2015-12-09 07:57:17 +00:00
<!DOCTYPE HTML>
< html lang = "zh-tw" >
< head >
< meta charset = "UTF-8" >
< meta http-equiv = "X-UA-Compatible" content = "IE=edge" / >
2015-12-31 08:20:27 +00:00
< title > 基於select的多路複用 | Go语言圣经< / title >
2015-12-09 07:57:17 +00:00
< meta content = "text/html; charset=utf-8" http-equiv = "Content-Type" >
< meta name = "description" content = "" >
< meta name = "generator" content = "GitBook 2.5.2" >
< meta name = "HandheldFriendly" content = "true" / >
< meta name = "viewport" content = "width=device-width, initial-scale=1, user-scalable=no" >
< meta name = "apple-mobile-web-app-capable" content = "yes" >
< meta name = "apple-mobile-web-app-status-bar-style" content = "black" >
< link rel = "apple-touch-icon-precomposed" sizes = "152x152" href = "../gitbook/images/apple-touch-icon-precomposed-152.png" >
< link rel = "shortcut icon" href = "../gitbook/images/favicon.ico" type = "image/x-icon" >
< link rel = "stylesheet" href = "../gitbook/style.css" >
2015-12-28 08:08:26 +00:00
< link rel = "stylesheet" href = "../gitbook/plugins/gitbook-plugin-katex/katex.min.css" >
2015-12-09 07:57:17 +00:00
< link rel = "stylesheet" href = "../gitbook/plugins/gitbook-plugin-highlight/website.css" >
< link rel = "stylesheet" href = "../gitbook/plugins/gitbook-plugin-fontsettings/website.css" >
< link rel = "next" href = "../ch8/ch8-08.html" / >
< link rel = "prev" href = "../ch8/ch8-06.html" / >
< / head >
< body >
2015-12-31 08:20:27 +00:00
< div class = "book" data-level = "8.7" data-chapter-title = "基於select的多路複用" data-filepath = "ch8/ch8-07.md" data-basepath = ".." data-revision = "Thu Dec 31 2015 16:18:40 GMT+0800 (中国标准时间)" >
2015-12-09 07:57:17 +00:00
< div class = "book-summary" >
< nav role = "navigation" >
< ul class = "summary" >
< li class = "chapter " data-level = "0" data-path = "index.html" >
< a href = "../index.html" >
< i class = "fa fa-check" > < / i >
前言
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "0.1" data-path = "ch0/ch0-01.html" >
< a href = "../ch0/ch0-01.html" >
< i class = "fa fa-check" > < / i >
< b > 0.1.< / b >
Go語言起源
< / a >
< / li >
< li class = "chapter " data-level = "0.2" data-path = "ch0/ch0-02.html" >
< a href = "../ch0/ch0-02.html" >
< i class = "fa fa-check" > < / i >
< b > 0.2.< / b >
Go語言項目
< / a >
< / li >
< li class = "chapter " data-level = "0.3" data-path = "ch0/ch0-03.html" >
< a href = "../ch0/ch0-03.html" >
< i class = "fa fa-check" > < / i >
< b > 0.3.< / b >
本書的組織
< / a >
< / li >
< li class = "chapter " data-level = "0.4" data-path = "ch0/ch0-04.html" >
< a href = "../ch0/ch0-04.html" >
< i class = "fa fa-check" > < / i >
< b > 0.4.< / b >
更多的信息
< / a >
< / li >
< li class = "chapter " data-level = "0.5" data-path = "ch0/ch0-05.html" >
< a href = "../ch0/ch0-05.html" >
< i class = "fa fa-check" > < / i >
< b > 0.5.< / b >
2015-12-21 04:55:18 +00:00
致謝
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "1" data-path = "ch1/ch1.html" >
< a href = "../ch1/ch1.html" >
< i class = "fa fa-check" > < / i >
< b > 1.< / b >
入門
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "1.1" data-path = "ch1/ch1-01.html" >
< a href = "../ch1/ch1-01.html" >
< i class = "fa fa-check" > < / i >
< b > 1.1.< / b >
Hello, World
< / a >
< / li >
< li class = "chapter " data-level = "1.2" data-path = "ch1/ch1-02.html" >
< a href = "../ch1/ch1-02.html" >
< i class = "fa fa-check" > < / i >
< b > 1.2.< / b >
命令行參數
< / a >
< / li >
< li class = "chapter " data-level = "1.3" data-path = "ch1/ch1-03.html" >
< a href = "../ch1/ch1-03.html" >
< i class = "fa fa-check" > < / i >
< b > 1.3.< / b >
2015-12-21 04:55:18 +00:00
査找重複的行
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "1.4" data-path = "ch1/ch1-04.html" >
< a href = "../ch1/ch1-04.html" >
< i class = "fa fa-check" > < / i >
< b > 1.4.< / b >
2015-12-21 04:55:18 +00:00
GIF動畵
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "1.5" data-path = "ch1/ch1-05.html" >
< a href = "../ch1/ch1-05.html" >
< i class = "fa fa-check" > < / i >
< b > 1.5.< / b >
2015-12-28 08:08:26 +00:00
獲取URL
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "1.6" data-path = "ch1/ch1-06.html" >
< a href = "../ch1/ch1-06.html" >
< i class = "fa fa-check" > < / i >
< b > 1.6.< / b >
2015-12-28 08:08:26 +00:00
併發獲取多個URL
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "1.7" data-path = "ch1/ch1-07.html" >
< a href = "../ch1/ch1-07.html" >
< i class = "fa fa-check" > < / i >
< b > 1.7.< / b >
Web服務
< / a >
< / li >
< li class = "chapter " data-level = "1.8" data-path = "ch1/ch1-08.html" >
