| // 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" |
| |
| "github.com/coreos/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 |
| } |