZIP.
+func NewGZIPDecompressor() Decompressor {
+        return &gzipDecompressor{}
+}
+
+func (d *gzipDecompressor) Do(r io.Reader) ([]byte, error) {
+        var z *gzip.Reader
+        switch maybeZ := d.pool.Get().(type) {
+        case nil:
+                newZ, err := gzip.NewReader(r)
+                if err != nil {
+                        return nil, err
+                }
+                z = newZ
+        case *gzip.Reader:
+                z = maybeZ
+                if err := z.Reset(r); err != nil {
+                        d.pool.Put(z)
+                        return nil, err
+                }
+        }
+
+        defer func() {
+                z.Close()
+                d.pool.Put(z)
+        }()
+        return ioutil.ReadAll(z)
+}
+
+func (d *gzipDecompressor) Type() string {
+        return "gzip"
+}
+
+// callInfo contains all related configuration and information about an RPC.
+type callInfo struct {
+        failFast              bool
+        headerMD              metadata.MD
+        trailerMD             metadata.MD
+        peer                  *peer.Peer
+        traceInfo             traceInfo // in trace.go
+        maxReceiveMessageSize *int
+        maxSendMessageSize    *int
+        creds                 credentials.PerRPCCredentials
+}
+
+var defaultCallInfo = callInfo{failFast: true}
+
+// CallOption configures a Call before it starts or extracts information from
+// a Call after it completes.
+type CallOption interface {
+        // before is called before the call is sent to any server.  If before
+        // returns a non-nil error, the RPC fails with that error.
+        before(*callInfo) error
+
+        // after is called after the call has completed.  after cannot return an
+        // error, so any failures should be reported via output parameters.
+        after(*callInfo)
+}
+
+// EmptyCallOption does not alter the Call configuration.
+// It can be embedded in another structure to carry satellite data for use
+// by interceptors.
+type EmptyCallOption struct{}
+
+func (EmptyCallOption) before(*callInfo) error { return nil }
+func (EmptyCallOption) after(*callInfo)        {}
+
+type beforeCall func(c *callInfo) error
+
+func (o beforeCall) before(c *callInfo) error { return o(c) }
+func (o beforeCall) after(c *callInfo)        {}
+
+type afterCall func(c *callInfo)
+
+func (o afterCall) before(c *callInfo) error { return nil }
+func (o afterCall) after(c *callInfo)        { o(c) }
+
+// Header returns a CallOptions that retrieves the header metadata
+// for a unary RPC.
+func Header(md *metadata.MD) CallOption {
+        return afterCall(func(c *callInfo) {
+                *md = c.headerMD
+        })
+}
+
+// Trailer returns a CallOptions that retrieves the trailer metadata
+// for a unary RPC.
+func Trailer(md *metadata.MD) CallOption {
+        return afterCall(func(c *callInfo) {
+                *md = c.trailerMD
+        })
+}
+
+// Peer returns a CallOption that retrieves peer information for a
+// unary RPC.
+func Peer(peer *peer.Peer) CallOption {
+        return afterCall(func(c *callInfo) {
+                if c.peer != nil {
+                        *peer = *c.peer
+                }
+        })
+}
+
+// FailFast configures the action to take when an RPC is attempted on broken
+// connections or unreachable servers. If failfast is true, the RPC will fail
+// immediately. Otherwise, the RPC client will block the call until a
+// connection is available (or the call is canceled or times out) and will retry
+// the call if it fails due to a transient error. Please refer to
+// https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md.
+// Note: failFast is default to true.
+func FailFast(failFast bool) CallOption {
+        return beforeCall(func(c *callInfo) error {
+                c.failFast = failFast
+                return nil
+        })
+}
+
+// MaxCallRecvMsgSize returns a CallOption which sets the maximum message size the client can receive.
+func MaxCallRecvMsgSize(s int) CallOption {
+        return beforeCall(func(o *callInfo) error {
+                o.maxReceiveMessageSize = &s
+                return nil
+        })
+}
+
+// MaxCallSendMsgSize returns a CallOption which sets the maximum message size the client can send.
+func MaxCallSendMsgSize(s int) CallOption {
+        return beforeCall(func(o *callInfo) error {
+                o.maxSendMessageSize = &s
+                return nil
+        })
+}
+
+// PerRPCCredentials returns a CallOption that sets credentials.PerRPCCredentials
+// for a call.
+func PerRPCCredentials(creds credentials.PerRPCCredentials) CallOption {
+        return beforeCall(func(c *callInfo) error {
+                c.creds = creds
+                return nil
+        })
+}
+
+// The format of the payload: compressed or not?
+type payloadFormat uint8
+
+const (
+        compressionNone payloadFormat = iota // no compression
+        compressionMade
+)
+
+// parser reads complete gRPC messages from the underlying reader.
+type parser struct {
+        // r is the underlying reader.
+        // See the comment on recvMsg for the permissible
+        // error types.
+        r io.Reader
+
+        // The header of a gRPC message. Find more detail
+        // at https://grpc.io/docs/guides/wire.html.
+        header [5]byte
+}
+
+// recvMsg reads a complete gRPC message from the stream.
+//
+// It returns the message and its payload (compression/encoding)
+// format. The caller owns the returned msg memory.
+//
+// If there is an error, possible values are:
+//   * io.EOF, when no messages remain
+//   * io.ErrUnexpectedEOF
+//   * of type transport.ConnectionError
+//   * of type transport.StreamError
+// No other error values or types must be returned, which also means
+// that the underlying io.Reader must not return an incompatible
+// error.
+func (p *parser) recvMsg(maxReceiveMessageSize int) (pf payloadFormat, msg []byte, err error) {
+        if _, err := p.r.Read(p.header[:]); err != nil {
+                return 0, nil, err
+        }
+
+        pf = payloadFormat(p.header[0])
+        length := binary.BigEndian.Uint32(p.header[1:])
+
+        if length == 0 {
+                return pf, nil, nil
+        }
+        if length > uint32(maxReceiveMessageSize) {
+                return 0, nil, Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", length, maxReceiveMessageSize)
+        }
+        // TODO(bradfitz,zhaoq): garbage. reuse buffer after proto decoding instead
+        // of making it for each message:
+        msg = make([]byte, int(length))
+        if _, err := p.r.Read(msg); err != nil {
+                if err == io.EOF {
+                        err = io.ErrUnexpectedEOF
+                }
+                return 0, nil, err
+        }
+        return pf, msg, nil
+}
+
+// encode serializes msg and prepends the message header. If msg is nil, it
+// generates the message header of 0 message length.
+func encode(c Codec, msg interface{}, cp Compressor, cbuf *bytes.Buffer, outPayload *stats.OutPayload) ([]byte, error) {
+        var (
+                b      []byte
+                length uint
+        )
+        if msg != nil {
+                var err error
+                // TODO(zhaoq): optimize to reduce memory alloc and copying.
+                b, err = c.Marshal(msg)
+                if err != nil {
+                        return nil, Errorf(codes.Internal, "grpc: error while marshaling: %v", err.Error())
+                }
+                if outPayload != nil {
+                        outPayload.Payload = msg
+                        // TODO truncate large payload.
+                        outPayload.Data = b
+                        outPayload.Length = len(b)
+                }
+                if cp != nil {
+                        if err := cp.Do(cbuf, b); err != nil {
+                                return nil, Errorf(codes.Internal, "grpc: error while compressing: %v", err.Error())
+                        }
+                        b = cbuf.Bytes()
+                }
+                length = uint(len(b))
+        }
+        if length > math.MaxUint32 {
+                return nil, Errorf(codes.ResourceExhausted, "grpc: message too large (%d bytes)", length)
+        }
+
+        const (
+                payloadLen = 1
+                sizeLen    = 4
+        )
+
+        var buf = make([]byte, payloadLen+sizeLen+len(b))
+
+        // Write payload format
+        if cp == nil {
+                buf[0] = byte(compressionNone)
+        } else {
+                buf[0] = byte(compressionMade)
+        }
+        // Write length of b into buf
+        binary.BigEndian.PutUint32(buf[1:], uint32(length))
+        // Copy encoded msg to buf
+        copy(buf[5:], b)
+
+        if outPayload != nil {
+                outPayload.WireLength = len(buf)
+        }
+
+        return buf, nil
+}
+
+func checkRecvPayload(pf payloadFormat, recvCompress string, dc Decompressor) error {
+        switch pf {
+        case compressionNone:
+        case compressionMade:
+                if dc == nil || recvCompress != dc.Type() {
+                        return Errorf(codes.Unimplemented, "grpc: Decompressor is not installed for grpc-encoding %q", recvCompress)
+                }
+        default:
+                return Errorf(codes.Internal, "grpc: received unexpected payload format %d", pf)
+        }
+        return nil
+}
+
+func recv(p *parser, c Codec, s *transport.Stream, dc Decompressor, m interface{}, maxReceiveMessageSize int, inPayload *stats.InPayload) error {
+        pf, d, err := p.recvMsg(maxReceiveMessageSize)
+        if err != nil {
+                return err
+        }
+        if inPayload != nil {
+                inPayload.WireLength = len(d)
+        }
+        if err := checkRecvPayload(pf, s.RecvCompress(), dc); err != nil {
+                return err
+        }
+        if pf == compressionMade {
+                d, err = dc.Do(bytes.NewReader(d))
+                if err != nil {
+                        return Errorf(codes.Internal, "grpc: failed to decompress the received message %v", err)
+                }
+        }
+        if len(d) > maxReceiveMessageSize {
+                // TODO: Revisit the error code. Currently keep it consistent with java
+                // implementation.
+                return Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", len(d), maxReceiveMessageSize)
+        }
+        if err := c.Unmarshal(d, m); err != nil {
+                return Errorf(codes.Internal, "grpc: failed to unmarshal the received message %v", err)
+        }
+        if inPayload != nil {
+                inPayload.RecvTime = time.Now()
+                inPayload.Payload = m
+                // TODO truncate large payload.
+                inPayload.Data = d
+                inPayload.Length = len(d)
+        }
+        return nil
+}
+
+type rpcInfo struct {
+        bytesSent     bool
+        bytesReceived bool
+}
+
+type rpcInfoContextKey struct{}
+
+func newContextWithRPCInfo(ctx context.Context) context.Context {
+        return context.WithValue(ctx, rpcInfoContextKey{}, &rpcInfo{})
+}
+
+func rpcInfoFromContext(ctx context.Context) (s *rpcInfo, ok bool) {
+        s, ok = ctx.Value(rpcInfoContextKey{}).(*rpcInfo)
+        return
+}
+
+func updateRPCInfoInContext(ctx context.Context, s rpcInfo) {
+        if ss, ok := rpcInfoFromContext(ctx); ok {
+                *ss = s
+        }
+        return
+}
+
+// Code returns the error code for err if it was produced by the rpc system.
+// Otherwise, it returns codes.Unknown.
+//
+// Deprecated; use status.FromError and Code method instead.
+func Code(err error) codes.Code {
+        if s, ok := status.FromError(err); ok {
+                return s.Code()
+        }
+        return codes.Unknown
+}
+
+// ErrorDesc returns the error description of err if it was produced by the rpc system.
+// Otherwise, it returns err.Error() or empty string when err is nil.
+//
+// Deprecated; use status.FromError and Message method instead.
+func ErrorDesc(err error) string {
+        if s, ok := status.FromError(err); ok {
+                return s.Message()
+        }
+        return err.Error()
+}
+
+// Errorf returns an error containing an error code and a description;
+// Errorf returns nil if c is OK.
+//
+// Deprecated; use status.Errorf instead.
+func Errorf(c codes.Code, format string, a ...interface{}) error {
+        return status.Errorf(c, format, a...)
+}
+
+// MethodConfig defines the configuration recommended by the service providers for a
+// particular method.
+// This is EXPERIMENTAL and subject to change.
+type MethodConfig struct {
+        // WaitForReady indicates whether RPCs sent to this method should wait until
+        // the connection is ready by default (!failfast). The value specified via the
+        // gRPC client API will override the value set here.
+        WaitForReady *bool
+        // Timeout is the default timeout for RPCs sent to this method. The actual
+        // deadline used will be the minimum of the value specified here and the value
+        // set by the application via the gRPC client API.  If either one is not set,
+        // then the other will be used.  If neither is set, then the RPC has no deadline.
+        Timeout *time.Duration
+        // MaxReqSize is the maximum allowed payload size for an individual request in a
+        // stream (client->server) in bytes. The size which is measured is the serialized
+        // payload after per-message compression (but before stream compression) in bytes.
+        // The actual value used is the minumum of the value specified here and the value set
+        // by the application via the gRPC client API. If either one is not set, then the other
+        // will be used.  If neither is set, then the built-in default is used.
+        MaxReqSize *int
+        // MaxRespSize is the maximum allowed payload size for an individual response in a
+        // stream (server->client) in bytes.
+        MaxRespSize *int
+}
+
+// ServiceConfig is provided by the service provider and contains parameters for how
+// clients that connect to the service should behave.
+// This is EXPERIMENTAL and subject to change.
+type ServiceConfig struct {
+        // LB is the load balancer the service providers recommends. The balancer specified
+        // via grpc.WithBalancer will override this.
+        LB Balancer
+        // Methods contains a map for the methods in this service.
+        // If there is an exact match for a method (i.e. /service/method) in the map, use the corresponding MethodConfig.
+        // If there's no exact match, look for the default config for the service (/service/) and use the corresponding MethodConfig if it exists.
+        // Otherwise, the method has no MethodConfig to use.
+        Methods map[string]MethodConfig
+}
+
+func min(a, b *int) *int {
+        if *a < *b {
+                return a
+        }
+        return b
+}
+
+func getMaxSize(mcMax, doptMax *int, defaultVal int) *int {
+        if mcMax == nil && doptMax == nil {
+                return &defaultVal
+        }
+        if mcMax != nil && doptMax != nil {
+                return min(mcMax, doptMax)
+        }
+        if mcMax != nil {
+                return mcMax
+        }
+        return doptMax
+}
+
+// SupportPackageIsVersion3 is referenced from generated protocol buffer files.
+// The latest support package version is 4.
+// SupportPackageIsVersion3 is kept for compability. It will be removed in the
+// next support package version update.
+const SupportPackageIsVersion3 = true
+
+// SupportPackageIsVersion4 is referenced from generated protocol buffer files
+// to assert that that code is compatible with this version of the grpc package.
+//
+// This constant may be renamed in the future if a change in the generated code
+// requires a synchronised update of grpc-go and protoc-gen-go. This constant
+// should not be referenced from any other code.
+const SupportPackageIsVersion4 = true
+
+// Version is the current grpc version.
+const Version = "1.6.0-dev"
+
+const grpcUA = "grpc-go/" + Version
diff --git a/vendor/google.golang.org/grpc/server.go b/vendor/google.golang.org/grpc/server.go
new file mode 100644
index 0000000..42733e2
--- /dev/null
+++ b/vendor/google.golang.org/grpc/server.go
@@ -0,0 +1,1159 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "bytes"
+        "errors"
+        "fmt"
+        "io"
+        "net"
+        "net/http"
+        "reflect"
+        "runtime"
+        "strings"
+        "sync"
+        "time"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/http2"
+        "golang.org/x/net/trace"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/grpclog"
+        "google.golang.org/grpc/internal"
+        "google.golang.org/grpc/keepalive"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/tap"
+        "google.golang.org/grpc/transport"
+)
+
+const (
+        defaultServerMaxReceiveMessageSize = 1024 * 1024 * 4
+        defaultServerMaxSendMessageSize    = 1024 * 1024 * 4
+)
+
+type methodHandler func(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor UnaryServerInterceptor) (interface{}, error)
+
+// MethodDesc represents an RPC service's method specification.
+type MethodDesc struct {
+        MethodName string
+        Handler    methodHandler
+}
+
+// ServiceDesc represents an RPC service's specification.
+type ServiceDesc struct {
+        ServiceName string
+        // The pointer to the service interface. Used to check whether the user
+        // provided implementation satisfies the interface requirements.
+        HandlerType interface{}
+        Methods     []MethodDesc
+        Streams     []StreamDesc
+        Metadata    interface{}
+}
+
+// service consists of the information of the server serving this service and
+// the methods in this service.
+type service struct {
+        server interface{} // the server for service methods
+        md     map[string]*MethodDesc
+        sd     map[string]*StreamDesc
+        mdata  interface{}
+}
+
+// Server is a gRPC server to serve RPC requests.
+type Server struct {
+        opts options
+
+        mu     sync.Mutex // guards following
+        lis    map[net.Listener]bool
+        conns  map[io.Closer]bool
+        serve  bool
+        drain  bool
+        ctx    context.Context
+        cancel context.CancelFunc
+        // A CondVar to let GracefulStop() blocks until all the pending RPCs are finished
+        // and all the transport goes away.
+        cv     *sync.Cond
+        m      map[string]*service // service name -> service info
+        events trace.EventLog
+}
+
+type options struct {
+        creds                 credentials.TransportCredentials
+        codec                 Codec
+        cp                    Compressor
+        dc                    Decompressor
+        unaryInt              UnaryServerInterceptor
+        streamInt             StreamServerInterceptor
+        inTapHandle           tap.ServerInHandle
+        statsHandler          stats.Handler
+        maxConcurrentStreams  uint32
+        maxReceiveMessageSize int
+        maxSendMessageSize    int
+        useHandlerImpl        bool // use http.Handler-based server
+        unknownStreamDesc     *StreamDesc
+        keepaliveParams       keepalive.ServerParameters
+        keepalivePolicy       keepalive.EnforcementPolicy
+        initialWindowSize     int32
+        initialConnWindowSize int32
+}
+
+var defaultServerOptions = options{
+        maxReceiveMessageSize: defaultServerMaxReceiveMessageSize,
+        maxSendMessageSize:    defaultServerMaxSendMessageSize,
+}
+
+// A ServerOption sets options such as credentials, codec and keepalive parameters, etc.
+type ServerOption func(*options)
+
+// InitialWindowSize returns a ServerOption that sets window size for stream.
+// The lower bound for window size is 64K and any value smaller than that will be ignored.
+func InitialWindowSize(s int32) ServerOption {
+        return func(o *options) {
+                o.initialWindowSize = s
+        }
+}
+
+// InitialConnWindowSize returns a ServerOption that sets window size for a connection.
+// The lower bound for window size is 64K and any value smaller than that will be ignored.
+func InitialConnWindowSize(s int32) ServerOption {
+        return func(o *options) {
+                o.initialConnWindowSize = s
+        }
+}
+
+// KeepaliveParams returns a ServerOption that sets keepalive and max-age parameters for the server.
+func KeepaliveParams(kp keepalive.ServerParameters) ServerOption {
+        return func(o *options) {
+                o.keepaliveParams = kp
+        }
+}
+
+// KeepaliveEnforcementPolicy returns a ServerOption that sets keepalive enforcement policy for the server.
+func KeepaliveEnforcementPolicy(kep keepalive.EnforcementPolicy) ServerOption {
+        return func(o *options) {
+                o.keepalivePolicy = kep
+        }
+}
+
+// CustomCodec returns a ServerOption that sets a codec for message marshaling and unmarshaling.
+func CustomCodec(codec Codec) ServerOption {
+        return func(o *options) {
+                o.codec = codec
+        }
+}
+
+// RPCCompressor returns a ServerOption that sets a compressor for outbound messages.
+func RPCCompressor(cp Compressor) ServerOption {
+        return func(o *options) {
+                o.cp = cp
+        }
+}
+
+// RPCDecompressor returns a ServerOption that sets a decompressor for inbound messages.
+func RPCDecompressor(dc Decompressor) ServerOption {
+        return func(o *options) {
+                o.dc = dc
+        }
+}
+
+// MaxMsgSize returns a ServerOption to set the max message size in bytes the server can receive.
+// If this is not set, gRPC uses the default limit. Deprecated: use MaxRecvMsgSize instead.
+func MaxMsgSize(m int) ServerOption {
+        return MaxRecvMsgSize(m)
+}
+
+// MaxRecvMsgSize returns a ServerOption to set the max message size in bytes the server can receive.
+// If this is not set, gRPC uses the default 4MB.
+func MaxRecvMsgSize(m int) ServerOption {
+        return func(o *options) {
+                o.maxReceiveMessageSize = m
+        }
+}
+
+// MaxSendMsgSize returns a ServerOption to set the max message size in bytes the server can send.
+// If this is not set, gRPC uses the default 4MB.
+func MaxSendMsgSize(m int) ServerOption {
+        return func(o *options) {
+                o.maxSendMessageSize = m
+        }
+}
+
+// MaxConcurrentStreams returns a ServerOption that will apply a limit on the number
+// of concurrent streams to each ServerTransport.
+func MaxConcurrentStreams(n uint32) ServerOption {
+        return func(o *options) {
+                o.maxConcurrentStreams = n
+        }
+}
+
+// Creds returns a ServerOption that sets credentials for server connections.
+func Creds(c credentials.TransportCredentials) ServerOption {
+        return func(o *options) {
+                o.creds = c
+        }
+}
+
+// UnaryInterceptor returns a ServerOption that sets the UnaryServerInterceptor for the
+// server. Only one unary interceptor can be installed. The construction of multiple
+// interceptors (e.g., chaining) can be implemented at the caller.
+func UnaryInterceptor(i UnaryServerInterceptor) ServerOption {
+        return func(o *options) {
+                if o.unaryInt != nil {
+                        panic("The unary server interceptor was already set and may not be reset.")
+                }
+                o.unaryInt = i
+        }
+}
+
+// StreamInterceptor returns a ServerOption that sets the StreamServerInterceptor for the
+// server. Only one stream interceptor can be installed.
+func StreamInterceptor(i StreamServerInterceptor) ServerOption {
+        return func(o *options) {
+                if o.streamInt != nil {
+                        panic("The stream server interceptor was already set and may not be reset.")
+                }
+                o.streamInt = i
+        }
+}
+
+// InTapHandle returns a ServerOption that sets the tap handle for all the server
+// transport to be created. Only one can be installed.
+func InTapHandle(h tap.ServerInHandle) ServerOption {
+        return func(o *options) {
+                if o.inTapHandle != nil {
+                        panic("The tap handle was already set and may not be reset.")
+                }
+                o.inTapHandle = h
+        }
+}
+
+// StatsHandler returns a ServerOption that sets the stats handler for the server.
+func StatsHandler(h stats.Handler) ServerOption {
+        return func(o *options) {
+                o.statsHandler = h
+        }
+}
+
+// UnknownServiceHandler returns a ServerOption that allows for adding a custom
+// unknown service handler. The provided method is a bidi-streaming RPC service
+// handler that will be invoked instead of returning the "unimplemented" gRPC
+// error whenever a request is received for an unregistered service or method.
+// The handling function has full access to the Context of the request and the
+// stream, and the invocation passes through interceptors.
+func UnknownServiceHandler(streamHandler StreamHandler) ServerOption {
+        return func(o *options) {
+                o.unknownStreamDesc = &StreamDesc{
+                        StreamName: "unknown_service_handler",
+                        Handler:    streamHandler,
+                        // We need to assume that the users of the streamHandler will want to use both.
+                        ClientStreams: true,
+                        ServerStreams: true,
+                }
+        }
+}
+
+// NewServer creates a gRPC server which has no service registered and has not
+// started to accept requests yet.
+func NewServer(opt ...ServerOption) *Server {
+        opts := defaultServerOptions
+        for _, o := range opt {
+                o(&opts)
+        }
+        if opts.codec == nil {
+                // Set the default codec.
+                opts.codec = protoCodec{}
+        }
+        s := &Server{
+                lis:   make(map[net.Listener]bool),
+                opts:  opts,
+                conns: make(map[io.Closer]bool),
+                m:     make(map[string]*service),
+        }
+        s.cv = sync.NewCond(&s.mu)
+        s.ctx, s.cancel = context.WithCancel(context.Background())
+        if EnableTracing {
+                _, file, line, _ := runtime.Caller(1)
+                s.events = trace.NewEventLog("grpc.Server", fmt.Sprintf("%s:%d", file, line))
+        }
+        return s
+}
+
+// printf records an event in s's event log, unless s has been stopped.
+// REQUIRES s.mu is held.
+func (s *Server) printf(format string, a ...interface{}) {
+        if s.events != nil {
+                s.events.Printf(format, a...)
+        }
+}
+
+// errorf records an error in s's event log, unless s has been stopped.
+// REQUIRES s.mu is held.
+func (s *Server) errorf(format string, a ...interface{}) {
+        if s.events != nil {
+                s.events.Errorf(format, a...)
+        }
+}
+
+// RegisterService registers a service and its implementation to the gRPC
+// server. It is called from the IDL generated code. This must be called before
+// invoking Serve.
+func (s *Server) RegisterService(sd *ServiceDesc, ss interface{}) {
+        ht := reflect.TypeOf(sd.HandlerType).Elem()
+        st := reflect.TypeOf(ss)
+        if !st.Implements(ht) {
+                grpclog.Fatalf("grpc: Server.RegisterService found the handler of type %v that does not satisfy %v", st, ht)
+        }
+        s.register(sd, ss)
+}
+
+func (s *Server) register(sd *ServiceDesc, ss interface{}) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        s.printf("RegisterService(%q)", sd.ServiceName)
+        if s.serve {
+                grpclog.Fatalf("grpc: Server.RegisterService after Server.Serve for %q", sd.ServiceName)
+        }
+        if _, ok := s.m[sd.ServiceName]; ok {
+                grpclog.Fatalf("grpc: Server.RegisterService found duplicate service registration for %q", sd.ServiceName)
+        }
+        srv := &service{
+                server: ss,
+                md:     make(map[string]*MethodDesc),
+                sd:     make(map[string]*StreamDesc),
+                mdata:  sd.Metadata,
+        }
+        for i := range sd.Methods {
+                d := &sd.Methods[i]
+                srv.md[d.MethodName] = d
+        }
+        for i := range sd.Streams {
+                d := &sd.Streams[i]
+                srv.sd[d.StreamName] = d
+        }
+        s.m[sd.ServiceName] = srv
+}
+
+// MethodInfo contains the information of an RPC including its method name and type.
+type MethodInfo struct {
+        // Name is the method name only, without the service name or package name.
+        Name string
+        // IsClientStream indicates whether the RPC is a client streaming RPC.
+        IsClientStream bool
+        // IsServerStream indicates whether the RPC is a server streaming RPC.
+        IsServerStream bool
+}
+
+// ServiceInfo contains unary RPC method info, streaming RPC method info and metadata for a service.
+type ServiceInfo struct {
+        Methods []MethodInfo
+        // Metadata is the metadata specified in ServiceDesc when registering service.
+        Metadata interface{}
+}
+
+// GetServiceInfo returns a map from service names to ServiceInfo.
+// Service names include the package names, in the form of <package>.<service>.
+func (s *Server) GetServiceInfo() map[string]ServiceInfo {
+        ret := make(map[string]ServiceInfo)
+        for n, srv := range s.m {
+                methods := make([]MethodInfo, 0, len(srv.md)+len(srv.sd))
+                for m := range srv.md {
+                        methods = append(methods, MethodInfo{
+                                Name:           m,
+                                IsClientStream: false,
+                                IsServerStream: false,
+                        })
+                }
+                for m, d := range srv.sd {
+                        methods = append(methods, MethodInfo{
+                                Name:           m,
+                                IsClientStream: d.ClientStreams,
+                                IsServerStream: d.ServerStreams,
+                        })
+                }
+
+                ret[n] = ServiceInfo{
+                        Methods:  methods,
+                        Metadata: srv.mdata,
+                }
+        }
+        return ret
+}
+
+var (
+        // ErrServerStopped indicates that the operation is now illegal because of
+        // the server being stopped.
+        ErrServerStopped = errors.New("grpc: the server has been stopped")
+)
+
+func (s *Server) useTransportAuthenticator(rawConn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+        if s.opts.creds == nil {
+                return rawConn, nil, nil
+        }
+        return s.opts.creds.ServerHandshake(rawConn)
+}
+
+// Serve accepts incoming connections on the listener lis, creating a new
+// ServerTransport and service goroutine for each. The service goroutines
+// read gRPC requests and then call the registered handlers to reply to them.
+// Serve returns when lis.Accept fails with fatal errors.  lis will be closed when
+// this method returns.
+// Serve always returns non-nil error.
+func (s *Server) Serve(lis net.Listener) error {
+        s.mu.Lock()
+        s.printf("serving")
+        s.serve = true
+        if s.lis == nil {
+                s.mu.Unlock()
+                lis.Close()
+                return ErrServerStopped
+        }
+        s.lis[lis] = true
+        s.mu.Unlock()
+        defer func() {
+                s.mu.Lock()
+                if s.lis != nil && s.lis[lis] {
+                        lis.Close()
+                        delete(s.lis, lis)
+                }
+                s.mu.Unlock()
+        }()
+
+        var tempDelay time.Duration // how long to sleep on accept failure
+
+        for {
+                rawConn, err := lis.Accept()
+                if err != nil {
+                        if ne, ok := err.(interface {
+                                Temporary() bool
+                        }); ok && ne.Temporary() {
+                                if tempDelay == 0 {
+                                        tempDelay = 5 * time.Millisecond
+                                } else {
+                                        tempDelay *= 2
+                                }
+                                if max := 1 * time.Second; tempDelay > max {
+                                        tempDelay = max
+                                }
+                                s.mu.Lock()
+                                s.printf("Accept error: %v; retrying in %v", err, tempDelay)
+                                s.mu.Unlock()
+                                timer := time.NewTimer(tempDelay)
+                                select {
+                                case <-timer.C:
+                                case <-s.ctx.Done():
+                                }
+                                timer.Stop()
+                                continue
+                        }
+                        s.mu.Lock()
+                        s.printf("done serving; Accept = %v", err)
+                        s.mu.Unlock()
+                        return err
+                }
+                tempDelay = 0
+                // Start a new goroutine to deal with rawConn
+                // so we don't stall this Accept loop goroutine.
+                go s.handleRawConn(rawConn)
+        }
+}
+
+// handleRawConn is run in its own goroutine and handles a just-accepted
+// connection that has not had any I/O performed on it yet.
+func (s *Server) handleRawConn(rawConn net.Conn) {
+        conn, authInfo, err := s.useTransportAuthenticator(rawConn)
+        if err != nil {
+                s.mu.Lock()
+                s.errorf("ServerHandshake(%q) failed: %v", rawConn.RemoteAddr(), err)
+                s.mu.Unlock()
+                grpclog.Warningf("grpc: Server.Serve failed to complete security handshake from %q: %v", rawConn.RemoteAddr(), err)
+                // If serverHandShake returns ErrConnDispatched, keep rawConn open.
