mirror of
https://github.com/etcd-io/etcd.git
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75 lines
1.9 KiB
Go
75 lines
1.9 KiB
Go
// Copyright 2015 CoreOS, Inc.
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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 storage
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import (
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"sync"
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"github.com/coreos/etcd/storage/storagepb"
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)
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// Watcher watches on the KV. It will be notified if there is an event
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// happened on the watched key or prefix.
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type Watcher interface {
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// Event returns a channel that receives observed event that matches the
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// context of watcher. When watch finishes or is canceled or aborted, the
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// channel is closed and returns empty event.
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// Successive calls to Event return the same value.
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Event() <-chan storagepb.Event
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// Err returns a non-nil error value after Event is closed. Err returns
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// Compacted if the history was compacted, Canceled if watch is canceled,
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// or EOF if watch reaches the end revision. No other values for Err are defined.
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// After Event is closed, successive calls to Err return the same value.
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Err() error
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}
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type watcher struct {
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key []byte
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prefix bool
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cur int64
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ch chan storagepb.Event
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mu sync.Mutex
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err error
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}
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func newWatcher(key []byte, prefix bool, start int64) *watcher {
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return &watcher{
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key: key,
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prefix: prefix,
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cur: start,
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ch: make(chan storagepb.Event, 10),
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}
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}
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func (w *watcher) Event() <-chan storagepb.Event { return w.ch }
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func (w *watcher) Err() error {
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w.mu.Lock()
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defer w.mu.Unlock()
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return w.err
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}
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func (w *watcher) stopWithError(err error) {
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if w.err != nil {
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return
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}
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close(w.ch)
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w.mu.Lock()
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w.err = err
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w.mu.Unlock()
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}
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