// select.go
package main

import (
    "fmt"
    "time"

    //"time"
)

func main() {
    //声明一个channel
    ch := make(chan int)

    //声明一个匿名函数，传入一个参数整型channel类型ch
    go func(ch chan int) {
        ch <- 1
        //往channel写入一个数据，此时阻塞
    }(ch)

    //由于goroutine执行太快，先让它sleep 1秒
    time.Sleep(time.Second)

    select {
    //读取ch，解除阻塞
    case <-ch:
        fmt.Print("come to read ch!")
    default:
        fmt.Print("come to default!")
    }
}

---

// select.go
//整型channel类型ch一直处于读取状态，所以处于阻塞,使用select实现超时控制
package main

import (
    "fmt"
    "time"
)

func main() {
    ch := make(chan int)
    //buffer channel,1个元素前非阻塞
    timeout := make(chan int, 1)

    go func() {
        time.Sleep(time.Second)
        //写channel
        timeout <- 1
    }()

    select {
    //读channel
    case <-ch:
        fmt.Print("come to read ch!")
        //没有读到channel，实现超时控制
    case <-timeout:
        fmt.Print("come to timeout!")
    }

    fmt.Print("end of code!")
}

---

// select.go
//使用time.After实现超时控制
package main

import (
    "fmt"
    "time"
)

func main() {
    ch := make(chan int)

    select {
    case <-ch:
        fmt.Print("come to read ch!")
    case <-time.After(time.Second):
        fmt.Print("come to timeout!")
    }

    fmt.Print("end of code!")
}

分享文章：golang中select实现非阻塞及超时控制
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