non-blocking-channel-operations.go

package main

import "fmt"

func main() {
	// 常规的通过通道发送和接收数据是阻塞的。然而，我们可以 使用带一个 default 子句的 select 来实现非阻塞 的 发送、接收，
	// 甚至是非阻塞的多路 select
	messages := make(chan string)
	signals := make(chan bool)

	select {
	case msg := <-messages:
		fmt.Println("received message:", msg)
	default:
		fmt.Println("no message received")
	}

	msg := "hi"
	select {
	case messages <- msg:
		fmt.Println("sent message:", msg)
	default:
		fmt.Println("no message sent")
	}

	select {
	case msg := <-messages:
		fmt.Println("received message:", msg)
	case sig := <-signals:
		fmt.Println("received signal:", sig)
	default:
		fmt.Println("no activity")
	}
}