timeout with golang using context.WithTimeout()

main.go

package main

import (
	"context"
	"fmt"
	"time"
)

func f(ctx context.Context) {
	fmt.Println(time.Now().UTC())

	for {
		select {
		case <-ctx.Done():
			fmt.Println(time.Now().UTC())
			fmt.Println("i've timed out or what?")
			return
		default:
			fmt.Println(time.Now().UTC())
			fmt.Println("still waiting...")
			time.Sleep(1 * time.Second)
		}
	}

}

func main() {

	ctx := context.Background()
	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()

	fmt.Println(time.Now().UTC())
	time.Sleep(8 * time.Second)
	fmt.Println(time.Now().UTC())

	f(ctx)
}