github.com/pingcap/ticdc@v0.0.0-20220526033649-485a10ef2652/pkg/util/cancel_monitor.go (about)

     1  // Copyright 2020 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package util
    15  
    16  import (
    17  	"context"
    18  	"time"
    19  
    20  	"github.com/pingcap/log"
    21  	"go.uber.org/zap"
    22  )
    23  
    24  // MonitorCancelLatency monitors the latency from ctx being cancelled and the returned function being called
    25  func MonitorCancelLatency(ctx context.Context, identifier string) func() {
    26  	finishedCh := make(chan struct{})
    27  	go func() {
    28  		select {
    29  		case <-ctx.Done():
    30  			log.Debug("MonitorCancelLatency: Cancelled", zap.String("identifier", identifier))
    31  			ticker := time.NewTicker(time.Second)
    32  			defer ticker.Stop()
    33  			elapsed := 0
    34  			for {
    35  				select {
    36  				case <-finishedCh:
    37  					log.Debug("MonitorCancelLatency: Monitored routine exited", zap.String("identifier", identifier))
    38  					return
    39  				case <-ticker.C:
    40  					elapsed++
    41  					log.Warn("MonitorCancelLatency: Cancellation is taking too long", zap.String("identifier", identifier), zap.Int("elapsed seconds", elapsed), zap.Error(ctx.Err()))
    42  				}
    43  			}
    44  		case <-finishedCh:
    45  		}
    46  	}()
    47  	return func() {
    48  		close(finishedCh)
    49  	}
    50  }