< a href = "../ch1/ch1-08.html" >
< i class = "fa fa-check" > < / i >
< b > 1.8.< / b >
本章要點
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "2" data-path = "ch2/ch2.html" >
< a href = "../ch2/ch2.html" >
< i class = "fa fa-check" > < / i >
< b > 2.< / b >
程序結構
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "2.1" data-path = "ch2/ch2-01.html" >
< a href = "../ch2/ch2-01.html" >
< i class = "fa fa-check" > < / i >
< b > 2.1.< / b >
命名
< / a >
< / li >
< li class = "chapter " data-level = "2.2" data-path = "ch2/ch2-02.html" >
< a href = "../ch2/ch2-02.html" >
< i class = "fa fa-check" > < / i >
< b > 2.2.< / b >
聲明
< / a >
< / li >
< li class = "chapter " data-level = "2.3" data-path = "ch2/ch2-03.html" >
< a href = "../ch2/ch2-03.html" >
< i class = "fa fa-check" > < / i >
< b > 2.3.< / b >
變量
< / a >
< / li >
< li class = "chapter " data-level = "2.4" data-path = "ch2/ch2-04.html" >
< a href = "../ch2/ch2-04.html" >
< i class = "fa fa-check" > < / i >
< b > 2.4.< / b >
賦值
< / a >
< / li >
< li class = "chapter " data-level = "2.5" data-path = "ch2/ch2-05.html" >
< a href = "../ch2/ch2-05.html" >
< i class = "fa fa-check" > < / i >
< b > 2.5.< / b >
類型
< / a >
< / li >
< li class = "chapter " data-level = "2.6" data-path = "ch2/ch2-06.html" >
< a href = "../ch2/ch2-06.html" >
< i class = "fa fa-check" > < / i >
< b > 2.6.< / b >
包和文件
< / a >
< / li >
< li class = "chapter " data-level = "2.7" data-path = "ch2/ch2-07.html" >
< a href = "../ch2/ch2-07.html" >
< i class = "fa fa-check" > < / i >
< b > 2.7.< / b >
作用域
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "3" data-path = "ch3/ch3.html" >
< a href = "../ch3/ch3.html" >
< i class = "fa fa-check" > < / i >
< b > 3.< / b >
基礎數據類型
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "3.1" data-path = "ch3/ch3-01.html" >
< a href = "../ch3/ch3-01.html" >
< i class = "fa fa-check" > < / i >
< b > 3.1.< / b >
整型
< / a >
< / li >
< li class = "chapter " data-level = "3.2" data-path = "ch3/ch3-02.html" >
< a href = "../ch3/ch3-02.html" >
< i class = "fa fa-check" > < / i >
< b > 3.2.< / b >
浮點數
< / a >
< / li >
< li class = "chapter " data-level = "3.3" data-path = "ch3/ch3-03.html" >
< a href = "../ch3/ch3-03.html" >
< i class = "fa fa-check" > < / i >
< b > 3.3.< / b >
2015-12-21 04:55:18 +00:00
複數
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "3.4" data-path = "ch3/ch3-04.html" >
< a href = "../ch3/ch3-04.html" >
< i class = "fa fa-check" > < / i >
< b > 3.4.< / b >
2015-12-21 04:55:18 +00:00
布爾型
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "3.5" data-path = "ch3/ch3-05.html" >
< a href = "../ch3/ch3-05.html" >
< i class = "fa fa-check" > < / i >
< b > 3.5.< / b >
字符串
< / a >
< / li >
< li class = "chapter " data-level = "3.6" data-path = "ch3/ch3-06.html" >
< a href = "../ch3/ch3-06.html" >
< i class = "fa fa-check" > < / i >
< b > 3.6.< / b >
常量
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "4" data-path = "ch4/ch4.html" >
< a href = "../ch4/ch4.html" >
< i class = "fa fa-check" > < / i >
< b > 4.< / b >
2015-12-21 04:55:18 +00:00
複合數據類型
2015-12-09 07:57:17 +00:00
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "4.1" data-path = "ch4/ch4-01.html" >
< a href = "../ch4/ch4-01.html" >
< i class = "fa fa-check" > < / i >
< b > 4.1.< / b >
數組
< / a >
< / li >
< li class = "chapter " data-level = "4.2" data-path = "ch4/ch4-02.html" >
< a href = "../ch4/ch4-02.html" >
< i class = "fa fa-check" > < / i >
< b > 4.2.< / b >
2015-12-31 08:20:27 +00:00
Slice
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "4.3" data-path = "ch4/ch4-03.html" >
< a href = "../ch4/ch4-03.html" >
< i class = "fa fa-check" > < / i >
< b > 4.3.< / b >
2015-12-31 08:20:27 +00:00
Map
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "4.4" data-path = "ch4/ch4-04.html" >
< a href = "../ch4/ch4-04.html" >
< i class = "fa fa-check" > < / i >
< b > 4.4.< / b >
結構體
< / a >
< / li >
< li class = "chapter " data-level = "4.5" data-path = "ch4/ch4-05.html" >
< a href = "../ch4/ch4-05.html" >
< i class = "fa fa-check" > < / i >
< b > 4.5.< / b >
JSON
< / a >
< / li >
< li class = "chapter " data-level = "4.6" data-path = "ch4/ch4-06.html" >
< a href = "../ch4/ch4-06.html" >
< i class = "fa fa-check" > < / i >
< b > 4.6.< / b >
文本和HTML模闆
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "5" data-path = "ch5/ch5.html" >
< a href = "../ch5/ch5.html" >
< i class = "fa fa-check" > < / i >
< b > 5.< / b >
函數
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "5.1" data-path = "ch5/ch5-01.html" >
