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

   1 /*
   2  *
   3  * Copyright 2017 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 connectivity defines connectivity semantics.
  20 // For details, see https://github.com/grpc/grpc/blob/master/doc/connectivity-semantics-and-api.md.
  21 // All APIs in this package are experimental.
  22 package connectivity
  23
  24 import (
  25         "golang.org/x/net/context"
  26         "google.golang.org/grpc/grpclog"
  27 )
  28
  29 // State indicates the state of connectivity.
  30 // It can be the state of a ClientConn or SubConn.
  31 type State int
  32
  33 func (s State) String() string {
  34         switch s {
  35         case Idle:
  36                 return "IDLE"
  37         case Connecting:
  38                 return "CONNECTING"
  39         case Ready:
  40                 return "READY"
  41         case TransientFailure:
  42                 return "TRANSIENT_FAILURE"
  43         case Shutdown:
  44                 return "SHUTDOWN"
  45         default:
  46                 grpclog.Errorf("unknown connectivity state: %d", s)
  47                 return "Invalid-State"
  48         }
  49 }
  50
  51 const (
  52         // Idle indicates the ClientConn is idle.
  53         Idle State = iota
  54         // Connecting indicates the ClienConn is connecting.
  55         Connecting
  56         // Ready indicates the ClientConn is ready for work.
  57         Ready
  58         // TransientFailure indicates the ClientConn has seen a failure but expects to recover.
  59         TransientFailure
  60         // Shutdown indicates the ClientConn has started shutting down.
  61         Shutdown
  62 )
  63
  64 // Reporter reports the connectivity states.
  65 type Reporter interface {
  66         // CurrentState returns the current state of the reporter.
  67         CurrentState() State
  68         // WaitForStateChange blocks until the reporter's state is different from the given state,
  69         // and returns true.
  70         // It returns false if <-ctx.Done() can proceed (ctx got timeout or got canceled).
  71         WaitForStateChange(context.Context, State) bool
  72 }