+                if err != credentials.ErrConnDispatched {
+                        rawConn.Close()
+                }
+                return
+        }
+
+        s.mu.Lock()
+        if s.conns == nil {
+                s.mu.Unlock()
+                conn.Close()
+                return
+        }
+        s.mu.Unlock()
+
+        if s.opts.useHandlerImpl {
+                s.serveUsingHandler(conn)
+        } else {
+                s.serveHTTP2Transport(conn, authInfo)
+        }
+}
+
+// serveHTTP2Transport sets up a http/2 transport (using the
+// gRPC http2 server transport in transport/http2_server.go) and
+// serves streams on it.
+// This is run in its own goroutine (it does network I/O in
+// transport.NewServerTransport).
+func (s *Server) serveHTTP2Transport(c net.Conn, authInfo credentials.AuthInfo) {
+        config := &transport.ServerConfig{
+                MaxStreams:            s.opts.maxConcurrentStreams,
+                AuthInfo:              authInfo,
+                InTapHandle:           s.opts.inTapHandle,
+                StatsHandler:          s.opts.statsHandler,
+                KeepaliveParams:       s.opts.keepaliveParams,
+                KeepalivePolicy:       s.opts.keepalivePolicy,
+                InitialWindowSize:     s.opts.initialWindowSize,
+                InitialConnWindowSize: s.opts.initialConnWindowSize,
+        }
+        st, err := transport.NewServerTransport("http2", c, config)
+        if err != nil {
+                s.mu.Lock()
+                s.errorf("NewServerTransport(%q) failed: %v", c.RemoteAddr(), err)
+                s.mu.Unlock()
+                c.Close()
+                grpclog.Warningln("grpc: Server.Serve failed to create ServerTransport: ", err)
+                return
+        }
+        if !s.addConn(st) {
+                st.Close()
+                return
+        }
+        s.serveStreams(st)
+}
+
+func (s *Server) serveStreams(st transport.ServerTransport) {
+        defer s.removeConn(st)
+        defer st.Close()
+        var wg sync.WaitGroup
+        st.HandleStreams(func(stream *transport.Stream) {
+                wg.Add(1)
+                go func() {
+                        defer wg.Done()
+                        s.handleStream(st, stream, s.traceInfo(st, stream))
+                }()
+        }, func(ctx context.Context, method string) context.Context {
+                if !EnableTracing {
+                        return ctx
+                }
+                tr := trace.New("grpc.Recv."+methodFamily(method), method)
+                return trace.NewContext(ctx, tr)
+        })
+        wg.Wait()
+}
+
+var _ http.Handler = (*Server)(nil)
+
+// serveUsingHandler is called from handleRawConn when s is configured
+// to handle requests via the http.Handler interface. It sets up a
+// net/http.Server to handle the just-accepted conn. The http.Server
+// is configured to route all incoming requests (all HTTP/2 streams)
+// to ServeHTTP, which creates a new ServerTransport for each stream.
+// serveUsingHandler blocks until conn closes.
+//
+// This codepath is only used when Server.TestingUseHandlerImpl has
+// been configured. This lets the end2end tests exercise the ServeHTTP
+// method as one of the environment types.
+//
+// conn is the *tls.Conn that's already been authenticated.
+func (s *Server) serveUsingHandler(conn net.Conn) {
+        if !s.addConn(conn) {
+                conn.Close()
+                return
+        }
+        defer s.removeConn(conn)
+        h2s := &http2.Server{
+                MaxConcurrentStreams: s.opts.maxConcurrentStreams,
+        }
+        h2s.ServeConn(conn, &http2.ServeConnOpts{
+                Handler: s,
+        })
+}
+
+// ServeHTTP implements the Go standard library's http.Handler
+// interface by responding to the gRPC request r, by looking up
+// the requested gRPC method in the gRPC server s.
+//
+// The provided HTTP request must have arrived on an HTTP/2
+// connection. When using the Go standard library's server,
+// practically this means that the Request must also have arrived
+// over TLS.
+//
+// To share one port (such as 443 for https) between gRPC and an
+// existing http.Handler, use a root http.Handler such as:
+//
+//   if r.ProtoMajor == 2 && strings.HasPrefix(
+//      r.Header.Get("Content-Type"), "application/grpc") {
+//      grpcServer.ServeHTTP(w, r)
+//   } else {
+//      yourMux.ServeHTTP(w, r)
+//   }
+//
+// Note that ServeHTTP uses Go's HTTP/2 server implementation which is totally
+// separate from grpc-go's HTTP/2 server. Performance and features may vary
+// between the two paths. ServeHTTP does not support some gRPC features
+// available through grpc-go's HTTP/2 server, and it is currently EXPERIMENTAL
+// and subject to change.
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+        st, err := transport.NewServerHandlerTransport(w, r)
+        if err != nil {
+                http.Error(w, err.Error(), http.StatusInternalServerError)
+                return
+        }
+        if !s.addConn(st) {
+                st.Close()
+                return
+        }
+        defer s.removeConn(st)
+        s.serveStreams(st)
+}
+
+// traceInfo returns a traceInfo and associates it with stream, if tracing is enabled.
+// If tracing is not enabled, it returns nil.
+func (s *Server) traceInfo(st transport.ServerTransport, stream *transport.Stream) (trInfo *traceInfo) {
+        tr, ok := trace.FromContext(stream.Context())
+        if !ok {
+                return nil
+        }
+
+        trInfo = &traceInfo{
+                tr: tr,
+        }
+        trInfo.firstLine.client = false
+        trInfo.firstLine.remoteAddr = st.RemoteAddr()
+
+        if dl, ok := stream.Context().Deadline(); ok {
+                trInfo.firstLine.deadline = dl.Sub(time.Now())
+        }
+        return trInfo
+}
+
+func (s *Server) addConn(c io.Closer) bool {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.conns == nil || s.drain {
+                return false
+        }
+        s.conns[c] = true
+        return true
+}
+
+func (s *Server) removeConn(c io.Closer) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.conns != nil {
+                delete(s.conns, c)
+                s.cv.Broadcast()
+        }
+}
+
+func (s *Server) sendResponse(t transport.ServerTransport, stream *transport.Stream, msg interface{}, cp Compressor, opts *transport.Options) error {
+        var (
+                cbuf       *bytes.Buffer
+                outPayload *stats.OutPayload
+        )
+        if cp != nil {
+                cbuf = new(bytes.Buffer)
+        }
+        if s.opts.statsHandler != nil {
+                outPayload = &stats.OutPayload{}
+        }
+        p, err := encode(s.opts.codec, msg, cp, cbuf, outPayload)
+        if err != nil {
+                grpclog.Errorln("grpc: server failed to encode response: ", err)
+                return err
+        }
+        if len(p) > s.opts.maxSendMessageSize {
+                return status.Errorf(codes.ResourceExhausted, "grpc: trying to send message larger than max (%d vs. %d)", len(p), s.opts.maxSendMessageSize)
+        }
+        err = t.Write(stream, p, opts)
+        if err == nil && outPayload != nil {
+                outPayload.SentTime = time.Now()
+                s.opts.statsHandler.HandleRPC(stream.Context(), outPayload)
+        }
+        return err
+}
+
+func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.Stream, srv *service, md *MethodDesc, trInfo *traceInfo) (err error) {
+        sh := s.opts.statsHandler
+        if sh != nil {
+                begin := &stats.Begin{
+                        BeginTime: time.Now(),
+                }
+                sh.HandleRPC(stream.Context(), begin)
+                defer func() {
+                        end := &stats.End{
+                                EndTime: time.Now(),
+                        }
+                        if err != nil && err != io.EOF {
+                                end.Error = toRPCErr(err)
+                        }
+                        sh.HandleRPC(stream.Context(), end)
+                }()
+        }
+        if trInfo != nil {
+                defer trInfo.tr.Finish()
+                trInfo.firstLine.client = false
+                trInfo.tr.LazyLog(&trInfo.firstLine, false)
+                defer func() {
+                        if err != nil && err != io.EOF {
+                                trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                                trInfo.tr.SetError()
+                        }
+                }()
+        }
+        if s.opts.cp != nil {
+                // NOTE: this needs to be ahead of all handling, https://github.com/grpc/grpc-go/issues/686.
+                stream.SetSendCompress(s.opts.cp.Type())
+        }
+        p := &parser{r: stream}
+        pf, req, err := p.recvMsg(s.opts.maxReceiveMessageSize)
+        if err == io.EOF {
+                // The entire stream is done (for unary RPC only).
+                return err
+        }
+        if err == io.ErrUnexpectedEOF {
+                err = Errorf(codes.Internal, io.ErrUnexpectedEOF.Error())
+        }
+        if err != nil {
+                if st, ok := status.FromError(err); ok {
+                        if e := t.WriteStatus(stream, st); e != nil {
+                                grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
+                        }
+                } else {
+                        switch st := err.(type) {
+                        case transport.ConnectionError:
+                                // Nothing to do here.
+                        case transport.StreamError:
+                                if e := t.WriteStatus(stream, status.New(st.Code, st.Desc)); e != nil {
+                                        grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
+                                }
+                        default:
+                                panic(fmt.Sprintf("grpc: Unexpected error (%T) from recvMsg: %v", st, st))
+                        }
+                }
+                return err
+        }
+
+        if err := checkRecvPayload(pf, stream.RecvCompress(), s.opts.dc); err != nil {
+                if st, ok := status.FromError(err); ok {
+                        if e := t.WriteStatus(stream, st); e != nil {
+                                grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
+                        }
+                        return err
+                }
+                if e := t.WriteStatus(stream, status.New(codes.Internal, err.Error())); e != nil {
+                        grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
+                }
+
+                // TODO checkRecvPayload always return RPC error. Add a return here if necessary.
+        }
+        var inPayload *stats.InPayload
+        if sh != nil {
+                inPayload = &stats.InPayload{
+                        RecvTime: time.Now(),
+                }
+        }
+        df := func(v interface{}) error {
+                if inPayload != nil {
+                        inPayload.WireLength = len(req)
+                }
+                if pf == compressionMade {
+                        var err error
+                        req, err = s.opts.dc.Do(bytes.NewReader(req))
+                        if err != nil {
+                                return Errorf(codes.Internal, err.Error())
+                        }
+                }
+                if len(req) > s.opts.maxReceiveMessageSize {
+                        // TODO: Revisit the error code. Currently keep it consistent with
+                        // java implementation.
+                        return status.Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", len(req), s.opts.maxReceiveMessageSize)
+                }
+                if err := s.opts.codec.Unmarshal(req, v); err != nil {
+                        return status.Errorf(codes.Internal, "grpc: error unmarshalling request: %v", err)
+                }
+                if inPayload != nil {
+                        inPayload.Payload = v
+                        inPayload.Data = req
+                        inPayload.Length = len(req)
+                        sh.HandleRPC(stream.Context(), inPayload)
+                }
+                if trInfo != nil {
+                        trInfo.tr.LazyLog(&payload{sent: false, msg: v}, true)
+                }
+                return nil
+        }
+        reply, appErr := md.Handler(srv.server, stream.Context(), df, s.opts.unaryInt)
+        if appErr != nil {
+                appStatus, ok := status.FromError(appErr)
+                if !ok {
+                        // Convert appErr if it is not a grpc status error.
+                        appErr = status.Error(convertCode(appErr), appErr.Error())
+                        appStatus, _ = status.FromError(appErr)
+                }
+                if trInfo != nil {
+                        trInfo.tr.LazyLog(stringer(appStatus.Message()), true)
+                        trInfo.tr.SetError()
+                }
+                if e := t.WriteStatus(stream, appStatus); e != nil {
+                        grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status: %v", e)
+                }
+                return appErr
+        }
+        if trInfo != nil {
+                trInfo.tr.LazyLog(stringer("OK"), false)
+        }
+        opts := &transport.Options{
+                Last:  true,
+                Delay: false,
+        }
+        if err := s.sendResponse(t, stream, reply, s.opts.cp, opts); err != nil {
+                if err == io.EOF {
+                        // The entire stream is done (for unary RPC only).
+                        return err
+                }
+                if s, ok := status.FromError(err); ok {
+                        if e := t.WriteStatus(stream, s); e != nil {
+                                grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status: %v", e)
+                        }
+                } else {
+                        switch st := err.(type) {
+                        case transport.ConnectionError:
+                                // Nothing to do here.
+                        case transport.StreamError:
+                                if e := t.WriteStatus(stream, status.New(st.Code, st.Desc)); e != nil {
+                                        grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
+                                }
+                        default:
+                                panic(fmt.Sprintf("grpc: Unexpected error (%T) from sendResponse: %v", st, st))
+                        }
+                }
+                return err
+        }
+        if trInfo != nil {
+                trInfo.tr.LazyLog(&payload{sent: true, msg: reply}, true)
+        }
+        // TODO: Should we be logging if writing status failed here, like above?
+        // Should the logging be in WriteStatus?  Should we ignore the WriteStatus
+        // error or allow the stats handler to see it?
+        return t.WriteStatus(stream, status.New(codes.OK, ""))
+}
+
+func (s *Server) processStreamingRPC(t transport.ServerTransport, stream *transport.Stream, srv *service, sd *StreamDesc, trInfo *traceInfo) (err error) {
+        sh := s.opts.statsHandler
+        if sh != nil {
+                begin := &stats.Begin{
+                        BeginTime: time.Now(),
+                }
+                sh.HandleRPC(stream.Context(), begin)
+                defer func() {
+                        end := &stats.End{
+                                EndTime: time.Now(),
+                        }
+                        if err != nil && err != io.EOF {
+                                end.Error = toRPCErr(err)
+                        }
+                        sh.HandleRPC(stream.Context(), end)
+                }()
+        }
+        if s.opts.cp != nil {
+                stream.SetSendCompress(s.opts.cp.Type())
+        }
+        ss := &serverStream{
+                t:     t,
+                s:     stream,
+                p:     &parser{r: stream},
+                codec: s.opts.codec,
+                cp:    s.opts.cp,
+                dc:    s.opts.dc,
+                maxReceiveMessageSize: s.opts.maxReceiveMessageSize,
+                maxSendMessageSize:    s.opts.maxSendMessageSize,
+                trInfo:                trInfo,
+                statsHandler:          sh,
+        }
+        if ss.cp != nil {
+                ss.cbuf = new(bytes.Buffer)
+        }
+        if trInfo != nil {
+                trInfo.tr.LazyLog(&trInfo.firstLine, false)
+                defer func() {
+                        ss.mu.Lock()
+                        if err != nil && err != io.EOF {
+                                ss.trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                                ss.trInfo.tr.SetError()
+                        }
+                        ss.trInfo.tr.Finish()
+                        ss.trInfo.tr = nil
+                        ss.mu.Unlock()
+                }()
+        }
+        var appErr error
+        var server interface{}
+        if srv != nil {
+                server = srv.server
+        }
+        if s.opts.streamInt == nil {
+                appErr = sd.Handler(server, ss)
+        } else {
+                info := &StreamServerInfo{
+                        FullMethod:     stream.Method(),
+                        IsClientStream: sd.ClientStreams,
+                        IsServerStream: sd.ServerStreams,
+                }
+                appErr = s.opts.streamInt(server, ss, info, sd.Handler)
+        }
+        if appErr != nil {
+                appStatus, ok := status.FromError(appErr)
+                if !ok {
+                        switch err := appErr.(type) {
+                        case transport.StreamError:
+                                appStatus = status.New(err.Code, err.Desc)
+                        default:
+                                appStatus = status.New(convertCode(appErr), appErr.Error())
+                        }
+                        appErr = appStatus.Err()
+                }
+                if trInfo != nil {
+                        ss.mu.Lock()
+                        ss.trInfo.tr.LazyLog(stringer(appStatus.Message()), true)
+                        ss.trInfo.tr.SetError()
+                        ss.mu.Unlock()
+                }
+                t.WriteStatus(ss.s, appStatus)
+                // TODO: Should we log an error from WriteStatus here and below?
+                return appErr
+        }
+        if trInfo != nil {
+                ss.mu.Lock()
+                ss.trInfo.tr.LazyLog(stringer("OK"), false)
+                ss.mu.Unlock()
+        }
+        return t.WriteStatus(ss.s, status.New(codes.OK, ""))
+
+}
+
+func (s *Server) handleStream(t transport.ServerTransport, stream *transport.Stream, trInfo *traceInfo) {
+        sm := stream.Method()
+        if sm != "" && sm[0] == '/' {
+                sm = sm[1:]
+        }
+        pos := strings.LastIndex(sm, "/")
+        if pos == -1 {
+                if trInfo != nil {
+                        trInfo.tr.LazyLog(&fmtStringer{"Malformed method name %q", []interface{}{sm}}, true)
+                        trInfo.tr.SetError()
+                }
+                errDesc := fmt.Sprintf("malformed method name: %q", stream.Method())
+                if err := t.WriteStatus(stream, status.New(codes.ResourceExhausted, errDesc)); err != nil {
+                        if trInfo != nil {
+                                trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                                trInfo.tr.SetError()
+                        }
+                        grpclog.Warningf("grpc: Server.handleStream failed to write status: %v", err)
+                }
+                if trInfo != nil {
+                        trInfo.tr.Finish()
+                }
+                return
+        }
+        service := sm[:pos]
+        method := sm[pos+1:]
+        srv, ok := s.m[service]
+        if !ok {
+                if unknownDesc := s.opts.unknownStreamDesc; unknownDesc != nil {
+                        s.processStreamingRPC(t, stream, nil, unknownDesc, trInfo)
+                        return
+                }
+                if trInfo != nil {
+                        trInfo.tr.LazyLog(&fmtStringer{"Unknown service %v", []interface{}{service}}, true)
+                        trInfo.tr.SetError()
+                }
+                errDesc := fmt.Sprintf("unknown service %v", service)
+                if err := t.WriteStatus(stream, status.New(codes.Unimplemented, errDesc)); err != nil {
+                        if trInfo != nil {
+                                trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                                trInfo.tr.SetError()
+                        }
+                        grpclog.Warningf("grpc: Server.handleStream failed to write status: %v", err)
+                }
+                if trInfo != nil {
+                        trInfo.tr.Finish()
+                }
+                return
+        }
+        // Unary RPC or Streaming RPC?
+        if md, ok := srv.md[method]; ok {
+                s.processUnaryRPC(t, stream, srv, md, trInfo)
+                return
+        }
+        if sd, ok := srv.sd[method]; ok {
+                s.processStreamingRPC(t, stream, srv, sd, trInfo)
+                return
+        }
+        if trInfo != nil {
+                trInfo.tr.LazyLog(&fmtStringer{"Unknown method %v", []interface{}{method}}, true)
+                trInfo.tr.SetError()
+        }
+        if unknownDesc := s.opts.unknownStreamDesc; unknownDesc != nil {
+                s.processStreamingRPC(t, stream, nil, unknownDesc, trInfo)
+                return
+        }
+        errDesc := fmt.Sprintf("unknown method %v", method)
+        if err := t.WriteStatus(stream, status.New(codes.Unimplemented, errDesc)); err != nil {
+                if trInfo != nil {
+                        trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                        trInfo.tr.SetError()
+                }
+                grpclog.Warningf("grpc: Server.handleStream failed to write status: %v", err)
+        }
+        if trInfo != nil {
+                trInfo.tr.Finish()
+        }
+}
+
+// Stop stops the gRPC server. It immediately closes all open
+// connections and listeners.
+// It cancels all active RPCs on the server side and the corresponding
+// pending RPCs on the client side will get notified by connection
+// errors.
+func (s *Server) Stop() {
+        s.mu.Lock()
+        listeners := s.lis
+        s.lis = nil
+        st := s.conns
+        s.conns = nil
+        // interrupt GracefulStop if Stop and GracefulStop are called concurrently.
+        s.cv.Broadcast()
+        s.mu.Unlock()
+
+        for lis := range listeners {
+                lis.Close()
+        }
+        for c := range st {
+                c.Close()
+        }
+
+        s.mu.Lock()
+        s.cancel()
+        if s.events != nil {
+                s.events.Finish()
+                s.events = nil
+        }
+        s.mu.Unlock()
+}
+
+// GracefulStop stops the gRPC server gracefully. It stops the server from
+// accepting new connections and RPCs and blocks until all the pending RPCs are
+// finished.
+func (s *Server) GracefulStop() {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.conns == nil {
+                return
+        }
+        for lis := range s.lis {
+                lis.Close()
+        }
+        s.lis = nil
+        s.cancel()
+        if !s.drain {
+                for c := range s.conns {
+                        c.(transport.ServerTransport).Drain()
+                }
+                s.drain = true
+        }
+        for len(s.conns) != 0 {
+                s.cv.Wait()
+        }
+        s.conns = nil
+        if s.events != nil {
+                s.events.Finish()
+                s.events = nil
+        }
+}
+
+func init() {
+        internal.TestingCloseConns = func(arg interface{}) {
+                arg.(*Server).testingCloseConns()
+        }
+        internal.TestingUseHandlerImpl = func(arg interface{}) {
+                arg.(*Server).opts.useHandlerImpl = true
+        }
+}
+
+// testingCloseConns closes all existing transports but keeps s.lis
+// accepting new connections.
+func (s *Server) testingCloseConns() {
+        s.mu.Lock()
+        for c := range s.conns {
+                c.Close()
+                delete(s.conns, c)
+        }
+        s.mu.Unlock()
+}
+
+// SetHeader sets the header metadata.
+// When called multiple times, all the provided metadata will be merged.
+// All the metadata will be sent out when one of the following happens:
+//  - grpc.SendHeader() is called;
+//  - The first response is sent out;
+//  - An RPC status is sent out (error or success).
+func SetHeader(ctx context.Context, md metadata.MD) error {
+        if md.Len() == 0 {
+                return nil
+        }
+        stream, ok := transport.StreamFromContext(ctx)
+        if !ok {
+                return Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
+        }
+        return stream.SetHeader(md)
+}
+
+// SendHeader sends header metadata. It may be called at most once.
+// The provided md and headers set by SetHeader() will be sent.
+func SendHeader(ctx context.Context, md metadata.MD) error {
+        stream, ok := transport.StreamFromContext(ctx)
+        if !ok {
+                return Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
+        }
+        t := stream.ServerTransport()
+        if t == nil {
+                grpclog.Fatalf("grpc: SendHeader: %v has no ServerTransport to send header metadata.", stream)
+        }
+        if err := t.WriteHeader(stream, md); err != nil {
+                return toRPCErr(err)
+        }
+        return nil
+}
+
+// SetTrailer sets the trailer metadata that will be sent when an RPC returns.
+// When called more than once, all the provided metadata will be merged.
+func SetTrailer(ctx context.Context, md metadata.MD) error {
+        if md.Len() == 0 {
+                return nil
+        }
+        stream, ok := transport.StreamFromContext(ctx)
+        if !ok {
+                return Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
+        }
+        return stream.SetTrailer(md)
+}
diff --git a/vendor/google.golang.org/grpc/stats/handlers.go b/vendor/google.golang.org/grpc/stats/handlers.go
new file mode 100644
index 0000000..05b384c
--- /dev/null
+++ b/vendor/google.golang.org/grpc/stats/handlers.go
@@ -0,0 +1,64 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package stats
+
+import (
+        "net"
+
+        "golang.org/x/net/context"
+)
+
+// ConnTagInfo defines the relevant information needed by connection context tagger.
+type ConnTagInfo struct {
+        // RemoteAddr is the remote address of the corresponding connection.
+        RemoteAddr net.Addr
+        // LocalAddr is the local address of the corresponding connection.
+        LocalAddr net.Addr
+}
+
+// RPCTagInfo defines the relevant information needed by RPC context tagger.
+type RPCTagInfo struct {
+        // FullMethodName is the RPC method in the format of /package.service/method.
+        FullMethodName string
+        // FailFast indicates if this RPC is failfast.
+        // This field is only valid on client side, it's always false on server side.
+        FailFast bool
+}
+
+// Handler defines the interface for the related stats handling (e.g., RPCs, connections).
+type Handler interface {
+        // TagRPC can attach some information to the given context.
+        // The context used for the rest lifetime of the RPC will be derived from
+        // the returned context.
+        TagRPC(context.Context, *RPCTagInfo) context.Context
+        // HandleRPC processes the RPC stats.
+        HandleRPC(context.Context, RPCStats)
+
+        // TagConn can attach some information to the given context.
+        // The returned context will be used for stats handling.
+        // For conn stats handling, the context used in HandleConn for this
+        // connection will be derived from the context returned.
+        // For RPC stats handling,
+        //  - On server side, the context used in HandleRPC for all RPCs on this
+        // connection will be derived from the context returned.
+        //  - On client side, the context is not derived from the context returned.
+        TagConn(context.Context, *ConnTagInfo) context.Context
+        // HandleConn processes the Conn stats.
+        HandleConn(context.Context, ConnStats)
+}
diff --git a/vendor/google.golang.org/grpc/stats/stats.go b/vendor/google.golang.org/grpc/stats/stats.go
new file mode 100644
index 0000000..338a3a7
--- /dev/null
+++ b/vendor/google.golang.org/grpc/stats/stats.go
@@ -0,0 +1,210 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package stats is for collecting and reporting various network and RPC stats.
+// This package is for monitoring purpose only. All fields are read-only.
+// All APIs are experimental.
+package stats // import "google.golang.org/grpc/stats"
+
+import (
+        "net"
+        "time"
+)
+
+// RPCStats contains stats information about RPCs.
+type RPCStats interface {
+        isRPCStats()
+        // IsClient returns true if this RPCStats is from client side.
+        IsClient() bool
+}
+
+// Begin contains stats when an RPC begins.
+// FailFast is only valid if this Begin is from client side.
+type Begin struct {
+        // Client is true if this Begin is from client side.
+        Client bool
+        // BeginTime is the time when the RPC begins.
+        BeginTime time.Time
+        // FailFast indicates if this RPC is failfast.
+        FailFast bool
+}
+
+// IsClient indicates if the stats information is from client side.
+func (s *Begin) IsClient() bool { return s.Client }
+
+func (s *Begin) isRPCStats() {}
+
+// InPayload contains the information for an incoming payload.
+type InPayload struct {
+        // Client is true if this InPayload is from client side.
+        Client bool
+        // Payload is the payload with original type.
+        Payload interface{}
+        // Data is the serialized message payload.
+        Data []byte
+        // Length is the length of uncompressed data.
+        Length int
+        // WireLength is the length of data on wire (compressed, signed, encrypted).
+        WireLength int
+        // RecvTime is the time when the payload is received.
+        RecvTime time.Time
+}
+
+// IsClient indicates if the stats information is from client side.
+func (s *InPayload) IsClient() bool { return s.Client }
+
+func (s *InPayload) isRPCStats() {}
+
+// InHeader contains stats when a header is received.
+type InHeader struct {
+        // Client is true if this InHeader is from client side.
+        Client bool
+        // WireLength is the wire length of header.
+        WireLength int
+
+        // The following fields are valid only if Client is false.
+        // FullMethod is the full RPC method string, i.e., /package.service/method.
+        FullMethod string
+        // RemoteAddr is the remote address of the corresponding connection.
+        RemoteAddr net.Addr
+        // LocalAddr is the local address of the corresponding connection.
+        LocalAddr net.Addr
+        // Compression is the compression algorithm used for the RPC.
+        Compression string
+}
+
+// IsClient indicates if the stats information is from client side.
+func (s *InHeader) IsClient() bool { return s.Client }
+
+func (s *InHeader) isRPCStats() {}
+
+// InTrailer contains stats when a trailer is received.
+type InTrailer struct {
+        // Client is true if this InTrailer is from client side.
+        Client bool
+        // WireLength is the wire length of trailer.
+        WireLength int
+}
+
+// IsClient indicates if the stats information is from client side.
+func (s *InTrailer) IsClient() bool { return s.Client }
+
+func (s *InTrailer) isRPCStats() {}
+
+// OutPayload contains the information for an outgoing payload.
+type OutPayload struct {
+        // Client is true if this OutPayload is from client side.
+        Client bool
+        // Payload is the payload with original type.
+        Payload interface{}
+        // Data is the serialized message payload.
+        Data []byte
+        // Length is the length of uncompressed data.
+        Length int
+        // WireLength is the length of data on wire (compressed, signed, encrypted).
+        WireLength int
+        // SentTime is the time when the payload is sent.
+        SentTime time.Time
+}
+
+// IsClient indicates if this stats information is from client side.
+func (s *OutPayload) IsClient() bool { return s.Client }
+
+func (s *OutPayload) isRPCStats() {}
+
+// OutHeader contains stats when a header is sent.
+type OutHeader struct {
+        // Client is true if this OutHeader is from client side.
+        Client bool
+        // WireLength is the wire length of header.
+        WireLength int
+
+        // The following fields are valid only if Client is true.
+        // FullMethod is the full RPC method string, i.e., /package.service/method.
+        FullMethod string
+        // RemoteAddr is the remote address of the corresponding connection.
+        RemoteAddr net.Addr
+        // LocalAddr is the local address of the corresponding connection.
+        LocalAddr net.Addr
+        // Compression is the compression algorithm used for the RPC.
+        Compression string
+}
+
+// IsClient indicates if this stats information is from client side.
+func (s *OutHeader) IsClient() bool { return s.Client }
+
+func (s *OutHeader) isRPCStats() {}
+
+// OutTrailer contains stats when a trailer is sent.
+type OutTrailer struct {
+        // Client is true if this OutTrailer is from client side.
+        Client bool
+        // WireLength is the wire length of trailer.
+        WireLength int
+}
+
+// IsClient indicates if this stats information is from client side.
+func (s *OutTrailer) IsClient() bool { return s.Client }
+
+func (s *OutTrailer) isRPCStats() {}
+
+// End contains stats when an RPC ends.
+type End struct {
+        // Client is true if this End is from client side.
+        Client bool
+        // EndTime is the time when the RPC ends.
+        EndTime time.Time
+        // Error is the error the RPC ended with. It is an error generated from
+        // status.Status and can be converted back to status.Status using
+        // status.FromError if non-nil.
+        Error error
+}
+
+// IsClient indicates if this is from client side.
+func (s *End) IsClient() bool { return s.Client }
+
+func (s *End) isRPCStats() {}
+
+// ConnStats contains stats information about connections.
+type ConnStats interface {
+        isConnStats()
+        // IsClient returns true if this ConnStats is from client side.
+        IsClient() bool
+}
+
+// ConnBegin contains the stats of a connection when it is established.
+type ConnBegin struct {
+        // Client is true if this ConnBegin is from client side.
+        Client bool
+}
+
+// IsClient indicates if this is from client side.
+func (s *ConnBegin) IsClient() bool { return s.Client }
+
+func (s *ConnBegin) isConnStats() {}
+
+// ConnEnd contains the stats of a connection when it ends.
+type ConnEnd struct {
+        // Client is true if this ConnEnd is from client side.
+        Client bool
+}
+
+// IsClient indicates if this is from client side.
