Go by Example - Non-Blocking Channel Operations

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Go by Example

Go is an open source programming language designed for building simple, fast, and reliable software.

Go by Example is a hands-on introduction to Go using annotated example programs. Check out the first example or browse the full list below.

Go by Example: Non-Blocking Channel Operations

普通管道的发送与接收都是阻塞的，然而我们可以使用select的default条件来实现非阻塞的发送，接收和甚至是非阻塞的多路复用的selects。

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package main

import "fmt"

func main() {
    messages := make(chan string)
    signals := make(chan bool)

    // 这里是一个非阻塞的接收者，如果管道msg就绪的话select会使用管道值执行这条分支
    // 否则的话select会执行default分支
    select {
        case msg := <-messages:
            fmt.Println("recieved message", msg)
        default:
            fmt.Println("no message received")
    }

    // 类似的非阻塞的发送者
    msg := "hi"
    select {
        case messages <- msg:
            fmt.Println("sent message", msg)
        default:
            fmt.Println("no message sent")
    }

    // 可以在default分支前使用多个条件分支用于实现一个非阻塞的多路复用select
    // 下面的例子尝试同时非阻塞的接收messages和signals两个管道的值
    select {
        case msg := <-messages:
            fmt.Println("recieved messages", msg)
        case sig := <-signals:
            fmt.Println("recieved signals", sig)
        default:
            fmt.Println("no activity")
    }
}
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tashuo:golang ta_shuo$ go run non-blocking-channel.go
no message received
no message sent
no activity

原文链接：Go by Example: Non-Blocking Channel Operations