golang并发----安全的关闭通道

在接收方从通道内拿到所有数据后发送一个done来通知发送方关闭channel

func worker(msg chan string, done chan bool) {
    for {
        select {
        case <-done:
            fmt.Println("Done.")
            close(msg)
            return
        default:
            msg<-"hello world."
            time.Sleep(500*time.Millisecond)
        }
    }
}

func main() {
    msg := make(chan string)
    done := make(chan bool)
    timeout := time.After(5 * time.Second)
    // 将done传入worker 如果main接收完成通知worker关闭msg
    // 如果从worker直接关闭 main会继续接收msg的零值
    // 如果在main直接关闭 worker会向关闭的channel发送引起panic
    go worker(msg, done)

    for {
        select {
        case m := <-msg:
            fmt.Println("recieved msg:", m)
        case <-timeout:
            done <- true
            time.Sleep(500 * time.Millisecond)
            return
        }
    }
}