+func (s *ConnEnd) IsClient() bool { return s.Client }
+
+func (s *ConnEnd) isConnStats() {}
diff --git a/vendor/google.golang.org/grpc/status/status.go b/vendor/google.golang.org/grpc/status/status.go
new file mode 100644
index 0000000..871dc4b
--- /dev/null
+++ b/vendor/google.golang.org/grpc/status/status.go
@@ -0,0 +1,168 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package status implements errors returned by gRPC.  These errors are
+// serialized and transmitted on the wire between server and client, and allow
+// for additional data to be transmitted via the Details field in the status
+// proto.  gRPC service handlers should return an error created by this
+// package, and gRPC clients should expect a corresponding error to be
+// returned from the RPC call.
+//
+// This package upholds the invariants that a non-nil error may not
+// contain an OK code, and an OK code must result in a nil error.
+package status
+
+import (
+        "errors"
+        "fmt"
+
+        "github.com/golang/protobuf/proto"
+        "github.com/golang/protobuf/ptypes"
+        spb "google.golang.org/genproto/googleapis/rpc/status"
+        "google.golang.org/grpc/codes"
+)
+
+// statusError is an alias of a status proto.  It implements error and Status,
+// and a nil statusError should never be returned by this package.
+type statusError spb.Status
+
+func (se *statusError) Error() string {
+        p := (*spb.Status)(se)
+        return fmt.Sprintf("rpc error: code = %s desc = %s", codes.Code(p.GetCode()), p.GetMessage())
+}
+
+func (se *statusError) status() *Status {
+        return &Status{s: (*spb.Status)(se)}
+}
+
+// Status represents an RPC status code, message, and details.  It is immutable
+// and should be created with New, Newf, or FromProto.
+type Status struct {
+        s *spb.Status
+}
+
+// Code returns the status code contained in s.
+func (s *Status) Code() codes.Code {
+        if s == nil || s.s == nil {
+                return codes.OK
+        }
+        return codes.Code(s.s.Code)
+}
+
+// Message returns the message contained in s.
+func (s *Status) Message() string {
+        if s == nil || s.s == nil {
+                return ""
+        }
+        return s.s.Message
+}
+
+// Proto returns s's status as an spb.Status proto message.
+func (s *Status) Proto() *spb.Status {
+        if s == nil {
+                return nil
+        }
+        return proto.Clone(s.s).(*spb.Status)
+}
+
+// Err returns an immutable error representing s; returns nil if s.Code() is
+// OK.
+func (s *Status) Err() error {
+        if s.Code() == codes.OK {
+                return nil
+        }
+        return (*statusError)(s.s)
+}
+
+// New returns a Status representing c and msg.
+func New(c codes.Code, msg string) *Status {
+        return &Status{s: &spb.Status{Code: int32(c), Message: msg}}
+}
+
+// Newf returns New(c, fmt.Sprintf(format, a...)).
+func Newf(c codes.Code, format string, a ...interface{}) *Status {
+        return New(c, fmt.Sprintf(format, a...))
+}
+
+// Error returns an error representing c and msg.  If c is OK, returns nil.
+func Error(c codes.Code, msg string) error {
+        return New(c, msg).Err()
+}
+
+// Errorf returns Error(c, fmt.Sprintf(format, a...)).
+func Errorf(c codes.Code, format string, a ...interface{}) error {
+        return Error(c, fmt.Sprintf(format, a...))
+}
+
+// ErrorProto returns an error representing s.  If s.Code is OK, returns nil.
+func ErrorProto(s *spb.Status) error {
+        return FromProto(s).Err()
+}
+
+// FromProto returns a Status representing s.
+func FromProto(s *spb.Status) *Status {
+        return &Status{s: proto.Clone(s).(*spb.Status)}
+}
+
+// FromError returns a Status representing err if it was produced from this
+// package, otherwise it returns nil, false.
+func FromError(err error) (s *Status, ok bool) {
+        if err == nil {
+                return &Status{s: &spb.Status{Code: int32(codes.OK)}}, true
+        }
+        if s, ok := err.(*statusError); ok {
+                return s.status(), true
+        }
+        return nil, false
+}
+
+// WithDetails returns a new status with the provided details messages appended to the status.
+// If any errors are encountered, it returns nil and the first error encountered.
+func (s *Status) WithDetails(details ...proto.Message) (*Status, error) {
+        if s.Code() == codes.OK {
+                return nil, errors.New("no error details for status with code OK")
+        }
+        // s.Code() != OK implies that s.Proto() != nil.
+        p := s.Proto()
+        for _, detail := range details {
+                any, err := ptypes.MarshalAny(detail)
+                if err != nil {
+                        return nil, err
+                }
+                p.Details = append(p.Details, any)
+        }
+        return &Status{s: p}, nil
+}
+
+// Details returns a slice of details messages attached to the status.
+// If a detail cannot be decoded, the error is returned in place of the detail.
+func (s *Status) Details() []interface{} {
+        if s == nil || s.s == nil {
+                return nil
+        }
+        details := make([]interface{}, 0, len(s.s.Details))
+        for _, any := range s.s.Details {
+                detail := &ptypes.DynamicAny{}
+                if err := ptypes.UnmarshalAny(any, detail); err != nil {
+                        details = append(details, err)
+                        continue
+                }
+                details = append(details, detail.Message)
+        }
+        return details
+}
diff --git a/vendor/google.golang.org/grpc/stream.go b/vendor/google.golang.org/grpc/stream.go
new file mode 100644
index 0000000..1c621ba
--- /dev/null
+++ b/vendor/google.golang.org/grpc/stream.go
@@ -0,0 +1,661 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "bytes"
+        "errors"
+        "io"
+        "sync"
+        "time"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/trace"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/peer"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/transport"
+)
+
+// StreamHandler defines the handler called by gRPC server to complete the
+// execution of a streaming RPC.
+type StreamHandler func(srv interface{}, stream ServerStream) error
+
+// StreamDesc represents a streaming RPC service's method specification.
+type StreamDesc struct {
+        StreamName string
+        Handler    StreamHandler
+
+        // At least one of these is true.
+        ServerStreams bool
+        ClientStreams bool
+}
+
+// Stream defines the common interface a client or server stream has to satisfy.
+type Stream interface {
+        // Context returns the context for this stream.
+        Context() context.Context
+        // SendMsg blocks until it sends m, the stream is done or the stream
+        // breaks.
+        // On error, it aborts the stream and returns an RPC status on client
+        // side. On server side, it simply returns the error to the caller.
+        // SendMsg is called by generated code. Also Users can call SendMsg
+        // directly when it is really needed in their use cases.
+        // It's safe to have a goroutine calling SendMsg and another goroutine calling
+        // recvMsg on the same stream at the same time.
+        // But it is not safe to call SendMsg on the same stream in different goroutines.
+        SendMsg(m interface{}) error
+        // RecvMsg blocks until it receives a message or the stream is
+        // done. On client side, it returns io.EOF when the stream is done. On
+        // any other error, it aborts the stream and returns an RPC status. On
+        // server side, it simply returns the error to the caller.
+        // It's safe to have a goroutine calling SendMsg and another goroutine calling
+        // recvMsg on the same stream at the same time.
+        // But it is not safe to call RecvMsg on the same stream in different goroutines.
+        RecvMsg(m interface{}) error
+}
+
+// ClientStream defines the interface a client stream has to satisfy.
+type ClientStream interface {
+        // Header returns the header metadata received from the server if there
+        // is any. It blocks if the metadata is not ready to read.
+        Header() (metadata.MD, error)
+        // Trailer returns the trailer metadata from the server, if there is any.
+        // It must only be called after stream.CloseAndRecv has returned, or
+        // stream.Recv has returned a non-nil error (including io.EOF).
+        Trailer() metadata.MD
+        // CloseSend closes the send direction of the stream. It closes the stream
+        // when non-nil error is met.
+        CloseSend() error
+        // Stream.SendMsg() may return a non-nil error when something wrong happens sending
+        // the request. The returned error indicates the status of this sending, not the final
+        // status of the RPC.
+        // Always call Stream.RecvMsg() to get the final status if you care about the status of
+        // the RPC.
+        Stream
+}
+
+// NewClientStream creates a new Stream for the client side. This is called
+// by generated code.
+func NewClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (_ ClientStream, err error) {
+        if cc.dopts.streamInt != nil {
+                return cc.dopts.streamInt(ctx, desc, cc, method, newClientStream, opts...)
+        }
+        return newClientStream(ctx, desc, cc, method, opts...)
+}
+
+func newClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (_ ClientStream, err error) {
+        var (
+                t      transport.ClientTransport
+                s      *transport.Stream
+                put    func()
+                cancel context.CancelFunc
+        )
+        c := defaultCallInfo
+        mc := cc.GetMethodConfig(method)
+        if mc.WaitForReady != nil {
+                c.failFast = !*mc.WaitForReady
+        }
+
+        if mc.Timeout != nil {
+                ctx, cancel = context.WithTimeout(ctx, *mc.Timeout)
+        }
+
+        opts = append(cc.dopts.callOptions, opts...)
+        for _, o := range opts {
+                if err := o.before(&c); err != nil {
+                        return nil, toRPCErr(err)
+                }
+        }
+        c.maxSendMessageSize = getMaxSize(mc.MaxReqSize, c.maxSendMessageSize, defaultClientMaxSendMessageSize)
+        c.maxReceiveMessageSize = getMaxSize(mc.MaxRespSize, c.maxReceiveMessageSize, defaultClientMaxReceiveMessageSize)
+
+        callHdr := &transport.CallHdr{
+                Host:   cc.authority,
+                Method: method,
+                // If it's not client streaming, we should already have the request to be sent,
+                // so we don't flush the header.
+                // If it's client streaming, the user may never send a request or send it any
+                // time soon, so we ask the transport to flush the header.
+                Flush: desc.ClientStreams,
+        }
+        if cc.dopts.cp != nil {
+                callHdr.SendCompress = cc.dopts.cp.Type()
+        }
+        if c.creds != nil {
+                callHdr.Creds = c.creds
+        }
+        var trInfo traceInfo
+        if EnableTracing {
+                trInfo.tr = trace.New("grpc.Sent."+methodFamily(method), method)
+                trInfo.firstLine.client = true
+                if deadline, ok := ctx.Deadline(); ok {
+                        trInfo.firstLine.deadline = deadline.Sub(time.Now())
+                }
+                trInfo.tr.LazyLog(&trInfo.firstLine, false)
+                ctx = trace.NewContext(ctx, trInfo.tr)
+                defer func() {
+                        if err != nil {
+                                // Need to call tr.finish() if error is returned.
+                                // Because tr will not be returned to caller.
+                                trInfo.tr.LazyPrintf("RPC: [%v]", err)
+                                trInfo.tr.SetError()
+                                trInfo.tr.Finish()
+                        }
+                }()
+        }
+        ctx = newContextWithRPCInfo(ctx)
+        sh := cc.dopts.copts.StatsHandler
+        if sh != nil {
+                ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: method, FailFast: c.failFast})
+                begin := &stats.Begin{
+                        Client:    true,
+                        BeginTime: time.Now(),
+                        FailFast:  c.failFast,
+                }
+                sh.HandleRPC(ctx, begin)
+                defer func() {
+                        if err != nil {
+                                // Only handle end stats if err != nil.
+                                end := &stats.End{
+                                        Client: true,
+                                        Error:  err,
+                                }
+                                sh.HandleRPC(ctx, end)
+                        }
+                }()
+        }
+        gopts := BalancerGetOptions{
+                BlockingWait: !c.failFast,
+        }
+        for {
+                t, put, err = cc.getTransport(ctx, gopts)
+                if err != nil {
+                        // TODO(zhaoq): Probably revisit the error handling.
+                        if _, ok := status.FromError(err); ok {
+                                return nil, err
+                        }
+                        if err == errConnClosing || err == errConnUnavailable {
+                                if c.failFast {
+                                        return nil, Errorf(codes.Unavailable, "%v", err)
+                                }
+                                continue
+                        }
+                        // All the other errors are treated as Internal errors.
+                        return nil, Errorf(codes.Internal, "%v", err)
+                }
+
+                s, err = t.NewStream(ctx, callHdr)
+                if err != nil {
+                        if _, ok := err.(transport.ConnectionError); ok && put != nil {
+                                // If error is connection error, transport was sending data on wire,
+                                // and we are not sure if anything has been sent on wire.
+                                // If error is not connection error, we are sure nothing has been sent.
+                                updateRPCInfoInContext(ctx, rpcInfo{bytesSent: true, bytesReceived: false})
+                        }
+                        if put != nil {
+                                put()
+                                put = nil
+                        }
+                        if _, ok := err.(transport.ConnectionError); (ok || err == transport.ErrStreamDrain) && !c.failFast {
+                                continue
+                        }
+                        return nil, toRPCErr(err)
+                }
+                break
+        }
+        // Set callInfo.peer object from stream's context.
+        if peer, ok := peer.FromContext(s.Context()); ok {
+                c.peer = peer
+        }
+        cs := &clientStream{
+                opts:   opts,
+                c:      c,
+                desc:   desc,
+                codec:  cc.dopts.codec,
+                cp:     cc.dopts.cp,
+                dc:     cc.dopts.dc,
+                cancel: cancel,
+
+                put: put,
+                t:   t,
+                s:   s,
+                p:   &parser{r: s},
+
+                tracing: EnableTracing,
+                trInfo:  trInfo,
+
+                statsCtx:     ctx,
+                statsHandler: cc.dopts.copts.StatsHandler,
+        }
+        if cc.dopts.cp != nil {
+                cs.cbuf = new(bytes.Buffer)
+        }
+        // Listen on ctx.Done() to detect cancellation and s.Done() to detect normal termination
+        // when there is no pending I/O operations on this stream.
+        go func() {
+                select {
+                case <-t.Error():
+                        // Incur transport error, simply exit.
+                case <-cc.ctx.Done():
+                        cs.finish(ErrClientConnClosing)
+                        cs.closeTransportStream(ErrClientConnClosing)
+                case <-s.Done():
+                        // TODO: The trace of the RPC is terminated here when there is no pending
+                        // I/O, which is probably not the optimal solution.
+                        cs.finish(s.Status().Err())
+                        cs.closeTransportStream(nil)
+                case <-s.GoAway():
+                        cs.finish(errConnDrain)
+                        cs.closeTransportStream(errConnDrain)
+                case <-s.Context().Done():
+                        err := s.Context().Err()
+                        cs.finish(err)
+                        cs.closeTransportStream(transport.ContextErr(err))
+                }
+        }()
+        return cs, nil
+}
+
+// clientStream implements a client side Stream.
+type clientStream struct {
+        opts   []CallOption
+        c      callInfo
+        t      transport.ClientTransport
+        s      *transport.Stream
+        p      *parser
+        desc   *StreamDesc
+        codec  Codec
+        cp     Compressor
+        cbuf   *bytes.Buffer
+        dc     Decompressor
+        cancel context.CancelFunc
+
+        tracing bool // set to EnableTracing when the clientStream is created.
+
+        mu       sync.Mutex
+        put      func()
+        closed   bool
+        finished bool
+        // trInfo.tr is set when the clientStream is created (if EnableTracing is true),
+        // and is set to nil when the clientStream's finish method is called.
+        trInfo traceInfo
+
+        // statsCtx keeps the user context for stats handling.
+        // All stats collection should use the statsCtx (instead of the stream context)
+        // so that all the generated stats for a particular RPC can be associated in the processing phase.
+        statsCtx     context.Context
+        statsHandler stats.Handler
+}
+
+func (cs *clientStream) Context() context.Context {
+        return cs.s.Context()
+}
+
+func (cs *clientStream) Header() (metadata.MD, error) {
+        m, err := cs.s.Header()
+        if err != nil {
+                if _, ok := err.(transport.ConnectionError); !ok {
+                        cs.closeTransportStream(err)
+                }
+        }
+        return m, err
+}
+
+func (cs *clientStream) Trailer() metadata.MD {
+        return cs.s.Trailer()
+}
+
+func (cs *clientStream) SendMsg(m interface{}) (err error) {
+        if cs.tracing {
+                cs.mu.Lock()
+                if cs.trInfo.tr != nil {
+                        cs.trInfo.tr.LazyLog(&payload{sent: true, msg: m}, true)
+                }
+                cs.mu.Unlock()
+        }
+        // TODO Investigate how to signal the stats handling party.
+        // generate error stats if err != nil && err != io.EOF?
+        defer func() {
+                if err != nil {
+                        cs.finish(err)
+                }
+                if err == nil {
+                        return
+                }
+                if err == io.EOF {
+                        // Specialize the process for server streaming. SendMesg is only called
+                        // once when creating the stream object. io.EOF needs to be skipped when
+                        // the rpc is early finished (before the stream object is created.).
+                        // TODO: It is probably better to move this into the generated code.
+                        if !cs.desc.ClientStreams && cs.desc.ServerStreams {
+                                err = nil
+                        }
+                        return
+                }
+                if _, ok := err.(transport.ConnectionError); !ok {
+                        cs.closeTransportStream(err)
+                }
+                err = toRPCErr(err)
+        }()
+        var outPayload *stats.OutPayload
+        if cs.statsHandler != nil {
+                outPayload = &stats.OutPayload{
+                        Client: true,
+                }
+        }
+        out, err := encode(cs.codec, m, cs.cp, cs.cbuf, outPayload)
+        defer func() {
+                if cs.cbuf != nil {
+                        cs.cbuf.Reset()
+                }
+        }()
+        if err != nil {
+                return err
+        }
+        if cs.c.maxSendMessageSize == nil {
+                return Errorf(codes.Internal, "callInfo maxSendMessageSize field uninitialized(nil)")
+        }
+        if len(out) > *cs.c.maxSendMessageSize {
+                return Errorf(codes.ResourceExhausted, "trying to send message larger than max (%d vs. %d)", len(out), *cs.c.maxSendMessageSize)
+        }
+        err = cs.t.Write(cs.s, out, &transport.Options{Last: false})
+        if err == nil && outPayload != nil {
+                outPayload.SentTime = time.Now()
+                cs.statsHandler.HandleRPC(cs.statsCtx, outPayload)
+        }
+        return err
+}
+
+func (cs *clientStream) RecvMsg(m interface{}) (err error) {
+        var inPayload *stats.InPayload
+        if cs.statsHandler != nil {
+                inPayload = &stats.InPayload{
+                        Client: true,
+                }
+        }
+        if cs.c.maxReceiveMessageSize == nil {
+                return Errorf(codes.Internal, "callInfo maxReceiveMessageSize field uninitialized(nil)")
+        }
+        err = recv(cs.p, cs.codec, cs.s, cs.dc, m, *cs.c.maxReceiveMessageSize, inPayload)
+        defer func() {
+                // err != nil indicates the termination of the stream.
+                if err != nil {
+                        cs.finish(err)
+                }
+        }()
+        if err == nil {
+                if cs.tracing {
+                        cs.mu.Lock()
+                        if cs.trInfo.tr != nil {
+                                cs.trInfo.tr.LazyLog(&payload{sent: false, msg: m}, true)
+                        }
+                        cs.mu.Unlock()
+                }
+                if inPayload != nil {
+                        cs.statsHandler.HandleRPC(cs.statsCtx, inPayload)
+                }
+                if !cs.desc.ClientStreams || cs.desc.ServerStreams {
+                        return
+                }
+                // Special handling for client streaming rpc.
+                // This recv expects EOF or errors, so we don't collect inPayload.
+                if cs.c.maxReceiveMessageSize == nil {
+                        return Errorf(codes.Internal, "callInfo maxReceiveMessageSize field uninitialized(nil)")
+                }
+                err = recv(cs.p, cs.codec, cs.s, cs.dc, m, *cs.c.maxReceiveMessageSize, nil)
+                cs.closeTransportStream(err)
+                if err == nil {
+                        return toRPCErr(errors.New("grpc: client streaming protocol violation: get <nil>, want <EOF>"))
+                }
+                if err == io.EOF {
+                        if se := cs.s.Status().Err(); se != nil {
+                                return se
+                        }
+                        cs.finish(err)
+                        return nil
+                }
+                return toRPCErr(err)
+        }
+        if _, ok := err.(transport.ConnectionError); !ok {
+                cs.closeTransportStream(err)
+        }
+        if err == io.EOF {
+                if statusErr := cs.s.Status().Err(); statusErr != nil {
+                        return statusErr
+                }
+                // Returns io.EOF to indicate the end of the stream.
+                return
+        }
+        return toRPCErr(err)
+}
+
+func (cs *clientStream) CloseSend() (err error) {
+        err = cs.t.Write(cs.s, nil, &transport.Options{Last: true})
+        defer func() {
+                if err != nil {
+                        cs.finish(err)
+                }
+        }()
+        if err == nil || err == io.EOF {
+                return nil
+        }
+        if _, ok := err.(transport.ConnectionError); !ok {
+                cs.closeTransportStream(err)
+        }
+        err = toRPCErr(err)
+        return
+}
+
+func (cs *clientStream) closeTransportStream(err error) {
+        cs.mu.Lock()
+        if cs.closed {
+                cs.mu.Unlock()
+                return
+        }
+        cs.closed = true
+        cs.mu.Unlock()
+        cs.t.CloseStream(cs.s, err)
+}
+
+func (cs *clientStream) finish(err error) {
+        cs.mu.Lock()
+        defer cs.mu.Unlock()
+        if cs.finished {
+                return
+        }
+        cs.finished = true
+        defer func() {
+                if cs.cancel != nil {
+                        cs.cancel()
+                }
+        }()
+        for _, o := range cs.opts {
+                o.after(&cs.c)
+        }
+        if cs.put != nil {
+                updateRPCInfoInContext(cs.s.Context(), rpcInfo{
+                        bytesSent:     cs.s.BytesSent(),
+                        bytesReceived: cs.s.BytesReceived(),
+                })
+                cs.put()
+                cs.put = nil
+        }
+        if cs.statsHandler != nil {
+                end := &stats.End{
+                        Client:  true,
+                        EndTime: time.Now(),
+                }
+                if err != io.EOF {
+                        // end.Error is nil if the RPC finished successfully.
+                        end.Error = toRPCErr(err)
+                }
+                cs.statsHandler.HandleRPC(cs.statsCtx, end)
+        }
+        if !cs.tracing {
+                return
+        }
+        if cs.trInfo.tr != nil {
+                if err == nil || err == io.EOF {
+                        cs.trInfo.tr.LazyPrintf("RPC: [OK]")
+                } else {
+                        cs.trInfo.tr.LazyPrintf("RPC: [%v]", err)
+                        cs.trInfo.tr.SetError()
+                }
+                cs.trInfo.tr.Finish()
+                cs.trInfo.tr = nil
+        }
+}
+
+// ServerStream defines the interface a server stream has to satisfy.
+type ServerStream interface {
+        // SetHeader sets the header metadata. It may be called multiple times.
+        // When call multiple times, all the provided metadata will be merged.
+        // All the metadata will be sent out when one of the following happens:
+        //  - ServerStream.SendHeader() is called;
+        //  - The first response is sent out;
+        //  - An RPC status is sent out (error or success).
+        SetHeader(metadata.MD) error
+        // SendHeader sends the header metadata.
+        // The provided md and headers set by SetHeader() will be sent.
+        // It fails if called multiple times.
+        SendHeader(metadata.MD) error
+        // SetTrailer sets the trailer metadata which will be sent with the RPC status.
+        // When called more than once, all the provided metadata will be merged.
+        SetTrailer(metadata.MD)
+        Stream
+}
+
+// serverStream implements a server side Stream.
+type serverStream struct {
+        t                     transport.ServerTransport
+        s                     *transport.Stream
+        p                     *parser
+        codec                 Codec
+        cp                    Compressor
+        dc                    Decompressor
+        cbuf                  *bytes.Buffer
+        maxReceiveMessageSize int
+        maxSendMessageSize    int
+        trInfo                *traceInfo
+
+        statsHandler stats.Handler
+
+        mu sync.Mutex // protects trInfo.tr after the service handler runs.
+}
+
+func (ss *serverStream) Context() context.Context {
+        return ss.s.Context()
+}
+
+func (ss *serverStream) SetHeader(md metadata.MD) error {
+        if md.Len() == 0 {
+                return nil
+        }
+        return ss.s.SetHeader(md)
+}
+
+func (ss *serverStream) SendHeader(md metadata.MD) error {
+        return ss.t.WriteHeader(ss.s, md)
+}
+
+func (ss *serverStream) SetTrailer(md metadata.MD) {
+        if md.Len() == 0 {
+                return
+        }
+        ss.s.SetTrailer(md)
+        return
+}
+
+func (ss *serverStream) SendMsg(m interface{}) (err error) {
+        defer func() {
+                if ss.trInfo != nil {
+                        ss.mu.Lock()
+                        if ss.trInfo.tr != nil {
+                                if err == nil {
+                                        ss.trInfo.tr.LazyLog(&payload{sent: true, msg: m}, true)
+                                } else {
+                                        ss.trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                                        ss.trInfo.tr.SetError()
+                                }
+                        }
+                        ss.mu.Unlock()
+                }
+        }()
+        var outPayload *stats.OutPayload
+        if ss.statsHandler != nil {
+                outPayload = &stats.OutPayload{}
+        }
+        out, err := encode(ss.codec, m, ss.cp, ss.cbuf, outPayload)
+        defer func() {
+                if ss.cbuf != nil {
+                        ss.cbuf.Reset()
+                }
+        }()
+        if err != nil {
+                return err
+        }
+        if len(out) > ss.maxSendMessageSize {
+                return Errorf(codes.ResourceExhausted, "trying to send message larger than max (%d vs. %d)", len(out), ss.maxSendMessageSize)
+        }
+        if err := ss.t.Write(ss.s, out, &transport.Options{Last: false}); err != nil {
+                return toRPCErr(err)
+        }
+        if outPayload != nil {
+                outPayload.SentTime = time.Now()
+                ss.statsHandler.HandleRPC(ss.s.Context(), outPayload)
+        }
+        return nil
+}
+
+func (ss *serverStream) RecvMsg(m interface{}) (err error) {
+        defer func() {
+                if ss.trInfo != nil {
+                        ss.mu.Lock()
+                        if ss.trInfo.tr != nil {
+                                if err == nil {
+                                        ss.trInfo.tr.LazyLog(&payload{sent: false, msg: m}, true)
+                                } else if err != io.EOF {
+                                        ss.trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
+                                        ss.trInfo.tr.SetError()
+                                }
+                        }
+                        ss.mu.Unlock()
+                }
+        }()
+        var inPayload *stats.InPayload
+        if ss.statsHandler != nil {
+                inPayload = &stats.InPayload{}
+        }
+        if err := recv(ss.p, ss.codec, ss.s, ss.dc, m, ss.maxReceiveMessageSize, inPayload); err != nil {
+                if err == io.EOF {
+                        return err
+                }
+                if err == io.ErrUnexpectedEOF {
+                        err = Errorf(codes.Internal, io.ErrUnexpectedEOF.Error())
+                }
+                return toRPCErr(err)
+        }
+        if inPayload != nil {
+                ss.statsHandler.HandleRPC(ss.s.Context(), inPayload)
+        }
+        return nil
+}
diff --git a/vendor/google.golang.org/grpc/tap/tap.go b/vendor/google.golang.org/grpc/tap/tap.go
new file mode 100644
index 0000000..decb678
--- /dev/null
+++ b/vendor/google.golang.org/grpc/tap/tap.go
@@ -0,0 +1,39 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package tap defines the function handles which are executed on the transport
+// layer of gRPC-Go and related information. Everything here is EXPERIMENTAL.
+package tap
+
+import (
+        "golang.org/x/net/context"
+)
+
+// Info defines the relevant information needed by the handles.
+type Info struct {
+        // FullMethodName is the string of grpc method (in the format of
+        // /package.service/method).
+        FullMethodName string
+        // TODO: More to be added.
+}
+
+// ServerInHandle defines the function which runs when a new stream is created
+// on the server side. Note that it is executed in the per-connection I/O goroutine(s) instead
+// of per-RPC goroutine. Therefore, users should NOT have any blocking/time-consuming
+// work in this handle. Otherwise all the RPCs would slow down.
+type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error)
diff --git a/vendor/google.golang.org/grpc/trace.go b/vendor/google.golang.org/grpc/trace.go
new file mode 100644
index 0000000..b419c9e
--- /dev/null
+++ b/vendor/google.golang.org/grpc/trace.go
@@ -0,0 +1,104 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+        "bytes"
+        "fmt"
+        "io"
+        "net"
+        "strings"
+        "time"
+
+        "golang.org/x/net/trace"
+)
+
+// EnableTracing controls whether to trace RPCs using the golang.org/x/net/trace package.
+// This should only be set before any RPCs are sent or received by this program.
+var EnableTracing = true
+
+// methodFamily returns the trace family for the given method.
+// It turns "/pkg.Service/GetFoo" into "pkg.Service".
+func methodFamily(m string) string {
+        m = strings.TrimPrefix(m, "/") // remove leading slash
+        if i := strings.Index(m, "/"); i >= 0 {
+                m = m[:i] // remove everything from second slash
+        }
+        if i := strings.LastIndex(m, "."); i >= 0 {
+                m = m[i+1:] // cut down to last dotted component
+        }
+        return m
+}
+
+// traceInfo contains tracing information for an RPC.
+type traceInfo struct {
+        tr        trace.Trace
+        firstLine firstLine
+}
+
+// firstLine is the first line of an RPC trace.
+type firstLine struct {
+        client     bool // whether this is a client (outgoing) RPC
+        remoteAddr net.Addr
+        deadline   time.Duration // may be zero
+}
+
+func (f *firstLine) String() string {
+        var line bytes.Buffer
+        io.WriteString(&line, "RPC: ")
+        if f.client {
+                io.WriteString(&line, "to")
+        } else {
+                io.WriteString(&line, "from")
+        }
+        fmt.Fprintf(&line, " %v deadline:", f.remoteAddr)
+        if f.deadline != 0 {
+                fmt.Fprint(&line, f.deadline)
+        } else {
+                io.WriteString(&line, "none")
+        }
+        return line.String()
+}
+
+// payload represents an RPC request or response payload.
+type payload struct {
+        sent bool        // whether this is an outgoing payload
+        msg  interface{} // e.g. a proto.Message
+        // TODO(dsymonds): add stringifying info to codec, and limit how much we hold here?
+}
+
+func (p payload) String() string {
+        if p.sent {
+                return fmt.Sprintf("sent: %v", p.msg)
+        }
+        return fmt.Sprintf("recv: %v", p.msg)
+}
+
+type fmtStringer struct {
+        format string
+        a      []interface{}
+}
+
+func (f *fmtStringer) String() string {
+        return fmt.Sprintf(f.format, f.a...)
+}
+
+type stringer string
+
+func (s stringer) String() string { return string(s) }
diff --git a/vendor/google.golang.org/grpc/transport/bdp_estimator.go b/vendor/google.golang.org/grpc/transport/bdp_estimator.go
new file mode 100644
index 0000000..667edb8
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/bdp_estimator.go
@@ -0,0 +1,143 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "sync"
+        "time"
+)
+
+const (
+        // bdpLimit is the maximum value the flow control windows
+        // will be increased to.
