3 * Copyright 2017 gRPC authors.
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
9 * http://www.apache.org/licenses/LICENSE-2.0
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.
22 "golang.org/x/net/context"
23 "google.golang.org/grpc/balancer"
24 "google.golang.org/grpc/connectivity"
25 "google.golang.org/grpc/grpclog"
26 "google.golang.org/grpc/resolver"
29 func newPickfirstBuilder() balancer.Builder {
30 return &pickfirstBuilder{}
33 type pickfirstBuilder struct{}
35 func (*pickfirstBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
36 return &pickfirstBalancer{cc: cc}
39 func (*pickfirstBuilder) Name() string {
43 type pickfirstBalancer struct {
44 cc balancer.ClientConn
48 func (b *pickfirstBalancer) HandleResolvedAddrs(addrs []resolver.Address, err error) {
50 grpclog.Infof("pickfirstBalancer: HandleResolvedAddrs called with error %v", err)
54 b.sc, err = b.cc.NewSubConn(addrs, balancer.NewSubConnOptions{})
56 grpclog.Errorf("pickfirstBalancer: failed to NewSubConn: %v", err)
59 b.cc.UpdateBalancerState(connectivity.Idle, &picker{sc: b.sc})
62 b.sc.UpdateAddresses(addrs)
67 func (b *pickfirstBalancer) HandleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
68 grpclog.Infof("pickfirstBalancer: HandleSubConnStateChange: %p, %v", sc, s)
70 grpclog.Infof("pickfirstBalancer: ignored state change because sc is not recognized")
73 if s == connectivity.Shutdown {
79 case connectivity.Ready, connectivity.Idle:
80 b.cc.UpdateBalancerState(s, &picker{sc: sc})
81 case connectivity.Connecting:
82 b.cc.UpdateBalancerState(s, &picker{err: balancer.ErrNoSubConnAvailable})
83 case connectivity.TransientFailure:
84 b.cc.UpdateBalancerState(s, &picker{err: balancer.ErrTransientFailure})
88 func (b *pickfirstBalancer) Close() {
96 func (p *picker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
98 return nil, nil, p.err
100 return p.sc, nil, nil
104 balancer.Register(newPickfirstBuilder())