84 lines
2.2 KiB
Go
84 lines
2.2 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 namespace
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import (
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"context"
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"sync"
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"go.etcd.io/etcd/clientv3"
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)
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type watcherPrefix struct {
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clientv3.Watcher
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pfx string
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wg sync.WaitGroup
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stopc chan struct{}
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stopOnce sync.Once
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}
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// NewWatcher wraps a Watcher instance so that all Watch requests
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// are prefixed with a given string and all Watch responses have
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// the prefix removed.
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func NewWatcher(w clientv3.Watcher, prefix string) clientv3.Watcher {
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return &watcherPrefix{Watcher: w, pfx: prefix, stopc: make(chan struct{})}
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}
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func (w *watcherPrefix) Watch(ctx context.Context, key string, opts ...clientv3.OpOption) clientv3.WatchChan {
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// since OpOption is opaque, determine range for prefixing through an OpGet
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op := clientv3.OpGet(key, opts...)
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end := op.RangeBytes()
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pfxBegin, pfxEnd := prefixInterval(w.pfx, []byte(key), end)
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if pfxEnd != nil {
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opts = append(opts, clientv3.WithRange(string(pfxEnd)))
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}
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wch := w.Watcher.Watch(ctx, string(pfxBegin), opts...)
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// translate watch events from prefixed to unprefixed
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pfxWch := make(chan clientv3.WatchResponse)
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w.wg.Add(1)
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go func() {
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defer func() {
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close(pfxWch)
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w.wg.Done()
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}()
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for wr := range wch {
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for i := range wr.Events {
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wr.Events[i].Kv.Key = wr.Events[i].Kv.Key[len(w.pfx):]
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if wr.Events[i].PrevKv != nil {
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wr.Events[i].PrevKv.Key = wr.Events[i].Kv.Key
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}
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}
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select {
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case pfxWch <- wr:
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case <-ctx.Done():
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return
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case <-w.stopc:
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return
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}
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}
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}()
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return pfxWch
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}
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func (w *watcherPrefix) Close() error {
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err := w.Watcher.Close()
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w.stopOnce.Do(func() { close(w.stopc) })
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w.wg.Wait()
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return err
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}
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