cmd/bpa-operator/vendor/google.golang.org/grpc/pickfirst.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 grpc
  20
  21 import (
  22         "context"
  23
  24         "google.golang.org/grpc/balancer"
  25         "google.golang.org/grpc/connectivity"
  26         "google.golang.org/grpc/grpclog"
  27         "google.golang.org/grpc/resolver"
  28 )
  29
  30 // PickFirstBalancerName is the name of the pick_first balancer.
  31 const PickFirstBalancerName = "pick_first"
  32
  33 func newPickfirstBuilder() balancer.Builder {
  34         return &pickfirstBuilder{}
  35 }
  36
  37 type pickfirstBuilder struct{}
  38
  39 func (*pickfirstBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
  40         return &pickfirstBalancer{cc: cc}
  41 }
  42
  43 func (*pickfirstBuilder) Name() string {
  44         return PickFirstBalancerName
  45 }
  46
  47 type pickfirstBalancer struct {
  48         cc balancer.ClientConn
  49         sc balancer.SubConn
  50 }
  51
  52 func (b *pickfirstBalancer) HandleResolvedAddrs(addrs []resolver.Address, err error) {
  53         if err != nil {
  54                 grpclog.Infof("pickfirstBalancer: HandleResolvedAddrs called with error %v", err)
  55                 return
  56         }
  57         if b.sc == nil {
  58                 b.sc, err = b.cc.NewSubConn(addrs, balancer.NewSubConnOptions{})
  59                 if err != nil {
  60                         //TODO(yuxuanli): why not change the cc state to Idle?
  61                         grpclog.Errorf("pickfirstBalancer: failed to NewSubConn: %v", err)
  62                         return
  63                 }
  64                 b.cc.UpdateBalancerState(connectivity.Idle, &picker{sc: b.sc})
  65                 b.sc.Connect()
  66         } else {
  67                 b.sc.UpdateAddresses(addrs)
  68                 b.sc.Connect()
  69         }
  70 }
  71
  72 func (b *pickfirstBalancer) HandleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
  73         grpclog.Infof("pickfirstBalancer: HandleSubConnStateChange: %p, %v", sc, s)
  74         if b.sc != sc {
  75                 grpclog.Infof("pickfirstBalancer: ignored state change because sc is not recognized")
  76                 return
  77         }
  78         if s == connectivity.Shutdown {
  79                 b.sc = nil
  80                 return
  81         }
  82
  83         switch s {
  84         case connectivity.Ready, connectivity.Idle:
  85                 b.cc.UpdateBalancerState(s, &picker{sc: sc})
  86         case connectivity.Connecting:
  87                 b.cc.UpdateBalancerState(s, &picker{err: balancer.ErrNoSubConnAvailable})
  88         case connectivity.TransientFailure:
  89                 b.cc.UpdateBalancerState(s, &picker{err: balancer.ErrTransientFailure})
  90         }
  91 }
  92
  93 func (b *pickfirstBalancer) Close() {
  94 }
  95
  96 type picker struct {
  97         err error
  98         sc  balancer.SubConn
  99 }
 100
 101 func (p *picker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
 102         if p.err != nil {
 103                 return nil, nil, p.err
 104         }
 105         return p.sc, nil, nil
 106 }
 107
 108 func init() {
 109         balancer.Register(newPickfirstBuilder())
 110 }