main.go

// Copyright 2016 Google Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to writing, software distributed
// under the License is distributed on a "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied.
//
// See the License for the specific language governing permissions and
// limitations under the License.

package main

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

func main() {
	ctx := context.Background()

	ctx, cancel := context.WithTimeout(ctx, time.Second)
	cancel()

	mySleepAndTalk(ctx, 5*time.Second, "hello")
}

func mySleepAndTalk(ctx context.Context, d time.Duration, msg string) {
	select {
	case <-time.After(d):
		fmt.Println(msg)
	case <-ctx.Done():
		log.Print(ctx.Err())
	}
}