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- <li class="chapter " data-level="2.1.5" data-path="../网络编程/socket的阻塞模式和非阻塞模式.html">
-
- <a href="../网络编程/socket的阻塞模式和非阻塞模式.html">
-
-
- socket 的阻塞模式和非阻塞模式
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="2.1.6" data-path="../网络编程/非阻塞模式下send和recv函数的返回值.html">
-
- <a href="../网络编程/非阻塞模式下send和recv函数的返回值.html">
-
-
- 非阻塞模式下 send 和 recv 函数的返回值
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="2.1.7" data-path="../网络编程/服务器开发通信协议设计介绍.html">
-
- <a href="../网络编程/服务器开发通信协议设计介绍.html">
-
-
- 服务器开发通信协议设计介绍
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="2.1.8" data-path="../网络编程/TCP协议如何解决粘包、半包问题.html">
-
- <a href="../网络编程/TCP协议如何解决粘包、半包问题.html">
-
-
- TCP 协议如何解决粘包、半包问题
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="2.1.9" data-path="../网络编程/网络通信中收发数据的正确姿势.html">
-
- <a href="../网络编程/网络通信中收发数据的正确姿势.html">
-
-
- 网络通信中收发数据的正确姿势
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="2.1.10" data-path="../网络编程/服务器端发数据时，如果对端一直不收，怎么办？.html">
-
- <a href="../网络编程/服务器端发数据时，如果对端一直不收，怎么办？.html">
-
-
- 服务器端发数据时，如果对端一直不收，怎么办？
-
- </a>
-
-
- </li>
-
- </ul>
-
- </li>
-
-
-
- <li class="divider"></li>
-
-
-
- <li class="chapter " data-level="3.1" data-path="../程序员必知必会的网络命令/">
-
- <a href="../程序员必知必会的网络命令/">
-
-
- 程序员必知必会的网络命令
-
- </a>
-
-
- <ul class="articles">
-
-
- <li class="chapter " data-level="3.1.1" data-path="../程序员必知必会的网络命令/利用telnet命令发电子邮件.html">
-
- <a href="../程序员必知必会的网络命令/利用telnet命令发电子邮件.html">
-
-
- 利用telnet命令发电子邮件
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="3.1.2" data-path="../程序员必知必会的网络命令/做Java或者C++开发都应该知道的lsof命令.html">
-
- <a href="../程序员必知必会的网络命令/做Java或者C++开发都应该知道的lsof命令.html">
-
-
- 做Java或者C++开发都应该知道的lsof命令
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="3.1.3" data-path="../程序员必知必会的网络命令/Linux网络故障排查的瑞士军刀.html">
-
- <a href="../程序员必知必会的网络命令/Linux网络故障排查的瑞士军刀.html">
-
-
- Linux网络故障排查的瑞士军刀nc命令
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="3.1.4" data-path="../程序员必知必会的网络命令/Linuxtcpdump使用介绍.html">
-
- <a href="../程序员必知必会的网络命令/Linuxtcpdump使用介绍.html">
-
-
- Linux tcpdump使用详解
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="3.1.5" data-path="../程序员必知必会的网络命令/从抓包的角度分析connect函数的连接过程.html">
-
- <a href="../程序员必知必会的网络命令/从抓包的角度分析connect函数的连接过程.html">
-
-
- 从抓包的角度分析connect函数的连接过程
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="3.1.6" data-path="../程序员必知必会的网络命令/服务器开发中网络数据分析与故障排查经验漫谈.html">
-
- <a href="../程序员必知必会的网络命令/服务器开发中网络数据分析与故障排查经验漫谈.html">
-
-
- 服务器开发中网络数据分析与故障排查经验漫谈
-
- </a>
-
-
- </li>
-
- </ul>
-
- </li>
-
-
-
- <li class="header">Part II</li>
-
-
-
- <li class="chapter " data-level="4.1" data-path="../高性能服务器框架设计/">
-
- <a href="../高性能服务器框架设计/">
-
-
- 高性能服务器框架设计
-
- </a>
-
-
- <ul class="articles">
-
-
- <li class="chapter " data-level="4.1.1" data-path="../高性能服务器框架设计/主线程与工作线程的分工.html">
-
- <a href="../高性能服务器框架设计/主线程与工作线程的分工.html">
-
-
- 主线程与工作线程的分工
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.2" data-path="../高性能服务器框架设计/Reactor模式.html">
-
- <a href="../高性能服务器框架设计/Reactor模式.html">
-
-
- Reactor模式
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.3" data-path="../高性能服务器框架设计/实例：一个服务器程序的架构介绍.html">
-
- <a href="../高性能服务器框架设计/实例：一个服务器程序的架构介绍.html">
-
-
- 实例：一个服务器程序的架构介绍
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.4" data-path="../高性能服务器框架设计/错误码系统的设计.html">
-
- <a href="../高性能服务器框架设计/错误码系统的设计.html">
-
-
- 错误码系统的设计
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.5" data-path="../高性能服务器框架设计/日志系统的设计.html">
-
- <a href="../高性能服务器框架设计/日志系统的设计.html">
-
-
- 日志系统的设计
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.6" data-path="../高性能服务器框架设计/如何设计断线自动重连机制.html">
-
- <a href="../高性能服务器框架设计/如何设计断线自动重连机制.html">
-
-
- 如何设计断线自动重连机制
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.7" data-path="../高性能服务器框架设计/心跳包机制设计详解.html">
-
- <a href="../高性能服务器框架设计/心跳包机制设计详解.html">
-
-
- 心跳包机制设计详解
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.8" data-path="../高性能服务器框架设计/业务数据处理一定要单独开线程吗.html">
-
- <a href="../高性能服务器框架设计/业务数据处理一定要单独开线程吗.html">
-
-