< a href = "../ch5/ch5-01.html" >
< i class = "fa fa-check" > < / i >
< b > 5.1.< / b >
函數聲明
< / a >
< / li >
< li class = "chapter " data-level = "5.2" data-path = "ch5/ch5-02.html" >
< a href = "../ch5/ch5-02.html" >
< i class = "fa fa-check" > < / i >
< b > 5.2.< / b >
遞歸
< / a >
< / li >
< li class = "chapter " data-level = "5.3" data-path = "ch5/ch5-03.html" >
< a href = "../ch5/ch5-03.html" >
< i class = "fa fa-check" > < / i >
< b > 5.3.< / b >
多返迴值
< / a >
< / li >
< li class = "chapter " data-level = "5.4" data-path = "ch5/ch5-04.html" >
< a href = "../ch5/ch5-04.html" >
< i class = "fa fa-check" > < / i >
< b > 5.4.< / b >
錯誤
< / a >
< / li >
< li class = "chapter " data-level = "5.5" data-path = "ch5/ch5-05.html" >
< a href = "../ch5/ch5-05.html" >
< i class = "fa fa-check" > < / i >
< b > 5.5.< / b >
函數值
< / a >
< / li >
< li class = "chapter " data-level = "5.6" data-path = "ch5/ch5-06.html" >
< a href = "../ch5/ch5-06.html" >
< i class = "fa fa-check" > < / i >
< b > 5.6.< / b >
匿名函數
< / a >
< / li >
< li class = "chapter " data-level = "5.7" data-path = "ch5/ch5-07.html" >
< a href = "../ch5/ch5-07.html" >
< i class = "fa fa-check" > < / i >
< b > 5.7.< / b >
可變參數
< / a >
< / li >
< li class = "chapter " data-level = "5.8" data-path = "ch5/ch5-08.html" >
< a href = "../ch5/ch5-08.html" >
< i class = "fa fa-check" > < / i >
< b > 5.8.< / b >
Deferred函數
< / a >
< / li >
< li class = "chapter " data-level = "5.9" data-path = "ch5/ch5-09.html" >
< a href = "../ch5/ch5-09.html" >
< i class = "fa fa-check" > < / i >
< b > 5.9.< / b >
Panic異常
< / a >
< / li >
< li class = "chapter " data-level = "5.10" data-path = "ch5/ch5-10.html" >
< a href = "../ch5/ch5-10.html" >
< i class = "fa fa-check" > < / i >
< b > 5.10.< / b >
2015-12-28 08:08:26 +00:00
Recover捕獲異常
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "6" data-path = "ch6/ch6.html" >
< a href = "../ch6/ch6.html" >
< i class = "fa fa-check" > < / i >
< b > 6.< / b >
方法
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "6.1" data-path = "ch6/ch6-01.html" >
< a href = "../ch6/ch6-01.html" >
< i class = "fa fa-check" > < / i >
< b > 6.1.< / b >
方法聲明
< / a >
< / li >
< li class = "chapter " data-level = "6.2" data-path = "ch6/ch6-02.html" >
< a href = "../ch6/ch6-02.html" >
< i class = "fa fa-check" > < / i >
< b > 6.2.< / b >
2015-12-21 04:55:18 +00:00
基於指針對象的方法
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "6.3" data-path = "ch6/ch6-03.html" >
< a href = "../ch6/ch6-03.html" >
< i class = "fa fa-check" > < / i >
< b > 6.3.< / b >
通過嵌入結構體來擴展類型
< / a >
< / li >
< li class = "chapter " data-level = "6.4" data-path = "ch6/ch6-04.html" >
< a href = "../ch6/ch6-04.html" >
< i class = "fa fa-check" > < / i >
< b > 6.4.< / b >
2015-12-21 04:55:18 +00:00
方法值和方法表達式
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "6.5" data-path = "ch6/ch6-05.html" >
< a href = "../ch6/ch6-05.html" >
< i class = "fa fa-check" > < / i >
< b > 6.5.< / b >
示例: Bit數組
< / a >
< / li >
< li class = "chapter " data-level = "6.6" data-path = "ch6/ch6-06.html" >
< a href = "../ch6/ch6-06.html" >
< i class = "fa fa-check" > < / i >
< b > 6.6.< / b >
封裝
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "7" data-path = "ch7/ch7.html" >
< a href = "../ch7/ch7.html" >
< i class = "fa fa-check" > < / i >
< b > 7.< / b >
接口
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "7.1" data-path = "ch7/ch7-01.html" >
< a href = "../ch7/ch7-01.html" >
< i class = "fa fa-check" > < / i >
< b > 7.1.< / b >
2015-12-21 04:55:18 +00:00
接口是合約
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "7.2" data-path = "ch7/ch7-02.html" >
< a href = "../ch7/ch7-02.html" >
< i class = "fa fa-check" > < / i >
< b > 7.2.< / b >
接口類型
< / a >
< / li >
< li class = "chapter " data-level = "7.3" data-path = "ch7/ch7-03.html" >
< a href = "../ch7/ch7-03.html" >
< i class = "fa fa-check" > < / i >
< b > 7.3.< / b >
實現接口的條件
< / a >
< / li >
< li class = "chapter " data-level = "7.4" data-path = "ch7/ch7-04.html" >
< a href = "../ch7/ch7-04.html" >
< i class = "fa fa-check" > < / i >
< b > 7.4.< / b >
flag.Value接口
< / a >
< / li >
< li class = "chapter " data-level = "7.5" data-path = "ch7/ch7-05.html" >
< a href = "../ch7/ch7-05.html" >
< i class = "fa fa-check" > < / i >
< b > 7.5.< / b >
接口值
< / a >
< / li >
< li class = "chapter " data-level = "7.6" data-path = "ch7/ch7-06.html" >
< a href = "../ch7/ch7-06.html" >
< i class = "fa fa-check" > < / i >
< b > 7.6.< / b >
sort.Interface接口
< / a >
< / li >
