英文:
How to stop a periodic function in golang
问题
所以我有一个函数，每隔2秒钟调用一次。像这样：
package main
import (
"fmt"
"time"
)
func doEvery(d time.Duration, f func(time.Time)) {
for x := range time.Tick(d) {
f(x)
}
}
func helloworld(t time.Time) {
fmt.Printf("%v: Hello, World!\n", t)
}
func main() {
doEvery(20*time.Millisecond, helloworld)
}
现在假设我不再希望这个函数每隔2秒钟执行一次。在golang中有没有办法实现这一点？或者在golang中调用定期函数是否有更好的方法？谢谢。
英文:
So I have a function that is called after every 2 seconds. Like this
package main
import (
"fmt"
"time"
)
func doEvery(d time.Duration, f func(time.Time)) {
for x := range time.Tick(d) {
f(x)
}
}
func helloworld(t time.Time) {
fmt.Printf("%v: Hello, World!\n", t)
}
func main() {
doEvery(20*time.Millisecond, helloworld)
}
Now lets say I no longer want this function to execute after every 2 seconds. Is there a way I can achieve this in golang? Or is there any better way than this to call a periodic function in golang? Thank you.
答案1
得分: 4
time.Tick()的文档说明表示它无法停止：
> Tick是NewTicker的便利包装，仅提供对滴答通道的访问。虽然Tick对于不需要关闭Ticker的客户端很有用，但请注意，如果没有关闭它的方法，底层的Ticker将无法被垃圾回收器回收；它会“泄漏”。
如果你需要停止它，请改用time.NewTicker()。在一个新的goroutine中运行doEvery()，并传递一个通道给它，通过关闭通道来停止它，例如：
func doEvery(d time.Duration, done chan bool, f func(time.Time)) {
ticker := time.NewTicker(d)
defer ticker.Stop()
for {
select {
case <-done:
fmt.Println("Done!")
return
case t := <-ticker.C:
f(t)
}
}
}
进行测试：
done := make(chan bool)
go doEvery(300*time.Millisecond, done, helloworld)
time.Sleep(time.Second)
close(done)
time.Sleep(time.Second)
fmt.Println("Quitting")
这将输出（在Go Playground上尝试）：
2009-11-10 23:00:00.3 +0000 UTC m=+0.300000001: Hello, World!
2009-11-10 23:00:00.6 +0000 UTC m=+0.600000001: Hello, World!
2009-11-10 23:00:00.9 +0000 UTC m=+0.900000001: Hello, World!
Done!
Quitting
英文:
Documentation of time.Tick() states it cannot be stopped:
> Tick is a convenience wrapper for NewTicker providing access to the ticking channel only. While Tick is useful for clients that have no need to shut down the Ticker, be aware that without a way to shut it down the underlying Ticker cannot be recovered by the garbage collector; it "leaks".
If you need to stop it, use time.NewTicker() instead. Run doEvery() in a new goroutine, and pass a channel to it which gives you a mean to stop it, e.g. by closing the channel:
func doEvery(d time.Duration, done chan bool, f func(time.Time)) {
ticker := time.NewTicker(d)
defer ticker.Stop()
for {
select {
case <-done:
fmt.Println("Done!")
return
case t := <-ticker.C:
f(t)
}
}
}
Testing it:
done := make(chan bool)
go doEvery(300*time.Millisecond, done, helloworld)
time.Sleep(time.Second)
close(done)
time.Sleep(time.Second)
fmt.Println("Quitting")
This will output (try it on the Go Playground):
2009-11-10 23:00:00.3 +0000 UTC m=+0.300000001: Hello, World!
2009-11-10 23:00:00.6 +0000 UTC m=+0.600000001: Hello, World!
2009-11-10 23:00:00.9 +0000 UTC m=+0.900000001: Hello, World!
Done!
Quitting
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