- 业务数据处理一定要单独开线程吗
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="4.1.9" data-path="../高性能服务器框架设计/C++高性能服务器网络框架设计细节.html">
-
- <a href="../高性能服务器框架设计/C++高性能服务器网络框架设计细节.html">
-
-
- C++ 高性能服务器网络框架设计细节
-
- </a>
-
-
- </li>
-
- </ul>
-
- </li>
-
-
-
- <li class="divider"></li>
-
-
-
- <li class="chapter " data-level="5.1" data-path="../服务器开发案例实战/">
-
- <a href="../服务器开发案例实战/">
-
-
- 服务器开发案例实战
-
- </a>
-
-
- <ul class="articles">
-
-
- <li class="chapter " data-level="5.1.1" data-path="../服务器开发案例实战/从零实现一个http服务器.html">
-
- <a href="../服务器开发案例实战/从零实现一个http服务器.html">
-
-
- 从零实现一个http服务器
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.2" data-path="../服务器开发案例实战/从零实现一款12306刷票软件.html">
-
- <a href="../服务器开发案例实战/从零实现一款12306刷票软件.html">
-
-
- 从零实现一款12306刷票软件
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.3" data-path="../服务器开发案例实战/从零实现一个邮件收发客户端.html">
-
- <a href="../服务器开发案例实战/从零实现一个邮件收发客户端.html">
-
-
- 从零实现一个邮件收发客户端
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.4" data-path="../服务器开发案例实战/从零开发一个WebSocket服务器.html">
-
- <a href="../服务器开发案例实战/从零开发一个WebSocket服务器.html">
-
-
- 从零开发一个WebSocket服务器
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.5" data-path="../服务器开发案例实战/1从一款多人联机实时对战游戏开始.html">
-
- <a href="../服务器开发案例实战/1从一款多人联机实时对战游戏开始.html">
-
-
- 从零学习开源项目系列（一） 从一款多人联机实时对战游戏开始
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.6" data-path="../服务器开发案例实战/2最后一战概况.html">
-
- <a href="../服务器开发案例实战/2最后一战概况.html">
-
-
- 从零学习开源项目系列（二） 最后一战概况
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.7" data-path="../服务器开发案例实战/3CSBattleMgr服务源码研究.html">
-
- <a href="../服务器开发案例实战/3CSBattleMgr服务源码研究.html">
-
-
- 从零学习开源项目系列（三） CSBattleMgr服务源码研究
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="5.1.8" data-path="../服务器开发案例实战/4LogServer源码探究.html">
-
- <a href="../服务器开发案例实战/4LogServer源码探究.html">
-
-
- 从零学习开源项目系列（四）LogServer源码探究
-
- </a>
-
-
- </li>
-
- </ul>
-
- </li>
-
-
-
- <li class="header">Part III</li>
-
-
-
- <li class="chapter " data-level="6.1" data-path="../TeamTalk源码解析/">
-
- <a href="../TeamTalk源码解析/">
-
-
- TeamTalk IM源码分析
-
- </a>
-
-
- <ul class="articles">
-
-
- <li class="chapter " data-level="6.1.1" data-path="../TeamTalk源码解析/01TeamTalk介绍.html">
-
- <a href="../TeamTalk源码解析/01TeamTalk介绍.html">
-
-
- 01 TeamTalk介绍
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.2" data-path="../TeamTalk源码解析/02服务器端的程序的编译与部署.html">
-
- <a href="../TeamTalk源码解析/02服务器端的程序的编译与部署.html">
-
-
- 02 服务器端的程序的编译与部署
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.3" data-path="../TeamTalk源码解析/03服务器端的程序架构介绍.html">
-
- <a href="../TeamTalk源码解析/03服务器端的程序架构介绍.html">
-
-
- 03 服务器端的程序架构介绍
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.4" data-path="../TeamTalk源码解析/04服务器端db_proxy_server源码分析.html">
-
- <a href="../TeamTalk源码解析/04服务器端db_proxy_server源码分析.html">
-
-
- 04 服务器端db_proxy_server源码分析
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.5" data-path="../TeamTalk源码解析/05服务器端msg_server源码分析.html">
-
- <a href="../TeamTalk源码解析/05服务器端msg_server源码分析.html">
-
-
- 05 服务器端msg_server源码分析
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.6" data-path="../TeamTalk源码解析/06服务器端login_server源码分析.html">
-
- <a href="../TeamTalk源码解析/06服务器端login_server源码分析.html">
-
-
- 06 服务器端login_server源码分析
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.7" data-path="../TeamTalk源码解析/07服务器端msfs源码分析.html">
-
- <a href="../TeamTalk源码解析/07服务器端msfs源码分析.html">
-
-
- 07 服务器端msfs源码分析
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.8" data-path="../TeamTalk源码解析/08服务器端file_server源码分析.html">
-
- <a href="../TeamTalk源码解析/08服务器端file_server源码分析.html">
-
-
- 08 服务器端file_server源码分析
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.9" data-path="../TeamTalk源码解析/09服务器端route_server源码分析.html">
-
- <a href="../TeamTalk源码解析/09服务器端route_server源码分析.html">
-
-
- 09 服务器端route_server源码分析
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.10" data-path="../TeamTalk源码解析/10开放一个TeamTalk测试服务器地址和几个测试账号.html">
-
- <a href="../TeamTalk源码解析/10开放一个TeamTalk测试服务器地址和几个测试账号.html">
-
-
- 10 开放一个TeamTalk测试服务器地址和几个测试账号
