Tickers

Timers are for when you want to do something once in the future - tickers are for when you want to do something repeatedly at regular intervals. Here’s an example of a ticker that ticks periodically until we stop it.

package main

import (
    "fmt"
    "time"
)

func main() {

    // Tickers use a similar mechanism to timers:
    // a channel that is sent values. 
    // Here we’ll use the select builtin on the channel 
    // to await the values as they arrive every 500ms.
    ticker := time.NewTicker(500 * time.Millisecond)
    done := make(chan bool)

    go func() {
        for {
            select {
            case <-done:
                return
            case t := <-ticker.C:
                fmt.Println("Tick at", t)
            }
        }
    }()

    // Tickers can be stopped like timers. 
    // Once a ticker is stopped it won’t receive any more values on its channel. 
    // We’ll stop ours after 1600ms.
    time.Sleep(1600 * time.Millisecond)
    ticker.Stop()
    done <- true
    fmt.Println("Ticker stopped")
}

When we run this program the ticker should tick 3 times before we stop it.

$ go run tickers.go
Tick at 2012-09-23 11:29:56.487625 -0700 PDT
Tick at 2012-09-23 11:29:56.988063 -0700 PDT
Tick at 2012-09-23 11:29:57.488076 -0700 PDT
Ticker stopped