GO语言练习：channel select 超时机制

1、代码

2、运行

3、解析

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1、代码

 1 package main  2 
 3 import (  4     "time"
 5     "fmt"
 6 )  7 
 8 func waitFor(ch chan int) {  9     fmt.Println(time.Now(), "writing ...") 10  time.Sleep(1e9) 11     ch <- 10
12     fmt.Println(time.Now(), "wrote ...") 13 } 14 
15 func main() { 16     var a chan int = make(chan int) 17     var b chan int = make(chan int) 18     var ch chan int = make(chan int) 19 
20  go waitFor(ch) 21 
22     var r int = 0
23     fmt.Println(time.Now(), "select ...") 24  select { 25     case x := <-a : 26         fmt.Println(time.Now(), "read from a...") 27         r = x 28     case x := <-b : 29         fmt.Println(time.Now(), "read from b...") 30         r = x 31     case x := <-ch : 32         fmt.Println(time.Now(), "read from ch...") 33         r = x 34  } 35     fmt.Println(time.Now(), "select over.., r = ", r) 36  time.Sleep(1e9) 37     fmt.Println(time.Now(), "over..") 38 }

2、运行

1 $ go run timeout.go 2 2015-07-19 00:35:23.859684465 +0800 CST select ... 3 2015-07-19 00:35:23.861022451 +0800 CST writing ... 4 2015-07-19 00:35:24.864462549 +0800 CST wrote ... 5 2015-07-19 00:35:24.865185396 +0800 CST read from ch... 6 2015-07-19 00:35:24.874655353 +0800 CST select over.., r =  10
7 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