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="6.1.11" data-path="../TeamTalk源码解析/11pc客户端源码分析.html">
-
- <a href="../TeamTalk源码解析/11pc客户端源码分析.html">
-
-
- 11 pc客户端源码分析
-
- </a>
-
-
- </li>
-
- </ul>
-
- </li>
-
-
-
- <li class="divider"></li>
-
-
-
- <li class="chapter " data-level="7.1" data-path="../libevent源码深度剖析/">
-
- <a href="../libevent源码深度剖析/">
-
-
- libevent源码深度剖析
-
- </a>
-
-
- <ul class="articles">
-
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- <li class="chapter " data-level="7.1.1" data-path="../libevent源码深度剖析/libevent源码深度剖析01.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析01.html">
-
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- libevent源码深度剖析01
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="7.1.2" data-path="../libevent源码深度剖析/libevent源码深度剖析02.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析02.html">
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- libevent源码深度剖析02
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="7.1.3" data-path="../libevent源码深度剖析/libevent源码深度剖析03.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析03.html">
-
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- libevent源码深度剖析03
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="7.1.4" data-path="../libevent源码深度剖析/libevent源码深度剖析04.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析04.html">
-
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- libevent源码深度剖析04
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="7.1.5" data-path="../libevent源码深度剖析/libevent源码深度剖析05.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析05.html">
-
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- libevent源码深度剖析05
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="7.1.6" data-path="../libevent源码深度剖析/libevent源码深度剖析06.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析06.html">
-
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- libevent源码深度剖析06
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="7.1.7" data-path="../libevent源码深度剖析/libevent源码深度剖析07.html">
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- <a href="../libevent源码深度剖析/libevent源码深度剖析07.html">
-
-
- libevent源码深度剖析07
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="7.1.8" data-path="../libevent源码深度剖析/libevent源码深度剖析08.html">
-
- <a href="../libevent源码深度剖析/libevent源码深度剖析08.html">
-
-
- libevent源码深度剖析08
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="7.1.9" data-path="../libevent源码深度剖析/libevent源码深度剖析09.html">
-
- <a href="../libevent源码深度剖析/libevent源码深度剖析09.html">
-
-
- libevent源码深度剖析09
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="7.1.10" data-path="../libevent源码深度剖析/libevent源码深度剖析10.html">
-
- <a href="../libevent源码深度剖析/libevent源码深度剖析10.html">
-
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- libevent源码深度剖析10
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="7.1.11" data-path="../libevent源码深度剖析/libevent源码深度剖析11.html">
-
- <a href="../libevent源码深度剖析/libevent源码深度剖析11.html">
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- libevent源码深度剖析11
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- </a>
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- <li class="chapter " data-level="7.1.12" data-path="../libevent源码深度剖析/libevent源码深度剖析12.html">
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- <a href="./">
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- leveldb源码分析
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- leveldb源码分析1
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- leveldb源码分析2
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- </a>
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- <li class="chapter " data-level="7.2.3" data-path="leveldb源码分析3.html">
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- leveldb源码分析3
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- </a>
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- <li class="chapter " data-level="7.2.4" data-path="leveldb源码分析4.html">
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- leveldb源码分析4
