GO语言练习：channel select 超时机制

1、代码

2、运行

3、解析

 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