Go 语言实现简单的定时器函数

package utils

import "time"

/*
一个简单的定时器: 延迟执行action
返回stop方法, 可在外部停止定时器
*/
func Timer(action func(), delay time.Duration) func() {
   var stopped bool
   var stopC = make(chan struct{}, 1)
   go func() {
      defer func() { stopped = true; close(stopC) }()
      select {
      case <-stopC:
         return
      case <-time.After(delay):
         action()
      }
   }()
   return func() {
      if stopped {
         return
      }
      stopC <- struct{}{}
   }
}

/*
轮询定时器: 固定间隔执行action, 如果action返回true停止轮询, count为轮询次数
返回stop方法, 可在外部停止轮询定时器
*/
func Polling(action func() bool, duration time.Duration, count int) func() {
   var stopped bool
   stopC := make(chan struct{}, 1)
   go func() {
      defer func() { stopped = true; close(stopC) }()
      ticker := time.NewTicker(duration)
      for i := 0; i < count; i++ {
         select {
         case <-stopC:
            return
         case <-ticker.C:
            if action() {
               return
            }
         }
      }
   }()
   return func() {
      if stopped {
         return
      }
      stopC <- struct{}{}
   }
}

/*
定时任务:  固定间隔执行action
返回stop方法, 可在外部停止定时任务
*/
func LoopTask(action func(), duration time.Duration) func() {
   var stopped bool
   stopC := make(chan struct{}, 1)
   go func() {
      defer func() { stopped = true; close(stopC) }()
      ticker := time.NewTicker(duration)
      for {
         select {
         case <-stopC:
            return
         case <-ticker.C:
            action()
         }
      }
   }()
   return func() {
      if stopped {
         return
      }
      stopC <- struct{}{}
   }
}