/
periodic_task.go
76 lines (65 loc) · 1.62 KB
/
periodic_task.go
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// Copyright 2020 Google LLC
//
// 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
//
// https://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
package wire
import (
"time"
)
// periodicTask manages a recurring background task.
type periodicTask struct {
period time.Duration
task func()
ticker *time.Ticker
stop chan struct{}
}
func newPeriodicTask(period time.Duration, task func()) *periodicTask {
return &periodicTask{
period: period,
task: task,
}
}
// Start the polling goroutine. No-op if the goroutine is already running.
// The task is executed after the polling period.
func (pt *periodicTask) Start() {
if pt.ticker != nil || pt.period <= 0 {
return
}
pt.ticker = time.NewTicker(pt.period)
pt.stop = make(chan struct{})
go pt.poll(pt.ticker, pt.stop)
}
// Stop/pause the periodic task.
func (pt *periodicTask) Stop() {
if pt.ticker == nil {
return
}
pt.ticker.Stop()
close(pt.stop)
pt.ticker = nil
pt.stop = nil
}
func (pt *periodicTask) poll(ticker *time.Ticker, stop chan struct{}) {
for {
// stop has higher priority.
select {
case <-stop:
return // Ends the goroutine.
default:
}
select {
case <-stop:
return // Ends the goroutine.
case <-ticker.C:
pt.task()
}
}
}