我有一些必須定期運行的功能。我為此使用了自動收報機。但是如果代碼已經在運行，并且時間間隔再次過去，它不應該再次執行。package mainimport ( "fmt" "time")func main() { ticker := time.NewTicker(3*time.Second) flag := 0 defer ticker.Stop() for { select { case t := <-ticker.C: flag = flag + 1 if (flag % 2 ==0 ) { time.Sleep(time.Second*4) } fmt.Println("Current time: ", t) } }}https://play.golang.org/p/2xV2MYInn4I在操場上，自動收報機每 3 秒打印一次，但每次自動收報機的偶數轉一圈，作業所花費的時間都比間隔時間長。我希望它不會運行并放棄那些滴答聲。我該怎么做呢？
2 回答
莫回無
TA貢獻1865條經驗 獲得超7個贊
睡在同一個 goroutine 中只會延遲執行。同時，ticker 在一個單獨的 goroutine 中運行。因此，即使您使用全局變量來維持執行狀態 - 它也不會為您提供所需的睡眠結果。然而，在一個單獨的 goroutine 中遷移整個“睡眠”會產生：
package main
import (
"fmt"
"time"
)
type Tick struct {
ticker *time.Ticker
executing bool
}
func somethingYouWantToDo(tick *Tick, flag *int, t time.Time) {
if tick.executing {
return
}
tick.executing = true
*flag = *flag + 1
if (*flag % 2 ==0 ) {
time.Sleep(time.Second*4)
}
fmt.Println("Current time: ", t)
tick.executing = false
}
func main() {
tick := &Tick{
ticker: time.NewTicker(3*time.Second),
}
flag := 0
defer tick.ticker.Stop()
for {
select {
case t := <-tick.ticker.C:
go somethingYouWantToDo(tick, &flag, t)
}
}
}
// output
// Current time: 2009-11-10 23:00:03 +0000 UTC m=+3.000000001
// Current time: 2009-11-10 23:00:06 +0000 UTC m=+6.000000001
// Current time: 2009-11-10 23:00:12 +0000 UTC m=+12.000000001
// Current time: 2009-11-10 23:00:15 +0000 UTC m=+15.000000001
// Current time: 2009-11-10 23:00:21 +0000 UTC m=+21.000000001
// Current time: 2009-11-10 23:00:24 +0000 UTC m=+24.000000001
// Current time: 2009-11-10 23:00:30 +0000 UTC m=+30.000000001
// Current time: 2009-11-10 23:00:33 +0000 UTC m=+33.000000001
// Current time: 2009-11-10 23:00:39 +0000 UTC m=+39.000000001
// Current time: 2009-11-10 23:00:42 +0000 UTC m=+42.000000001
// Current time: 2009-11-10 23:00:48 +0000 UTC m=+48.000000001
// Current time: 2009-11-10 23:00:51 +0000 UTC m=+51.000000001
// Current time: 2009-11-10 23:00:57 +0000 UTC m=+57.000000001
// Current time: 2009-11-10 23:01:00 +0000 UTC m=+60.000000001
// Current time: 2009-11-10 23:01:06 +0000 UTC m=+66.000000001
// Current time: 2009-11-10 23:01:09 +0000 UTC m=+69.000000001
HUX布斯
TA貢獻1876條經驗 獲得超6個贊
代碼通道是緩沖的，這就是為什么您可能會一個接一個地看到多個觸發器。您可以通過簡單地將代碼的值傳輸到無緩沖通道來防止這種情況（另請注意，從代碼接收的 time.Time 值不是當前時間，而是最后一次滴答的時間）：
package main
import (
"fmt"
"time"
)
func main() {
c := make(chan time.Time) // unbuffered
ticker := time.NewTicker(3 * time.Second)
defer ticker.Stop()
go func() {
for t := range ticker.C {
select {
case c <- t:
default:
}
}
}()
for flag := 0; flag < 8; flag++ {
<-c
if flag%2 == 0 {
time.Sleep(time.Second * 4)
}
fmt.Println("Current time: ", time.Now())
}
}
// Output:
// Current time: 2020-02-19 12:21:57.095433032 +0100 CET m=+3.000213350
// Current time: 2020-02-19 12:22:04.095585208 +0100 CET m=+10.000365520
// Current time: 2020-02-19 12:22:06.095363327 +0100 CET m=+12.000143680
// Current time: 2020-02-19 12:22:13.095605268 +0100 CET m=+19.000385598
// Current time: 2020-02-19 12:22:15.095371885 +0100 CET m=+21.000152174
// Current time: 2020-02-19 12:22:22.095537562 +0100 CET m=+28.000317857
// Current time: 2020-02-19 12:22:24.095431317 +0100 CET m=+30.000211625
// Current time: 2020-02-19 12:22:31.095524308 +0100 CET m=+37.000304595
在操場上試一試：https: //play.golang.org/p/jDe5uJiRVe2
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