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- </a>
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- <li class="chapter " data-level="7.2.5" data-path="leveldb源码分析5.html">
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- leveldb源码分析5
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- <li class="chapter " data-level="7.2.6" data-path="leveldb源码分析6.html">
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- leveldb源码分析6
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- <li class="chapter " data-level="7.2.7" data-path="leveldb源码分析7.html">
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- leveldb源码分析7
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- <li class="chapter " data-level="7.2.8" data-path="leveldb源码分析8.html">
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- leveldb源码分析8
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- <li class="chapter " data-level="7.2.9" data-path="leveldb源码分析9.html">
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- leveldb源码分析9
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- <li class="chapter " data-level="7.2.10" data-path="leveldb源码分析10.html">
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- leveldb源码分析10
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- <li class="chapter " data-level="7.2.11" data-path="leveldb源码分析11.html">
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- leveldb源码分析11
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- <li class="chapter " data-level="7.2.12" data-path="leveldb源码分析12.html">
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- leveldb源码分析12
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- </a>
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- <li class="chapter " data-level="7.2.13" data-path="leveldb源码分析13.html">
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- leveldb源码分析13
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- <li class="chapter " data-level="7.2.14" data-path="leveldb源码分析14.html">
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- leveldb源码分析14
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- </a>
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- </li>
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- <li class="chapter " data-level="7.2.15" data-path="leveldb源码分析15.html">
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- leveldb源码分析15
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- </a>
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- </li>
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- <li class="chapter " data-level="7.2.16" data-path="leveldb源码分析16.html">
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- leveldb源码分析16
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- </a>
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- </li>
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- <li class="chapter " data-level="7.2.17" data-path="leveldb源码分析17.html">
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- leveldb源码分析17
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- </a>
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- </li>
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- <li class="chapter " data-level="7.2.18" data-path="leveldb源码分析18.html">
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- leveldb源码分析18
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- </a>
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-
- </li>
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- <li class="chapter " data-level="7.2.19" data-path="leveldb源码分析19.html">
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- <a href="leveldb源码分析19.html">
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- leveldb源码分析19
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- </a>
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-
- </li>
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- <li class="chapter active" data-level="7.2.20" data-path="leveldb源码分析20.html">
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- <a href="leveldb源码分析20.html">
