Files
tidb/pkg/ddl/util/watcher.go

81 lines
2.2 KiB
Go

// Copyright 2024 PingCAP, Inc.
//
// 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 util
import (
"context"
"sync"
"time"
"github.com/pingcap/tidb/pkg/ddl/logutil"
"github.com/pingcap/tidb/pkg/metrics"
clientv3 "go.etcd.io/etcd/client/v3"
)
// Watcher is responsible for watching the etcd path related operations.
type Watcher interface {
// WatchChan returns the chan for watching etcd path.
WatchChan() clientv3.WatchChan
// Watch watches the etcd path.
Watch(ctx context.Context, etcdCli *clientv3.Client, path string)
// Rewatch rewatches the etcd path.
Rewatch(ctx context.Context, etcdCli *clientv3.Client, path string)
}
type watcher struct {
wCh clientv3.WatchChan
sync.RWMutex
}
// NewWatcher creates a new watcher.
func NewWatcher() Watcher {
return &watcher{}
}
// WatchChan implements SyncerWatch.WatchChan interface.
func (w *watcher) WatchChan() clientv3.WatchChan {
w.RLock()
defer w.RUnlock()
return w.wCh
}
// Watch implements SyncerWatch.Watch interface.
func (w *watcher) Watch(ctx context.Context, etcdCli *clientv3.Client, path string) {
w.Lock()
w.wCh = etcdCli.Watch(ctx, path)
w.Unlock()
}
// Rewatch implements SyncerWatch.Rewatch interface.
func (w *watcher) Rewatch(ctx context.Context, etcdCli *clientv3.Client, path string) {
startTime := time.Now()
// Make sure the wCh doesn't receive the information of 'close' before we finish the rewatch.
w.Lock()
w.wCh = nil
w.Unlock()
go func() {
defer func() {
metrics.DeploySyncerHistogram.WithLabelValues(metrics.SyncerRewatch, metrics.RetLabel(nil)).Observe(time.Since(startTime).Seconds())
}()
wCh := etcdCli.Watch(ctx, path)
w.Lock()
w.wCh = wCh
w.Unlock()
logutil.DDLLogger().Info("syncer rewatch global info finished")
}()
}