< li class = "chapter " data-level = "7.7" data-path = "ch7/ch7-07.html" >
< a href = "../ch7/ch7-07.html" >
< i class = "fa fa-check" > < / i >
< b > 7.7.< / b >
http.Handler接口
< / a >
< / li >
< li class = "chapter " data-level = "7.8" data-path = "ch7/ch7-08.html" >
< a href = "../ch7/ch7-08.html" >
< i class = "fa fa-check" > < / i >
< b > 7.8.< / b >
error接口
< / a >
< / li >
< li class = "chapter " data-level = "7.9" data-path = "ch7/ch7-09.html" >
< a href = "../ch7/ch7-09.html" >
< i class = "fa fa-check" > < / i >
< b > 7.9.< / b >
2015-12-21 04:55:18 +00:00
示例: 表達式求值
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "7.10" data-path = "ch7/ch7-10.html" >
< a href = "../ch7/ch7-10.html" >
< i class = "fa fa-check" > < / i >
< b > 7.10.< / b >
類型斷言
< / a >
< / li >
< li class = "chapter " data-level = "7.11" data-path = "ch7/ch7-11.html" >
< a href = "../ch7/ch7-11.html" >
< i class = "fa fa-check" > < / i >
< b > 7.11.< / b >
2015-12-21 04:55:18 +00:00
基於類型斷言識别錯誤類型
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "7.12" data-path = "ch7/ch7-12.html" >
< a href = "../ch7/ch7-12.html" >
< i class = "fa fa-check" > < / i >
< b > 7.12.< / b >
通過類型斷言査詢接口
< / a >
< / li >
< li class = "chapter " data-level = "7.13" data-path = "ch7/ch7-13.html" >
< a href = "../ch7/ch7-13.html" >
< i class = "fa fa-check" > < / i >
< b > 7.13.< / b >
類型分支
< / a >
< / li >
< li class = "chapter " data-level = "7.14" data-path = "ch7/ch7-14.html" >
< a href = "../ch7/ch7-14.html" >
< i class = "fa fa-check" > < / i >
< b > 7.14.< / b >
示例: 基於標記的XML解碼
< / a >
< / li >
< li class = "chapter " data-level = "7.15" data-path = "ch7/ch7-15.html" >
< a href = "../ch7/ch7-15.html" >
< i class = "fa fa-check" > < / i >
< b > 7.15.< / b >
補充幾點
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "8" data-path = "ch8/ch8.html" >
< a href = "../ch8/ch8.html" >
< i class = "fa fa-check" > < / i >
< b > 8.< / b >
Goroutines和Channels
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "8.1" data-path = "ch8/ch8-01.html" >
< a href = "../ch8/ch8-01.html" >
< i class = "fa fa-check" > < / i >
< b > 8.1.< / b >
Goroutines
< / a >
< / li >
< li class = "chapter " data-level = "8.2" data-path = "ch8/ch8-02.html" >
< a href = "../ch8/ch8-02.html" >
< i class = "fa fa-check" > < / i >
< b > 8.2.< / b >
2015-12-21 04:55:18 +00:00
示例: 併發的Clock服務
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "8.3" data-path = "ch8/ch8-03.html" >
< a href = "../ch8/ch8-03.html" >
< i class = "fa fa-check" > < / i >
< b > 8.3.< / b >
2015-12-21 04:55:18 +00:00
示例: 併發的Echo服務
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "8.4" data-path = "ch8/ch8-04.html" >
< a href = "../ch8/ch8-04.html" >
< i class = "fa fa-check" > < / i >
< b > 8.4.< / b >
Channels
< / a >
< / li >
< li class = "chapter " data-level = "8.5" data-path = "ch8/ch8-05.html" >
< a href = "../ch8/ch8-05.html" >
< i class = "fa fa-check" > < / i >
< b > 8.5.< / b >
併行的循環
< / a >
< / li >
< li class = "chapter " data-level = "8.6" data-path = "ch8/ch8-06.html" >
< a href = "../ch8/ch8-06.html" >
< i class = "fa fa-check" > < / i >
< b > 8.6.< / b >
2015-12-21 04:55:18 +00:00
示例: 併發的Web爬蟲
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter active" data-level = "8.7" data-path = "ch8/ch8-07.html" >
< a href = "../ch8/ch8-07.html" >
< i class = "fa fa-check" > < / i >
< b > 8.7.< / b >
2015-12-21 04:55:18 +00:00
基於select的多路複用
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "8.8" data-path = "ch8/ch8-08.html" >
< a href = "../ch8/ch8-08.html" >
< i class = "fa fa-check" > < / i >
< b > 8.8.< / b >
2015-12-21 04:55:18 +00:00
示例: 併發的字典遍歷
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "8.9" data-path = "ch8/ch8-09.html" >
< a href = "../ch8/ch8-09.html" >
< i class = "fa fa-check" > < / i >
< b > 8.9.< / b >
2015-12-28 08:08:26 +00:00
併發的退出
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "8.10" data-path = "ch8/ch8-10.html" >
< a href = "../ch8/ch8-10.html" >
< i class = "fa fa-check" > < / i >
< b > 8.10.< / b >
示例: 聊天服務
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "9" data-path = "ch9/ch9.html" >
< a href = "../ch9/ch9.html" >
< i class = "fa fa-check" > < / i >
< b > 9.< / b >
2015-12-21 04:55:18 +00:00
基於共享變量的併發
2015-12-09 07:57:17 +00:00
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "9.1" data-path = "ch9/ch9-01.html" >
< a href = "../ch9/ch9-01.html" >
< i class = "fa fa-check" > < / i >
< b > 9.1.< / b >
競爭條件
< / a >
< / li >
< li class = "chapter " data-level = "9.2" data-path = "ch9/ch9-02.html" >
< a href = "../ch9/ch9-02.html" >