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-
- leveldb源码分析20
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="7.2.21" data-path="leveldb源码分析21.html">
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- <a href="leveldb源码分析21.html">
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-
- leveldb源码分析21
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="7.2.22" data-path="leveldb源码分析22.html">
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- <a href="leveldb源码分析22.html">
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-
- leveldb源码分析22
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- </a>
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-
- </li>
-
- </ul>
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- </li>
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- <li class="divider"></li>
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- <li class="chapter " data-level="8.1" data-path="../Memcached源码分析/">
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- <a href="../Memcached源码分析/">
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-
- Memcached源码分析
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- </a>
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-
- <ul class="articles">
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-
- <li class="chapter " data-level="8.1.1" data-path="../Memcached源码分析/00服务器资源调整.html">
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- <a href="../Memcached源码分析/00服务器资源调整.html">
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- 00 服务器资源调整
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.2" data-path="../Memcached源码分析/01初始化参数解析.html">
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- <a href="../Memcached源码分析/01初始化参数解析.html">
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-
- 01 初始化参数解析
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.3" data-path="../Memcached源码分析/02网络监听的建立.html">
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- <a href="../Memcached源码分析/02网络监听的建立.html">
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-
- 02 网络监听的建立
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.4" data-path="../Memcached源码分析/03网络连接建立.html">
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- <a href="../Memcached源码分析/03网络连接建立.html">
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-
- 03 网络连接建立
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.5" data-path="../Memcached源码分析/04内存初始化.html">
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- <a href="../Memcached源码分析/04内存初始化.html">
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-
- 04 内存初始化
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.6" data-path="../Memcached源码分析/05资源初始化.html">
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- <a href="../Memcached源码分析/05资源初始化.html">
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-
- 05 资源初始化
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.7" data-path="../Memcached源码分析/06get过程.html">
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- <a href="../Memcached源码分析/06get过程.html">
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-
- 06 get过程
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- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.8" data-path="../Memcached源码分析/07cas属性.html">
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- <a href="../Memcached源码分析/07cas属性.html">
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-
- 07 cas属性
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.9" data-path="../Memcached源码分析/08内存池.html">
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- <a href="../Memcached源码分析/08内存池.html">
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-
- 08 内存池
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.10" data-path="../Memcached源码分析/09连接队列.html">
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- <a href="../Memcached源码分析/09连接队列.html">
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-
- 09 连接队列
