TimeTimer
TimeTimer
The Timer type represents a single event. When the Timer expires, the current time will be sent on C, unless the Timer was created by AfterFunc. A Timer must be created with NewTimer or AfterFunc.
type Timer struct {
C <-chan Time
// contains filtered or unexported fields
}
两种一定时间后的方式
select
下面select是一直阻塞的
func GoAfter1() {
timer := time.NewTimer(time.Second)
select {
case <-timer.C:
fmt.Println("时间到了，玩游戏")
}
// 函数下面能运行到吗？
fmt.Println("上面阻塞了，所以最后才能到这")
}
改进
看下面的select运行几次
func GoAfter2() {
timer := time.NewTimer(time.Second)
go func() {
// 看select运行几次
select {
case <-timer.C:
fmt.Println("时间到了，玩游戏")
}
}()
// 函数下面能当然能运行
fmt.Println("所以最后才能到这")
time.Sleep(time.Second * 3)
}
#代码输出
所以最后才能到这
时间到了，玩游戏
PASS
ok go-newbase/time/timer-base 3.200s
加上for循环呢？
func GoAfter3() {
timer := time.NewTimer(time.Second)
go func() {
// 看select运行几次
for {
select {
case <-timer.C:
fmt.Println("时间到了，玩游戏")
}
}
}()
// 函数下面能当然能运行
fmt.Println("所以最后才能到这")
time.Sleep(time.Second * 3)
}
#代码输出
所以最后才能到这
时间到了，玩游戏
PASS
ok go-newbase/time/timer-base 3.207s
下面是实现一直运行，就需要重置定时器
func GoAfter4() {
timer := time.NewTimer(time.Second)
go func() {
// 看select运行几次
for {
select {
case <-timer.C:
fmt.Println("时间到了，玩游戏")
timer.Reset(time.Second)
}
}
}()
// 函数下面能当然能运行
fmt.Println("所以最后才能到这")
time.Sleep(time.Second * 3)
}
#代码输出
所以最后才能到这
时间到了，玩游戏
时间到了，玩游戏
时间到了，玩游戏
PASS
ok go-newbase/time/timer-base 3.211s
Afterfunc形式
因为下面函数不是阻塞的，主线程退出，所以没执行
func AfterPrint() {
time.AfterFunc(time.Second, func() {
fmt.Println("时间已到，吃饭")
})
}
# 代码输出
啥也没输出
更改能输出的
func AfterPrint() {
time.AfterFunc(time.Second, func() {
fmt.Println("时间已到，吃饭")
})
time.Sleep(time.Second * 2)
}
# 代码输出
时间已到，吃饭
PASS
ok go-newbase/time/timer-base 2.207s
Ticker
一个自动收报机持有一个通道，它每隔一段时间就发送一个时钟的“滴答声”。
A Ticker holds a channel that delivers `ticks' of a clock at intervals.
type Ticker struct {
C <-chan Time // The channel on which the ticks are delivered.
// contains filtered or unexported fields
}
官方文档用法
package main
import (
"fmt"
"time"
)
func main() {
ticker := time.NewTicker(time.Second)
defer ticker.Stop()
done := make(chan bool)
go func() {
time.Sleep(3 * time.Second)
done <- true
}()
for {
select {
case <-done:
fmt.Println("Done!")
return
case t := <-ticker.C:
fmt.Println("Current time: ", t)
}
}
}
# 代码输出
Current time: 2020-11-20 09:31:02.598433 +0800 CST m=+1.003463301
Current time: 2020-11-20 09:31:03.5981403 +0800 CST m=+2.003170601
Current time: 2020-11-20 09:31:04.5986842 +0800 CST m=+3.003714501
Done!
Api
func (t *Ticker) Reset(d Duration)
Reset stops a ticker and resets its period to the specified duration. The next tick will arrive after the new period elapses.
func (t *Ticker) Stop()
Stop turns off a ticker. After Stop, no more ticks will be sent. Stop does not close the channel, to prevent a concurrent goroutine reading from the channel from seeing an erroneous "tick".