< i class = "fa fa-check" > < / i >
< b > 9.2.< / b >
sync.Mutex互斥鎖
< / a >
< / li >
< li class = "chapter " data-level = "9.3" data-path = "ch9/ch9-03.html" >
< a href = "../ch9/ch9-03.html" >
< i class = "fa fa-check" > < / i >
< b > 9.3.< / b >
sync.RWMutex讀寫鎖
< / a >
< / li >
< li class = "chapter " data-level = "9.4" data-path = "ch9/ch9-04.html" >
< a href = "../ch9/ch9-04.html" >
< i class = "fa fa-check" > < / i >
< b > 9.4.< / b >
2015-12-21 04:55:18 +00:00
內存同步
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "9.5" data-path = "ch9/ch9-05.html" >
< a href = "../ch9/ch9-05.html" >
< i class = "fa fa-check" > < / i >
< b > 9.5.< / b >
sync.Once初始化
< / a >
< / li >
< li class = "chapter " data-level = "9.6" data-path = "ch9/ch9-06.html" >
< a href = "../ch9/ch9-06.html" >
< i class = "fa fa-check" > < / i >
< b > 9.6.< / b >
競爭條件檢測
< / a >
< / li >
< li class = "chapter " data-level = "9.7" data-path = "ch9/ch9-07.html" >
< a href = "../ch9/ch9-07.html" >
< i class = "fa fa-check" > < / i >
< b > 9.7.< / b >
2015-12-21 04:55:18 +00:00
示例: 併發的非阻塞緩存
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "9.8" data-path = "ch9/ch9-08.html" >
< a href = "../ch9/ch9-08.html" >
< i class = "fa fa-check" > < / i >
< b > 9.8.< / b >
2015-12-21 04:55:18 +00:00
Goroutines和線程
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "10" data-path = "ch10/ch10.html" >
< a href = "../ch10/ch10.html" >
< i class = "fa fa-check" > < / i >
< b > 10.< / b >
包和工具
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "10.1" data-path = "ch10/ch10-01.html" >
< a href = "../ch10/ch10-01.html" >
< i class = "fa fa-check" > < / i >
< b > 10.1.< / b >
簡介
< / a >
< / li >
< li class = "chapter " data-level = "10.2" data-path = "ch10/ch10-02.html" >
< a href = "../ch10/ch10-02.html" >
< i class = "fa fa-check" > < / i >
< b > 10.2.< / b >
導入路徑
< / a >
< / li >
< li class = "chapter " data-level = "10.3" data-path = "ch10/ch10-03.html" >
< a href = "../ch10/ch10-03.html" >
< i class = "fa fa-check" > < / i >
< b > 10.3.< / b >
包聲明
< / a >
< / li >
< li class = "chapter " data-level = "10.4" data-path = "ch10/ch10-04.html" >
< a href = "../ch10/ch10-04.html" >
< i class = "fa fa-check" > < / i >
< b > 10.4.< / b >
導入聲明
< / a >
< / li >
< li class = "chapter " data-level = "10.5" data-path = "ch10/ch10-05.html" >
< a href = "../ch10/ch10-05.html" >
< i class = "fa fa-check" > < / i >
< b > 10.5.< / b >
匿名導入
< / a >
< / li >
< li class = "chapter " data-level = "10.6" data-path = "ch10/ch10-06.html" >
< a href = "../ch10/ch10-06.html" >
< i class = "fa fa-check" > < / i >
< b > 10.6.< / b >
包和命名
< / a >
< / li >
< li class = "chapter " data-level = "10.7" data-path = "ch10/ch10-07.html" >
< a href = "../ch10/ch10-07.html" >
< i class = "fa fa-check" > < / i >
< b > 10.7.< / b >
工具
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "11" data-path = "ch11/ch11.html" >
< a href = "../ch11/ch11.html" >
< i class = "fa fa-check" > < / i >
< b > 11.< / b >
測試
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "11.1" data-path = "ch11/ch11-01.html" >
< a href = "../ch11/ch11-01.html" >
< i class = "fa fa-check" > < / i >
< b > 11.1.< / b >
go test
< / a >
< / li >
< li class = "chapter " data-level = "11.2" data-path = "ch11/ch11-02.html" >
< a href = "../ch11/ch11-02.html" >
< i class = "fa fa-check" > < / i >
< b > 11.2.< / b >
測試函數
< / a >
< / li >
< li class = "chapter " data-level = "11.3" data-path = "ch11/ch11-03.html" >
< a href = "../ch11/ch11-03.html" >
< i class = "fa fa-check" > < / i >
< b > 11.3.< / b >
測試覆蓋率
< / a >
< / li >
< li class = "chapter " data-level = "11.4" data-path = "ch11/ch11-04.html" >
< a href = "../ch11/ch11-04.html" >
< i class = "fa fa-check" > < / i >
< b > 11.4.< / b >
基準測試
< / a >
< / li >
< li class = "chapter " data-level = "11.5" data-path = "ch11/ch11-05.html" >
< a href = "../ch11/ch11-05.html" >
< i class = "fa fa-check" > < / i >
< b > 11.5.< / b >
剖析
< / a >
< / li >
< li class = "chapter " data-level = "11.6" data-path = "ch11/ch11-06.html" >
< a href = "../ch11/ch11-06.html" >
< i class = "fa fa-check" > < / i >
< b > 11.6.< / b >
示例函數
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "12" data-path = "ch12/ch12.html" >
< a href = "../ch12/ch12.html" >
< i class = "fa fa-check" > < / i >
< b > 12.< / b >
反射
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "12.1" data-path = "ch12/ch12-01.html" >
< a href = "../ch12/ch12-01.html" >
< i class = "fa fa-check" > < / i >
< b > 12.1.< / b >
2015-12-21 04:55:18 +00:00
爲何需要反射?