+        bdpLimit = (1 << 20) * 4
+        // alpha is a constant factor used to keep a moving average
+        // of RTTs.
+        alpha = 0.9
+        // If the current bdp sample is greater than or equal to
+        // our beta * our estimated bdp and the current bandwidth
+        // sample is the maximum bandwidth observed so far, we
+        // increase our bbp estimate by a factor of gamma.
+        beta = 0.66
+        // To put our bdp to be smaller than or equal to twice the real BDP,
+        // we should multiply our current sample with 4/3, however to round things out
+        // we use 2 as the multiplication factor.
+        gamma = 2
+)
+
+var (
+        // Adding arbitrary data to ping so that its ack can be
+        // identified.
+        // Easter-egg: what does the ping message say?
+        bdpPing = &ping{data: [8]byte{2, 4, 16, 16, 9, 14, 7, 7}}
+)
+
+type bdpEstimator struct {
+        // sentAt is the time when the ping was sent.
+        sentAt time.Time
+
+        mu sync.Mutex
+        // bdp is the current bdp estimate.
+        bdp uint32
+        // sample is the number of bytes received in one measurement cycle.
+        sample uint32
+        // bwMax is the maximum bandwidth noted so far (bytes/sec).
+        bwMax float64
+        // bool to keep track of the begining of a new measurement cycle.
+        isSent bool
+        // Callback to update the window sizes.
+        updateFlowControl func(n uint32)
+        // sampleCount is the number of samples taken so far.
+        sampleCount uint64
+        // round trip time (seconds)
+        rtt float64
+}
+
+// timesnap registers the time bdp ping was sent out so that
+// network rtt can be calculated when its ack is recieved.
+// It is called (by controller) when the bdpPing is
+// being written on the wire.
+func (b *bdpEstimator) timesnap(d [8]byte) {
+        if bdpPing.data != d {
+                return
+        }
+        b.sentAt = time.Now()
+}
+
+// add adds bytes to the current sample for calculating bdp.
+// It returns true only if a ping must be sent. This can be used
+// by the caller (handleData) to make decision about batching
+// a window update with it.
+func (b *bdpEstimator) add(n uint32) bool {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if b.bdp == bdpLimit {
+                return false
+        }
+        if !b.isSent {
+                b.isSent = true
+                b.sample = n
+                b.sentAt = time.Time{}
+                b.sampleCount++
+                return true
+        }
+        b.sample += n
+        return false
+}
+
+// calculate is called when an ack for a bdp ping is received.
+// Here we calculate the current bdp and bandwidth sample and
+// decide if the flow control windows should go up.
+func (b *bdpEstimator) calculate(d [8]byte) {
+        // Check if the ping acked for was the bdp ping.
+        if bdpPing.data != d {
+                return
+        }
+        b.mu.Lock()
+        rttSample := time.Since(b.sentAt).Seconds()
+        if b.sampleCount < 10 {
+                // Bootstrap rtt with an average of first 10 rtt samples.
+                b.rtt += (rttSample - b.rtt) / float64(b.sampleCount)
+        } else {
+                // Heed to the recent past more.
+                b.rtt += (rttSample - b.rtt) * float64(alpha)
+        }
+        b.isSent = false
+        // The number of bytes accumalated so far in the sample is smaller
+        // than or equal to 1.5 times the real BDP on a saturated connection.
+        bwCurrent := float64(b.sample) / (b.rtt * float64(1.5))
+        if bwCurrent > b.bwMax {
+                b.bwMax = bwCurrent
+        }
+        // If the current sample (which is smaller than or equal to the 1.5 times the real BDP) is
+        // greater than or equal to 2/3rd our perceived bdp AND this is the maximum bandwidth seen so far, we
+        // should update our perception of the network BDP.
+        if float64(b.sample) >= beta*float64(b.bdp) && bwCurrent == b.bwMax && b.bdp != bdpLimit {
+                sampleFloat := float64(b.sample)
+                b.bdp = uint32(gamma * sampleFloat)
+                if b.bdp > bdpLimit {
+                        b.bdp = bdpLimit
+                }
+                bdp := b.bdp
+                b.mu.Unlock()
+                b.updateFlowControl(bdp)
+                return
+        }
+        b.mu.Unlock()
+}
diff --git a/vendor/google.golang.org/grpc/transport/control.go b/vendor/google.golang.org/grpc/transport/control.go
new file mode 100644
index 0000000..501eb03
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/control.go
@@ -0,0 +1,246 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "fmt"
+        "math"
+        "sync"
+        "time"
+
+        "golang.org/x/net/http2"
+)
+
+const (
+        // The default value of flow control window size in HTTP2 spec.
+        defaultWindowSize = 65535
+        // The initial window size for flow control.
+        initialWindowSize             = defaultWindowSize // for an RPC
+        infinity                      = time.Duration(math.MaxInt64)
+        defaultClientKeepaliveTime    = infinity
+        defaultClientKeepaliveTimeout = time.Duration(20 * time.Second)
+        defaultMaxStreamsClient       = 100
+        defaultMaxConnectionIdle      = infinity
+        defaultMaxConnectionAge       = infinity
+        defaultMaxConnectionAgeGrace  = infinity
+        defaultServerKeepaliveTime    = time.Duration(2 * time.Hour)
+        defaultServerKeepaliveTimeout = time.Duration(20 * time.Second)
+        defaultKeepalivePolicyMinTime = time.Duration(5 * time.Minute)
+        // max window limit set by HTTP2 Specs.
+        maxWindowSize = math.MaxInt32
+)
+
+// The following defines various control items which could flow through
+// the control buffer of transport. They represent different aspects of
+// control tasks, e.g., flow control, settings, streaming resetting, etc.
+type windowUpdate struct {
+        streamID  uint32
+        increment uint32
+        flush     bool
+}
+
+func (*windowUpdate) item() {}
+
+type settings struct {
+        ack bool
+        ss  []http2.Setting
+}
+
+func (*settings) item() {}
+
+type resetStream struct {
+        streamID uint32
+        code     http2.ErrCode
+}
+
+func (*resetStream) item() {}
+
+type goAway struct {
+        code      http2.ErrCode
+        debugData []byte
+        headsUp   bool
+        closeConn bool
+}
+
+func (*goAway) item() {}
+
+type flushIO struct {
+}
+
+func (*flushIO) item() {}
+
+type ping struct {
+        ack  bool
+        data [8]byte
+}
+
+func (*ping) item() {}
+
+// quotaPool is a pool which accumulates the quota and sends it to acquire()
+// when it is available.
+type quotaPool struct {
+        c chan int
+
+        mu    sync.Mutex
+        quota int
+}
+
+// newQuotaPool creates a quotaPool which has quota q available to consume.
+func newQuotaPool(q int) *quotaPool {
+        qb := &quotaPool{
+                c: make(chan int, 1),
+        }
+        if q > 0 {
+                qb.c <- q
+        } else {
+                qb.quota = q
+        }
+        return qb
+}
+
+// add cancels the pending quota sent on acquired, incremented by v and sends
+// it back on acquire.
+func (qb *quotaPool) add(v int) {
+        qb.mu.Lock()
+        defer qb.mu.Unlock()
+        select {
+        case n := <-qb.c:
+                qb.quota += n
+        default:
+        }
+        qb.quota += v
+        if qb.quota <= 0 {
+                return
+        }
+        // After the pool has been created, this is the only place that sends on
+        // the channel. Since mu is held at this point and any quota that was sent
+        // on the channel has been retrieved, we know that this code will always
+        // place any positive quota value on the channel.
+        select {
+        case qb.c <- qb.quota:
+                qb.quota = 0
+        default:
+        }
+}
+
+// acquire returns the channel on which available quota amounts are sent.
+func (qb *quotaPool) acquire() <-chan int {
+        return qb.c
+}
+
+// inFlow deals with inbound flow control
+type inFlow struct {
+        mu sync.Mutex
+        // The inbound flow control limit for pending data.
+        limit uint32
+        // pendingData is the overall data which have been received but not been
+        // consumed by applications.
+        pendingData uint32
+        // The amount of data the application has consumed but grpc has not sent
+        // window update for them. Used to reduce window update frequency.
+        pendingUpdate uint32
+        // delta is the extra window update given by receiver when an application
+        // is reading data bigger in size than the inFlow limit.
+        delta uint32
+}
+
+// newLimit updates the inflow window to a new value n.
+// It assumes that n is always greater than the old limit.
+func (f *inFlow) newLimit(n uint32) uint32 {
+        f.mu.Lock()
+        defer f.mu.Unlock()
+        d := n - f.limit
+        f.limit = n
+        return d
+}
+
+func (f *inFlow) maybeAdjust(n uint32) uint32 {
+        if n > uint32(math.MaxInt32) {
+                n = uint32(math.MaxInt32)
+        }
+        f.mu.Lock()
+        defer f.mu.Unlock()
+        // estSenderQuota is the receiver's view of the maximum number of bytes the sender
+        // can send without a window update.
+        estSenderQuota := int32(f.limit - (f.pendingData + f.pendingUpdate))
+        // estUntransmittedData is the maximum number of bytes the sends might not have put
+        // on the wire yet. A value of 0 or less means that we have already received all or
+        // more bytes than the application is requesting to read.
+        estUntransmittedData := int32(n - f.pendingData) // Casting into int32 since it could be negative.
+        // This implies that unless we send a window update, the sender won't be able to send all the bytes
+        // for this message. Therefore we must send an update over the limit since there's an active read
+        // request from the application.
+        if estUntransmittedData > estSenderQuota {
+                // Sender's window shouldn't go more than 2^31 - 1 as speecified in the HTTP spec.
+                if f.limit+n > maxWindowSize {
+                        f.delta = maxWindowSize - f.limit
+                } else {
+                        // Send a window update for the whole message and not just the difference between
+                        // estUntransmittedData and estSenderQuota. This will be helpful in case the message
+                        // is padded; We will fallback on the current available window(at least a 1/4th of the limit).
+                        f.delta = n
+                }
+                return f.delta
+        }
+        return 0
+}
+
+// onData is invoked when some data frame is received. It updates pendingData.
+func (f *inFlow) onData(n uint32) error {
+        f.mu.Lock()
+        defer f.mu.Unlock()
+        f.pendingData += n
+        if f.pendingData+f.pendingUpdate > f.limit+f.delta {
+                return fmt.Errorf("received %d-bytes data exceeding the limit %d bytes", f.pendingData+f.pendingUpdate, f.limit)
+        }
+        return nil
+}
+
+// onRead is invoked when the application reads the data. It returns the window size
+// to be sent to the peer.
+func (f *inFlow) onRead(n uint32) uint32 {
+        f.mu.Lock()
+        defer f.mu.Unlock()
+        if f.pendingData == 0 {
+                return 0
+        }
+        f.pendingData -= n
+        if n > f.delta {
+                n -= f.delta
+                f.delta = 0
+        } else {
+                f.delta -= n
+                n = 0
+        }
+        f.pendingUpdate += n
+        if f.pendingUpdate >= f.limit/4 {
+                wu := f.pendingUpdate
+                f.pendingUpdate = 0
+                return wu
+        }
+        return 0
+}
+
+func (f *inFlow) resetPendingUpdate() uint32 {
+        f.mu.Lock()
+        defer f.mu.Unlock()
+        n := f.pendingUpdate
+        f.pendingUpdate = 0
+        return n
+}
diff --git a/vendor/google.golang.org/grpc/transport/go16.go b/vendor/google.golang.org/grpc/transport/go16.go
new file mode 100644
index 0000000..7cffee1
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/go16.go
@@ -0,0 +1,45 @@
+// +build go1.6,!go1.7
+
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "net"
+
+        "google.golang.org/grpc/codes"
+
+        "golang.org/x/net/context"
+)
+
+// dialContext connects to the address on the named network.
+func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
+        return (&net.Dialer{Cancel: ctx.Done()}).Dial(network, address)
+}
+
+// ContextErr converts the error from context package into a StreamError.
+func ContextErr(err error) StreamError {
+        switch err {
+        case context.DeadlineExceeded:
+                return streamErrorf(codes.DeadlineExceeded, "%v", err)
+        case context.Canceled:
+                return streamErrorf(codes.Canceled, "%v", err)
+        }
+        return streamErrorf(codes.Internal, "Unexpected error from context packet: %v", err)
+}
diff --git a/vendor/google.golang.org/grpc/transport/go17.go b/vendor/google.golang.org/grpc/transport/go17.go
new file mode 100644
index 0000000..2464e69
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/go17.go
@@ -0,0 +1,46 @@
+// +build go1.7
+
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "context"
+        "net"
+
+        "google.golang.org/grpc/codes"
+
+        netctx "golang.org/x/net/context"
+)
+
+// dialContext connects to the address on the named network.
+func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
+        return (&net.Dialer{}).DialContext(ctx, network, address)
+}
+
+// ContextErr converts the error from context package into a StreamError.
+func ContextErr(err error) StreamError {
+        switch err {
+        case context.DeadlineExceeded, netctx.DeadlineExceeded:
+                return streamErrorf(codes.DeadlineExceeded, "%v", err)
+        case context.Canceled, netctx.Canceled:
+                return streamErrorf(codes.Canceled, "%v", err)
+        }
+        return streamErrorf(codes.Internal, "Unexpected error from context packet: %v", err)
+}
diff --git a/vendor/google.golang.org/grpc/transport/handler_server.go b/vendor/google.golang.org/grpc/transport/handler_server.go
new file mode 100644
index 0000000..27372b5
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/handler_server.go
@@ -0,0 +1,393 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// This file is the implementation of a gRPC server using HTTP/2 which
+// uses the standard Go http2 Server implementation (via the
+// http.Handler interface), rather than speaking low-level HTTP/2
+// frames itself. It is the implementation of *grpc.Server.ServeHTTP.
+
+package transport
+
+import (
+        "errors"
+        "fmt"
+        "io"
+        "net"
+        "net/http"
+        "strings"
+        "sync"
+        "time"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/http2"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/peer"
+        "google.golang.org/grpc/status"
+)
+
+// NewServerHandlerTransport returns a ServerTransport handling gRPC
+// from inside an http.Handler. It requires that the http Server
+// supports HTTP/2.
+func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request) (ServerTransport, error) {
+        if r.ProtoMajor != 2 {
+                return nil, errors.New("gRPC requires HTTP/2")
+        }
+        if r.Method != "POST" {
+                return nil, errors.New("invalid gRPC request method")
+        }
+        if !validContentType(r.Header.Get("Content-Type")) {
+                return nil, errors.New("invalid gRPC request content-type")
+        }
+        if _, ok := w.(http.Flusher); !ok {
+                return nil, errors.New("gRPC requires a ResponseWriter supporting http.Flusher")
+        }
+        if _, ok := w.(http.CloseNotifier); !ok {
+                return nil, errors.New("gRPC requires a ResponseWriter supporting http.CloseNotifier")
+        }
+
+        st := &serverHandlerTransport{
+                rw:       w,
+                req:      r,
+                closedCh: make(chan struct{}),
+                writes:   make(chan func()),
+        }
+
+        if v := r.Header.Get("grpc-timeout"); v != "" {
+                to, err := decodeTimeout(v)
+                if err != nil {
+                        return nil, streamErrorf(codes.Internal, "malformed time-out: %v", err)
+                }
+                st.timeoutSet = true
+                st.timeout = to
+        }
+
+        var metakv []string
+        if r.Host != "" {
+                metakv = append(metakv, ":authority", r.Host)
+        }
+        for k, vv := range r.Header {
+                k = strings.ToLower(k)
+                if isReservedHeader(k) && !isWhitelistedPseudoHeader(k) {
+                        continue
+                }
+                for _, v := range vv {
+                        v, err := decodeMetadataHeader(k, v)
+                        if err != nil {
+                                return nil, streamErrorf(codes.InvalidArgument, "malformed binary metadata: %v", err)
+                        }
+                        metakv = append(metakv, k, v)
+                }
+        }
+        st.headerMD = metadata.Pairs(metakv...)
+
+        return st, nil
+}
+
+// serverHandlerTransport is an implementation of ServerTransport
+// which replies to exactly one gRPC request (exactly one HTTP request),
+// using the net/http.Handler interface. This http.Handler is guaranteed
+// at this point to be speaking over HTTP/2, so it's able to speak valid
+// gRPC.
+type serverHandlerTransport struct {
+        rw               http.ResponseWriter
+        req              *http.Request
+        timeoutSet       bool
+        timeout          time.Duration
+        didCommonHeaders bool
+
+        headerMD metadata.MD
+
+        closeOnce sync.Once
+        closedCh  chan struct{} // closed on Close
+
+        // writes is a channel of code to run serialized in the
+        // ServeHTTP (HandleStreams) goroutine. The channel is closed
+        // when WriteStatus is called.
+        writes chan func()
+}
+
+func (ht *serverHandlerTransport) Close() error {
+        ht.closeOnce.Do(ht.closeCloseChanOnce)
+        return nil
+}
+
+func (ht *serverHandlerTransport) closeCloseChanOnce() { close(ht.closedCh) }
+
+func (ht *serverHandlerTransport) RemoteAddr() net.Addr { return strAddr(ht.req.RemoteAddr) }
+
+// strAddr is a net.Addr backed by either a TCP "ip:port" string, or
+// the empty string if unknown.
+type strAddr string
+
+func (a strAddr) Network() string {
+        if a != "" {
+                // Per the documentation on net/http.Request.RemoteAddr, if this is
+                // set, it's set to the IP:port of the peer (hence, TCP):
+                // https://golang.org/pkg/net/http/#Request
+                //
+                // If we want to support Unix sockets later, we can
+                // add our own grpc-specific convention within the
+                // grpc codebase to set RemoteAddr to a different
+                // format, or probably better: we can attach it to the
+                // context and use that from serverHandlerTransport.RemoteAddr.
+                return "tcp"
+        }
+        return ""
+}
+
+func (a strAddr) String() string { return string(a) }
+
+// do runs fn in the ServeHTTP goroutine.
+func (ht *serverHandlerTransport) do(fn func()) error {
+        // Avoid a panic writing to closed channel. Imperfect but maybe good enough.
+        select {
+        case <-ht.closedCh:
+                return ErrConnClosing
+        default:
+                select {
+                case ht.writes <- fn:
+                        return nil
+                case <-ht.closedCh:
+                        return ErrConnClosing
+                }
+
+        }
+}
+
+func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) error {
+        err := ht.do(func() {
+                ht.writeCommonHeaders(s)
+
+                // And flush, in case no header or body has been sent yet.
+                // This forces a separation of headers and trailers if this is the
+                // first call (for example, in end2end tests's TestNoService).
+                ht.rw.(http.Flusher).Flush()
+
+                h := ht.rw.Header()
+                h.Set("Grpc-Status", fmt.Sprintf("%d", st.Code()))
+                if m := st.Message(); m != "" {
+                        h.Set("Grpc-Message", encodeGrpcMessage(m))
+                }
+
+                // TODO: Support Grpc-Status-Details-Bin
+
+                if md := s.Trailer(); len(md) > 0 {
+                        for k, vv := range md {
+                                // Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+                                if isReservedHeader(k) {
+                                        continue
+                                }
+                                for _, v := range vv {
+                                        // http2 ResponseWriter mechanism to send undeclared Trailers after
+                                        // the headers have possibly been written.
+                                        h.Add(http2.TrailerPrefix+k, encodeMetadataHeader(k, v))
+                                }
+                        }
+                }
+        })
+        close(ht.writes)
+        return err
+}
+
+// writeCommonHeaders sets common headers on the first write
+// call (Write, WriteHeader, or WriteStatus).
+func (ht *serverHandlerTransport) writeCommonHeaders(s *Stream) {
+        if ht.didCommonHeaders {
+                return
+        }
+        ht.didCommonHeaders = true
+
+        h := ht.rw.Header()
+        h["Date"] = nil // suppress Date to make tests happy; TODO: restore
+        h.Set("Content-Type", "application/grpc")
+
+        // Predeclare trailers we'll set later in WriteStatus (after the body).
+        // This is a SHOULD in the HTTP RFC, and the way you add (known)
+        // Trailers per the net/http.ResponseWriter contract.
+        // See https://golang.org/pkg/net/http/#ResponseWriter
+        // and https://golang.org/pkg/net/http/#example_ResponseWriter_trailers
+        h.Add("Trailer", "Grpc-Status")
+        h.Add("Trailer", "Grpc-Message")
+        // TODO: Support Grpc-Status-Details-Bin
+
+        if s.sendCompress != "" {
+                h.Set("Grpc-Encoding", s.sendCompress)
+        }
+}
+
+func (ht *serverHandlerTransport) Write(s *Stream, data []byte, opts *Options) error {
+        return ht.do(func() {
+                ht.writeCommonHeaders(s)
+                ht.rw.Write(data)
+                if !opts.Delay {
+                        ht.rw.(http.Flusher).Flush()
+                }
+        })
+}
+
+func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
+        return ht.do(func() {
+                ht.writeCommonHeaders(s)
+                h := ht.rw.Header()
+                for k, vv := range md {
+                        // Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+                        if isReservedHeader(k) {
+                                continue
+                        }
+                        for _, v := range vv {
+                                v = encodeMetadataHeader(k, v)
+                                h.Add(k, v)
+                        }
+                }
+                ht.rw.WriteHeader(200)
+                ht.rw.(http.Flusher).Flush()
+        })
+}
+
+func (ht *serverHandlerTransport) HandleStreams(startStream func(*Stream), traceCtx func(context.Context, string) context.Context) {
+        // With this transport type there will be exactly 1 stream: this HTTP request.
+
+        var ctx context.Context
+        var cancel context.CancelFunc
+        if ht.timeoutSet {
+                ctx, cancel = context.WithTimeout(context.Background(), ht.timeout)
+        } else {
+                ctx, cancel = context.WithCancel(context.Background())
+        }
+
+        // requestOver is closed when either the request's context is done
+        // or the status has been written via WriteStatus.
+        requestOver := make(chan struct{})
+
+        // clientGone receives a single value if peer is gone, either
+        // because the underlying connection is dead or because the
+        // peer sends an http2 RST_STREAM.
+        clientGone := ht.rw.(http.CloseNotifier).CloseNotify()
+        go func() {
+                select {
+                case <-requestOver:
+                        return
+                case <-ht.closedCh:
+                case <-clientGone:
+                }
+                cancel()
+        }()
+
+        req := ht.req
+
+        s := &Stream{
+                id:           0, // irrelevant
+                requestRead:  func(int) {},
+                cancel:       cancel,
+                buf:          newRecvBuffer(),
+                st:           ht,
+                method:       req.URL.Path,
+                recvCompress: req.Header.Get("grpc-encoding"),
+        }
+        pr := &peer.Peer{
+                Addr: ht.RemoteAddr(),
+        }
+        if req.TLS != nil {
+                pr.AuthInfo = credentials.TLSInfo{State: *req.TLS}
+        }
+        ctx = metadata.NewIncomingContext(ctx, ht.headerMD)
+        ctx = peer.NewContext(ctx, pr)
+        s.ctx = newContextWithStream(ctx, s)
+        s.trReader = &transportReader{
+                reader:        &recvBufferReader{ctx: s.ctx, recv: s.buf},
+                windowHandler: func(int) {},
+        }
+
+        // readerDone is closed when the Body.Read-ing goroutine exits.
+        readerDone := make(chan struct{})
+        go func() {
+                defer close(readerDone)
+
+                // TODO: minimize garbage, optimize recvBuffer code/ownership
+                const readSize = 8196
+                for buf := make([]byte, readSize); ; {
+                        n, err := req.Body.Read(buf)
+                        if n > 0 {
+                                s.buf.put(recvMsg{data: buf[:n:n]})
+                                buf = buf[n:]
+                        }
+                        if err != nil {
+                                s.buf.put(recvMsg{err: mapRecvMsgError(err)})
+                                return
+                        }
+                        if len(buf) == 0 {
+                                buf = make([]byte, readSize)
+                        }
+                }
+        }()
+
+        // startStream is provided by the *grpc.Server's serveStreams.
+        // It starts a goroutine serving s and exits immediately.
+        // The goroutine that is started is the one that then calls
+        // into ht, calling WriteHeader, Write, WriteStatus, Close, etc.
+        startStream(s)
+
+        ht.runStream()
+        close(requestOver)
+
+        // Wait for reading goroutine to finish.
+        req.Body.Close()
+        <-readerDone
+}
+
+func (ht *serverHandlerTransport) runStream() {
+        for {
+                select {
+                case fn, ok := <-ht.writes:
+                        if !ok {
+                                return
+                        }
+                        fn()
+                case <-ht.closedCh:
+                        return
+                }
+        }
+}
+
+func (ht *serverHandlerTransport) Drain() {
+        panic("Drain() is not implemented")
+}
+
+// mapRecvMsgError returns the non-nil err into the appropriate
+// error value as expected by callers of *grpc.parser.recvMsg.
+// In particular, in can only be:
+//   * io.EOF
+//   * io.ErrUnexpectedEOF
+//   * of type transport.ConnectionError
+//   * of type transport.StreamError
+func mapRecvMsgError(err error) error {
+        if err == io.EOF || err == io.ErrUnexpectedEOF {
+                return err
+        }
+        if se, ok := err.(http2.StreamError); ok {
+                if code, ok := http2ErrConvTab[se.Code]; ok {
+                        return StreamError{
+                                Code: code,
+                                Desc: se.Error(),
+                        }
+                }
+        }
+        return connectionErrorf(true, err, err.Error())
+}
diff --git a/vendor/google.golang.org/grpc/transport/http2_client.go b/vendor/google.golang.org/grpc/transport/http2_client.go
new file mode 100644
index 0000000..516ea06
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/http2_client.go
@@ -0,0 +1,1369 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "bytes"
+        "io"
+        "math"
+        "net"
+        "strings"
+        "sync"
+        "sync/atomic"
+        "time"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/http2"
+        "golang.org/x/net/http2/hpack"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/keepalive"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/peer"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+)
+
+// http2Client implements the ClientTransport interface with HTTP2.
+type http2Client struct {
+        ctx        context.Context
+        target     string // server name/addr
+        userAgent  string
+        md         interface{}
+        conn       net.Conn // underlying communication channel
+        remoteAddr net.Addr
+        localAddr  net.Addr
+        authInfo   credentials.AuthInfo // auth info about the connection
+        nextID     uint32               // the next stream ID to be used
+
+        // writableChan synchronizes write access to the transport.
+        // A writer acquires the write lock by sending a value on writableChan
+        // and releases it by receiving from writableChan.
+        writableChan chan int
+        // shutdownChan is closed when Close is called.
+        // Blocking operations should select on shutdownChan to avoid
+        // blocking forever after Close.
+        // TODO(zhaoq): Maybe have a channel context?
+        shutdownChan chan struct{}
+        // errorChan is closed to notify the I/O error to the caller.
+        errorChan chan struct{}
+        // goAway is closed to notify the upper layer (i.e., addrConn.transportMonitor)
+        // that the server sent GoAway on this transport.
+        goAway chan struct{}
+        // awakenKeepalive is used to wake up keepalive when after it has gone dormant.
+        awakenKeepalive chan struct{}
+
+        framer *framer
+        hBuf   *bytes.Buffer  // the buffer for HPACK encoding
+        hEnc   *hpack.Encoder // HPACK encoder
+
+        // controlBuf delivers all the control related tasks (e.g., window
+        // updates, reset streams, and various settings) to the controller.
+        controlBuf *controlBuffer
+        fc         *inFlow
+        // sendQuotaPool provides flow control to outbound message.
+        sendQuotaPool *quotaPool
+        // streamsQuota limits the max number of concurrent streams.
+        streamsQuota *quotaPool
+
+        // The scheme used: https if TLS is on, http otherwise.
+        scheme string
+
+        isSecure bool
+
+        creds []credentials.PerRPCCredentials
+
+        // Boolean to keep track of reading activity on transport.
+        // 1 is true and 0 is false.
+        activity uint32 // Accessed atomically.
+        kp       keepalive.ClientParameters
+
+        statsHandler stats.Handler
+
+        initialWindowSize int32
+
+        bdpEst          *bdpEstimator
+        outQuotaVersion uint32
+
+        mu            sync.Mutex     // guard the following variables
+        state         transportState // the state of underlying connection
+        activeStreams map[uint32]*Stream
+        // The max number of concurrent streams
+        maxStreams int
+        // the per-stream outbound flow control window size set by the peer.
+        streamSendQuota uint32
+        // prevGoAway ID records the Last-Stream-ID in the previous GOAway frame.
+        prevGoAwayID uint32
+        // goAwayReason records the http2.ErrCode and debug data received with the
+        // GoAway frame.
+        goAwayReason GoAwayReason
+}
+
+func dial(ctx context.Context, fn func(context.Context, string) (net.Conn, error), addr string) (net.Conn, error) {
+        if fn != nil {
+                return fn(ctx, addr)
+        }
+        return dialContext(ctx, "tcp", addr)
+}
+
+func isTemporary(err error) bool {
+        switch err {
+        case io.EOF:
+                // Connection closures may be resolved upon retry, and are thus
+                // treated as temporary.
+                return true
+        case context.DeadlineExceeded:
+                // In Go 1.7, context.DeadlineExceeded implements Timeout(), and this
+                // special case is not needed. Until then, we need to keep this
+                // clause.
+                return true
+        }
+
+        switch err := err.(type) {
+        case interface {
+                Temporary() bool
+        }:
+                return err.Temporary()
+        case interface {
+                Timeout() bool
+        }:
+                // Timeouts may be resolved upon retry, and are thus treated as
+                // temporary.
+                return err.Timeout()
+        }
+        return false
+}
+
+// newHTTP2Client constructs a connected ClientTransport to addr based on HTTP2
+// and starts to receive messages on it. Non-nil error returns if construction
+// fails.
+func newHTTP2Client(ctx context.Context, addr TargetInfo, opts ConnectOptions) (_ ClientTransport, err error) {
+        scheme := "http"
+        conn, err := dial(ctx, opts.Dialer, addr.Addr)
+        if err != nil {
+                if opts.FailOnNonTempDialError {
+                        return nil, connectionErrorf(isTemporary(err), err, "transport: error while dialing: %v", err)
+                }
+                return nil, connectionErrorf(true, err, "transport: Error while dialing %v", err)
+        }
+        // Any further errors will close the underlying connection
+        defer func(conn net.Conn) {
+                if err != nil {
+                        conn.Close()
+                }
+        }(conn)
+        var (
+                isSecure bool
+                authInfo credentials.AuthInfo
+        )
+        if creds := opts.TransportCredentials; creds != nil {
+                scheme = "https"
+                conn, authInfo, err = creds.ClientHandshake(ctx, addr.Addr, conn)
+                if err != nil {
+                        // Credentials handshake errors are typically considered permanent
+                        // to avoid retrying on e.g. bad certificates.