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.11" data-path="../Memcached源码分析/10Hash表操作.html">
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- <a href="../Memcached源码分析/10Hash表操作.html">
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-
- 10 Hash表操作
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.12" data-path="../Memcached源码分析/12set操作.html">
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- <a href="../Memcached源码分析/12set操作.html">
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-
- 12 set操作
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- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.13" data-path="../Memcached源码分析/13do_item_alloc操作.html">
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- <a href="../Memcached源码分析/13do_item_alloc操作.html">
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-
- 13 do_item_alloc操作
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="8.1.14" data-path="../Memcached源码分析/14item结构.html">
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- <a href="../Memcached源码分析/14item结构.html">
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-
- 14 item结构
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.15" data-path="../Memcached源码分析/15Hash表扩容.html">
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- <a href="../Memcached源码分析/15Hash表扩容.html">
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-
- 15 Hash表扩容
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.16" data-path="../Memcached源码分析/16线程交互.html">
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- <a href="../Memcached源码分析/16线程交互.html">
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-
- 16 线程交互
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="8.1.17" data-path="../Memcached源码分析/17状态机.html">
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- <a href="../Memcached源码分析/17状态机.html">
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-
- 17 状态机
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- </a>
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-
- </li>
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- </ul>
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- </li>
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- <li class="divider"></li>
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- 游戏开发专题
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-
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- <ul class="articles">
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- <li class="chapter " data-level="9.1.1" data-path="../游戏开发专题/1游戏服务器开发的基本体系与服务器端开发的一些建议.html">
-
- <a href="../游戏开发专题/1游戏服务器开发的基本体系与服务器端开发的一些建议.html">
-
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- 1 游戏服务器开发的基本体系与服务器端开发的一些建议
-
- </a>
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-
- </li>
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- <li class="chapter " data-level="9.1.2" data-path="../游戏开发专题/2网络游戏服务器开发框架设计介绍.html">
-
- <a href="../游戏开发专题/2网络游戏服务器开发框架设计介绍.html">
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- 2 网络游戏服务器开发框架设计介绍
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="9.1.3" data-path="../游戏开发专题/3游戏后端开发需要掌握的知识.html">
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- <a href="../游戏开发专题/3游戏后端开发需要掌握的知识.html">
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-
- 3 游戏后端开发需要掌握的知识
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="9.1.4" data-path="../游戏开发专题/4关于游戏服务端架构的整理.html">
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- <a href="../游戏开发专题/4关于游戏服务端架构的整理.html">
-
-
- 4 关于游戏服务端架构的整理
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="9.1.5" data-path="../游戏开发专题/5各类游戏对应的服务端架构.html">
-
- <a href="../游戏开发专题/5各类游戏对应的服务端架构.html">
-
-
- 5 各类游戏对应的服务端架构
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="9.1.6" data-path="../游戏开发专题/6从腾讯QQgame高性能服务器集群架构看“分而治之”与“自治”等分布式架构设计原则.html">
-
- <a href="../游戏开发专题/6从腾讯QQgame高性能服务器集群架构看“分而治之”与“自治”等分布式架构设计原则.html">
-
-
- 6 从腾讯QQgame高性能服务器集群架构看“分而治之”与“自治”等分布式架构设计原则
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="9.1.7" data-path="../游戏开发专题/7QQ游戏百万人同时在线服务器架构实现.html">