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "12.2" data-path = "ch12/ch12-02.html" >
< a href = "../ch12/ch12-02.html" >
< i class = "fa fa-check" > < / i >
< b > 12.2.< / b >
reflect.Type和reflect.Value
< / a >
< / li >
< li class = "chapter " data-level = "12.3" data-path = "ch12/ch12-03.html" >
< a href = "../ch12/ch12-03.html" >
< i class = "fa fa-check" > < / i >
< b > 12.3.< / b >
Display遞歸打印
< / a >
< / li >
< li class = "chapter " data-level = "12.4" data-path = "ch12/ch12-04.html" >
< a href = "../ch12/ch12-04.html" >
< i class = "fa fa-check" > < / i >
< b > 12.4.< / b >
2015-12-21 04:55:18 +00:00
示例: 編碼S表達式
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "12.5" data-path = "ch12/ch12-05.html" >
< a href = "../ch12/ch12-05.html" >
< i class = "fa fa-check" > < / i >
< b > 12.5.< / b >
通過reflect.Value脩改值
< / a >
< / li >
< li class = "chapter " data-level = "12.6" data-path = "ch12/ch12-06.html" >
< a href = "../ch12/ch12-06.html" >
< i class = "fa fa-check" > < / i >
< b > 12.6.< / b >
2015-12-21 04:55:18 +00:00
示例: 解碼S表達式
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "12.7" data-path = "ch12/ch12-07.html" >
< a href = "../ch12/ch12-07.html" >
< i class = "fa fa-check" > < / i >
< b > 12.7.< / b >
2015-12-28 08:08:26 +00:00
獲取結構體字段標識
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "chapter " data-level = "12.8" data-path = "ch12/ch12-08.html" >
< a href = "../ch12/ch12-08.html" >
< i class = "fa fa-check" > < / i >
< b > 12.8.< / b >
顯示一個類型的方法集
< / a >
< / li >
< li class = "chapter " data-level = "12.9" data-path = "ch12/ch12-09.html" >
< a href = "../ch12/ch12-09.html" >
< i class = "fa fa-check" > < / i >
< b > 12.9.< / b >
幾點忠告
< / a >
< / li >
< / ul >
< / li >
< li class = "chapter " data-level = "13" data-path = "ch13/ch13.html" >
< a href = "../ch13/ch13.html" >
< i class = "fa fa-check" > < / i >
< b > 13.< / b >
底層編程
< / a >
< ul class = "articles" >
< li class = "chapter " data-level = "13.1" data-path = "ch13/ch13-01.html" >
< a href = "../ch13/ch13-01.html" >
< i class = "fa fa-check" > < / i >
< b > 13.1.< / b >
unsafe.Sizeof, Alignof 和 Offsetof
< / a >
< / li >
< li class = "chapter " data-level = "13.2" data-path = "ch13/ch13-02.html" >
< a href = "../ch13/ch13-02.html" >
< i class = "fa fa-check" > < / i >
< b > 13.2.< / b >
unsafe.Pointer
< / a >
< / li >
< li class = "chapter " data-level = "13.3" data-path = "ch13/ch13-03.html" >
< a href = "../ch13/ch13-03.html" >
< i class = "fa fa-check" > < / i >
< b > 13.3.< / b >
示例: 深度相等判斷
< / a >
< / li >
< li class = "chapter " data-level = "13.4" data-path = "ch13/ch13-04.html" >
< a href = "../ch13/ch13-04.html" >
< i class = "fa fa-check" > < / i >
< b > 13.4.< / b >
通過cgo調用C代碼
< / a >
< / li >
< li class = "chapter " data-level = "13.5" data-path = "ch13/ch13-05.html" >
< a href = "../ch13/ch13-05.html" >
< i class = "fa fa-check" > < / i >
< b > 13.5.< / b >
幾點忠告
< / a >
< / li >
< / ul >
< / li >
2015-12-24 06:47:06 +00:00
< li class = "chapter " data-level = "14" data-path = "CONTRIBUTORS.html" >
2015-12-09 07:57:17 +00:00
2015-12-24 06:47:06 +00:00
< a href = "../CONTRIBUTORS.html" >
2015-12-09 07:57:17 +00:00
< i class = "fa fa-check" > < / i >
2015-12-21 04:55:18 +00:00
< b > 14.< / b >
2015-12-09 07:57:17 +00:00
2015-12-24 06:47:06 +00:00
附録
2015-12-09 07:57:17 +00:00
< / a >
< / li >
< li class = "divider" > < / li >
< li >
< a href = "https://www.gitbook.com" target = "blank" class = "gitbook-link" >
本書使用 GitBook 釋出
< / a >
< / li >
< / ul >
< / nav >
< / div >
< div class = "book-body" >
< div class = "body-inner" >
< div class = "book-header" role = "navigation" >
<!-- Actions Left -->
<!-- Title -->
< h1 >
< i class = "fa fa-circle-o-notch fa-spin" > < / i >
2015-12-31 08:20:27 +00:00
< a href = "../" > Go语言圣经< / a >
2015-12-09 07:57:17 +00:00
< / h1 >
< / div >
< div class = "page-wrapper" tabindex = "-1" role = "main" >
< div class = "page-inner" >
< section class = "normal" id = "section-" >
2015-12-21 04:55:18 +00:00
< h2 id = "87-基於select的多路複用" > 8.7. 基 於 select的 多 路 複 用 < / h2 >
2015-12-31 08:20:27 +00:00
< p > 下 面 的 程 序 會 進 行 火 箭 發 射 的 倒 計 時 。 time.Tick函 數 返 迴 一 個 channel， 程 序 會 週 期 性 地 像 一 個 節 拍 器 一 樣 向 這 個 channel發 送 事 件 。 每 一 個 事 件 的 值 是 一 個 時 間 戳 ， 不 過 更 有 意 思 的 是 其 傳 送 方 式 。 < / p >
< pre > < code class = "lang-go" > gopl.io/ch8/countdown1
< span class = "hljs-keyword" > func< / span > main() {
fmt.Println(< span class = "hljs-string" > " Commencing countdown." < / span > )