+                        temp := isTemporary(err)
+                        return nil, connectionErrorf(temp, err, "transport: authentication handshake failed: %v", err)
+                }
+                isSecure = true
+        }
+        kp := opts.KeepaliveParams
+        // Validate keepalive parameters.
+        if kp.Time == 0 {
+                kp.Time = defaultClientKeepaliveTime
+        }
+        if kp.Timeout == 0 {
+                kp.Timeout = defaultClientKeepaliveTimeout
+        }
+        dynamicWindow := true
+        icwz := int32(initialWindowSize)
+        if opts.InitialConnWindowSize >= defaultWindowSize {
+                icwz = opts.InitialConnWindowSize
+                dynamicWindow = false
+        }
+        var buf bytes.Buffer
+        t := &http2Client{
+                ctx:        ctx,
+                target:     addr.Addr,
+                userAgent:  opts.UserAgent,
+                md:         addr.Metadata,
+                conn:       conn,
+                remoteAddr: conn.RemoteAddr(),
+                localAddr:  conn.LocalAddr(),
+                authInfo:   authInfo,
+                // The client initiated stream id is odd starting from 1.
+                nextID:            1,
+                writableChan:      make(chan int, 1),
+                shutdownChan:      make(chan struct{}),
+                errorChan:         make(chan struct{}),
+                goAway:            make(chan struct{}),
+                awakenKeepalive:   make(chan struct{}, 1),
+                framer:            newFramer(conn),
+                hBuf:              &buf,
+                hEnc:              hpack.NewEncoder(&buf),
+                controlBuf:        newControlBuffer(),
+                fc:                &inFlow{limit: uint32(icwz)},
+                sendQuotaPool:     newQuotaPool(defaultWindowSize),
+                scheme:            scheme,
+                state:             reachable,
+                activeStreams:     make(map[uint32]*Stream),
+                isSecure:          isSecure,
+                creds:             opts.PerRPCCredentials,
+                maxStreams:        defaultMaxStreamsClient,
+                streamsQuota:      newQuotaPool(defaultMaxStreamsClient),
+                streamSendQuota:   defaultWindowSize,
+                kp:                kp,
+                statsHandler:      opts.StatsHandler,
+                initialWindowSize: initialWindowSize,
+        }
+        if opts.InitialWindowSize >= defaultWindowSize {
+                t.initialWindowSize = opts.InitialWindowSize
+                dynamicWindow = false
+        }
+        if dynamicWindow {
+                t.bdpEst = &bdpEstimator{
+                        bdp:               initialWindowSize,
+                        updateFlowControl: t.updateFlowControl,
+                }
+        }
+        // Make sure awakenKeepalive can't be written upon.
+        // keepalive routine will make it writable, if need be.
+        t.awakenKeepalive <- struct{}{}
+        if t.statsHandler != nil {
+                t.ctx = t.statsHandler.TagConn(t.ctx, &stats.ConnTagInfo{
+                        RemoteAddr: t.remoteAddr,
+                        LocalAddr:  t.localAddr,
+                })
+                connBegin := &stats.ConnBegin{
+                        Client: true,
+                }
+                t.statsHandler.HandleConn(t.ctx, connBegin)
+        }
+        // Start the reader goroutine for incoming message. Each transport has
+        // a dedicated goroutine which reads HTTP2 frame from network. Then it
+        // dispatches the frame to the corresponding stream entity.
+        go t.reader()
+        // Send connection preface to server.
+        n, err := t.conn.Write(clientPreface)
+        if err != nil {
+                t.Close()
+                return nil, connectionErrorf(true, err, "transport: failed to write client preface: %v", err)
+        }
+        if n != len(clientPreface) {
+                t.Close()
+                return nil, connectionErrorf(true, err, "transport: preface mismatch, wrote %d bytes; want %d", n, len(clientPreface))
+        }
+        if t.initialWindowSize != defaultWindowSize {
+                err = t.framer.writeSettings(true, http2.Setting{
+                        ID:  http2.SettingInitialWindowSize,
+                        Val: uint32(t.initialWindowSize),
+                })
+        } else {
+                err = t.framer.writeSettings(true)
+        }
+        if err != nil {
+                t.Close()
+                return nil, connectionErrorf(true, err, "transport: failed to write initial settings frame: %v", err)
+        }
+        // Adjust the connection flow control window if needed.
+        if delta := uint32(icwz - defaultWindowSize); delta > 0 {
+                if err := t.framer.writeWindowUpdate(true, 0, delta); err != nil {
+                        t.Close()
+                        return nil, connectionErrorf(true, err, "transport: failed to write window update: %v", err)
+                }
+        }
+        go t.controller()
+        if t.kp.Time != infinity {
+                go t.keepalive()
+        }
+        t.writableChan <- 0
+        return t, nil
+}
+
+func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *Stream {
+        // TODO(zhaoq): Handle uint32 overflow of Stream.id.
+        s := &Stream{
+                id:            t.nextID,
+                done:          make(chan struct{}),
+                goAway:        make(chan struct{}),
+                method:        callHdr.Method,
+                sendCompress:  callHdr.SendCompress,
+                buf:           newRecvBuffer(),
+                fc:            &inFlow{limit: uint32(t.initialWindowSize)},
+                sendQuotaPool: newQuotaPool(int(t.streamSendQuota)),
+                headerChan:    make(chan struct{}),
+        }
+        t.nextID += 2
+        s.requestRead = func(n int) {
+                t.adjustWindow(s, uint32(n))
+        }
+        // The client side stream context should have exactly the same life cycle with the user provided context.
+        // That means, s.ctx should be read-only. And s.ctx is done iff ctx is done.
+        // So we use the original context here instead of creating a copy.
+        s.ctx = ctx
+        s.trReader = &transportReader{
+                reader: &recvBufferReader{
+                        ctx:    s.ctx,
+                        goAway: s.goAway,
+                        recv:   s.buf,
+                },
+                windowHandler: func(n int) {
+                        t.updateWindow(s, uint32(n))
+                },
+        }
+
+        return s
+}
+
+// NewStream creates a stream and registers it into the transport as "active"
+// streams.
+func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Stream, err error) {
+        pr := &peer.Peer{
+                Addr: t.remoteAddr,
+        }
+        // Attach Auth info if there is any.
+        if t.authInfo != nil {
+                pr.AuthInfo = t.authInfo
+        }
+        ctx = peer.NewContext(ctx, pr)
+        var (
+                authData = make(map[string]string)
+                audience string
+        )
+        // Create an audience string only if needed.
+        if len(t.creds) > 0 || callHdr.Creds != nil {
+                // Construct URI required to get auth request metadata.
+                var port string
+                if pos := strings.LastIndex(t.target, ":"); pos != -1 {
+                        // Omit port if it is the default one.
+                        if t.target[pos+1:] != "443" {
+                                port = ":" + t.target[pos+1:]
+                        }
+                }
+                pos := strings.LastIndex(callHdr.Method, "/")
+                if pos == -1 {
+                        pos = len(callHdr.Method)
+                }
+                audience = "https://" + callHdr.Host + port + callHdr.Method[:pos]
+        }
+        for _, c := range t.creds {
+                data, err := c.GetRequestMetadata(ctx, audience)
+                if err != nil {
+                        return nil, streamErrorf(codes.Internal, "transport: %v", err)
+                }
+                for k, v := range data {
+                        // Capital header names are illegal in HTTP/2.
+                        k = strings.ToLower(k)
+                        authData[k] = v
+                }
+        }
+        callAuthData := make(map[string]string)
+        // Check if credentials.PerRPCCredentials were provided via call options.
+        // Note: if these credentials are provided both via dial options and call
+        // options, then both sets of credentials will be applied.
+        if callCreds := callHdr.Creds; callCreds != nil {
+                if !t.isSecure && callCreds.RequireTransportSecurity() {
+                        return nil, streamErrorf(codes.Unauthenticated, "transport: cannot send secure credentials on an insecure conneciton")
+                }
+                data, err := callCreds.GetRequestMetadata(ctx, audience)
+                if err != nil {
+                        return nil, streamErrorf(codes.Internal, "transport: %v", err)
+                }
+                for k, v := range data {
+                        // Capital header names are illegal in HTTP/2
+                        k = strings.ToLower(k)
+                        callAuthData[k] = v
+                }
+        }
+        t.mu.Lock()
+        if t.activeStreams == nil {
+                t.mu.Unlock()
+                return nil, ErrConnClosing
+        }
+        if t.state == draining {
+                t.mu.Unlock()
+                return nil, ErrStreamDrain
+        }
+        if t.state != reachable {
+                t.mu.Unlock()
+                return nil, ErrConnClosing
+        }
+        t.mu.Unlock()
+        sq, err := wait(ctx, nil, nil, t.shutdownChan, t.streamsQuota.acquire())
+        if err != nil {
+                return nil, err
+        }
+        // Returns the quota balance back.
+        if sq > 1 {
+                t.streamsQuota.add(sq - 1)
+        }
+        if _, err := wait(ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
+                // Return the quota back now because there is no stream returned to the caller.
+                if _, ok := err.(StreamError); ok {
+                        t.streamsQuota.add(1)
+                }
+                return nil, err
+        }
+        t.mu.Lock()
+        if t.state == draining {
+                t.mu.Unlock()
+                t.streamsQuota.add(1)
+                // Need to make t writable again so that the rpc in flight can still proceed.
+                t.writableChan <- 0
+                return nil, ErrStreamDrain
+        }
+        if t.state != reachable {
+                t.mu.Unlock()
+                return nil, ErrConnClosing
+        }
+        s := t.newStream(ctx, callHdr)
+        t.activeStreams[s.id] = s
+        // If the number of active streams change from 0 to 1, then check if keepalive
+        // has gone dormant. If so, wake it up.
+        if len(t.activeStreams) == 1 {
+                select {
+                case t.awakenKeepalive <- struct{}{}:
+                        t.framer.writePing(false, false, [8]byte{})
+                default:
+                }
+        }
+
+        t.mu.Unlock()
+
+        // HPACK encodes various headers. Note that once WriteField(...) is
+        // called, the corresponding headers/continuation frame has to be sent
+        // because hpack.Encoder is stateful.
+        t.hBuf.Reset()
+        t.hEnc.WriteField(hpack.HeaderField{Name: ":method", Value: "POST"})
+        t.hEnc.WriteField(hpack.HeaderField{Name: ":scheme", Value: t.scheme})
+        t.hEnc.WriteField(hpack.HeaderField{Name: ":path", Value: callHdr.Method})
+        t.hEnc.WriteField(hpack.HeaderField{Name: ":authority", Value: callHdr.Host})
+        t.hEnc.WriteField(hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
+        t.hEnc.WriteField(hpack.HeaderField{Name: "user-agent", Value: t.userAgent})
+        t.hEnc.WriteField(hpack.HeaderField{Name: "te", Value: "trailers"})
+
+        if callHdr.SendCompress != "" {
+                t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-encoding", Value: callHdr.SendCompress})
+        }
+        if dl, ok := ctx.Deadline(); ok {
+                // Send out timeout regardless its value. The server can detect timeout context by itself.
+                timeout := dl.Sub(time.Now())
+                t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-timeout", Value: encodeTimeout(timeout)})
+        }
+
+        for k, v := range authData {
+                t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+        }
+        for k, v := range callAuthData {
+                t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+        }
+        var (
+                endHeaders bool
+        )
+        if md, ok := metadata.FromOutgoingContext(ctx); ok {
+                for k, vv := range md {
+                        // HTTP doesn't allow you to set pseudoheaders after non pseudoheaders were set.
+                        if isReservedHeader(k) {
+                                continue
+                        }
+                        for _, v := range vv {
+                                t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+                        }
+                }
+        }
+        if md, ok := t.md.(*metadata.MD); ok {
+                for k, vv := range *md {
+                        if isReservedHeader(k) {
+                                continue
+                        }
+                        for _, v := range vv {
+                                t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+                        }
+                }
+        }
+        first := true
+        bufLen := t.hBuf.Len()
+        // Sends the headers in a single batch even when they span multiple frames.
+        for !endHeaders {
+                size := t.hBuf.Len()
+                if size > http2MaxFrameLen {
+                        size = http2MaxFrameLen
+                } else {
+                        endHeaders = true
+                }
+                var flush bool
+                if callHdr.Flush && endHeaders {
+                        flush = true
+                }
+                if first {
+                        // Sends a HeadersFrame to server to start a new stream.
+                        p := http2.HeadersFrameParam{
+                                StreamID:      s.id,
+                                BlockFragment: t.hBuf.Next(size),
+                                EndStream:     false,
+                                EndHeaders:    endHeaders,
+                        }
+                        // Do a force flush for the buffered frames iff it is the last headers frame
+                        // and there is header metadata to be sent. Otherwise, there is flushing until
+                        // the corresponding data frame is written.
+                        err = t.framer.writeHeaders(flush, p)
+                        first = false
+                } else {
+                        // Sends Continuation frames for the leftover headers.
+                        err = t.framer.writeContinuation(flush, s.id, endHeaders, t.hBuf.Next(size))
+                }
+                if err != nil {
+                        t.notifyError(err)
+                        return nil, connectionErrorf(true, err, "transport: %v", err)
+                }
+        }
+        s.mu.Lock()
+        s.bytesSent = true
+        s.mu.Unlock()
+
+        if t.statsHandler != nil {
+                outHeader := &stats.OutHeader{
+                        Client:      true,
+                        WireLength:  bufLen,
+                        FullMethod:  callHdr.Method,
+                        RemoteAddr:  t.remoteAddr,
+                        LocalAddr:   t.localAddr,
+                        Compression: callHdr.SendCompress,
+                }
+                t.statsHandler.HandleRPC(s.ctx, outHeader)
+        }
+        t.writableChan <- 0
+        return s, nil
+}
+
+// CloseStream clears the footprint of a stream when the stream is not needed any more.
+// This must not be executed in reader's goroutine.
+func (t *http2Client) CloseStream(s *Stream, err error) {
+        t.mu.Lock()
+        if t.activeStreams == nil {
+                t.mu.Unlock()
+                return
+        }
+        if err != nil {
+                // notify in-flight streams, before the deletion
+                s.write(recvMsg{err: err})
+        }
+        delete(t.activeStreams, s.id)
+        if t.state == draining && len(t.activeStreams) == 0 {
+                // The transport is draining and s is the last live stream on t.
+                t.mu.Unlock()
+                t.Close()
+                return
+        }
+        t.mu.Unlock()
+        // rstStream is true in case the stream is being closed at the client-side
+        // and the server needs to be intimated about it by sending a RST_STREAM
+        // frame.
+        // To make sure this frame is written to the wire before the headers of the
+        // next stream waiting for streamsQuota, we add to streamsQuota pool only
+        // after having acquired the writableChan to send RST_STREAM out (look at
+        // the controller() routine).
+        var rstStream bool
+        var rstError http2.ErrCode
+        defer func() {
+                // In case, the client doesn't have to send RST_STREAM to server
+                // we can safely add back to streamsQuota pool now.
+                if !rstStream {
+                        t.streamsQuota.add(1)
+                        return
+                }
+                t.controlBuf.put(&resetStream{s.id, rstError})
+        }()
+        s.mu.Lock()
+        rstStream = s.rstStream
+        rstError = s.rstError
+        if s.state == streamDone {
+                s.mu.Unlock()
+                return
+        }
+        if !s.headerDone {
+                close(s.headerChan)
+                s.headerDone = true
+        }
+        s.state = streamDone
+        s.mu.Unlock()
+        if _, ok := err.(StreamError); ok {
+                rstStream = true
+                rstError = http2.ErrCodeCancel
+        }
+}
+
+// Close kicks off the shutdown process of the transport. This should be called
+// only once on a transport. Once it is called, the transport should not be
+// accessed any more.
+func (t *http2Client) Close() (err error) {
+        t.mu.Lock()
+        if t.state == closing {
+                t.mu.Unlock()
+                return
+        }
+        if t.state == reachable || t.state == draining {
+                close(t.errorChan)
+        }
+        t.state = closing
+        t.mu.Unlock()
+        close(t.shutdownChan)
+        err = t.conn.Close()
+        t.mu.Lock()
+        streams := t.activeStreams
+        t.activeStreams = nil
+        t.mu.Unlock()
+        // Notify all active streams.
+        for _, s := range streams {
+                s.mu.Lock()
+                if !s.headerDone {
+                        close(s.headerChan)
+                        s.headerDone = true
+                }
+                s.mu.Unlock()
+                s.write(recvMsg{err: ErrConnClosing})
+        }
+        if t.statsHandler != nil {
+                connEnd := &stats.ConnEnd{
+                        Client: true,
+                }
+                t.statsHandler.HandleConn(t.ctx, connEnd)
+        }
+        return
+}
+
+func (t *http2Client) GracefulClose() error {
+        t.mu.Lock()
+        switch t.state {
+        case unreachable:
+                // The server may close the connection concurrently. t is not available for
+                // any streams. Close it now.
+                t.mu.Unlock()
+                t.Close()
+                return nil
+        case closing:
+                t.mu.Unlock()
+                return nil
+        }
+        if t.state == draining {
+                t.mu.Unlock()
+                return nil
+        }
+        t.state = draining
+        active := len(t.activeStreams)
+        t.mu.Unlock()
+        if active == 0 {
+                return t.Close()
+        }
+        return nil
+}
+
+// Write formats the data into HTTP2 data frame(s) and sends it out. The caller
+// should proceed only if Write returns nil.
+// TODO(zhaoq): opts.Delay is ignored in this implementation. Support it later
+// if it improves the performance.
+func (t *http2Client) Write(s *Stream, data []byte, opts *Options) error {
+        r := bytes.NewBuffer(data)
+        var (
+                p   []byte
+                oqv uint32
+        )
+        for {
+                oqv = atomic.LoadUint32(&t.outQuotaVersion)
+                if r.Len() > 0 || p != nil {
+                        size := http2MaxFrameLen
+                        // Wait until the stream has some quota to send the data.
+                        sq, err := wait(s.ctx, s.done, s.goAway, t.shutdownChan, s.sendQuotaPool.acquire())
+                        if err != nil {
+                                return err
+                        }
+                        // Wait until the transport has some quota to send the data.
+                        tq, err := wait(s.ctx, s.done, s.goAway, t.shutdownChan, t.sendQuotaPool.acquire())
+                        if err != nil {
+                                return err
+                        }
+                        if sq < size {
+                                size = sq
+                        }
+                        if tq < size {
+                                size = tq
+                        }
+                        if p == nil {
+                                p = r.Next(size)
+                        }
+                        ps := len(p)
+                        if ps < sq {
+                                // Overbooked stream quota. Return it back.
+                                s.sendQuotaPool.add(sq - ps)
+                        }
+                        if ps < tq {
+                                // Overbooked transport quota. Return it back.
+                                t.sendQuotaPool.add(tq - ps)
+                        }
+                }
+                var (
+                        endStream  bool
+                        forceFlush bool
+                )
+                if opts.Last && r.Len() == 0 {
+                        endStream = true
+                }
+                // Indicate there is a writer who is about to write a data frame.
+                t.framer.adjustNumWriters(1)
+                // Got some quota. Try to acquire writing privilege on the transport.
+                if _, err := wait(s.ctx, s.done, s.goAway, t.shutdownChan, t.writableChan); err != nil {
+                        if _, ok := err.(StreamError); ok || err == io.EOF {
+                                // Return the connection quota back.
+                                t.sendQuotaPool.add(len(p))
+                        }
+                        if t.framer.adjustNumWriters(-1) == 0 {
+                                // This writer is the last one in this batch and has the
+                                // responsibility to flush the buffered frames. It queues
+                                // a flush request to controlBuf instead of flushing directly
+                                // in order to avoid the race with other writing or flushing.
+                                t.controlBuf.put(&flushIO{})
+                        }
+                        return err
+                }
+                select {
+                case <-s.ctx.Done():
+                        t.sendQuotaPool.add(len(p))
+                        if t.framer.adjustNumWriters(-1) == 0 {
+                                t.controlBuf.put(&flushIO{})
+                        }
+                        t.writableChan <- 0
+                        return ContextErr(s.ctx.Err())
+                default:
+                }
+                if oqv != atomic.LoadUint32(&t.outQuotaVersion) {
+                        // InitialWindowSize settings frame must have been received after we
+                        // acquired send quota but before we got the writable channel.
+                        // We must forsake this write.
+                        t.sendQuotaPool.add(len(p))
+                        s.sendQuotaPool.add(len(p))
+                        if t.framer.adjustNumWriters(-1) == 0 {
+                                t.controlBuf.put(&flushIO{})
+                        }
+                        t.writableChan <- 0
+                        continue
+                }
+                if r.Len() == 0 && t.framer.adjustNumWriters(0) == 1 {
+                        // Do a force flush iff this is last frame for the entire gRPC message
+                        // and the caller is the only writer at this moment.
+                        forceFlush = true
+                }
+                // If WriteData fails, all the pending streams will be handled
+                // by http2Client.Close(). No explicit CloseStream() needs to be
+                // invoked.
+                if err := t.framer.writeData(forceFlush, s.id, endStream, p); err != nil {
+                        t.notifyError(err)
+                        return connectionErrorf(true, err, "transport: %v", err)
+                }
+                p = nil
+                if t.framer.adjustNumWriters(-1) == 0 {
+                        t.framer.flushWrite()
+                }
+                t.writableChan <- 0
+                if r.Len() == 0 {
+                        break
+                }
+        }
+        if !opts.Last {
+                return nil
+        }
+        s.mu.Lock()
+        if s.state != streamDone {
+                s.state = streamWriteDone
+        }
+        s.mu.Unlock()
+        return nil
+}
+
+func (t *http2Client) getStream(f http2.Frame) (*Stream, bool) {
+        t.mu.Lock()
+        defer t.mu.Unlock()
+        s, ok := t.activeStreams[f.Header().StreamID]
+        return s, ok
+}
+
+// adjustWindow sends out extra window update over the initial window size
+// of stream if the application is requesting data larger in size than
+// the window.
+func (t *http2Client) adjustWindow(s *Stream, n uint32) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.state == streamDone {
+                return
+        }
+        if w := s.fc.maybeAdjust(n); w > 0 {
+                // Piggyback conneciton's window update along.
+                if cw := t.fc.resetPendingUpdate(); cw > 0 {
+                        t.controlBuf.put(&windowUpdate{0, cw, false})
+                }
+                t.controlBuf.put(&windowUpdate{s.id, w, true})
+        }
+}
+
+// updateWindow adjusts the inbound quota for the stream and the transport.
+// Window updates will deliver to the controller for sending when
+// the cumulative quota exceeds the corresponding threshold.
+func (t *http2Client) updateWindow(s *Stream, n uint32) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.state == streamDone {
+                return
+        }
+        if w := s.fc.onRead(n); w > 0 {
+                if cw := t.fc.resetPendingUpdate(); cw > 0 {
+                        t.controlBuf.put(&windowUpdate{0, cw, false})
+                }
+                t.controlBuf.put(&windowUpdate{s.id, w, true})
+        }
+}
+
+// updateFlowControl updates the incoming flow control windows
+// for the transport and the stream based on the current bdp
+// estimation.
+func (t *http2Client) updateFlowControl(n uint32) {
+        t.mu.Lock()
+        for _, s := range t.activeStreams {
+                s.fc.newLimit(n)
+        }
+        t.initialWindowSize = int32(n)
+        t.mu.Unlock()
+        t.controlBuf.put(&windowUpdate{0, t.fc.newLimit(n), false})
+        t.controlBuf.put(&settings{
+                ack: false,
+                ss: []http2.Setting{
+                        {
+                                ID:  http2.SettingInitialWindowSize,
+                                Val: uint32(n),
+                        },
+                },
+        })
+}
+
+func (t *http2Client) handleData(f *http2.DataFrame) {
+        size := f.Header().Length
+        var sendBDPPing bool
+        if t.bdpEst != nil {
+                sendBDPPing = t.bdpEst.add(uint32(size))
+        }
+        // Decouple connection's flow control from application's read.
+        // An update on connection's flow control should not depend on
+        // whether user application has read the data or not. Such a
+        // restriction is already imposed on the stream's flow control,
+        // and therefore the sender will be blocked anyways.
+        // Decoupling the connection flow control will prevent other
+        // active(fast) streams from starving in presence of slow or
+        // inactive streams.
+        //
+        // Furthermore, if a bdpPing is being sent out we can piggyback
+        // connection's window update for the bytes we just received.
+        if sendBDPPing {
+                t.controlBuf.put(&windowUpdate{0, uint32(size), false})
+                t.controlBuf.put(bdpPing)
+        } else {
+                if err := t.fc.onData(uint32(size)); err != nil {
+                        t.notifyError(connectionErrorf(true, err, "%v", err))
+                        return
+                }
+                if w := t.fc.onRead(uint32(size)); w > 0 {
+                        t.controlBuf.put(&windowUpdate{0, w, true})
+                }
+        }
+        // Select the right stream to dispatch.
+        s, ok := t.getStream(f)
+        if !ok {
+                return
+        }
+        if size > 0 {
+                s.mu.Lock()
+                if s.state == streamDone {
+                        s.mu.Unlock()
+                        return
+                }
+                if err := s.fc.onData(uint32(size)); err != nil {
+                        s.rstStream = true
+                        s.rstError = http2.ErrCodeFlowControl
+                        s.finish(status.New(codes.Internal, err.Error()))
+                        s.mu.Unlock()
+                        s.write(recvMsg{err: io.EOF})
+                        return
+                }
+                if f.Header().Flags.Has(http2.FlagDataPadded) {
+                        if w := s.fc.onRead(uint32(size) - uint32(len(f.Data()))); w > 0 {
+                                t.controlBuf.put(&windowUpdate{s.id, w, true})
+                        }
+                }
+                s.mu.Unlock()
+                // TODO(bradfitz, zhaoq): A copy is required here because there is no
+                // guarantee f.Data() is consumed before the arrival of next frame.
+                // Can this copy be eliminated?
+                if len(f.Data()) > 0 {
+                        data := make([]byte, len(f.Data()))
+                        copy(data, f.Data())
+                        s.write(recvMsg{data: data})
+                }
+        }
+        // The server has closed the stream without sending trailers.  Record that
+        // the read direction is closed, and set the status appropriately.
+        if f.FrameHeader.Flags.Has(http2.FlagDataEndStream) {
+                s.mu.Lock()
+                if s.state == streamDone {
+                        s.mu.Unlock()
+                        return
+                }
+                s.finish(status.New(codes.Internal, "server closed the stream without sending trailers"))
+                s.mu.Unlock()
+                s.write(recvMsg{err: io.EOF})
+        }
+}
+
+func (t *http2Client) handleRSTStream(f *http2.RSTStreamFrame) {
+        s, ok := t.getStream(f)
+        if !ok {
+                return
+        }
+        s.mu.Lock()
+        if s.state == streamDone {
+                s.mu.Unlock()
+                return
+        }
+        if !s.headerDone {
+                close(s.headerChan)
+                s.headerDone = true
+        }
+        statusCode, ok := http2ErrConvTab[http2.ErrCode(f.ErrCode)]
+        if !ok {
+                warningf("transport: http2Client.handleRSTStream found no mapped gRPC status for the received http2 error %v", f.ErrCode)
+                statusCode = codes.Unknown
+        }
+        s.finish(status.Newf(statusCode, "stream terminated by RST_STREAM with error code: %d", f.ErrCode))
+        s.mu.Unlock()
+        s.write(recvMsg{err: io.EOF})
+}
+
+func (t *http2Client) handleSettings(f *http2.SettingsFrame) {
+        if f.IsAck() {
+                return
+        }
+        var ss []http2.Setting
+        f.ForeachSetting(func(s http2.Setting) error {
+                ss = append(ss, s)
+                return nil
+        })
+        // The settings will be applied once the ack is sent.
+        t.controlBuf.put(&settings{ack: true, ss: ss})
+}
+
+func (t *http2Client) handlePing(f *http2.PingFrame) {
+        if f.IsAck() {
+                // Maybe it's a BDP ping.
+                if t.bdpEst != nil {
+                        t.bdpEst.calculate(f.Data)
+                }
+                return
+        }
+        pingAck := &ping{ack: true}
+        copy(pingAck.data[:], f.Data[:])
+        t.controlBuf.put(pingAck)
+}
+
+func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
+        t.mu.Lock()
+        if t.state != reachable && t.state != draining {
+                t.mu.Unlock()
+                return
+        }
+        if f.ErrCode == http2.ErrCodeEnhanceYourCalm {
+                infof("Client received GoAway with http2.ErrCodeEnhanceYourCalm.")
+        }
+        id := f.LastStreamID
+        if id > 0 && id%2 != 1 {
+                t.mu.Unlock()
+                t.notifyError(connectionErrorf(true, nil, "received illegal http2 GOAWAY frame: stream ID %d is even", f.LastStreamID))
+                return
+        }
+        // A client can recieve multiple GoAways from server (look at https://github.com/grpc/grpc-go/issues/1387).
+        // The idea is that the first GoAway will be sent with an ID of MaxInt32 and the second GoAway will be sent after an RTT delay
+        // with the ID of the last stream the server will process.
+        // Therefore, when we get the first GoAway we don't really close any streams. While in case of second GoAway we
+        // close all streams created after the second GoAwayId. This way streams that were in-flight while the GoAway from server
+        // was being sent don't get killed.
+        select {
+        case <-t.goAway: // t.goAway has been closed (i.e.,multiple GoAways).
+                // If there are multiple GoAways the first one should always have an ID greater than the following ones.
+                if id > t.prevGoAwayID {
+                        t.mu.Unlock()
+                        t.notifyError(connectionErrorf(true, nil, "received illegal http2 GOAWAY frame: previously recv GOAWAY frame with LastStramID %d, currently recv %d", id, f.LastStreamID))
+                        return
+                }
+        default:
+                t.setGoAwayReason(f)
+                close(t.goAway)
+                t.state = draining
+        }
+        // All streams with IDs greater than the GoAwayId
+        // and smaller than the previous GoAway ID should be killed.
+        upperLimit := t.prevGoAwayID
+        if upperLimit == 0 { // This is the first GoAway Frame.
+                upperLimit = math.MaxUint32 // Kill all streams after the GoAway ID.
+        }
+        for streamID, stream := range t.activeStreams {
+                if streamID > id && streamID <= upperLimit {
+                        close(stream.goAway)
+                }
+        }
+        t.prevGoAwayID = id
+        active := len(t.activeStreams)
+        t.mu.Unlock()
+        if active == 0 {
+                t.Close()
+        }
+}
+
+// setGoAwayReason sets the value of t.goAwayReason based
+// on the GoAway frame received.
+// It expects a lock on transport's mutext to be held by
+// the caller.
