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110 lines
2.8 KiB
110 lines
2.8 KiB
/* |
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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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