-
- <a href="../游戏开发专题/7QQ游戏百万人同时在线服务器架构实现.html">
-
-
- 7 QQ游戏百万人同时在线服务器架构实现
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="9.1.8" data-path="../游戏开发专题/8大型多人在线游戏服务器架构设计.html">
-
- <a href="../游戏开发专题/8大型多人在线游戏服务器架构设计.html">
-
-
- 8 大型多人在线游戏服务器架构设计
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="9.1.9" data-path="../游戏开发专题/9百万用户级游戏服务器架构设计.html">
-
- <a href="../游戏开发专题/9百万用户级游戏服务器架构设计.html">
-
-
- 9 百万用户级游戏服务器架构设计
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="9.1.10" data-path="../游戏开发专题/10十万在线的WebGame的数据库设计思路.html">
-
- <a href="../游戏开发专题/10十万在线的WebGame的数据库设计思路.html">
-
-
- 10 十万在线的WebGame的数据库设计思路
-
- </a>
-
-
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-
- <li class="chapter " data-level="9.1.11" data-path="../游戏开发专题/11一种高性能网络游戏服务器架构设计.html">
-
- <a href="../游戏开发专题/11一种高性能网络游戏服务器架构设计.html">
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-
- 11 一种高性能网络游戏服务器架构设计
-
- </a>
-
-
- </li>
-
- <li class="chapter " data-level="9.1.12" data-path="../游戏开发专题/12经典游戏服务器端架构概述.html">
-
- <a href="../游戏开发专题/12经典游戏服务器端架构概述.html">
-
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- 12 经典游戏服务器端架构概述
-
- </a>
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-
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-
- <li class="chapter " data-level="9.1.13" data-path="../游戏开发专题/13游戏跨服架构进化之路.html">
-
- <a href="../游戏开发专题/13游戏跨服架构进化之路.html">
-
-
- 13 游戏跨服架构进化之路
-
- </a>
-
-
- </li>
-
- </ul>
-
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-
-
- <li class="header">Part IV</li>
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-
- <li class="chapter " data-level="10.1" data-path="../程序员面试题精讲/">
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- 程序员面试题精讲
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- <a href="../程序员面试题精讲/腾讯后台开发实习生技能要求.html">
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- 腾讯后台开发实习生技能要求
-
- </a>
-
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-
- <li class="chapter " data-level="10.1.2" data-path="../程序员面试题精讲/聊聊如何拿大厂的offer.html">
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- <a href="../程序员面试题精讲/聊聊如何拿大厂的offer.html">
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- 聊聊如何拿大厂的 offer
-
- </a>
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-
- </li>
-
- <li class="chapter " data-level="10.1.3" data-path="../程序员面试题精讲/网络通信题目集锦.html">
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- <a href="../程序员面试题精讲/网络通信题目集锦.html">
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- 网络通信题目集锦
-
- </a>
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-
- <li class="chapter " data-level="10.1.4" data-path="../程序员面试题精讲/我面试后端开发经理的经历.html">
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- <a href="../程序员面试题精讲/我面试后端开发经理的经历.html">
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- 我面试后端开发经理的经历
-
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-
- </li>
-
- <li class="chapter " data-level="10.1.5" data-path="../程序员面试题精讲/LinuxCC++后端开发面试问哪些问题.html">
-
- <a href="../程序员面试题精讲/LinuxCC++后端开发面试问哪些问题.html">
-
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- Linux C/C++后端开发面试问哪些问题
-
- </a>
-
-
- </li>
-
- </ul>
-
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- <li class="chapter " data-level="10.2" data-path="../职业规划/">
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- 职业规划
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- <ul class="articles">
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- <li class="chapter " data-level="10.2.1" data-path="../职业规划/给工作4年迷茫的程序员们的一点建议.html">
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- <a href="../职业规划/给工作4年迷茫的程序员们的一点建议.html">
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- 给工作 4 年迷茫的程序员们的一点建议