+func (t *http2Client) setGoAwayReason(f *http2.GoAwayFrame) {
+        t.goAwayReason = NoReason
+        switch f.ErrCode {
+        case http2.ErrCodeEnhanceYourCalm:
+                if string(f.DebugData()) == "too_many_pings" {
+                        t.goAwayReason = TooManyPings
+                }
+        }
+}
+
+func (t *http2Client) GetGoAwayReason() GoAwayReason {
+        t.mu.Lock()
+        defer t.mu.Unlock()
+        return t.goAwayReason
+}
+
+func (t *http2Client) handleWindowUpdate(f *http2.WindowUpdateFrame) {
+        id := f.Header().StreamID
+        incr := f.Increment
+        if id == 0 {
+                t.sendQuotaPool.add(int(incr))
+                return
+        }
+        if s, ok := t.getStream(f); ok {
+                s.sendQuotaPool.add(int(incr))
+        }
+}
+
+// operateHeaders takes action on the decoded headers.
+func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
+        s, ok := t.getStream(frame)
+        if !ok {
+                return
+        }
+        s.mu.Lock()
+        s.bytesReceived = true
+        s.mu.Unlock()
+        var state decodeState
+        if err := state.decodeResponseHeader(frame); err != nil {
+                s.mu.Lock()
+                if !s.headerDone {
+                        close(s.headerChan)
+                        s.headerDone = true
+                }
+                s.mu.Unlock()
+                s.write(recvMsg{err: err})
+                // Something wrong. Stops reading even when there is remaining.
+                return
+        }
+
+        endStream := frame.StreamEnded()
+        var isHeader bool
+        defer func() {
+                if t.statsHandler != nil {
+                        if isHeader {
+                                inHeader := &stats.InHeader{
+                                        Client:     true,
+                                        WireLength: int(frame.Header().Length),
+                                }
+                                t.statsHandler.HandleRPC(s.ctx, inHeader)
+                        } else {
+                                inTrailer := &stats.InTrailer{
+                                        Client:     true,
+                                        WireLength: int(frame.Header().Length),
+                                }
+                                t.statsHandler.HandleRPC(s.ctx, inTrailer)
+                        }
+                }
+        }()
+
+        s.mu.Lock()
+        if !endStream {
+                s.recvCompress = state.encoding
+        }
+        if !s.headerDone {
+                if !endStream && len(state.mdata) > 0 {
+                        s.header = state.mdata
+                }
+                close(s.headerChan)
+                s.headerDone = true
+                isHeader = true
+        }
+        if !endStream || s.state == streamDone {
+                s.mu.Unlock()
+                return
+        }
+
+        if len(state.mdata) > 0 {
+                s.trailer = state.mdata
+        }
+        s.finish(state.status())
+        s.mu.Unlock()
+        s.write(recvMsg{err: io.EOF})
+}
+
+func handleMalformedHTTP2(s *Stream, err error) {
+        s.mu.Lock()
+        if !s.headerDone {
+                close(s.headerChan)
+                s.headerDone = true
+        }
+        s.mu.Unlock()
+        s.write(recvMsg{err: err})
+}
+
+// reader runs as a separate goroutine in charge of reading data from network
+// connection.
+//
+// TODO(zhaoq): currently one reader per transport. Investigate whether this is
+// optimal.
+// TODO(zhaoq): Check the validity of the incoming frame sequence.
+func (t *http2Client) reader() {
+        // Check the validity of server preface.
+        frame, err := t.framer.readFrame()
+        if err != nil {
+                t.notifyError(err)
+                return
+        }
+        atomic.CompareAndSwapUint32(&t.activity, 0, 1)
+        sf, ok := frame.(*http2.SettingsFrame)
+        if !ok {
+                t.notifyError(err)
+                return
+        }
+        t.handleSettings(sf)
+
+        // loop to keep reading incoming messages on this transport.
+        for {
+                frame, err := t.framer.readFrame()
+                atomic.CompareAndSwapUint32(&t.activity, 0, 1)
+                if err != nil {
+                        // Abort an active stream if the http2.Framer returns a
+                        // http2.StreamError. This can happen only if the server's response
+                        // is malformed http2.
+                        if se, ok := err.(http2.StreamError); ok {
+                                t.mu.Lock()
+                                s := t.activeStreams[se.StreamID]
+                                t.mu.Unlock()
+                                if s != nil {
+                                        // use error detail to provide better err message
+                                        handleMalformedHTTP2(s, streamErrorf(http2ErrConvTab[se.Code], "%v", t.framer.errorDetail()))
+                                }
+                                continue
+                        } else {
+                                // Transport error.
+                                t.notifyError(err)
+                                return
+                        }
+                }
+                switch frame := frame.(type) {
+                case *http2.MetaHeadersFrame:
+                        t.operateHeaders(frame)
+                case *http2.DataFrame:
+                        t.handleData(frame)
+                case *http2.RSTStreamFrame:
+                        t.handleRSTStream(frame)
+                case *http2.SettingsFrame:
+                        t.handleSettings(frame)
+                case *http2.PingFrame:
+                        t.handlePing(frame)
+                case *http2.GoAwayFrame:
+                        t.handleGoAway(frame)
+                case *http2.WindowUpdateFrame:
+                        t.handleWindowUpdate(frame)
+                default:
+                        errorf("transport: http2Client.reader got unhandled frame type %v.", frame)
+                }
+        }
+}
+
+func (t *http2Client) applySettings(ss []http2.Setting) {
+        for _, s := range ss {
+                switch s.ID {
+                case http2.SettingMaxConcurrentStreams:
+                        // TODO(zhaoq): This is a hack to avoid significant refactoring of the
+                        // code to deal with the unrealistic int32 overflow. Probably will try
+                        // to find a better way to handle this later.
+                        if s.Val > math.MaxInt32 {
+                                s.Val = math.MaxInt32
+                        }
+                        t.mu.Lock()
+                        ms := t.maxStreams
+                        t.maxStreams = int(s.Val)
+                        t.mu.Unlock()
+                        t.streamsQuota.add(int(s.Val) - ms)
+                case http2.SettingInitialWindowSize:
+                        t.mu.Lock()
+                        for _, stream := range t.activeStreams {
+                                // Adjust the sending quota for each stream.
+                                stream.sendQuotaPool.add(int(s.Val) - int(t.streamSendQuota))
+                        }
+                        t.streamSendQuota = s.Val
+                        t.mu.Unlock()
+                        atomic.AddUint32(&t.outQuotaVersion, 1)
+                }
+        }
+}
+
+// controller running in a separate goroutine takes charge of sending control
+// frames (e.g., window update, reset stream, setting, etc.) to the server.
+func (t *http2Client) controller() {
+        for {
+                select {
+                case i := <-t.controlBuf.get():
+                        t.controlBuf.load()
+                        select {
+                        case <-t.writableChan:
+                                switch i := i.(type) {
+                                case *windowUpdate:
+                                        t.framer.writeWindowUpdate(i.flush, i.streamID, i.increment)
+                                case *settings:
+                                        if i.ack {
+                                                t.framer.writeSettingsAck(true)
+                                                t.applySettings(i.ss)
+                                        } else {
+                                                t.framer.writeSettings(true, i.ss...)
+                                        }
+                                case *resetStream:
+                                        // If the server needs to be to intimated about stream closing,
+                                        // then we need to make sure the RST_STREAM frame is written to
+                                        // the wire before the headers of the next stream waiting on
+                                        // streamQuota. We ensure this by adding to the streamsQuota pool
+                                        // only after having acquired the writableChan to send RST_STREAM.
+                                        t.streamsQuota.add(1)
+                                        t.framer.writeRSTStream(true, i.streamID, i.code)
+                                case *flushIO:
+                                        t.framer.flushWrite()
+                                case *ping:
+                                        if !i.ack {
+                                                t.bdpEst.timesnap(i.data)
+                                        }
+                                        t.framer.writePing(true, i.ack, i.data)
+                                default:
+                                        errorf("transport: http2Client.controller got unexpected item type %v\n", i)
+                                }
+                                t.writableChan <- 0
+                                continue
+                        case <-t.shutdownChan:
+                                return
+                        }
+                case <-t.shutdownChan:
+                        return
+                }
+        }
+}
+
+// keepalive running in a separate goroutune makes sure the connection is alive by sending pings.
+func (t *http2Client) keepalive() {
+        p := &ping{data: [8]byte{}}
+        timer := time.NewTimer(t.kp.Time)
+        for {
+                select {
+                case <-timer.C:
+                        if atomic.CompareAndSwapUint32(&t.activity, 1, 0) {
+                                timer.Reset(t.kp.Time)
+                                continue
+                        }
+                        // Check if keepalive should go dormant.
+                        t.mu.Lock()
+                        if len(t.activeStreams) < 1 && !t.kp.PermitWithoutStream {
+                                // Make awakenKeepalive writable.
+                                <-t.awakenKeepalive
+                                t.mu.Unlock()
+                                select {
+                                case <-t.awakenKeepalive:
+                                        // If the control gets here a ping has been sent
+                                        // need to reset the timer with keepalive.Timeout.
+                                case <-t.shutdownChan:
+                                        return
+                                }
+                        } else {
+                                t.mu.Unlock()
+                                // Send ping.
+                                t.controlBuf.put(p)
+                        }
+
+                        // By the time control gets here a ping has been sent one way or the other.
+                        timer.Reset(t.kp.Timeout)
+                        select {
+                        case <-timer.C:
+                                if atomic.CompareAndSwapUint32(&t.activity, 1, 0) {
+                                        timer.Reset(t.kp.Time)
+                                        continue
+                                }
+                                t.Close()
+                                return
+                        case <-t.shutdownChan:
+                                if !timer.Stop() {
+                                        <-timer.C
+                                }
+                                return
+                        }
+                case <-t.shutdownChan:
+                        if !timer.Stop() {
+                                <-timer.C
+                        }
+                        return
+                }
+        }
+}
+
+func (t *http2Client) Error() <-chan struct{} {
+        return t.errorChan
+}
+
+func (t *http2Client) GoAway() <-chan struct{} {
+        return t.goAway
+}
+
+func (t *http2Client) notifyError(err error) {
+        t.mu.Lock()
+        // make sure t.errorChan is closed only once.
+        if t.state == draining {
+                t.mu.Unlock()
+                t.Close()
+                return
+        }
+        if t.state == reachable {
+                t.state = unreachable
+                close(t.errorChan)
+                infof("transport: http2Client.notifyError got notified that the client transport was broken %v.", err)
+        }
+        t.mu.Unlock()
+}
diff --git a/vendor/google.golang.org/grpc/transport/http2_server.go b/vendor/google.golang.org/grpc/transport/http2_server.go
new file mode 100644
index 0000000..b6f93e3
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/http2_server.go
@@ -0,0 +1,1195 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "bytes"
+        "errors"
+        "io"
+        "math"
+        "math/rand"
+        "net"
+        "strconv"
+        "sync"
+        "sync/atomic"
+        "time"
+
+        "github.com/golang/protobuf/proto"
+        "golang.org/x/net/context"
+        "golang.org/x/net/http2"
+        "golang.org/x/net/http2/hpack"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/keepalive"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/peer"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/tap"
+)
+
+// ErrIllegalHeaderWrite indicates that setting header is illegal because of
+// the stream's state.
+var ErrIllegalHeaderWrite = errors.New("transport: the stream is done or WriteHeader was already called")
+
+// http2Server implements the ServerTransport interface with HTTP2.
+type http2Server struct {
+        ctx         context.Context
+        conn        net.Conn
+        remoteAddr  net.Addr
+        localAddr   net.Addr
+        maxStreamID uint32               // max stream ID ever seen
+        authInfo    credentials.AuthInfo // auth info about the connection
+        inTapHandle tap.ServerInHandle
+        // writableChan synchronizes write access to the transport.
+        // A writer acquires the write lock by receiving a value on writableChan
+        // and releases it by sending on writableChan.
+        writableChan chan int
+        // shutdownChan is closed when Close is called.
+        // Blocking operations should select on shutdownChan to avoid
+        // blocking forever after Close.
+        shutdownChan chan struct{}
+        framer       *framer
+        hBuf         *bytes.Buffer  // the buffer for HPACK encoding
+        hEnc         *hpack.Encoder // HPACK encoder
+        // The max number of concurrent streams.
+        maxStreams uint32
+        // controlBuf delivers all the control related tasks (e.g., window
+        // updates, reset streams, and various settings) to the controller.
+        controlBuf *controlBuffer
+        fc         *inFlow
+        // sendQuotaPool provides flow control to outbound message.
+        sendQuotaPool *quotaPool
+        stats         stats.Handler
+        // Flag to keep track of reading activity on transport.
+        // 1 is true and 0 is false.
+        activity uint32 // Accessed atomically.
+        // Keepalive and max-age parameters for the server.
+        kp keepalive.ServerParameters
+
+        // Keepalive enforcement policy.
+        kep keepalive.EnforcementPolicy
+        // The time instance last ping was received.
+        lastPingAt time.Time
+        // Number of times the client has violated keepalive ping policy so far.
+        pingStrikes uint8
+        // Flag to signify that number of ping strikes should be reset to 0.
+        // This is set whenever data or header frames are sent.
+        // 1 means yes.
+        resetPingStrikes  uint32 // Accessed atomically.
+        initialWindowSize int32
+        bdpEst            *bdpEstimator
+
+        outQuotaVersion uint32
+
+        mu sync.Mutex // guard the following
+
+        // drainChan is initialized when drain(...) is called the first time.
+        // After which the server writes out the first GoAway(with ID 2^31-1) frame.
+        // Then an independent goroutine will be launched to later send the second GoAway.
+        // During this time we don't want to write another first GoAway(with ID 2^31 -1) frame.
+        // Thus call to drain(...) will be a no-op if drainChan is already initialized since draining is
+        // already underway.
+        drainChan     chan struct{}
+        state         transportState
+        activeStreams map[uint32]*Stream
+        // the per-stream outbound flow control window size set by the peer.
+        streamSendQuota uint32
+        // idle is the time instant when the connection went idle.
+        // This is either the begining of the connection or when the number of
+        // RPCs go down to 0.
+        // When the connection is busy, this value is set to 0.
+        idle time.Time
+}
+
+// newHTTP2Server constructs a ServerTransport based on HTTP2. ConnectionError is
+// returned if something goes wrong.
+func newHTTP2Server(conn net.Conn, config *ServerConfig) (_ ServerTransport, err error) {
+        framer := newFramer(conn)
+        // Send initial settings as connection preface to client.
+        var isettings []http2.Setting
+        // TODO(zhaoq): Have a better way to signal "no limit" because 0 is
+        // permitted in the HTTP2 spec.
+        maxStreams := config.MaxStreams
+        if maxStreams == 0 {
+                maxStreams = math.MaxUint32
+        } else {
+                isettings = append(isettings, http2.Setting{
+                        ID:  http2.SettingMaxConcurrentStreams,
+                        Val: maxStreams,
+                })
+        }
+        dynamicWindow := true
+        iwz := int32(initialWindowSize)
+        if config.InitialWindowSize >= defaultWindowSize {
+                iwz = config.InitialWindowSize
+                dynamicWindow = false
+        }
+        icwz := int32(initialWindowSize)
+        if config.InitialConnWindowSize >= defaultWindowSize {
+                icwz = config.InitialConnWindowSize
+                dynamicWindow = false
+        }
+        if iwz != defaultWindowSize {
+                isettings = append(isettings, http2.Setting{
+                        ID:  http2.SettingInitialWindowSize,
+                        Val: uint32(iwz)})
+        }
+        if err := framer.writeSettings(true, isettings...); err != nil {
+                return nil, connectionErrorf(true, err, "transport: %v", err)
+        }
+        // Adjust the connection flow control window if needed.
+        if delta := uint32(icwz - defaultWindowSize); delta > 0 {
+                if err := framer.writeWindowUpdate(true, 0, delta); err != nil {
+                        return nil, connectionErrorf(true, err, "transport: %v", err)
+                }
+        }
+        kp := config.KeepaliveParams
+        if kp.MaxConnectionIdle == 0 {
+                kp.MaxConnectionIdle = defaultMaxConnectionIdle
+        }
+        if kp.MaxConnectionAge == 0 {
+                kp.MaxConnectionAge = defaultMaxConnectionAge
+        }
+        // Add a jitter to MaxConnectionAge.
+        kp.MaxConnectionAge += getJitter(kp.MaxConnectionAge)
+        if kp.MaxConnectionAgeGrace == 0 {
+                kp.MaxConnectionAgeGrace = defaultMaxConnectionAgeGrace
+        }
+        if kp.Time == 0 {
+                kp.Time = defaultServerKeepaliveTime
+        }
+        if kp.Timeout == 0 {
+                kp.Timeout = defaultServerKeepaliveTimeout
+        }
+        kep := config.KeepalivePolicy
+        if kep.MinTime == 0 {
+                kep.MinTime = defaultKeepalivePolicyMinTime
+        }
+        var buf bytes.Buffer
+        t := &http2Server{
+                ctx:               context.Background(),
+                conn:              conn,
+                remoteAddr:        conn.RemoteAddr(),
+                localAddr:         conn.LocalAddr(),
+                authInfo:          config.AuthInfo,
+                framer:            framer,
+                hBuf:              &buf,
+                hEnc:              hpack.NewEncoder(&buf),
+                maxStreams:        maxStreams,
+                inTapHandle:       config.InTapHandle,
+                controlBuf:        newControlBuffer(),
+                fc:                &inFlow{limit: uint32(icwz)},
+                sendQuotaPool:     newQuotaPool(defaultWindowSize),
+                state:             reachable,
+                writableChan:      make(chan int, 1),
+                shutdownChan:      make(chan struct{}),
+                activeStreams:     make(map[uint32]*Stream),
+                streamSendQuota:   defaultWindowSize,
+                stats:             config.StatsHandler,
+                kp:                kp,
+                idle:              time.Now(),
+                kep:               kep,
+                initialWindowSize: iwz,
+        }
+        if dynamicWindow {
+                t.bdpEst = &bdpEstimator{
+                        bdp:               initialWindowSize,
+                        updateFlowControl: t.updateFlowControl,
+                }
+        }
+        if t.stats != nil {
+                t.ctx = t.stats.TagConn(t.ctx, &stats.ConnTagInfo{
+                        RemoteAddr: t.remoteAddr,
+                        LocalAddr:  t.localAddr,
+                })
+                connBegin := &stats.ConnBegin{}
+                t.stats.HandleConn(t.ctx, connBegin)
+        }
+        go t.controller()
+        go t.keepalive()
+        t.writableChan <- 0
+        return t, nil
+}
+
+// operateHeader takes action on the decoded headers.
+func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(*Stream), traceCtx func(context.Context, string) context.Context) (close bool) {
+        buf := newRecvBuffer()
+        s := &Stream{
+                id:  frame.Header().StreamID,
+                st:  t,
+                buf: buf,
+                fc:  &inFlow{limit: uint32(t.initialWindowSize)},
+        }
+
+        var state decodeState
+        for _, hf := range frame.Fields {
+                if err := state.processHeaderField(hf); err != nil {
+                        if se, ok := err.(StreamError); ok {
+                                t.controlBuf.put(&resetStream{s.id, statusCodeConvTab[se.Code]})
+                        }
+                        return
+                }
+        }
+
+        if frame.StreamEnded() {
+                // s is just created by the caller. No lock needed.
+                s.state = streamReadDone
+        }
+        s.recvCompress = state.encoding
+        if state.timeoutSet {
+                s.ctx, s.cancel = context.WithTimeout(t.ctx, state.timeout)
+        } else {
+                s.ctx, s.cancel = context.WithCancel(t.ctx)
+        }
+        pr := &peer.Peer{
+                Addr: t.remoteAddr,
+        }
+        // Attach Auth info if there is any.
+        if t.authInfo != nil {
+                pr.AuthInfo = t.authInfo
+        }
+        s.ctx = peer.NewContext(s.ctx, pr)
+        // Cache the current stream to the context so that the server application
+        // can find out. Required when the server wants to send some metadata
+        // back to the client (unary call only).
+        s.ctx = newContextWithStream(s.ctx, s)
+        // Attach the received metadata to the context.
+        if len(state.mdata) > 0 {
+                s.ctx = metadata.NewIncomingContext(s.ctx, state.mdata)
+        }
+        s.trReader = &transportReader{
+                reader: &recvBufferReader{
+                        ctx:  s.ctx,
+                        recv: s.buf,
+                },
+                windowHandler: func(n int) {
+                        t.updateWindow(s, uint32(n))
+                },
+        }
+        s.recvCompress = state.encoding
+        s.method = state.method
+        if t.inTapHandle != nil {
+                var err error
+                info := &tap.Info{
+                        FullMethodName: state.method,
+                }
+                s.ctx, err = t.inTapHandle(s.ctx, info)
+                if err != nil {
+                        warningf("transport: http2Server.operateHeaders got an error from InTapHandle: %v", err)
+                        t.controlBuf.put(&resetStream{s.id, http2.ErrCodeRefusedStream})
+                        return
+                }
+        }
+        t.mu.Lock()
+        if t.state != reachable {
+                t.mu.Unlock()
+                return
+        }
+        if uint32(len(t.activeStreams)) >= t.maxStreams {
+                t.mu.Unlock()
+                t.controlBuf.put(&resetStream{s.id, http2.ErrCodeRefusedStream})
+                return
+        }
+        if s.id%2 != 1 || s.id <= t.maxStreamID {
+                t.mu.Unlock()
+                // illegal gRPC stream id.
+                errorf("transport: http2Server.HandleStreams received an illegal stream id: %v", s.id)
+                return true
+        }
+        t.maxStreamID = s.id
+        s.sendQuotaPool = newQuotaPool(int(t.streamSendQuota))
+        t.activeStreams[s.id] = s
+        if len(t.activeStreams) == 1 {
+                t.idle = time.Time{}
+        }
+        t.mu.Unlock()
+        s.requestRead = func(n int) {
+                t.adjustWindow(s, uint32(n))
+        }
+        s.ctx = traceCtx(s.ctx, s.method)
+        if t.stats != nil {
+                s.ctx = t.stats.TagRPC(s.ctx, &stats.RPCTagInfo{FullMethodName: s.method})
+                inHeader := &stats.InHeader{
+                        FullMethod:  s.method,
+                        RemoteAddr:  t.remoteAddr,
+                        LocalAddr:   t.localAddr,
+                        Compression: s.recvCompress,
+                        WireLength:  int(frame.Header().Length),
+                }
+                t.stats.HandleRPC(s.ctx, inHeader)
+        }
+        handle(s)
+        return
+}
+
+// HandleStreams receives incoming streams using the given handler. This is
+// typically run in a separate goroutine.
+// traceCtx attaches trace to ctx and returns the new context.
+func (t *http2Server) HandleStreams(handle func(*Stream), traceCtx func(context.Context, string) context.Context) {
+        // Check the validity of client preface.
+        preface := make([]byte, len(clientPreface))
+        if _, err := io.ReadFull(t.conn, preface); err != nil {
+                // Only log if it isn't a simple tcp accept check (ie: tcp balancer doing open/close socket)
+                if err != io.EOF {
+                        errorf("transport: http2Server.HandleStreams failed to receive the preface from client: %v", err)
+                }
+                t.Close()
+                return
+        }
+        if !bytes.Equal(preface, clientPreface) {
+                errorf("transport: http2Server.HandleStreams received bogus greeting from client: %q", preface)
+                t.Close()
+                return
+        }
+
+        frame, err := t.framer.readFrame()
+        if err == io.EOF || err == io.ErrUnexpectedEOF {
+                t.Close()
+                return
+        }
+        if err != nil {
+                errorf("transport: http2Server.HandleStreams failed to read initial settings frame: %v", err)
+                t.Close()
+                return
+        }
+        atomic.StoreUint32(&t.activity, 1)
+        sf, ok := frame.(*http2.SettingsFrame)
+        if !ok {
+                errorf("transport: http2Server.HandleStreams saw invalid preface type %T from client", frame)
+                t.Close()
+                return
+        }
+        t.handleSettings(sf)
+
+        for {
+                frame, err := t.framer.readFrame()
+                atomic.StoreUint32(&t.activity, 1)
+                if err != nil {
+                        if se, ok := err.(http2.StreamError); ok {
+                                t.mu.Lock()
+                                s := t.activeStreams[se.StreamID]
+                                t.mu.Unlock()
+                                if s != nil {
+                                        t.closeStream(s)
+                                }
+                                t.controlBuf.put(&resetStream{se.StreamID, se.Code})
+                                continue
+                        }
+                        if err == io.EOF || err == io.ErrUnexpectedEOF {
+                                t.Close()
+                                return
+                        }
+                        warningf("transport: http2Server.HandleStreams failed to read frame: %v", err)
+                        t.Close()
+                        return
+                }
+                switch frame := frame.(type) {
+                case *http2.MetaHeadersFrame:
+                        if t.operateHeaders(frame, handle, traceCtx) {
+                                t.Close()
+                                break
+                        }
+                case *http2.DataFrame:
+                        t.handleData(frame)
+                case *http2.RSTStreamFrame:
+                        t.handleRSTStream(frame)
+                case *http2.SettingsFrame:
+                        t.handleSettings(frame)
+                case *http2.PingFrame:
+                        t.handlePing(frame)
+                case *http2.WindowUpdateFrame:
+                        t.handleWindowUpdate(frame)
+                case *http2.GoAwayFrame:
+                        // TODO: Handle GoAway from the client appropriately.
+                default:
+                        errorf("transport: http2Server.HandleStreams found unhandled frame type %v.", frame)
+                }
+        }
+}
+
+func (t *http2Server) getStream(f http2.Frame) (*Stream, bool) {
+        t.mu.Lock()
+        defer t.mu.Unlock()
+        if t.activeStreams == nil {
+                // The transport is closing.
+                return nil, false
+        }
+        s, ok := t.activeStreams[f.Header().StreamID]
+        if !ok {
+                // The stream is already done.
+                return nil, false
+        }
+        return s, true
+}
+
+// adjustWindow sends out extra window update over the initial window size
+// of stream if the application is requesting data larger in size than
+// the window.
+func (t *http2Server) adjustWindow(s *Stream, n uint32) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.state == streamDone {
+                return
+        }
+        if w := s.fc.maybeAdjust(n); w > 0 {
+                if cw := t.fc.resetPendingUpdate(); cw > 0 {
+                        t.controlBuf.put(&windowUpdate{0, cw, false})
+                }
+                t.controlBuf.put(&windowUpdate{s.id, w, true})
+        }
+}
+
+// updateWindow adjusts the inbound quota for the stream and the transport.
+// Window updates will deliver to the controller for sending when
+// the cumulative quota exceeds the corresponding threshold.
+func (t *http2Server) updateWindow(s *Stream, n uint32) {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.state == streamDone {
+                return
+        }
+        if w := s.fc.onRead(n); w > 0 {
+                if cw := t.fc.resetPendingUpdate(); cw > 0 {
+                        t.controlBuf.put(&windowUpdate{0, cw, false})
+                }
+                t.controlBuf.put(&windowUpdate{s.id, w, true})
+        }
+}
+
+// updateFlowControl updates the incoming flow control windows
+// for the transport and the stream based on the current bdp
+// estimation.
+func (t *http2Server) updateFlowControl(n uint32) {
+        t.mu.Lock()
+        for _, s := range t.activeStreams {
+                s.fc.newLimit(n)
+        }
+        t.initialWindowSize = int32(n)
+        t.mu.Unlock()
+        t.controlBuf.put(&windowUpdate{0, t.fc.newLimit(n), false})
+        t.controlBuf.put(&settings{
+                ack: false,
+                ss: []http2.Setting{
+                        {
+                                ID:  http2.SettingInitialWindowSize,
+                                Val: uint32(n),
+                        },
+                },
+        })
+
+}
+
+func (t *http2Server) handleData(f *http2.DataFrame) {
+        size := f.Header().Length
+        var sendBDPPing bool
+        if t.bdpEst != nil {
+                sendBDPPing = t.bdpEst.add(uint32(size))
+        }
+        // Decouple connection's flow control from application's read.
+        // An update on connection's flow control should not depend on
+        // whether user application has read the data or not. Such a
+        // restriction is already imposed on the stream's flow control,
+        // and therefore the sender will be blocked anyways.
+        // Decoupling the connection flow control will prevent other
+        // active(fast) streams from starving in presence of slow or
+        // inactive streams.
+        //
+        // Furthermore, if a bdpPing is being sent out we can piggyback
+        // connection's window update for the bytes we just received.
+        if sendBDPPing {
+                t.controlBuf.put(&windowUpdate{0, uint32(size), false})
+                t.controlBuf.put(bdpPing)
+        } else {
+                if err := t.fc.onData(uint32(size)); err != nil {
+                        errorf("transport: http2Server %v", err)
+                        t.Close()
+                        return
+                }
+                if w := t.fc.onRead(uint32(size)); w > 0 {
+                        t.controlBuf.put(&windowUpdate{0, w, true})
+                }
+        }
+        // Select the right stream to dispatch.
+        s, ok := t.getStream(f)
+        if !ok {
+                return
+        }
+        if size > 0 {
+                s.mu.Lock()
+                if s.state == streamDone {
+                        s.mu.Unlock()
+                        return
+                }
+                if err := s.fc.onData(uint32(size)); err != nil {
+                        s.mu.Unlock()
+                        t.closeStream(s)
+                        t.controlBuf.put(&resetStream{s.id, http2.ErrCodeFlowControl})
+                        return
+                }
+                if f.Header().Flags.Has(http2.FlagDataPadded) {
+                        if w := s.fc.onRead(uint32(size) - uint32(len(f.Data()))); w > 0 {
+                                t.controlBuf.put(&windowUpdate{s.id, w, true})
+                        }
+                }
+                s.mu.Unlock()
+                // TODO(bradfitz, zhaoq): A copy is required here because there is no
+                // guarantee f.Data() is consumed before the arrival of next frame.
+                // Can this copy be eliminated?
+                if len(f.Data()) > 0 {
+                        data := make([]byte, len(f.Data()))
+                        copy(data, f.Data())
+                        s.write(recvMsg{data: data})
+                }
+        }
+        if f.Header().Flags.Has(http2.FlagDataEndStream) {
+                // Received the end of stream from the client.
+                s.mu.Lock()
+                if s.state != streamDone {
+                        s.state = streamReadDone
+                }
+                s.mu.Unlock()
+                s.write(recvMsg{err: io.EOF})
+        }
+}
+
+func (t *http2Server) handleRSTStream(f *http2.RSTStreamFrame) {
+        s, ok := t.getStream(f)
+        if !ok {
+                return
+        }
+        t.closeStream(s)
+}
+
+func (t *http2Server) handleSettings(f *http2.SettingsFrame) {
+        if f.IsAck() {
+                return
+        }
+        var ss []http2.Setting
+        f.ForeachSetting(func(s http2.Setting) error {
+                ss = append(ss, s)
+                return nil
+        })
+        // The settings will be applied once the ack is sent.
