package main

import (
    "fmt"
    "os"
    "os/signal"
    "time"

    "golang.org/x/net/context"
)

func main() {
    c1, cancel := context.WithCancel(context.Background())

    exitCh := make(chan struct{})
    go func(ctx context.Context) {
        for {
            fmt.Println("In loop. Press ^C to stop.")
            // Do something useful in a real usecase.
            // Here we just sleep for this example.
            time.Sleep(time.Second)

            select {
            case <-ctx.Done():
                fmt.Println("received done, exiting in 500 milliseconds")
                time.Sleep(500 * time.Millisecond)
                exitCh <- struct{}{}
                return
            default:
            }
        }
    }(c1)

    signalCh := make(chan os.Signal, 1)
    signal.Notify(signalCh, os.Interrupt)
    go func() {
        select {
        case <-signalCh:
            cancel()
            return
        }
    }()
    <-exitCh
}