tick := time.Tick(< span class = "hljs-number" > 1< / span > * time.Second)
< span class = "hljs-keyword" > for< / span > countdown := < span class = "hljs-number" > 10< / span > ; countdown > < span class = "hljs-number" > 0< / span > ; countdown-- {
fmt.Println(countdown)
j< -tick
}
launch()
}
< / code > < / pre >
< p > 現 在 我 們 讓 這 個 程 序 支 持 在 倒 計 時 中 ， 用 戶 按 下 return鍵 時 直 接 中 斷 發 射 流 程 。 首 先 ， 我 們 啟 動 一 個 goroutine， 這 個 goroutine會 嚐 試 從 標 準 輸 入 中 調 入 一 個 單 獨 的 byte併 且 ， 如 果 成 功 了 ， 會 向 名 爲 abort的 channel發 送 一 個 值 。 < / p >
< pre > < code class = "lang-go" > gopl.io/ch8/countdown2
abort := < span class = "hljs-built_in" > make< / span > (< span class = "hljs-keyword" > chan< / span > < span class = "hljs-keyword" > struct< / span > {})
< span class = "hljs-keyword" > go< / span > < span class = "hljs-keyword" > func< / span > () {
os.Stdin.Read(< span class = "hljs-built_in" > make< / span > ([]< span class = "hljs-typename" > byte< / span > , < span class = "hljs-number" > 1< / span > )) < span class = "hljs-comment" > // read a single byte< / span >
abort < - < span class = "hljs-keyword" > struct< / span > {}{}
}()
< / code > < / pre >
< p > 現 在 每 一 次 計 數 循 環 的 迭 代 都 需 要 等 待 兩 個 channel中 的 其 中 一 個 返 迴 事 件 了 ： ticker channel當 一 切 正 常 時 (就 像 NASA jorgon的 " nominal" ， 譯 註 ： 這 梗 估 計 我 們 是 不 懂 了 )或 者 異 常 時 返 迴 的 abort事 件 。 我 們 無 法 做 到 從 每 一 個 channel中 接 收 信 息 ， 如 果 我 們 這 麽 做 的 話 ， 如 果 第 一 個 channel中 沒 有 事 件 發 過 來 那 麽 程 序 就 會 立 刻 被 阻 塞 ， 這 樣 我 們 就 無 法 收 到 第 二 個 channel中 發 過 來 的 事 件 。 這 時 候 我 們 需 要 多 路 複 用 (multiplex)這 些 操 作 了 ， 爲 了 能 夠 多 路 複 用 ， 我 們 使 用 了 select語 句 。 < / p >
< pre > < code class = "lang-go" > < span class = "hljs-keyword" > select< / span > {
< span class = "hljs-keyword" > case< / span > < -ch1:
< span class = "hljs-comment" > // ...< / span >
< span class = "hljs-keyword" > case< / span > x := < -ch2:
< span class = "hljs-comment" > // ...use x...< / span >
< span class = "hljs-keyword" > case< / span > ch3 < - y:
< span class = "hljs-comment" > // ...< / span >
< span class = "hljs-keyword" > default< / span > :
< span class = "hljs-comment" > // ...< / span >
}
< / code > < / pre >
< p > 上 面 是 select語 句 的 一 般 形 式 。 和 switch語 句 稍 微 有 點 相 似 ， 也 會 有 幾 個 case和 最 後 的 default選 擇 支 。 每 一 個 case代 表 一 個 通 信 操 作 (在 某 個 channel上 進 行 發 送 或 者 接 收 )併 且 會 包 含 一 些 語 句 組 成 的 一 個 語 句 塊 。 一 個 接 收 表 達 式 可 能 隻 包 含 接 收 表 達 式 自 身 (譯 註 ： 不 把 接 收 到 的 值 賦 值 給 變 量 什 麽 的 )， 就 像 上 面 的 第 一 個 case， 或 者 包 含 在 一 個 簡 短 的 變 量 聲 明 中 ， 像 第 二 個 case里 一 樣 ； 第 二 種 形 式 讓 你 能 夠 引 用 接 收 到 的 值 。 < / p >
< p > select會 等 待 case中 有 能 夠 執 行 的 case時 去 執 行 。 當 條 件 滿 足 時 ， select才 會 去 通 信 併 執 行 case之 後 的 語 句 ； 這 時 候 其 它 通 信 是 不 會 執 行 的 。 一 個 沒 有 任 何 case的 select語 句 寫 作 select{}， 會 永 遠 地 等 待 下 去 。 < / p >
< p > 讓 我 們 迴 到 我 們 的 火 箭 發 射 程 序 。 time.After函 數 會 立 卽 返 迴 一 個 channel， 併 起 一 個 新 的 goroutine在 經 過 特 定 的 時 間 後 向 該 channel發 送 一 個 獨 立 的 值 。 下 面 的 select語 句 會 會 一 直 等 待 到 兩 個 事 件 中 的 一 個 到 達 ， 無 論 是 abort事 件 或 者 一 個 10秒 經 過 的 事 件 。 如 果 10秒 經 過 了 還 沒 有 abort事 件 進 入 ， 那 麽 火 箭 就 會 發 射 。 < / p >
< pre > < code class = "lang-go" > < span class = "hljs-keyword" > func< / span > main() {
< span class = "hljs-comment" > // ...create abort channel...< / span >
fmt.Println(< span class = "hljs-string" > " Commencing countdown. Press return to abort." < / span > )
< span class = "hljs-keyword" > select< / span > {
< span class = "hljs-keyword" > case< / span > < -time.After(< span class = "hljs-number" > 10< / span > * time.Second):
< span class = "hljs-comment" > // Do nothing.< / span >
< span class = "hljs-keyword" > case< / span > < -abort:
fmt.Println(< span class = "hljs-string" > " Launch aborted!" < / span > )
< span class = "hljs-keyword" > return< / span >
}
launch()
}
< / code > < / pre >
< p > 下 面 這 個 例 子 更 微 秒 。 ch這 個 channel的 buffer大 小 是 1， 所 以 會 交 替 的 爲 空 或 爲 滿 ， 所 以 隻 有 一 個 case可 以 進 行 下 去 ， 無 論 i是 奇 數 或 者 偶 數 ， 它 都 會 打 印 0 2 4 6 8。 < / p >
< pre > < code class = "lang-go" > ch := < span class = "hljs-built_in" > make< / span > (< span class = "hljs-keyword" > chan< / span > < span class = "hljs-typename" > int< / span > , < span class = "hljs-number" > 1< / span > )
< span class = "hljs-keyword" > for< / span > i := < span class = "hljs-number" > 0< / span > ; i < < span class = "hljs-number" > 10< / span > ; i++ {
< span class = "hljs-keyword" > select< / span > {
< span class = "hljs-keyword" > case< / span > x := < -ch:
fmt.Println(x) < span class = "hljs-comment" > // " 0" " 2" " 4" " 6" " 8" < / span >
< span class = "hljs-keyword" > case< / span > ch < - i:
}
}
< / code > < / pre >
