vendor/google.golang.org/grpc/tap/tap.go

   1 /*
   2  *
   3  * Copyright 2016 gRPC authors.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  *
  17  */
  18
  19 // Package tap defines the function handles which are executed on the transport
  20 // layer of gRPC-Go and related information. Everything here is EXPERIMENTAL.
  21 package tap
  22
  23 import (
  24         "context"
  25 )
  26
  27 // Info defines the relevant information needed by the handles.
  28 type Info struct {
  29         // FullMethodName is the string of grpc method (in the format of
  30         // /package.service/method).
  31         FullMethodName string
  32         // TODO: More to be added.
  33 }
  34
  35 // ServerInHandle defines the function which runs before a new stream is created
  36 // on the server side. If it returns a non-nil error, the stream will not be
  37 // created and a RST_STREAM will be sent back to the client with REFUSED_STREAM.
  38 // The client will receive an RPC error "code = Unavailable, desc = stream
  39 // terminated by RST_STREAM with error code: REFUSED_STREAM".
  40 //
  41 // It's intended to be used in situations where you don't want to waste the
  42 // resources to accept the new stream (e.g. rate-limiting). And the content of
  43 // the error will be ignored and won't be sent back to the client. For other
  44 // general usages, please use interceptors.
  45 //
  46 // Note that it is executed in the per-connection I/O goroutine(s) instead of
  47 // per-RPC goroutine. Therefore, users should NOT have any
  48 // blocking/time-consuming work in this handle. Otherwise all the RPCs would
  49 // slow down. Also, for the same reason, this handle won't be called
  50 // concurrently by gRPC.
  51 type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error)