Timers and Tickers

Timers

Timers allow you to execute code at some point in the future. This is useful for executing code once after some time has passed.

timer := time.NewTimer(time.Second * 2) // after 2 seconds

<-timer.C //blocks on `timer`'s channel until the timer expires, then proceeds with execution
fmt.Println("Timer expired")

Timers can also be stopped before they expire.

timer := time.NewTimer(time.Second * 2) // after 2 seconds

go func(){
    <-timer.C
    fmt.Println("Timer expired")
}()

stop := timer.Stop() // stop the timer before it expires
if stop {
    fmt.Println("Timer stopped")
}

In the above example, as the goroutine runs in the background, waiting to print that it has "expired", the stop() function is called in the foreground, and the timer is stopped before it can expire.

Tickers

Tickers allow execution of code, at specific intervals.

ticker := time.NewTicker(time.Millisecond * 500) // every 500 milliseconds

//runs in the background until stopped
go func(){
    for t := range ticker.C {
        fmt.Println("Tick at", t)
    }
}()

time.Sleep(time.Millisecond * 1600) // sleep for 1600 milliseconds
//the ticker will have ticked 3 times by now
ticker.Stop() // stop the ticker
fmt.Println("Ticker stopped")