通道(Chanels)--协程交互（匿名函数）

package main

import (
    "fmt"
    "time"
)

var strChan = make(chan string, 3)

func main() {
    syncChan1 := make(chan struct{}, 1)
    syncChan2 := make(chan struct{}, 2)
    go func() { // 用于演示接收操作
        <-syncChan1
        fmt.Println("Received a sync signal and wait a second...[receiver]")
        time.Sleep(time.Second)
        for {
            if elem, ok := <-strChan; ok {
                fmt.Println("Received:", elem, "[receiver]")
            } else {
                break
            }
        }
        fmt.Println("Stopped. [receiver]")
        syncChan2 <- struct{}{}
    }()

    go func() { //用于演示发送操作
        for _, elem := range []string{"a", "b", "c", "d"} {
            strChan <- elem
            fmt.Println("Sent:", elem, "[sender]")
            if elem == "c" {
                syncChan1 <- struct{}{}
                fmt.Println("Sent a sync signal. [sender]")
            }
        }
        fmt.Println("Wait 2 seconds...[sender]")
        time.Sleep(time.Second * 2)
        close(strChan)
        syncChan2 <- struct{}{}
    }()

    //如果下面两个语句都注释掉的化，程序会瞬间执行结束
    <-syncChan2
    <-syncChan2
}


// 输出 结果:
/*

Sent: a [sender]
Sent: b [sender]
Sent: c [sender]
Sent a sync signal. [sender]
Received a sync signal and wait a second...[receiver]
Received: a [receiver]
Received: b [receiver]
Sent: d [sender]
Wait 2 seconds...[sender]
Received: c [receiver]
Received: d [receiver]
Stopped. [receiver]

Process finished with exit code 0

 */