GoTimerTickerTimerdurationchannelTimerTickerdurationchannelchannel文章主要涉及如下内容：
TimerTickerTimerTickerReset计时器的内部表示
Goruntime.timerrumtime.timertype timer struct {
pp puintptr
when int64
period int64
f func(interface{}, uintptr)
arg interface{}
seq uintptr
nextwhen int64
status uint32
}
复制代码rumtime.timerwhenperiodfargfnextWhentimerModifiedLater/timerModifiedEairlierwhenstatusruntime.timertime.Timertime.Tickertype Timer struct {
C <-chan Time
r runtimeTimer
}
type Ticker struct {
C <-chan Time
r runtimeTimer
}
复制代码Timer.CTicker.CchannelTimer计时器
time.Timertime.NewTimertime.AfterFunctime.AfterchannelchannelgoroutineTimerselectchannelchannelTimer//使用time.AfterFunc：
t := time.AfterFunc(d, f)
//使用time.After：
select {
case m := <-c:
handle(m)
case <-time.After(5 * time.Minute):
fmt.Println("timed out")
}
// 使用time.NewTimer:
t := time.NewTimer(5 * time.Minute)
select {
case m := <-c:
handle(m)
case <-t.C:
fmt.Println("timed out")
}
复制代码time.AfterFuncTimergoroutineffunc AfterFunc(d Duration, f func()) *Timer {
t := &Timer{
r: runtimeTimer{
when: when(d),
f: goFunc,
arg: f,
},
}
startTimer(&t.r)
return t
}
func goFunc(arg interface{}, seq uintptr) {
go arg.(func())()
}
复制代码AfterFuncffgoFuncgoFuncgoroutinefGogoroutinetimerproctimerprocgoroutineNewTimerAfterTimersendTimefunc NewTimer(d Duration) *Timer {
c := make(chan Time, 1)
t := &Timer{
C: c,
r: runtimeTimer{
when: when(d),
f: sendTime,
arg: c,
},
}
startTimer(&t.r)
return t
}
func sendTime(c interface{}, seq uintptr) {
select {
case c.(chan Time) <- Now():
default:
}
}
复制代码sendTimeTimerchanneltimerprocNewTimerchannelTimer.CchannelsendTimeTimer.CsendTimeselectTimer.CBufferTimerStopStoptrueStopStopfalseGoMin HeapStopTicker计时器
Tickertime.Tickertime.NewTickertime.Tick// 使用time.Tick:
go func() {
for t := range time.Tick(time.Minute) {
fmt.Println("Tick at", t)
}
}()
// 使用time.Ticker
var ticker *time.Ticker = time.NewTicker(1 * time.Second)
go func() {
for t := range ticker.C {
fmt.Println("Tick at", t)
}
}()
time.Sleep(time.Second * 5)
ticker.Stop()
fmt.Println("Ticker stopped")
复制代码time.Ticktime.Tickerchanneltime.Ticktime.TickTickertime.Ticktime.NewTickerTickerNewTickerNewTimerchannelchannelsendTimeTickerfunc NewTicker(d Duration) *Ticker {
if d <= 0 {
panic(errors.New("non-positive interval for NewTicker"))
}
// Give the channel a 1-element time buffer.
// If the client falls behind while reading, we drop ticks
// on the floor until the client catches up.
c := make(chan Time, 1)
t := &Ticker{
C: c,
r: runtimeTimer{
when: when(d),
period: int64(d),
f: sendTime,
arg: c,
},
}
startTimer(&t.r)
return t
}
复制代码Reset计时器时要注意的问题
Resetif !t.Stop() {
<-t.C
}
t.Reset(d)
复制代码producer goroutinefalsetrueconsumer goroutinetruefunc main() {
c := make(chan bool)
go func() {
for i := 0; i < 5; i++ {
time.Sleep(time.Second * 1)
c <- false
}
time.Sleep(time.Second * 1)
c <- true
}()
go func() {
// try to read from channel, block at most 5s.
// if timeout, print time event and go on loop.
