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watcher_single.go
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watcher_single.go
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// Copyright 2016 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package grpcproxy
import (
"github.com/coreos/etcd/clientv3"
"golang.org/x/net/context"
)
type watcherSingle struct {
// ch delievers events received from the etcd server
ch clientv3.WatchChan
// cancel is used to cancel the underlying etcd server watcher
// It should also close the ch.
cancel context.CancelFunc
// sws is the stream this watcherSingle attached to
sws *serverWatchStream
w watcher
lastStoreRev int64 // last seen revision of the remote mvcc store
donec chan struct{}
}
func newWatcherSingle(wch clientv3.WatchChan, c context.CancelFunc, w watcher, sws *serverWatchStream) *watcherSingle {
return &watcherSingle{
sws: sws,
ch: wch,
cancel: c,
w: w,
donec: make(chan struct{}),
}
}
func (ws watcherSingle) run() {
defer close(ws.donec)
for wr := range ws.ch {
ws.lastStoreRev = wr.Header.Revision
ws.w.send(wr)
if ws.sws.maybeCoalesceWatcher(ws) {
return
}
}
}
// canPromote returns true if a watcherSingle can promote itself to a watchergroup
// when it already caught up with the last seen revision from the response header
// of an etcd server.
func (ws watcherSingle) canPromote() bool {
return ws.w.rev == ws.lastStoreRev
}
func (ws watcherSingle) stop() {
ws.cancel()
<-ws.donec
}