< p > 如 果 多 個 case同 時 就 緒 時 ， select會 隨 機 地 選 擇 一 個 執 行 ， 這 樣 來 保 證 每 一 個 channel都 有 平 等 的 被 select的 機 會 。 增 加 前 一 個 例 子 的 buffer大 小 會 使 其 輸 出 變 得 不 確 定 ， 因 爲 當 buffer旣 不 爲 滿 也 不 爲 空 時 ， select語 句 的 執 行 情 況 就 像 是 拋 硬 幣 的 行 爲 一 樣 是 隨 機 的 。 < / p >
< p > 下 面 讓 我 們 的 發 射 程 序 打 印 倒 計 時 。 這 里 的 select語 句 會 使 每 次 循 環 迭 代 等 待 一 秒 來 執 行 退 出 操 作 。 < / p >
< pre > < code class = "lang-go" > gopl.io/ch8/countdown3
< span class = "hljs-keyword" > func< / span > main() {
< span class = "hljs-comment" > // ...create abort channel...< / span >
fmt.Println(< span class = "hljs-string" > " Commencing countdown. Press return to abort." < / span > )
tick := time.Tick(< span class = "hljs-number" > 1< / span > * time.Second)
< span class = "hljs-keyword" > for< / span > countdown := < span class = "hljs-number" > 10< / span > ; countdown > < span class = "hljs-number" > 0< / span > ; countdown-- {
fmt.Println(countdown)
< span class = "hljs-keyword" > select< / span > {
< span class = "hljs-keyword" > case< / span > < -tick:
< span class = "hljs-comment" > // Do nothing.< / span >
< span class = "hljs-keyword" > case< / span > < -abort:
fmt.Println(< span class = "hljs-string" > " Launch aborted!" < / span > )
< span class = "hljs-keyword" > return< / span >
}
}
launch()
}
< / code > < / pre >
< p > time.Tick函 數 表 現 得 好 像 它 創 建 了 一 個 在 循 環 中 調 用 time.Sleep的 goroutine， 每 次 被 喚 醒 時 發 送 一 個 事 件 。 當 countdown函 數 返 迴 時 ， 它 會 停 止 從 tick中 接 收 事 件 ， 但 是 ticker這 個 goroutine還 依 然 存 活 ， 繼 續 徒 勞 地 嚐 試 從 channel中 發 送 值 ， 然 而 這 時 候 已 經 沒 有 其 它 的 goroutine會 從 該 channel中 接 收 值 了 --這 被 稱 爲 goroutine洩 露 (§ 8.4.4)。 < / p >
< p > Tick函 數 挺 方 便 ， 但 是 隻 有 當 程 序 整 個 生 命 週 期 都 需 要 這 個 時 間 時 我 們 使 用 它 才 比 較 合 適 。 否 則 的 話 ， 我 們 應 該 使 用 下 面 的 這 種 模 式 ： < / p >
< pre > < code class = "lang-go" > ticker := time.NewTicker(< span class = "hljs-number" > 1< / span > * time.Second)
< -ticker.C < span class = "hljs-comment" > // receive from the ticker' s channel< / span >
ticker.Stop() < span class = "hljs-comment" > // cause the ticker' s goroutine to terminate< / span >
< / code > < / pre >
< p > 有 時 候 我 們 希 望 能 夠 從 channel中 發 送 或 者 接 收 值 ， 併 避 免 因 爲 發 送 或 者 接 收 導 致 的 阻 塞 ， 尤 其 是 當 channel沒 有 準 備 好 寫 或 者 讀 時 。 select語 句 就 可 以 實 現 這 樣 的 功 能 。 select會 有 一 個 default來 設 置 當 其 它 的 操 作 都 不 能 夠 馬 上 被 處 理 時 程 序 需 要 執 行 哪 些 邏 輯 。 < / p >
< p > 下 面 的 select語 句 會 在 abort channel中 有 值 時 ， 從 其 中 接 收 值 ； 無 值 時 什 麽 都 不 做 。 這 是 一 個 非 阻 塞 的 接 收 操 作 ； 反 複 地 做 這 樣 的 操 作 叫 做 “ 輪 詢 channel” 。 < / p >
< pre > < code class = "lang-go" > < span class = "hljs-keyword" > select< / span > {
< span class = "hljs-keyword" > case< / span > < -abort:
fmt.Printf(< span class = "hljs-string" > " Launch aborted!\n" < / span > )
< span class = "hljs-keyword" > return< / span >
< span class = "hljs-keyword" > default< / span > :
< span class = "hljs-comment" > // do nothing< / span >
}
< / code > < / pre >
< p > channel的 零 值 是 nil。 也 許 會 讓 你 覺 得 比 較 奇 怪 ， nil的 channel有 時 候 也 是 有 一 些 用 處 的 。 因 爲 對 一 個 nil的 channel發 送 和 接 收 操 作 會 永 遠 阻 塞 ， 在 select語 句 中 操 作 nil的 channel永 遠 都 不 會 被 select到 。 < / p >
< p > 這 使 得 我 們 可 以 用 nil來 激 活 或 者 禁 用 case， 來 達 成 處 理 其 它 輸 入 或 輸 出 事 件 時 超 時 和 取 消 的 邏 輯 。 我 們 會 在 下 一 節 中 看 到 一 個 例 子 。 < / p >
< p > 練 習 8.8: 使 用 select來 改 造 8.3節 中 的 echo服 務 器 ， 爲 其 增 加 超 時 ， 這 樣 服 務 器 可 以 在 客 戶 端 10秒 中 沒 有 任 何 喊 話 時 自 動 斷 開 連 接 。 < / p >
2015-12-09 07:57:17 +00:00
< / section >
< / div >
< / div >
< / div >
2015-12-21 04:55:18 +00:00
< a href = "../ch8/ch8-06.html" class = "navigation navigation-prev " aria-label = "Previous page: 示例: 併發的Web爬蟲" > < i class = "fa fa-angle-left" > < / i > < / a >
2015-12-09 07:57:17 +00:00
2015-12-21 04:55:18 +00:00
< a href = "../ch8/ch8-08.html" class = "navigation navigation-next " aria-label = "Next page: 示例: 併發的字典遍歷" > < i class = "fa fa-angle-right" > < / i > < / a >
2015-12-09 07:57:17 +00:00
< / div >
< / div >
< script src = "../gitbook/app.js" > < / script >
< script src = "../gitbook/plugins/gitbook-plugin-sharing/buttons.js" > < / script >
< script src = "../gitbook/plugins/gitbook-plugin-fontsettings/buttons.js" > < / script >
< script >
require(["gitbook"], function(gitbook) {
2015-12-28 08:08:26 +00:00
var config = {"katex":{},"highlight":{},"sharing":{"facebook":true,"twitter":true,"google":false,"weibo":false,"instapaper":false,"vk":false,"all":["facebook","google","twitter","weibo","instapaper"]},"fontsettings":{"theme":"white","family":"sans","size":2}};
2015-12-09 07:57:17 +00:00
gitbook.start(config);
});
< / script >
< / body >
< / html >