// if read a message which is not the type we want(we want true, not false),
// retry to read.
timer := time.NewTimer(time.Second * 5)
for {
// timer is active , not fired, stop always returns true, no problems occurs.
if !timer.Stop() {
<-timer.C
}
timer.Reset(time.Second * 5)
select {
case b := <-c:
if b == false {
fmt.Println(time.Now(), ":recv false. continue")
continue
}
//we want true, not false
fmt.Println(time.Now(), ":recv true. return")
return
case <-timer.C:
fmt.Println(time.Now(), ":timer expired")
continue
}
}
}()
//to avoid that all goroutine blocks.
var s string
fmt.Scanln(&s)
}
复制代码程序的输出如下：
2020-05-13 12:49:48.90292 +0800 CST m=+1.004554120 :recv false. continue
2020-05-13 12:49:49.906087 +0800 CST m=+2.007748042 :recv false. continue
2020-05-13 12:49:50.910208 +0800 CST m=+3.011892138 :recv false. continue
2020-05-13 12:49:51.914291 +0800 CST m=+4.015997373 :recv false. continue
2020-05-13 12:49:52.916762 +0800 CST m=+5.018489240 :recv false. continue
2020-05-13 12:49:53.920384 +0800 CST m=+6.022129708 :recv true. return
复制代码producer goroutinproducer goroutine6consumer gouroutine5 // producer
go func() {
for i := 0; i < 5; i++ {
time.Sleep(time.Second * 6)
c <- false
}
time.Sleep(time.Second * 6)
c <- true
}()
复制代码deadlock2020-05-13 13:09:11.166976 +0800 CST m=+5.005266022 :timer expired
复制代码timer.Ctimer.Cif !timer.Stop() {
<-timer.C
}
timer.Reset(time.Second * 5)
复制代码producer goroutinecomsumer goroutinefortimer.Stoptruefalsetimer.Cdrain channelconsumer goroutineResetdrain channelselectdrain channelchanneldrain//consumer
go func() {
// try to read from channel, block at most 5s.
// if timeout, print time event and go on loop.
// if read a message which is not the type we want(we want true, not false),
// retry to read.
timer := time.NewTimer(time.Second * 5)
for {
// timer may be not active, and fired
if !timer.Stop() {
select {
case <-timer.C: //try to drain from the channel
default:
}
}
timer.Reset(time.Second * 5)
select {
case b := <-c:
if b == false {
fmt.Println(time.Now(), ":recv false. continue")
continue
}
//we want true, not false
fmt.Println(time.Now(), ":recv true. return")
return
case <-timer.C:
fmt.Println(time.Now(), ":timer expired")
continue
}
}
}()
复制代码true2020-05-13 13:25:08.412679 +0800 CST m=+5.005475546 :timer expired
2020-05-13 13:25:09.409249 +0800 CST m=+6.002037341 :recv false. continue
2020-05-13 13:25:14.412282 +0800 CST m=+11.005029547 :timer expired
2020-05-13 13:25:15.414482 +0800 CST m=+12.007221569 :recv false. continue
2020-05-13 13:25:20.416826 +0800 CST m=+17.009524859 :timer expired
2020-05-13 13:25:21.418555 +0800 CST m=+18.011245687 :recv false. continue
2020-05-13 13:25:26.42388 +0800 CST m=+23.016530193 :timer expired
2020-05-13 13:25:27.42294 +0800 CST m=+24.015582511 :recv false. continue
2020-05-13 13:25:32.425666 +0800 CST m=+29.018267054 :timer expired
2020-05-13 13:25:33.428189 +0800 CST m=+30.020782483 :recv false. continue
2020-05-13 13:25:38.432428 +0800 CST m=+35.024980796 :timer expired
2020-05-13 13:25:39.428343 +0800 CST m=+36.020887629 :recv true. return
复制代码总结
GoTimerTickerruntime.timergoroutinetimerproctime.TickTickergcTimerTickerchanneltime.Aftertime.NewTimertime.NewTickersendTimesendTimeResetdrain channel