dex/vendor/go.etcd.io/etcd/clientv3/namespace/watch.go

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// Copyright 2017 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 namespace
import (
"context"
"sync"
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"go.etcd.io/etcd/clientv3"
)
type watcherPrefix struct {
clientv3.Watcher
pfx string
wg sync.WaitGroup
stopc chan struct{}
stopOnce sync.Once
}
// NewWatcher wraps a Watcher instance so that all Watch requests
// are prefixed with a given string and all Watch responses have
// the prefix removed.
func NewWatcher(w clientv3.Watcher, prefix string) clientv3.Watcher {
return &watcherPrefix{Watcher: w, pfx: prefix, stopc: make(chan struct{})}
}
func (w *watcherPrefix) Watch(ctx context.Context, key string, opts ...clientv3.OpOption) clientv3.WatchChan {
// since OpOption is opaque, determine range for prefixing through an OpGet
op := clientv3.OpGet(key, opts...)
end := op.RangeBytes()
pfxBegin, pfxEnd := prefixInterval(w.pfx, []byte(key), end)
if pfxEnd != nil {
opts = append(opts, clientv3.WithRange(string(pfxEnd)))
}
wch := w.Watcher.Watch(ctx, string(pfxBegin), opts...)
// translate watch events from prefixed to unprefixed
pfxWch := make(chan clientv3.WatchResponse)
w.wg.Add(1)
go func() {
defer func() {
close(pfxWch)
w.wg.Done()
}()
for wr := range wch {
for i := range wr.Events {
wr.Events[i].Kv.Key = wr.Events[i].Kv.Key[len(w.pfx):]
if wr.Events[i].PrevKv != nil {
wr.Events[i].PrevKv.Key = wr.Events[i].Kv.Key
}
}
select {
case pfxWch <- wr:
case <-ctx.Done():
return
case <-w.stopc:
return
}
}
}()
return pfxWch
}
func (w *watcherPrefix) Close() error {
err := w.Watcher.Close()
w.stopOnce.Do(func() { close(w.stopc) })
w.wg.Wait()
return err
}