timer(heap_timer, timing_wheel) in Golang
type Timer interface {// Reset changes the timer to expire after duration d.// It returns true if the timer had been active or had executed,// false if the timer been stopped.Reset(duration time.Duration) bool// Stop prevents the Timer from firing.// It returns true if the call stops the timer, false if the timer has already// been stopped.Stop() bool}
type TimerMgr interface {// OnceTimer waits for the duration to elapse and then calls f// in its own goroutine. It returns a Timer. It's done onceOnceTimer(d time.Duration, f func()) Timer// RepeatTimer waits for the duration to elapse and then calls f// in its own goroutine. It returns a Timer. It can be used to// cancel the call using its Stop method.RepeatTimer(d time.Duration, f func()) Timer}
精度较高。
低精度 timer, 最低精度为毫秒。
如果时间轮精度为10ms， 那么他的误差在 （0，10）ms之间。如果一个任务延迟 500ms，那它的执行时间在490～500ms之间。出错的概率均等的情况下，那么这个出错可能会延迟或提前最小刻度的一半，在这里就是10ms/2=5ms.
故，时间轮的interval 在总延迟时间上，应该不足以影响延迟执行函数处理的事务。
时间轮的一个周期为interval*bucketNum
NewTimeWheelMgr(interval time.Duration, bucketNum int)
func TestNewHeapTimerMgr(t *testing.T) {mgr := NewHeapTimerMgr()fmt.Println("new---", time.Now().String())timer1 := mgr.OnceTimer(time.Second, func() {fmt.Println("once1", time.Now().String())})timer2 := mgr.RepeatTimer(time.Second*2, func() {fmt.Println("repeat1", time.Now().String())})// 立即执行mgr.OnceTimer(0, func() {fmt.Println("once3", time.Now().String())})//mgr.RepeatTimer(0, func() {//fmt.Println("repeat4", time.Now().String())//})go func() {time.Sleep(time.Second * 5)fmt.Println("reset---", time.Now().String())fmt.Println(timer1.Reset(time.Second * 3))fmt.Println(timer2.Reset(time.Second))}()go func() {time.Sleep(time.Second * 10)fmt.Println("stop---", time.Now().String())timer1.Stop()timer2.Stop()fmt.Println(timer1.Reset(time.Second))}()time.Sleep(time.Second * 20)}