Go by Example: Timers

A Timer represents a single event in the future. You tell the Timer how long you want to wait, and it provides a channel that will be notified at that time.

package main

import (
	"fmt"
	"time"
)

func main() {
	timer1 := time.NewTimer(time.Second * 2)

	<-timer1.C
	fmt.Println("Timer 1 expired")

	timer2 := time.NewTimer(time.Second)
	go func() {
		<-timer2.C
		fmt.Println("Timer 2 expired")
	}()
	stop2 := timer2.Stop()
	if stop2 {
		fmt.Println("Timer 2 stopped")
	}
}

In this example, a timer is created with a duration of 2 seconds and waits for it to expire using the <-timer1.C channel. Another timer is created with a duration of 1 second and starts a goroutine that waits for it to expire using the <-timer2.C channel. The timer2.Stop() function is called to stop the timer before it expires. If the timer was stopped, the if statement will print “Timer 2 stopped”.

Timers are used to schedule events in the future. A Timer represents a single event in the future. The timer.After function returns a channel that blocks for a specified duration and then sends the current time. Timers can be stopped before the timer fires. The time.Timer type has a Stop method which returns a bool indicating if the timer was indeed stopped. The following example demonstrates the usage of timers:

package main

import (
	"fmt"
	"time"
)

func main() {
	timer1 := time.NewTimer(2 * time.Second)

	<-timer1.C
	fmt.Println("Timer 1 fired")

	timer2 := time.NewTimer(time.Second)
	go func() {
		<-timer2.C
		fmt.Println("Timer 2 fired")
	}()
	stop2 := timer2.Stop()
	if stop2 {
		fmt.Println("Timer 2 stopped")
	}
}

This program will output:

Timer 1 fired
Timer 2 stopped