+        t.controlBuf.put(&settings{ack: true, ss: ss})
+}
+
+const (
+        maxPingStrikes     = 2
+        defaultPingTimeout = 2 * time.Hour
+)
+
+func (t *http2Server) handlePing(f *http2.PingFrame) {
+        if f.IsAck() {
+                if f.Data == goAwayPing.data && t.drainChan != nil {
+                        close(t.drainChan)
+                        return
+                }
+                // Maybe it's a BDP ping.
+                if t.bdpEst != nil {
+                        t.bdpEst.calculate(f.Data)
+                }
+                return
+        }
+        pingAck := &ping{ack: true}
+        copy(pingAck.data[:], f.Data[:])
+        t.controlBuf.put(pingAck)
+
+        now := time.Now()
+        defer func() {
+                t.lastPingAt = now
+        }()
+        // A reset ping strikes means that we don't need to check for policy
+        // violation for this ping and the pingStrikes counter should be set
+        // to 0.
+        if atomic.CompareAndSwapUint32(&t.resetPingStrikes, 1, 0) {
+                t.pingStrikes = 0
+                return
+        }
+        t.mu.Lock()
+        ns := len(t.activeStreams)
+        t.mu.Unlock()
+        if ns < 1 && !t.kep.PermitWithoutStream {
+                // Keepalive shouldn't be active thus, this new ping should
+                // have come after atleast defaultPingTimeout.
+                if t.lastPingAt.Add(defaultPingTimeout).After(now) {
+                        t.pingStrikes++
+                }
+        } else {
+                // Check if keepalive policy is respected.
+                if t.lastPingAt.Add(t.kep.MinTime).After(now) {
+                        t.pingStrikes++
+                }
+        }
+
+        if t.pingStrikes > maxPingStrikes {
+                // Send goaway and close the connection.
+                t.controlBuf.put(&goAway{code: http2.ErrCodeEnhanceYourCalm, debugData: []byte("too_many_pings"), closeConn: true})
+        }
+}
+
+func (t *http2Server) handleWindowUpdate(f *http2.WindowUpdateFrame) {
+        id := f.Header().StreamID
+        incr := f.Increment
+        if id == 0 {
+                t.sendQuotaPool.add(int(incr))
+                return
+        }
+        if s, ok := t.getStream(f); ok {
+                s.sendQuotaPool.add(int(incr))
+        }
+}
+
+func (t *http2Server) writeHeaders(s *Stream, b *bytes.Buffer, endStream bool) error {
+        first := true
+        endHeaders := false
+        var err error
+        defer func() {
+                if err == nil {
+                        // Reset ping strikes when seding headers since that might cause the
+                        // peer to send ping.
+                        atomic.StoreUint32(&t.resetPingStrikes, 1)
+                }
+        }()
+        // Sends the headers in a single batch.
+        for !endHeaders {
+                size := t.hBuf.Len()
+                if size > http2MaxFrameLen {
+                        size = http2MaxFrameLen
+                } else {
+                        endHeaders = true
+                }
+                if first {
+                        p := http2.HeadersFrameParam{
+                                StreamID:      s.id,
+                                BlockFragment: b.Next(size),
+                                EndStream:     endStream,
+                                EndHeaders:    endHeaders,
+                        }
+                        err = t.framer.writeHeaders(endHeaders, p)
+                        first = false
+                } else {
+                        err = t.framer.writeContinuation(endHeaders, s.id, endHeaders, b.Next(size))
+                }
+                if err != nil {
+                        t.Close()
+                        return connectionErrorf(true, err, "transport: %v", err)
+                }
+        }
+        return nil
+}
+
+// WriteHeader sends the header metedata md back to the client.
+func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
+        s.mu.Lock()
+        if s.headerOk || s.state == streamDone {
+                s.mu.Unlock()
+                return ErrIllegalHeaderWrite
+        }
+        s.headerOk = true
+        if md.Len() > 0 {
+                if s.header.Len() > 0 {
+                        s.header = metadata.Join(s.header, md)
+                } else {
+                        s.header = md
+                }
+        }
+        md = s.header
+        s.mu.Unlock()
+        if _, err := wait(s.ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
+                return err
+        }
+        t.hBuf.Reset()
+        t.hEnc.WriteField(hpack.HeaderField{Name: ":status", Value: "200"})
+        t.hEnc.WriteField(hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
+        if s.sendCompress != "" {
+                t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-encoding", Value: s.sendCompress})
+        }
+        for k, vv := range md {
+                if isReservedHeader(k) {
+                        // Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+                        continue
+                }
+                for _, v := range vv {
+                        t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+                }
+        }
+        bufLen := t.hBuf.Len()
+        if err := t.writeHeaders(s, t.hBuf, false); err != nil {
+                return err
+        }
+        if t.stats != nil {
+                outHeader := &stats.OutHeader{
+                        WireLength: bufLen,
+                }
+                t.stats.HandleRPC(s.Context(), outHeader)
+        }
+        t.writableChan <- 0
+        return nil
+}
+
+// WriteStatus sends stream status to the client and terminates the stream.
+// There is no further I/O operations being able to perform on this stream.
+// TODO(zhaoq): Now it indicates the end of entire stream. Revisit if early
+// OK is adopted.
+func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
+        var headersSent, hasHeader bool
+        s.mu.Lock()
+        if s.state == streamDone {
+                s.mu.Unlock()
+                return nil
+        }
+        if s.headerOk {
+                headersSent = true
+        }
+        if s.header.Len() > 0 {
+                hasHeader = true
+        }
+        s.mu.Unlock()
+
+        if !headersSent && hasHeader {
+                t.WriteHeader(s, nil)
+                headersSent = true
+        }
+
+        if _, err := wait(s.ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
+                return err
+        }
+        t.hBuf.Reset()
+        if !headersSent {
+                t.hEnc.WriteField(hpack.HeaderField{Name: ":status", Value: "200"})
+                t.hEnc.WriteField(hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
+        }
+        t.hEnc.WriteField(
+                hpack.HeaderField{
+                        Name:  "grpc-status",
+                        Value: strconv.Itoa(int(st.Code())),
+                })
+        t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-message", Value: encodeGrpcMessage(st.Message())})
+
+        if p := st.Proto(); p != nil && len(p.Details) > 0 {
+                stBytes, err := proto.Marshal(p)
+                if err != nil {
+                        // TODO: return error instead, when callers are able to handle it.
+                        panic(err)
+                }
+
+                t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-status-details-bin", Value: encodeBinHeader(stBytes)})
+        }
+
+        // Attach the trailer metadata.
+        for k, vv := range s.trailer {
+                // Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+                if isReservedHeader(k) {
+                        continue
+                }
+                for _, v := range vv {
+                        t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+                }
+        }
+        bufLen := t.hBuf.Len()
+        if err := t.writeHeaders(s, t.hBuf, true); err != nil {
+                t.Close()
+                return err
+        }
+        if t.stats != nil {
+                outTrailer := &stats.OutTrailer{
+                        WireLength: bufLen,
+                }
+                t.stats.HandleRPC(s.Context(), outTrailer)
+        }
+        t.closeStream(s)
+        t.writableChan <- 0
+        return nil
+}
+
+// Write converts the data into HTTP2 data frame and sends it out. Non-nil error
+// is returns if it fails (e.g., framing error, transport error).
+func (t *http2Server) Write(s *Stream, data []byte, opts *Options) (err error) {
+        // TODO(zhaoq): Support multi-writers for a single stream.
+        var writeHeaderFrame bool
+        s.mu.Lock()
+        if s.state == streamDone {
+                s.mu.Unlock()
+                return streamErrorf(codes.Unknown, "the stream has been done")
+        }
+        if !s.headerOk {
+                writeHeaderFrame = true
+        }
+        s.mu.Unlock()
+        if writeHeaderFrame {
+                t.WriteHeader(s, nil)
+        }
+        r := bytes.NewBuffer(data)
+        var (
+                p   []byte
+                oqv uint32
+        )
+        for {
+                if r.Len() == 0 && p == nil {
+                        return nil
+                }
+                oqv = atomic.LoadUint32(&t.outQuotaVersion)
+                size := http2MaxFrameLen
+                // Wait until the stream has some quota to send the data.
+                sq, err := wait(s.ctx, nil, nil, t.shutdownChan, s.sendQuotaPool.acquire())
+                if err != nil {
+                        return err
+                }
+                // Wait until the transport has some quota to send the data.
+                tq, err := wait(s.ctx, nil, nil, t.shutdownChan, t.sendQuotaPool.acquire())
+                if err != nil {
+                        return err
+                }
+                if sq < size {
+                        size = sq
+                }
+                if tq < size {
+                        size = tq
+                }
+                if p == nil {
+                        p = r.Next(size)
+                }
+                ps := len(p)
+                if ps < sq {
+                        // Overbooked stream quota. Return it back.
+                        s.sendQuotaPool.add(sq - ps)
+                }
+                if ps < tq {
+                        // Overbooked transport quota. Return it back.
+                        t.sendQuotaPool.add(tq - ps)
+                }
+                t.framer.adjustNumWriters(1)
+                // Got some quota. Try to acquire writing privilege on the
+                // transport.
+                if _, err := wait(s.ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
+                        if _, ok := err.(StreamError); ok {
+                                // Return the connection quota back.
+                                t.sendQuotaPool.add(ps)
+                        }
+                        if t.framer.adjustNumWriters(-1) == 0 {
+                                // This writer is the last one in this batch and has the
+                                // responsibility to flush the buffered frames. It queues
+                                // a flush request to controlBuf instead of flushing directly
+                                // in order to avoid the race with other writing or flushing.
+                                t.controlBuf.put(&flushIO{})
+                        }
+                        return err
+                }
+                select {
+                case <-s.ctx.Done():
+                        t.sendQuotaPool.add(ps)
+                        if t.framer.adjustNumWriters(-1) == 0 {
+                                t.controlBuf.put(&flushIO{})
+                        }
+                        t.writableChan <- 0
+                        return ContextErr(s.ctx.Err())
+                default:
+                }
+                if oqv != atomic.LoadUint32(&t.outQuotaVersion) {
+                        // InitialWindowSize settings frame must have been received after we
+                        // acquired send quota but before we got the writable channel.
+                        // We must forsake this write.
+                        t.sendQuotaPool.add(ps)
+                        s.sendQuotaPool.add(ps)
+                        if t.framer.adjustNumWriters(-1) == 0 {
+                                t.controlBuf.put(&flushIO{})
+                        }
+                        t.writableChan <- 0
+                        continue
+                }
+                var forceFlush bool
+                if r.Len() == 0 && t.framer.adjustNumWriters(0) == 1 && !opts.Last {
+                        forceFlush = true
+                }
+                // Reset ping strikes when sending data since this might cause
+                // the peer to send ping.
+                atomic.StoreUint32(&t.resetPingStrikes, 1)
+                if err := t.framer.writeData(forceFlush, s.id, false, p); err != nil {
+                        t.Close()
+                        return connectionErrorf(true, err, "transport: %v", err)
+                }
+                p = nil
+                if t.framer.adjustNumWriters(-1) == 0 {
+                        t.framer.flushWrite()
+                }
+                t.writableChan <- 0
+        }
+
+}
+
+func (t *http2Server) applySettings(ss []http2.Setting) {
+        for _, s := range ss {
+                if s.ID == http2.SettingInitialWindowSize {
+                        t.mu.Lock()
+                        defer t.mu.Unlock()
+                        for _, stream := range t.activeStreams {
+                                stream.sendQuotaPool.add(int(s.Val) - int(t.streamSendQuota))
+                        }
+                        t.streamSendQuota = s.Val
+                        atomic.AddUint32(&t.outQuotaVersion, 1)
+                }
+
+        }
+}
+
+// keepalive running in a separate goroutine does the following:
+// 1. Gracefully closes an idle connection after a duration of keepalive.MaxConnectionIdle.
+// 2. Gracefully closes any connection after a duration of keepalive.MaxConnectionAge.
+// 3. Forcibly closes a connection after an additive period of keepalive.MaxConnectionAgeGrace over keepalive.MaxConnectionAge.
+// 4. Makes sure a connection is alive by sending pings with a frequency of keepalive.Time and closes a non-responsive connection
+// after an additional duration of keepalive.Timeout.
+func (t *http2Server) keepalive() {
+        p := &ping{}
+        var pingSent bool
+        maxIdle := time.NewTimer(t.kp.MaxConnectionIdle)
+        maxAge := time.NewTimer(t.kp.MaxConnectionAge)
+        keepalive := time.NewTimer(t.kp.Time)
+        // NOTE: All exit paths of this function should reset their
+        // respecitve timers. A failure to do so will cause the
+        // following clean-up to deadlock and eventually leak.
+        defer func() {
+                if !maxIdle.Stop() {
+                        <-maxIdle.C
+                }
+                if !maxAge.Stop() {
+                        <-maxAge.C
+                }
+                if !keepalive.Stop() {
+                        <-keepalive.C
+                }
+        }()
+        for {
+                select {
+                case <-maxIdle.C:
+                        t.mu.Lock()
+                        idle := t.idle
+                        if idle.IsZero() { // The connection is non-idle.
+                                t.mu.Unlock()
+                                maxIdle.Reset(t.kp.MaxConnectionIdle)
+                                continue
+                        }
+                        val := t.kp.MaxConnectionIdle - time.Since(idle)
+                        t.mu.Unlock()
+                        if val <= 0 {
+                                // The connection has been idle for a duration of keepalive.MaxConnectionIdle or more.
+                                // Gracefully close the connection.
+                                t.drain(http2.ErrCodeNo, []byte{})
+                                // Reseting the timer so that the clean-up doesn't deadlock.
+                                maxIdle.Reset(infinity)
+                                return
+                        }
+                        maxIdle.Reset(val)
+                case <-maxAge.C:
+                        t.drain(http2.ErrCodeNo, []byte{})
+                        maxAge.Reset(t.kp.MaxConnectionAgeGrace)
+                        select {
+                        case <-maxAge.C:
+                                // Close the connection after grace period.
+                                t.Close()
+                                // Reseting the timer so that the clean-up doesn't deadlock.
+                                maxAge.Reset(infinity)
+                        case <-t.shutdownChan:
+                        }
+                        return
+                case <-keepalive.C:
+                        if atomic.CompareAndSwapUint32(&t.activity, 1, 0) {
+                                pingSent = false
+                                keepalive.Reset(t.kp.Time)
+                                continue
+                        }
+                        if pingSent {
+                                t.Close()
+                                // Reseting the timer so that the clean-up doesn't deadlock.
+                                keepalive.Reset(infinity)
+                                return
+                        }
+                        pingSent = true
+                        t.controlBuf.put(p)
+                        keepalive.Reset(t.kp.Timeout)
+                case <-t.shutdownChan:
+                        return
+                }
+        }
+}
+
+var goAwayPing = &ping{data: [8]byte{1, 6, 1, 8, 0, 3, 3, 9}}
+
+// controller running in a separate goroutine takes charge of sending control
+// frames (e.g., window update, reset stream, setting, etc.) to the server.
+func (t *http2Server) controller() {
+        for {
+                select {
+                case i := <-t.controlBuf.get():
+                        t.controlBuf.load()
+                        select {
+                        case <-t.writableChan:
+                                switch i := i.(type) {
+                                case *windowUpdate:
+                                        t.framer.writeWindowUpdate(i.flush, i.streamID, i.increment)
+                                case *settings:
+                                        if i.ack {
+                                                t.framer.writeSettingsAck(true)
+                                                t.applySettings(i.ss)
+                                        } else {
+                                                t.framer.writeSettings(true, i.ss...)
+                                        }
+                                case *resetStream:
+                                        t.framer.writeRSTStream(true, i.streamID, i.code)
+                                case *goAway:
+                                        t.mu.Lock()
+                                        if t.state == closing {
+                                                t.mu.Unlock()
+                                                // The transport is closing.
+                                                return
+                                        }
+                                        sid := t.maxStreamID
+                                        if !i.headsUp {
+                                                // Stop accepting more streams now.
+                                                t.state = draining
+                                                t.mu.Unlock()
+                                                t.framer.writeGoAway(true, sid, i.code, i.debugData)
+                                                if i.closeConn {
+                                                        // Abruptly close the connection following the GoAway.
+                                                        t.Close()
+                                                }
+                                                t.writableChan <- 0
+                                                continue
+                                        }
+                                        t.mu.Unlock()
+                                        // For a graceful close, send out a GoAway with stream ID of MaxUInt32,
+                                        // Follow that with a ping and wait for the ack to come back or a timer
+                                        // to expire. During this time accept new streams since they might have
+                                        // originated before the GoAway reaches the client.
+                                        // After getting the ack or timer expiration send out another GoAway this
+                                        // time with an ID of the max stream server intends to process.
+                                        t.framer.writeGoAway(true, math.MaxUint32, http2.ErrCodeNo, []byte{})
+                                        t.framer.writePing(true, false, goAwayPing.data)
+                                        go func() {
+                                                timer := time.NewTimer(time.Minute)
+                                                defer timer.Stop()
+                                                select {
+                                                case <-t.drainChan:
+                                                case <-timer.C:
+                                                case <-t.shutdownChan:
+                                                        return
+                                                }
+                                                t.controlBuf.put(&goAway{code: i.code, debugData: i.debugData})
+                                        }()
+                                case *flushIO:
+                                        t.framer.flushWrite()
+                                case *ping:
+                                        if !i.ack {
+                                                t.bdpEst.timesnap(i.data)
+                                        }
+                                        t.framer.writePing(true, i.ack, i.data)
+                                default:
+                                        errorf("transport: http2Server.controller got unexpected item type %v\n", i)
+                                }
+                                t.writableChan <- 0
+                                continue
+                        case <-t.shutdownChan:
+                                return
+                        }
+                case <-t.shutdownChan:
+                        return
+                }
+        }
+}
+
+// Close starts shutting down the http2Server transport.
+// TODO(zhaoq): Now the destruction is not blocked on any pending streams. This
+// could cause some resource issue. Revisit this later.
+func (t *http2Server) Close() (err error) {
+        t.mu.Lock()
+        if t.state == closing {
+                t.mu.Unlock()
+                return errors.New("transport: Close() was already called")
+        }
+        t.state = closing
+        streams := t.activeStreams
+        t.activeStreams = nil
+        t.mu.Unlock()
+        close(t.shutdownChan)
+        err = t.conn.Close()
+        // Cancel all active streams.
+        for _, s := range streams {
+                s.cancel()
+        }
+        if t.stats != nil {
+                connEnd := &stats.ConnEnd{}
+                t.stats.HandleConn(t.ctx, connEnd)
+        }
+        return
+}
+
+// closeStream clears the footprint of a stream when the stream is not needed
+// any more.
+func (t *http2Server) closeStream(s *Stream) {
+        t.mu.Lock()
+        delete(t.activeStreams, s.id)
+        if len(t.activeStreams) == 0 {
+                t.idle = time.Now()
+        }
+        if t.state == draining && len(t.activeStreams) == 0 {
+                defer t.Close()
+        }
+        t.mu.Unlock()
+        // In case stream sending and receiving are invoked in separate
+        // goroutines (e.g., bi-directional streaming), cancel needs to be
+        // called to interrupt the potential blocking on other goroutines.
+        s.cancel()
+        s.mu.Lock()
+        if s.state == streamDone {
+                s.mu.Unlock()
+                return
+        }
+        s.state = streamDone
+        s.mu.Unlock()
+}
+
+func (t *http2Server) RemoteAddr() net.Addr {
+        return t.remoteAddr
+}
+
+func (t *http2Server) Drain() {
+        t.drain(http2.ErrCodeNo, []byte{})
+}
+
+func (t *http2Server) drain(code http2.ErrCode, debugData []byte) {
+        t.mu.Lock()
+        defer t.mu.Unlock()
+        if t.drainChan != nil {
+                return
+        }
+        t.drainChan = make(chan struct{})
+        t.controlBuf.put(&goAway{code: code, debugData: debugData, headsUp: true})
+}
+
+var rgen = rand.New(rand.NewSource(time.Now().UnixNano()))
+
+func getJitter(v time.Duration) time.Duration {
+        if v == infinity {
+                return 0
+        }
+        // Generate a jitter between +/- 10% of the value.
+        r := int64(v / 10)
+        j := rgen.Int63n(2*r) - r
+        return time.Duration(j)
+}
diff --git a/vendor/google.golang.org/grpc/transport/http_util.go b/vendor/google.golang.org/grpc/transport/http_util.go
new file mode 100644
index 0000000..685c6fb
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/http_util.go
@@ -0,0 +1,597 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+        "bufio"
+        "bytes"
+        "encoding/base64"
+        "fmt"
+        "io"
+        "net"
+        "net/http"
+        "strconv"
+        "strings"
+        "sync/atomic"
+        "time"
+
+        "github.com/golang/protobuf/proto"
+        "golang.org/x/net/http2"
+        "golang.org/x/net/http2/hpack"
+        spb "google.golang.org/genproto/googleapis/rpc/status"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/status"
+)
+
+const (
+        // http2MaxFrameLen specifies the max length of a HTTP2 frame.
+        http2MaxFrameLen = 16384 // 16KB frame
+        // http://http2.github.io/http2-spec/#SettingValues
+        http2InitHeaderTableSize = 4096
+        // http2IOBufSize specifies the buffer size for sending frames.
+        http2IOBufSize = 32 * 1024
+)
+
+var (
+        clientPreface   = []byte(http2.ClientPreface)
+        http2ErrConvTab = map[http2.ErrCode]codes.Code{
+                http2.ErrCodeNo:                 codes.Internal,
+                http2.ErrCodeProtocol:           codes.Internal,
+                http2.ErrCodeInternal:           codes.Internal,
+                http2.ErrCodeFlowControl:        codes.ResourceExhausted,
+                http2.ErrCodeSettingsTimeout:    codes.Internal,
+                http2.ErrCodeStreamClosed:       codes.Internal,
+                http2.ErrCodeFrameSize:          codes.Internal,
+                http2.ErrCodeRefusedStream:      codes.Unavailable,
+                http2.ErrCodeCancel:             codes.Canceled,
+                http2.ErrCodeCompression:        codes.Internal,
+                http2.ErrCodeConnect:            codes.Internal,
+                http2.ErrCodeEnhanceYourCalm:    codes.ResourceExhausted,
+                http2.ErrCodeInadequateSecurity: codes.PermissionDenied,
+                http2.ErrCodeHTTP11Required:     codes.FailedPrecondition,
+        }
+        statusCodeConvTab = map[codes.Code]http2.ErrCode{
+                codes.Internal:          http2.ErrCodeInternal,
+                codes.Canceled:          http2.ErrCodeCancel,
+                codes.Unavailable:       http2.ErrCodeRefusedStream,
+                codes.ResourceExhausted: http2.ErrCodeEnhanceYourCalm,
+                codes.PermissionDenied:  http2.ErrCodeInadequateSecurity,
+        }
+        httpStatusConvTab = map[int]codes.Code{
+                // 400 Bad Request - INTERNAL.
+                http.StatusBadRequest: codes.Internal,
+                // 401 Unauthorized  - UNAUTHENTICATED.
+                http.StatusUnauthorized: codes.Unauthenticated,
+                // 403 Forbidden - PERMISSION_DENIED.
+                http.StatusForbidden: codes.PermissionDenied,
+                // 404 Not Found - UNIMPLEMENTED.
+                http.StatusNotFound: codes.Unimplemented,
+                // 429 Too Many Requests - UNAVAILABLE.
+                http.StatusTooManyRequests: codes.Unavailable,
+                // 502 Bad Gateway - UNAVAILABLE.
+                http.StatusBadGateway: codes.Unavailable,
+                // 503 Service Unavailable - UNAVAILABLE.
+                http.StatusServiceUnavailable: codes.Unavailable,
+                // 504 Gateway timeout - UNAVAILABLE.
+                http.StatusGatewayTimeout: codes.Unavailable,
+        }
+)
+
+// Records the states during HPACK decoding. Must be reset once the
+// decoding of the entire headers are finished.
+type decodeState struct {
+        encoding string
+        // statusGen caches the stream status received from the trailer the server
+        // sent.  Client side only.  Do not access directly.  After all trailers are
+        // parsed, use the status method to retrieve the status.
+        statusGen *status.Status
+        // rawStatusCode and rawStatusMsg are set from the raw trailer fields and are not
+        // intended for direct access outside of parsing.
+        rawStatusCode *int
+        rawStatusMsg  string
+        httpStatus    *int
+        // Server side only fields.
+        timeoutSet bool
+        timeout    time.Duration
+        method     string
+        // key-value metadata map from the peer.
+        mdata map[string][]string
+}
+
+// isReservedHeader checks whether hdr belongs to HTTP2 headers
+// reserved by gRPC protocol. Any other headers are classified as the
+// user-specified metadata.
+func isReservedHeader(hdr string) bool {
+        if hdr != "" && hdr[0] == ':' {
+                return true
+        }
+        switch hdr {
+        case "content-type",
+                "grpc-message-type",
+                "grpc-encoding",
+                "grpc-message",
+                "grpc-status",
+                "grpc-timeout",
+                "grpc-status-details-bin",
+                "te":
+                return true
+        default:
+                return false
+        }
+}
+
+// isWhitelistedPseudoHeader checks whether hdr belongs to HTTP2 pseudoheaders
+// that should be propagated into metadata visible to users.
+func isWhitelistedPseudoHeader(hdr string) bool {
+        switch hdr {
+        case ":authority":
+                return true
+        default:
+                return false
+        }
+}
+
+func validContentType(t string) bool {
+        e := "application/grpc"
+        if !strings.HasPrefix(t, e) {
+                return false
+        }
+        // Support variations on the content-type
+        // (e.g. "application/grpc+blah", "application/grpc;blah").
+        if len(t) > len(e) && t[len(e)] != '+' && t[len(e)] != ';' {
+                return false
+        }
+        return true
+}
+
+func (d *decodeState) status() *status.Status {
+        if d.statusGen == nil {
+                // No status-details were provided; generate status using code/msg.
+                d.statusGen = status.New(codes.Code(int32(*(d.rawStatusCode))), d.rawStatusMsg)
+        }
+        return d.statusGen
+}
+
+const binHdrSuffix = "-bin"
+
+func encodeBinHeader(v []byte) string {
+        return base64.RawStdEncoding.EncodeToString(v)
+}
+
+func decodeBinHeader(v string) ([]byte, error) {
+        if len(v)%4 == 0 {
+                // Input was padded, or padding was not necessary.
+                return base64.StdEncoding.DecodeString(v)
+        }
+        return base64.RawStdEncoding.DecodeString(v)
+}
+
+func encodeMetadataHeader(k, v string) string {
+        if strings.HasSuffix(k, binHdrSuffix) {
+                return encodeBinHeader(([]byte)(v))
+        }
+        return v
+}
+
+func decodeMetadataHeader(k, v string) (string, error) {
+        if strings.HasSuffix(k, binHdrSuffix) {
+                b, err := decodeBinHeader(v)
+                return string(b), err
+        }
+        return v, nil
+}
+
+func (d *decodeState) decodeResponseHeader(frame *http2.MetaHeadersFrame) error {
+        for _, hf := range frame.Fields {
+                if err := d.processHeaderField(hf); err != nil {
+                        return err
+                }
+        }
+
+        // If grpc status exists, no need to check further.
+        if d.rawStatusCode != nil || d.statusGen != nil {
+                return nil
+        }
+
+        // If grpc status doesn't exist and http status doesn't exist,
+        // then it's a malformed header.
+        if d.httpStatus == nil {
+                return streamErrorf(codes.Internal, "malformed header: doesn't contain status(gRPC or HTTP)")
+        }
+
+        if *(d.httpStatus) != http.StatusOK {
+                code, ok := httpStatusConvTab[*(d.httpStatus)]
+                if !ok {
+                        code = codes.Unknown
+                }
+                return streamErrorf(code, http.StatusText(*(d.httpStatus)))
+        }
+
+        // gRPC status doesn't exist and http status is OK.
+        // Set rawStatusCode to be unknown and return nil error.
+        // So that, if the stream has ended this Unknown status
+        // will be propogated to the user.
+        // Otherwise, it will be ignored. In which case, status from
+        // a later trailer, that has StreamEnded flag set, is propogated.
+        code := int(codes.Unknown)
+        d.rawStatusCode = &code
+        return nil
+
+}
+
+func (d *decodeState) processHeaderField(f hpack.HeaderField) error {
+        switch f.Name {
+        case "content-type":
+                if !validContentType(f.Value) {
+                        return streamErrorf(codes.FailedPrecondition, "transport: received the unexpected content-type %q", f.Value)
+                }
+        case "grpc-encoding":
+                d.encoding = f.Value
+        case "grpc-status":
+                code, err := strconv.Atoi(f.Value)
+                if err != nil {
+                        return streamErrorf(codes.Internal, "transport: malformed grpc-status: %v", err)
+                }
+                d.rawStatusCode = &code
+        case "grpc-message":
+                d.rawStatusMsg = decodeGrpcMessage(f.Value)
+        case "grpc-status-details-bin":
+                v, err := decodeBinHeader(f.Value)
+                if err != nil {
+                        return streamErrorf(codes.Internal, "transport: malformed grpc-status-details-bin: %v", err)
+                }
+                s := &spb.Status{}
+                if err := proto.Unmarshal(v, s); err != nil {
+                        return streamErrorf(codes.Internal, "transport: malformed grpc-status-details-bin: %v", err)
+                }
+                d.statusGen = status.FromProto(s)
+        case "grpc-timeout":
+                d.timeoutSet = true
+                var err error
+                if d.timeout, err = decodeTimeout(f.Value); err != nil {
+                        return streamErrorf(codes.Internal, "transport: malformed time-out: %v", err)
+                }
+        case ":path":
+                d.method = f.Value
+        case ":status":
+                code, err := strconv.Atoi(f.Value)
+                if err != nil {
+                        return streamErrorf(codes.Internal, "transport: malformed http-status: %v", err)
+                }
+                d.httpStatus = &code
+        default:
+                if !isReservedHeader(f.Name) || isWhitelistedPseudoHeader(f.Name) {
+                        if d.mdata == nil {
+                                d.mdata = make(map[string][]string)
+                        }
+                        v, err := decodeMetadataHeader(f.Name, f.Value)
+                        if err != nil {
+                                errorf("Failed to decode metadata header (%q, %q): %v", f.Name, f.Value, err)
+                                return nil
+                        }
+                        d.mdata[f.Name] = append(d.mdata[f.Name], v)
+                }
+        }
+        return nil
+}
+
+type timeoutUnit uint8
+
+const (
+        hour        timeoutUnit = 'H'
+        minute      timeoutUnit = 'M'
+        second      timeoutUnit = 'S'
+        millisecond timeoutUnit = 'm'
+        microsecond timeoutUnit = 'u'
+        nanosecond  timeoutUnit = 'n'
+)
+
+func timeoutUnitToDuration(u timeoutUnit) (d time.Duration, ok bool) {
+        switch u {
+        case hour:
+                return time.Hour, true
+        case minute:
+                return time.Minute, true
+        case second:
+                return time.Second, true
+        case millisecond:
+                return time.Millisecond, true
+        case microsecond:
+                return time.Microsecond, true
+        case nanosecond:
+                return time.Nanosecond, true
+        default:
+        }
+        return
+}
+
+const maxTimeoutValue int64 = 100000000 - 1
+
+// div does integer division and round-up the result. Note that this is
+// equivalent to (d+r-1)/r but has less chance to overflow.
