hello-go/ctx_cancel.go

package main

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

var c chan bool

func init() {
	c = make(chan bool, 10)
	for i := 0; i < 10; i++ {
		c <- true
	}
}

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	close(c)
	println(1)
	cancel()
	println(2)
exit:
	for {
		select {
		case data, ok := <-c:
			fmt.Println(data, ok)
			time.Sleep(1 * time.Second)
		case <-ctx.Done():
			println(3)
			break exit
		}
	}
	println(4)
}