Go by Example - Select

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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: Select

select允许程序等待多个管道操作，使用select来组合goroutine和channel是golang的一项重要的功能。

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package main

import "time"
import "fmt"

func main() {
    // 定义两个管道用来测试`select`
    c1 := make(chan string)
    c2 := make(chan string)

    // 每个管道变量在独立的goroutine中隔若干时间后接收到一个值，用来模拟阻塞的RPC调用
    go func() {
        time.Sleep(time.Second * 1)
        c1 <- "one"
    }()
    go func() {
        time.Sleep(time.Second * 2)
        c2 <- "two"
    }()
    
    // 使用`select`同时等待这些管道变量，并且当管道有值时就将其打印出来
    for i := 0; i < 2; i++ {
        select {
            case msg1 <- c1:
                fmt.Println("received", msg1)

            case msg2 <- c2:
                fmt.Println("received", msg2)
        }
    }
}

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$ time go run select.go 
received one
received two

//  由于两个睡眠操作是并行执行的，所以执行时间并没有超过3秒
real 0m2.245s

原文链接：Go by Example: Select