110 lines
2.8 KiB
Go
110 lines
2.8 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpc
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import (
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"context"
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"google.golang.org/grpc/balancer"
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"google.golang.org/grpc/connectivity"
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"google.golang.org/grpc/grpclog"
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"google.golang.org/grpc/resolver"
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)
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// PickFirstBalancerName is the name of the pick_first balancer.
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const PickFirstBalancerName = "pick_first"
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func newPickfirstBuilder() balancer.Builder {
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return &pickfirstBuilder{}
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}
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type pickfirstBuilder struct{}
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func (*pickfirstBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
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return &pickfirstBalancer{cc: cc}
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}
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func (*pickfirstBuilder) Name() string {
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return PickFirstBalancerName
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}
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type pickfirstBalancer struct {
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cc balancer.ClientConn
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sc balancer.SubConn
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}
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func (b *pickfirstBalancer) HandleResolvedAddrs(addrs []resolver.Address, err error) {
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if err != nil {
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grpclog.Infof("pickfirstBalancer: HandleResolvedAddrs called with error %v", err)
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return
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}
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if b.sc == nil {
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b.sc, err = b.cc.NewSubConn(addrs, balancer.NewSubConnOptions{})
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if err != nil {
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//TODO(yuxuanli): why not change the cc state to Idle?
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grpclog.Errorf("pickfirstBalancer: failed to NewSubConn: %v", err)
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return
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}
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b.cc.UpdateBalancerState(connectivity.Idle, &picker{sc: b.sc})
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b.sc.Connect()
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} else {
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b.sc.UpdateAddresses(addrs)
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b.sc.Connect()
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}
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}
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func (b *pickfirstBalancer) HandleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
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grpclog.Infof("pickfirstBalancer: HandleSubConnStateChange: %p, %v", sc, s)
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if b.sc != sc {
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grpclog.Infof("pickfirstBalancer: ignored state change because sc is not recognized")
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return
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}
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if s == connectivity.Shutdown {
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b.sc = nil
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return
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}
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switch s {
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case connectivity.Ready, connectivity.Idle:
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b.cc.UpdateBalancerState(s, &picker{sc: sc})
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case connectivity.Connecting:
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b.cc.UpdateBalancerState(s, &picker{err: balancer.ErrNoSubConnAvailable})
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case connectivity.TransientFailure:
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b.cc.UpdateBalancerState(s, &picker{err: balancer.ErrTransientFailure})
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}
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}
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func (b *pickfirstBalancer) Close() {
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}
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type picker struct {
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err error
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sc balancer.SubConn
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}
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func (p *picker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
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if p.err != nil {
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return nil, nil, p.err
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}
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return p.sc, nil, nil
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}
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func init() {
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balancer.Register(newPickfirstBuilder())
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}
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