我有一些必须定期运行的功能。我为此使用了股票代码。但是,如果置顶器已经运行,并且时间间隔再次过去,则不应再次执行。
package main
import (
"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
[在操场上,自动收报机每3秒打印一次,但每转一次自动收报机,所需的时间就比间隔时间要长。我希望它在那时不运行并丢弃那些滴答声。
我该怎么做?
股票行情通道已缓冲,这就是为什么您可能会一个接一个地看到多个触发器的原因。您可以通过简单地将代码的值传输到未缓冲的通道来防止这种情况(还请注意,从代码中收到的time.Time值不是当前时间,而是最后一个时间的时间):
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
在同一个goroutine中睡觉只会延迟执行。同时行情自动收录器在单独的goroutine中运行。因此,即使您使用全局变量来维护执行状态,也无法通过睡眠获得所需的结果。但是,将整个“睡眠”迁移到单独的goroutine中会产生:
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)
}
}
}