GO语言练习：channel select 超时机制

1、代码

2、运行

3、解析

---

1、代码

 package main

 import (
     "time"
     "fmt"
 )

 func waitFor(ch chan int) {
     fmt.Println(time.Now(), "writing ...")
     time.Sleep(1e9)
     ch <- 10
     fmt.Println(time.Now(), "wrote ...")
 }

 func main() {
     var a chan int = make(chan int)
     var b chan int = make(chan int)
     var ch chan int = make(chan int)

     go waitFor(ch)

     var r int = 0
     fmt.Println(time.Now(), "select ...")
     select {
     case x := <-a :
         fmt.Println(time.Now(), "read from a...")
         r = x
     case x := <-b :
         fmt.Println(time.Now(), "read from b...")
         r = x
     case x := <-ch :
         fmt.Println(time.Now(), "read from ch...")
         r = x
     }
     fmt.Println(time.Now(), "select over.., r = ", r)
     time.Sleep(1e9)
     fmt.Println(time.Now(), "over..")
 }

2、运行

 $ go run timeout.go
 2015-07-19 00:35:23.859684465 +0800 CST select ...
 2015-07-19 00:35:23.861022451 +0800 CST writing ...
 2015-07-19 00:35:24.864462549 +0800 CST wrote ...
 2015-07-19 00:35:24.865185396 +0800 CST read from ch...
 2015-07-19 00:35:24.874655353 +0800 CST select over.., r =  10
 2015-07-19 00:35:25.888486739 +0800 CST over..

3、解析

　　1）主线程中的select开始运行，对select中的3个channel进行阻塞等待

　　2）在线程（协程）waitFor中向ch写入数据

　　3）select收到数据，进行读取

　　4）主线程退出