Example_cancellationByTimeout.go

package main

import (
	"fmt"
	"time"
)

func Example_cancellationByTimeout() {
	heavyWork := func(d time.Duration) {
		timeout := time.After(d)
		for i := 0; ; i++ {
			time.Sleep(50 * time.Millisecond)
			fmt.Println("iteration", i)

			select {
			case <-timeout:
				fmt.Println("timeout")
				return
			default:
			}
		}
	}

	wait := make(chan struct{})
	go func() {
		heavyWork(70 * time.Millisecond)
		close(wait)
	}()

	<-wait

	// Output:
	// iteration 0
	// iteration 1
	// timeout
}