+func div(d, r time.Duration) int64 {
+        if m := d % r; m > 0 {
+                return int64(d/r + 1)
+        }
+        return int64(d / r)
+}
+
+// TODO(zhaoq): It is the simplistic and not bandwidth efficient. Improve it.
+func encodeTimeout(t time.Duration) string {
+        if t <= 0 {
+                return "0n"
+        }
+        if d := div(t, time.Nanosecond); d <= maxTimeoutValue {
+                return strconv.FormatInt(d, 10) + "n"
+        }
+        if d := div(t, time.Microsecond); d <= maxTimeoutValue {
+                return strconv.FormatInt(d, 10) + "u"
+        }
+        if d := div(t, time.Millisecond); d <= maxTimeoutValue {
+                return strconv.FormatInt(d, 10) + "m"
+        }
+        if d := div(t, time.Second); d <= maxTimeoutValue {
+                return strconv.FormatInt(d, 10) + "S"
+        }
+        if d := div(t, time.Minute); d <= maxTimeoutValue {
+                return strconv.FormatInt(d, 10) + "M"
+        }
+        // Note that maxTimeoutValue * time.Hour > MaxInt64.
+        return strconv.FormatInt(div(t, time.Hour), 10) + "H"
+}
+
+func decodeTimeout(s string) (time.Duration, error) {
+        size := len(s)
+        if size < 2 {
+                return 0, fmt.Errorf("transport: timeout string is too short: %q", s)
+        }
+        unit := timeoutUnit(s[size-1])
+        d, ok := timeoutUnitToDuration(unit)
+        if !ok {
+                return 0, fmt.Errorf("transport: timeout unit is not recognized: %q", s)
+        }
+        t, err := strconv.ParseInt(s[:size-1], 10, 64)
+        if err != nil {
+                return 0, err
+        }
+        return d * time.Duration(t), nil
+}
+
+const (
+        spaceByte   = ' '
+        tildaByte   = '~'
+        percentByte = '%'
+)
+
+// encodeGrpcMessage is used to encode status code in header field
+// "grpc-message".
+// It checks to see if each individual byte in msg is an
+// allowable byte, and then either percent encoding or passing it through.
+// When percent encoding, the byte is converted into hexadecimal notation
+// with a '%' prepended.
+func encodeGrpcMessage(msg string) string {
+        if msg == "" {
+                return ""
+        }
+        lenMsg := len(msg)
+        for i := 0; i < lenMsg; i++ {
+                c := msg[i]
+                if !(c >= spaceByte && c < tildaByte && c != percentByte) {
+                        return encodeGrpcMessageUnchecked(msg)
+                }
+        }
+        return msg
+}
+
+func encodeGrpcMessageUnchecked(msg string) string {
+        var buf bytes.Buffer
+        lenMsg := len(msg)
+        for i := 0; i < lenMsg; i++ {
+                c := msg[i]
+                if c >= spaceByte && c < tildaByte && c != percentByte {
+                        buf.WriteByte(c)
+                } else {
+                        buf.WriteString(fmt.Sprintf("%%%02X", c))
+                }
+        }
+        return buf.String()
+}
+
+// decodeGrpcMessage decodes the msg encoded by encodeGrpcMessage.
+func decodeGrpcMessage(msg string) string {
+        if msg == "" {
+                return ""
+        }
+        lenMsg := len(msg)
+        for i := 0; i < lenMsg; i++ {
+                if msg[i] == percentByte && i+2 < lenMsg {
+                        return decodeGrpcMessageUnchecked(msg)
+                }
+        }
+        return msg
+}
+
+func decodeGrpcMessageUnchecked(msg string) string {
+        var buf bytes.Buffer
+        lenMsg := len(msg)
+        for i := 0; i < lenMsg; i++ {
+                c := msg[i]
+                if c == percentByte && i+2 < lenMsg {
+                        parsed, err := strconv.ParseUint(msg[i+1:i+3], 16, 8)
+                        if err != nil {
+                                buf.WriteByte(c)
+                        } else {
+                                buf.WriteByte(byte(parsed))
+                                i += 2
+                        }
+                } else {
+                        buf.WriteByte(c)
+                }
+        }
+        return buf.String()
+}
+
+type framer struct {
+        numWriters int32
+        reader     io.Reader
+        writer     *bufio.Writer
+        fr         *http2.Framer
+}
+
+func newFramer(conn net.Conn) *framer {
+        f := &framer{
+                reader: bufio.NewReaderSize(conn, http2IOBufSize),
+                writer: bufio.NewWriterSize(conn, http2IOBufSize),
+        }
+        f.fr = http2.NewFramer(f.writer, f.reader)
+        // Opt-in to Frame reuse API on framer to reduce garbage.
+        // Frames aren't safe to read from after a subsequent call to ReadFrame.
+        f.fr.SetReuseFrames()
+        f.fr.ReadMetaHeaders = hpack.NewDecoder(http2InitHeaderTableSize, nil)
+        return f
+}
+
+func (f *framer) adjustNumWriters(i int32) int32 {
+        return atomic.AddInt32(&f.numWriters, i)
+}
+
+// The following writeXXX functions can only be called when the caller gets
+// unblocked from writableChan channel (i.e., owns the privilege to write).
+
+func (f *framer) writeContinuation(forceFlush bool, streamID uint32, endHeaders bool, headerBlockFragment []byte) error {
+        if err := f.fr.WriteContinuation(streamID, endHeaders, headerBlockFragment); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeData(forceFlush bool, streamID uint32, endStream bool, data []byte) error {
+        if err := f.fr.WriteData(streamID, endStream, data); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeGoAway(forceFlush bool, maxStreamID uint32, code http2.ErrCode, debugData []byte) error {
+        if err := f.fr.WriteGoAway(maxStreamID, code, debugData); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeHeaders(forceFlush bool, p http2.HeadersFrameParam) error {
+        if err := f.fr.WriteHeaders(p); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writePing(forceFlush, ack bool, data [8]byte) error {
+        if err := f.fr.WritePing(ack, data); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writePriority(forceFlush bool, streamID uint32, p http2.PriorityParam) error {
+        if err := f.fr.WritePriority(streamID, p); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writePushPromise(forceFlush bool, p http2.PushPromiseParam) error {
+        if err := f.fr.WritePushPromise(p); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeRSTStream(forceFlush bool, streamID uint32, code http2.ErrCode) error {
+        if err := f.fr.WriteRSTStream(streamID, code); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeSettings(forceFlush bool, settings ...http2.Setting) error {
+        if err := f.fr.WriteSettings(settings...); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeSettingsAck(forceFlush bool) error {
+        if err := f.fr.WriteSettingsAck(); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) writeWindowUpdate(forceFlush bool, streamID, incr uint32) error {
+        if err := f.fr.WriteWindowUpdate(streamID, incr); err != nil {
+                return err
+        }
+        if forceFlush {
+                return f.writer.Flush()
+        }
+        return nil
+}
+
+func (f *framer) flushWrite() error {
+        return f.writer.Flush()
+}
+
+func (f *framer) readFrame() (http2.Frame, error) {
+        return f.fr.ReadFrame()
+}
+
+func (f *framer) errorDetail() error {
+        return f.fr.ErrorDetail()
+}
diff --git a/vendor/google.golang.org/grpc/transport/log.go b/vendor/google.golang.org/grpc/transport/log.go
new file mode 100644
index 0000000..ac8e358
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/log.go
@@ -0,0 +1,50 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// This file contains wrappers for grpclog functions.
+// The transport package only logs to verbose level 2 by default.
+
+package transport
+
+import "google.golang.org/grpc/grpclog"
+
+const logLevel = 2
+
+func infof(format string, args ...interface{}) {
+        if grpclog.V(logLevel) {
+                grpclog.Infof(format, args...)
+        }
+}
+
+func warningf(format string, args ...interface{}) {
+        if grpclog.V(logLevel) {
+                grpclog.Warningf(format, args...)
+        }
+}
+
+func errorf(format string, args ...interface{}) {
+        if grpclog.V(logLevel) {
+                grpclog.Errorf(format, args...)
+        }
+}
+
+func fatalf(format string, args ...interface{}) {
+        if grpclog.V(logLevel) {
+                grpclog.Fatalf(format, args...)
+        }
+}
diff --git a/vendor/google.golang.org/grpc/transport/transport.go b/vendor/google.golang.org/grpc/transport/transport.go
new file mode 100644
index 0000000..ec0fe67
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/transport.go
@@ -0,0 +1,730 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package transport defines and implements message oriented communication
+// channel to complete various transactions (e.g., an RPC).
+package transport // import "google.golang.org/grpc/transport"
+
+import (
+        "fmt"
+        "io"
+        "net"
+        "sync"
+
+        "golang.org/x/net/context"
+        "golang.org/x/net/http2"
+        "google.golang.org/grpc/codes"
+        "google.golang.org/grpc/credentials"
+        "google.golang.org/grpc/keepalive"
+        "google.golang.org/grpc/metadata"
+        "google.golang.org/grpc/stats"
+        "google.golang.org/grpc/status"
+        "google.golang.org/grpc/tap"
+)
+
+// recvMsg represents the received msg from the transport. All transport
+// protocol specific info has been removed.
+type recvMsg struct {
+        data []byte
+        // nil: received some data
+        // io.EOF: stream is completed. data is nil.
+        // other non-nil error: transport failure. data is nil.
+        err error
+}
+
+// recvBuffer is an unbounded channel of recvMsg structs.
+// Note recvBuffer differs from controlBuffer only in that recvBuffer
+// holds a channel of only recvMsg structs instead of objects implementing "item" interface.
+// recvBuffer is written to much more often than
+// controlBuffer and using strict recvMsg structs helps avoid allocation in "recvBuffer.put"
+type recvBuffer struct {
+        c       chan recvMsg
+        mu      sync.Mutex
+        backlog []recvMsg
+}
+
+func newRecvBuffer() *recvBuffer {
+        b := &recvBuffer{
+                c: make(chan recvMsg, 1),
+        }
+        return b
+}
+
+func (b *recvBuffer) put(r recvMsg) {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if len(b.backlog) == 0 {
+                select {
+                case b.c <- r:
+                        return
+                default:
+                }
+        }
+        b.backlog = append(b.backlog, r)
+}
+
+func (b *recvBuffer) load() {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if len(b.backlog) > 0 {
+                select {
+                case b.c <- b.backlog[0]:
+                        b.backlog[0] = recvMsg{}
+                        b.backlog = b.backlog[1:]
+                default:
+                }
+        }
+}
+
+// get returns the channel that receives a recvMsg in the buffer.
+//
+// Upon receipt of a recvMsg, the caller should call load to send another
+// recvMsg onto the channel if there is any.
+func (b *recvBuffer) get() <-chan recvMsg {
+        return b.c
+}
+
+// recvBufferReader implements io.Reader interface to read the data from
+// recvBuffer.
+type recvBufferReader struct {
+        ctx    context.Context
+        goAway chan struct{}
+        recv   *recvBuffer
+        last   []byte // Stores the remaining data in the previous calls.
+        err    error
+}
+
+// Read reads the next len(p) bytes from last. If last is drained, it tries to
+// read additional data from recv. It blocks if there no additional data available
+// in recv. If Read returns any non-nil error, it will continue to return that error.
+func (r *recvBufferReader) Read(p []byte) (n int, err error) {
+        if r.err != nil {
+                return 0, r.err
+        }
+        n, r.err = r.read(p)
+        return n, r.err
+}
+
+func (r *recvBufferReader) read(p []byte) (n int, err error) {
+        if r.last != nil && len(r.last) > 0 {
+                // Read remaining data left in last call.
+                copied := copy(p, r.last)
+                r.last = r.last[copied:]
+                return copied, nil
+        }
+        select {
+        case <-r.ctx.Done():
+                return 0, ContextErr(r.ctx.Err())
+        case <-r.goAway:
+                return 0, ErrStreamDrain
+        case m := <-r.recv.get():
+                r.recv.load()
+                if m.err != nil {
+                        return 0, m.err
+                }
+                copied := copy(p, m.data)
+                r.last = m.data[copied:]
+                return copied, nil
+        }
+}
+
+// All items in an out of a controlBuffer should be the same type.
+type item interface {
+        item()
+}
+
+// controlBuffer is an unbounded channel of item.
+type controlBuffer struct {
+        c       chan item
+        mu      sync.Mutex
+        backlog []item
+}
+
+func newControlBuffer() *controlBuffer {
+        b := &controlBuffer{
+                c: make(chan item, 1),
+        }
+        return b
+}
+
+func (b *controlBuffer) put(r item) {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if len(b.backlog) == 0 {
+                select {
+                case b.c <- r:
+                        return
+                default:
+                }
+        }
+        b.backlog = append(b.backlog, r)
+}
+
+func (b *controlBuffer) load() {
+        b.mu.Lock()
+        defer b.mu.Unlock()
+        if len(b.backlog) > 0 {
+                select {
+                case b.c <- b.backlog[0]:
+                        b.backlog[0] = nil
+                        b.backlog = b.backlog[1:]
+                default:
+                }
+        }
+}
+
+// get returns the channel that receives an item in the buffer.
+//
+// Upon receipt of an item, the caller should call load to send another
+// item onto the channel if there is any.
+func (b *controlBuffer) get() <-chan item {
+        return b.c
+}
+
+type streamState uint8
+
+const (
+        streamActive    streamState = iota
+        streamWriteDone             // EndStream sent
+        streamReadDone              // EndStream received
+        streamDone                  // the entire stream is finished.
+)
+
+// Stream represents an RPC in the transport layer.
+type Stream struct {
+        id uint32
+        // nil for client side Stream.
+        st ServerTransport
+        // ctx is the associated context of the stream.
+        ctx context.Context
+        // cancel is always nil for client side Stream.
+        cancel context.CancelFunc
+        // done is closed when the final status arrives.
+        done chan struct{}
+        // goAway is closed when the server sent GoAways signal before this stream was initiated.
+        goAway chan struct{}
+        // method records the associated RPC method of the stream.
+        method       string
+        recvCompress string
+        sendCompress string
+        buf          *recvBuffer
+        trReader     io.Reader
+        fc           *inFlow
+        recvQuota    uint32
+
+        // TODO: Remote this unused variable.
+        // The accumulated inbound quota pending for window update.
+        updateQuota uint32
+
+        // Callback to state application's intentions to read data. This
+        // is used to adjust flow control, if need be.
+        requestRead func(int)
+
+        sendQuotaPool *quotaPool
+        // Close headerChan to indicate the end of reception of header metadata.
+        headerChan chan struct{}
+        // header caches the received header metadata.
+        header metadata.MD
+        // The key-value map of trailer metadata.
+        trailer metadata.MD
+
+        mu sync.RWMutex // guard the following
+        // headerOK becomes true from the first header is about to send.
+        headerOk bool
+        state    streamState
+        // true iff headerChan is closed. Used to avoid closing headerChan
+        // multiple times.
+        headerDone bool
+        // the status error received from the server.
+        status *status.Status
+        // rstStream indicates whether a RST_STREAM frame needs to be sent
+        // to the server to signify that this stream is closing.
+        rstStream bool
+        // rstError is the error that needs to be sent along with the RST_STREAM frame.
+        rstError http2.ErrCode
+        // bytesSent and bytesReceived indicates whether any bytes have been sent or
+        // received on this stream.
+        bytesSent     bool
+        bytesReceived bool
+}
+
+// RecvCompress returns the compression algorithm applied to the inbound
+// message. It is empty string if there is no compression applied.
+func (s *Stream) RecvCompress() string {
+        return s.recvCompress
+}
+
+// SetSendCompress sets the compression algorithm to the stream.
+func (s *Stream) SetSendCompress(str string) {
+        s.sendCompress = str
+}
+
+// Done returns a chanel which is closed when it receives the final status
+// from the server.
+func (s *Stream) Done() <-chan struct{} {
+        return s.done
+}
+
+// GoAway returns a channel which is closed when the server sent GoAways signal
+// before this stream was initiated.
+func (s *Stream) GoAway() <-chan struct{} {
+        return s.goAway
+}
+
+// Header acquires the key-value pairs of header metadata once it
+// is available. It blocks until i) the metadata is ready or ii) there is no
+// header metadata or iii) the stream is canceled/expired.
+func (s *Stream) Header() (metadata.MD, error) {
+        var err error
+        select {
+        case <-s.ctx.Done():
+                err = ContextErr(s.ctx.Err())
+        case <-s.goAway:
+                err = ErrStreamDrain
+        case <-s.headerChan:
+                return s.header.Copy(), nil
+        }
+        // Even if the stream is closed, header is returned if available.
+        select {
+        case <-s.headerChan:
+                return s.header.Copy(), nil
+        default:
+        }
+        return nil, err
+}
+
+// Trailer returns the cached trailer metedata. Note that if it is not called
+// after the entire stream is done, it could return an empty MD. Client
+// side only.
+func (s *Stream) Trailer() metadata.MD {
+        s.mu.RLock()
+        defer s.mu.RUnlock()
+        return s.trailer.Copy()
+}
+
+// ServerTransport returns the underlying ServerTransport for the stream.
+// The client side stream always returns nil.
+func (s *Stream) ServerTransport() ServerTransport {
+        return s.st
+}
+
+// Context returns the context of the stream.
+func (s *Stream) Context() context.Context {
+        return s.ctx
+}
+
+// Method returns the method for the stream.
+func (s *Stream) Method() string {
+        return s.method
+}
+
+// Status returns the status received from the server.
+func (s *Stream) Status() *status.Status {
+        return s.status
+}
+
+// SetHeader sets the header metadata. This can be called multiple times.
+// Server side only.
+func (s *Stream) SetHeader(md metadata.MD) error {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        if s.headerOk || s.state == streamDone {
+                return ErrIllegalHeaderWrite
+        }
+        if md.Len() == 0 {
+                return nil
+        }
+        s.header = metadata.Join(s.header, md)
+        return nil
+}
+
+// SetTrailer sets the trailer metadata which will be sent with the RPC status
+// by the server. This can be called multiple times. Server side only.
+func (s *Stream) SetTrailer(md metadata.MD) error {
+        if md.Len() == 0 {
+                return nil
+        }
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        s.trailer = metadata.Join(s.trailer, md)
+        return nil
+}
+
+func (s *Stream) write(m recvMsg) {
+        s.buf.put(m)
+}
+
+// Read reads all p bytes from the wire for this stream.
+func (s *Stream) Read(p []byte) (n int, err error) {
+        // Don't request a read if there was an error earlier
+        if er := s.trReader.(*transportReader).er; er != nil {
+                return 0, er
+        }
+        s.requestRead(len(p))
+        return io.ReadFull(s.trReader, p)
+}
+
+// tranportReader reads all the data available for this Stream from the transport and
+// passes them into the decoder, which converts them into a gRPC message stream.
+// The error is io.EOF when the stream is done or another non-nil error if
+// the stream broke.
+type transportReader struct {
+        reader io.Reader
+        // The handler to control the window update procedure for both this
+        // particular stream and the associated transport.
+        windowHandler func(int)
+        er            error
+}
+
+func (t *transportReader) Read(p []byte) (n int, err error) {
+        n, err = t.reader.Read(p)
+        if err != nil {
+                t.er = err
+                return
+        }
+        t.windowHandler(n)
+        return
+}
+
+// finish sets the stream's state and status, and closes the done channel.
+// s.mu must be held by the caller.  st must always be non-nil.
+func (s *Stream) finish(st *status.Status) {
+        s.status = st
+        s.state = streamDone
+        close(s.done)
+}
+
+// BytesSent indicates whether any bytes have been sent on this stream.
+func (s *Stream) BytesSent() bool {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        return s.bytesSent
+}
+
+// BytesReceived indicates whether any bytes have been received on this stream.
+func (s *Stream) BytesReceived() bool {
+        s.mu.Lock()
+        defer s.mu.Unlock()
+        return s.bytesReceived
+}
+
+// GoString is implemented by Stream so context.String() won't
+// race when printing %#v.
+func (s *Stream) GoString() string {
+        return fmt.Sprintf("<stream: %p, %v>", s, s.method)
+}
+
+// The key to save transport.Stream in the context.
+type streamKey struct{}
+
+// newContextWithStream creates a new context from ctx and attaches stream
+// to it.
+func newContextWithStream(ctx context.Context, stream *Stream) context.Context {
+        return context.WithValue(ctx, streamKey{}, stream)
+}
+
+// StreamFromContext returns the stream saved in ctx.
+func StreamFromContext(ctx context.Context) (s *Stream, ok bool) {
+        s, ok = ctx.Value(streamKey{}).(*Stream)
+        return
+}
+
+// state of transport
+type transportState int
+
+const (
+        reachable transportState = iota
+        unreachable
+        closing
+        draining
+)
+
+// ServerConfig consists of all the configurations to establish a server transport.
+type ServerConfig struct {
+        MaxStreams            uint32
+        AuthInfo              credentials.AuthInfo
+        InTapHandle           tap.ServerInHandle
+        StatsHandler          stats.Handler
+        KeepaliveParams       keepalive.ServerParameters
+        KeepalivePolicy       keepalive.EnforcementPolicy
+        InitialWindowSize     int32
+        InitialConnWindowSize int32
+}
+
+// NewServerTransport creates a ServerTransport with conn or non-nil error
+// if it fails.
+func NewServerTransport(protocol string, conn net.Conn, config *ServerConfig) (ServerTransport, error) {
+        return newHTTP2Server(conn, config)
+}
+
+// ConnectOptions covers all relevant options for communicating with the server.
+type ConnectOptions struct {
+        // UserAgent is the application user agent.
+        UserAgent string
+        // Authority is the :authority pseudo-header to use. This field has no effect if
+        // TransportCredentials is set.
+        Authority string
+        // Dialer specifies how to dial a network address.
+        Dialer func(context.Context, string) (net.Conn, error)
+        // FailOnNonTempDialError specifies if gRPC fails on non-temporary dial errors.
+        FailOnNonTempDialError bool
+        // PerRPCCredentials stores the PerRPCCredentials required to issue RPCs.
+        PerRPCCredentials []credentials.PerRPCCredentials
+        // TransportCredentials stores the Authenticator required to setup a client connection.
+        TransportCredentials credentials.TransportCredentials
+        // KeepaliveParams stores the keepalive parameters.
+        KeepaliveParams keepalive.ClientParameters
+        // StatsHandler stores the handler for stats.
+        StatsHandler stats.Handler
+        // InitialWindowSize sets the intial window size for a stream.
+        InitialWindowSize int32
+        // InitialConnWindowSize sets the intial window size for a connection.
+        InitialConnWindowSize int32
+}
+
+// TargetInfo contains the information of the target such as network address and metadata.
+type TargetInfo struct {
+        Addr     string
+        Metadata interface{}
+}
+
+// NewClientTransport establishes the transport with the required ConnectOptions
+// and returns it to the caller.
+func NewClientTransport(ctx context.Context, target TargetInfo, opts ConnectOptions) (ClientTransport, error) {
+        return newHTTP2Client(ctx, target, opts)
+}
+
+// Options provides additional hints and information for message
+// transmission.
+type Options struct {
+        // Last indicates whether this write is the last piece for
+        // this stream.
+        Last bool
+
+        // Delay is a hint to the transport implementation for whether
+        // the data could be buffered for a batching write. The
+        // Transport implementation may ignore the hint.
+        Delay bool
+}
+
+// CallHdr carries the information of a particular RPC.
+type CallHdr struct {
+        // Host specifies the peer's host.
+        Host string
+
+        // Method specifies the operation to perform.
+        Method string
+
+        // RecvCompress specifies the compression algorithm applied on
+        // inbound messages.
+        RecvCompress string
+
+        // SendCompress specifies the compression algorithm applied on
+        // outbound message.
+        SendCompress string
+
+        // Creds specifies credentials.PerRPCCredentials for a call.
+        Creds credentials.PerRPCCredentials
+
+        // Flush indicates whether a new stream command should be sent
+        // to the peer without waiting for the first data. This is
+        // only a hint.
+        // If it's true, the transport may modify the flush decision
+        // for performance purposes.
+        // If it's false, new stream will never be flushed.
+        Flush bool
+}
+
+// ClientTransport is the common interface for all gRPC client-side transport
+// implementations.
+type ClientTransport interface {
+        // Close tears down this transport. Once it returns, the transport
+        // should not be accessed any more. The caller must make sure this
+        // is called only once.
+        Close() error
+
+        // GracefulClose starts to tear down the transport. It stops accepting
+        // new RPCs and wait the completion of the pending RPCs.
+        GracefulClose() error
+
+        // Write sends the data for the given stream. A nil stream indicates
+        // the write is to be performed on the transport as a whole.
+        Write(s *Stream, data []byte, opts *Options) error
+
+        // NewStream creates a Stream for an RPC.
+        NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error)
+
+        // CloseStream clears the footprint of a stream when the stream is
+        // not needed any more. The err indicates the error incurred when
+        // CloseStream is called. Must be called when a stream is finished
+        // unless the associated transport is closing.
+        CloseStream(stream *Stream, err error)
+
+        // Error returns a channel that is closed when some I/O error
+        // happens. Typically the caller should have a goroutine to monitor
+        // this in order to take action (e.g., close the current transport
+        // and create a new one) in error case. It should not return nil
+        // once the transport is initiated.
+        Error() <-chan struct{}
+
+        // GoAway returns a channel that is closed when ClientTransport
+        // receives the draining signal from the server (e.g., GOAWAY frame in
+        // HTTP/2).
+        GoAway() <-chan struct{}
+
+        // GetGoAwayReason returns the reason why GoAway frame was received.
+        GetGoAwayReason() GoAwayReason
+}
+
+// ServerTransport is the common interface for all gRPC server-side transport
+// implementations.
+//
+// Methods may be called concurrently from multiple goroutines, but
+// Write methods for a given Stream will be called serially.
+type ServerTransport interface {
+        // HandleStreams receives incoming streams using the given handler.
+        HandleStreams(func(*Stream), func(context.Context, string) context.Context)
+
+        // WriteHeader sends the header metadata for the given stream.
+        // WriteHeader may not be called on all streams.
+        WriteHeader(s *Stream, md metadata.MD) error
+
+        // Write sends the data for the given stream.
+        // Write may not be called on all streams.
+        Write(s *Stream, data []byte, opts *Options) error
+
+        // WriteStatus sends the status of a stream to the client.  WriteStatus is
+        // the final call made on a stream and always occurs.
+        WriteStatus(s *Stream, st *status.Status) error
+
+        // Close tears down the transport. Once it is called, the transport
+        // should not be accessed any more. All the pending streams and their
+        // handlers will be terminated asynchronously.
+        Close() error
+
+        // RemoteAddr returns the remote network address.
+        RemoteAddr() net.Addr
+
+        // Drain notifies the client this ServerTransport stops accepting new RPCs.
+        Drain()
+}
+
+// streamErrorf creates an StreamError with the specified error code and description.
+func streamErrorf(c codes.Code, format string, a ...interface{}) StreamError {
+        return StreamError{
+                Code: c,
+                Desc: fmt.Sprintf(format, a...),
+        }
+}
+
+// connectionErrorf creates an ConnectionError with the specified error description.
+func connectionErrorf(temp bool, e error, format string, a ...interface{}) ConnectionError {
+        return ConnectionError{
+                Desc: fmt.Sprintf(format, a...),
+                temp: temp,
+                err:  e,
+        }
+}
+
+// ConnectionError is an error that results in the termination of the
+// entire connection and the retry of all the active streams.
+type ConnectionError struct {
+        Desc string
+        temp bool
+        err  error
+}
+
+func (e ConnectionError) Error() string {
+        return fmt.Sprintf("connection error: desc = %q", e.Desc)
+}
+
+// Temporary indicates if this connection error is temporary or fatal.
+func (e ConnectionError) Temporary() bool {
+        return e.temp
+}
+
+// Origin returns the original error of this connection error.
+func (e ConnectionError) Origin() error {
+        // Never return nil error here.
+        // If the original error is nil, return itself.
+        if e.err == nil {
+                return e
+        }
+        return e.err
+}
+
+var (
+        // ErrConnClosing indicates that the transport is closing.
+        ErrConnClosing = connectionErrorf(true, nil, "transport is closing")
+        // ErrStreamDrain indicates that the stream is rejected by the server because
+        // the server stops accepting new RPCs.
+        ErrStreamDrain = streamErrorf(codes.Unavailable, "the server stops accepting new RPCs")
+)
+
+// TODO: See if we can replace StreamError with status package errors.
+
+// StreamError is an error that only affects one stream within a connection.
+type StreamError struct {
+        Code codes.Code
+        Desc string
+}
+
+func (e StreamError) Error() string {
+        return fmt.Sprintf("stream error: code = %s desc = %q", e.Code, e.Desc)
+}
+
+// wait blocks until it can receive from ctx.Done, closing, or proceed.
+// If it receives from ctx.Done, it returns 0, the StreamError for ctx.Err.
+// If it receives from done, it returns 0, io.EOF if ctx is not done; otherwise
+// it return the StreamError for ctx.Err.
+// If it receives from goAway, it returns 0, ErrStreamDrain.
+// If it receives from closing, it returns 0, ErrConnClosing.
+// If it receives from proceed, it returns the received integer, nil.
+func wait(ctx context.Context, done, goAway, closing <-chan struct{}, proceed <-chan int) (int, error) {
+        select {
+        case <-ctx.Done():
+                return 0, ContextErr(ctx.Err())
+        case <-done:
+                // User cancellation has precedence.
+                select {
+                case <-ctx.Done():
+                        return 0, ContextErr(ctx.Err())
+                default:
+                }
+                return 0, io.EOF
+        case <-goAway:
+                return 0, ErrStreamDrain
+        case <-closing:
+                return 0, ErrConnClosing
+        case i := <-proceed:
+                return i, nil
+        }
+}
+
+// GoAwayReason contains the reason for the GoAway frame received.
+type GoAwayReason uint8
+
+const (
+        // Invalid indicates that no GoAway frame is received.
+        Invalid GoAwayReason = 0
+        // NoReason is the default value when GoAway frame is received.
+        NoReason GoAwayReason = 1
+        // TooManyPings indicates that a GoAway frame with ErrCodeEnhanceYourCalm
+        // was recieved and that the debug data said "too_many_pings".
+        TooManyPings GoAwayReason = 2
+)