mirror of
https://github.com/etcd-io/etcd.git
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49a0a63fc3
Move out of watch code since will be shared with lease code. Also assumes leader does not exist unless watch can be successfully created.
95 lines
2.3 KiB
Go
95 lines
2.3 KiB
Go
// Copyright 2017 The etcd 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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package grpcproxy
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import (
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"math"
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"sync"
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"golang.org/x/net/context"
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"golang.org/x/time/rate"
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"google.golang.org/grpc"
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"github.com/coreos/etcd/clientv3"
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)
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const (
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lostLeaderKey = "__lostleader" // watched to detect leader loss
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retryPerSecond = 10
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)
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type leader struct {
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ctx context.Context
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w clientv3.Watcher
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// mu protects leaderc updates.
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mu sync.RWMutex
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leaderc chan struct{}
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disconnc chan struct{}
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donec chan struct{}
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}
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func newLeader(ctx context.Context, w clientv3.Watcher) *leader {
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l := &leader{
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ctx: clientv3.WithRequireLeader(ctx),
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w: w,
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leaderc: make(chan struct{}),
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disconnc: make(chan struct{}),
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donec: make(chan struct{}),
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}
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// begin assuming leader is lost
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close(l.leaderc)
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go l.recvLoop()
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return l
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}
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func (l *leader) recvLoop() {
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defer close(l.donec)
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limiter := rate.NewLimiter(rate.Limit(retryPerSecond), retryPerSecond)
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rev := int64(math.MaxInt64 - 2)
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for limiter.Wait(l.ctx) == nil {
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wch := l.w.Watch(l.ctx, lostLeaderKey, clientv3.WithRev(rev), clientv3.WithCreatedNotify())
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cresp, ok := <-wch
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if !ok {
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continue
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}
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if cresp.Err() != nil {
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if grpc.ErrorDesc(cresp.Err()) == grpc.ErrClientConnClosing.Error() {
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close(l.disconnc)
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return
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}
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continue
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}
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// leader is available
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l.mu.Lock()
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l.leaderc = make(chan struct{})
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l.mu.Unlock()
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<-wch
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close(l.leaderc)
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}
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}
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func (l *leader) disconnectNotify() <-chan struct{} { return l.disconnc }
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func (l *leader) stopNotify() <-chan struct{} { return l.donec }
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// lostNotify returns a channel that is closed if there has been
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// a leader loss not yet followed by a leader reacquire.
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func (l *leader) lostNotify() <-chan struct{} {
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l.mu.RLock()
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defer l.mu.RUnlock()
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return l.leaderc
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}
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