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- <div id="anchor-navigation-ex-navbar"><i class="fa fa-navicon"></i><ul><li><span class="title-icon "></span><a href="#leveldb源码分析20"><b></b>leveldb源码分析20</a></li><ul><li><span class="title-icon "></span><a href="#本系列《leveldb源码分析》共有22篇文章，这是第二十篇"><b></b>本系列《leveldb源码分析》共有22篇文章，这是第二十篇</a></li><ul><li><span class="title-icon "></span><a href="#12-db的打开"><b></b>12 DB的打开</a></li><li><span class="title-icon "></span><a href="#121-dbopen"><b></b>12.1 DB::Open()</a></li><li><span class="title-icon "></span><a href="#123-dbimpnewdb"><b></b>12.3 DBImp::NewDB()</a></li><li><span class="title-icon "></span><a href="#125-dbimpldeleteobsoletefiles"><b></b>12.5 DBImpl::DeleteObsoleteFiles()</a></li><li><span class="title-icon "></span><a href="#126-dbimplrecoverlogfile"><b></b>12.6 DBImpl::RecoverLogFile()</a></li></ul><li><span class="title-icon "></span><a href="#_1"><b></b> </a></li><ul><li><span class="title-icon "></span><a href="#13-db的关闭销毁"><b></b>13 DB的关闭&销毁</a></li><li><span class="title-icon "></span><a href="#131-db关闭"><b></b>13.1 DB关闭</a></li><li><span class="title-icon "></span><a href="#132-db销毁"><b></b>13.2 DB销毁</a></li></ul></ul></ul></div><h1 id="leveldb源码分析20"><a name="leveldb源码分析20" class="anchor-navigation-ex-anchor" href="#leveldb源码分析20"><i class="fa fa-link" aria-hidden="true"></i></a>leveldb源码分析20</h1>
- <h2 id="本系列《leveldb源码分析》共有22篇文章，这是第二十篇"><a name="本系列《leveldb源码分析》共有22篇文章，这是第二十篇" class="anchor-navigation-ex-anchor" href="#本系列《leveldb源码分析》共有22篇文章，这是第二十篇"><i class="fa fa-link" aria-hidden="true"></i></a>本系列《leveldb源码分析》共有22篇文章，这是第二十篇</h2>
- <h3 id="12-db的打开"><a name="12-db的打开" class="anchor-navigation-ex-anchor" href="#12-db的打开"><i class="fa fa-link" aria-hidden="true"></i></a>12 DB的打开</h3>
- <p>先分析LevelDB是如何打开db的，万物始于创建。在打开流程中有几个辅助函数：<strong>DBImpl()，DBImpl::Recover, DBImpl::DeleteObsoleteFiles, DBImpl::RecoverLogFile, DBImpl::MaybeScheduleCompaction</strong>。</p>
- <h3 id="121-dbopen"><a name="121-dbopen" class="anchor-navigation-ex-anchor" href="#121-dbopen"><i class="fa fa-link" aria-hidden="true"></i></a>12.1 DB::Open()</h3>
- <p>打开一个db，进行PUT、GET操作，就是前面的静态函数<strong>DB::Open</strong>的工作。如果操作成功，它就返回一个db指针。前面说过DB就是一个接口类，其具体实现在DBImp类中，这是一个DB的子类。
- 函数声明为：</p>
- <pre class="language-"><code>Status DB::Open(const Options& options, const std::string&dbname, DB** dbptr);
- </code></pre><p>分解来看，Open()函数主要有以下5个执行步骤。
- S1 创建DBImpl对象，其后进入<strong>DBImpl::Recover()</strong>函数执行S2和S3。
- S2 从已存在的db文件恢复db数据，根据CURRENT记录的MANIFEST文件读取db元信息；这通过调用<strong>VersionSet::Recover()</strong>完成。
- S3 然后过滤出那些最近的更新log，前一个版本可能新加了这些log，但并没有记录在MANIFEST中。然后依次根据时间顺序，调用<strong>DBImpl::RecoverLogFile()</strong>从旧到新回放这些操作log。回放log时可能会修改db元信息，比如dump了新的level 0文件，因此它将返回一个VersionEdit对象，记录db元信息的变动。
- S4 如果<strong>DBImpl::Recover()</strong>返回成功，就执行<strong>VersionSet::LogAndApply()</strong>应用VersionEdit，并保存当前的DB信息到新的MANIFEST文件中。
- S5 最后删除一些过期文件，并检查是否需要执行compaction，如果需要，就启动后台线程执行。
- 下面就来具体分析Open函数的代码，在Open函数中涉及到上面的3个流程。
- S1 首先创建DBImpl对象，锁定并试图做Recover操作。Recover操作用来处理创建flag，比如存在就返回失败等等，尝试从已存在的sstable文件恢复db。并返回db元信息的变动信息，一个VersionEdit对象。</p>
- <pre class="language-"><code>1DBImpl* impl = newDBImpl(options, dbname);
- 2impl->mutex_.Lock(); // 锁db
- 3VersionEdit edit;
- 4Status s =impl->Recover(&edit); // 处理flag&恢复：create_if_missing,error_if_exists
- </code></pre><p>S2 如果Recover返回成功，则调用VersionSet取得新的log文件编号——实际上是在当前基础上+1，准备新的log文件。如果log文件创建成功，则根据log文件创建log::Writer。然后执行VersionSet::LogAndApply，根据edit记录的增量变动生成新的current version，并写入MANIFEST文件。</p>
- <p>函数<strong>NewFileNumber(){returnnext<em>file_number</em>++;}</strong>，直接返回<strong>next<em>file_number</em></strong>。</p>
- <pre class="language-"><code> 1uint64_t new_log_number = impl->versions_->NewFileNumber();
- 2WritableFile* lfile;
- 3s = options.env->NewWritableFile(LogFileName(dbname, new_log_number), &lfile);
- 4if (s.ok()) {
- 5 edit.SetLogNumber(new_log_number);
- 6 impl->logfile_ = lfile;
- 7 impl->logfile_number_ = new_log_number;
- 8 impl->log_ = newlog::Writer(lfile);
- 9 s = impl->versions_->LogAndApply(&edit, &impl->mutex_);
- 10}
- </code></pre><p>S3 如果VersionSet::LogAndApply返回成功，则删除过期文件，检查是否需要执行compaction，最终返回创建的DBImpl对象。</p>
- <pre class="language-"><code>1if (s.ok()) {
- 2 impl->DeleteObsoleteFiles();
- 3 impl->MaybeScheduleCompaction();
- 4}
- 5impl->mutex_.Unlock();
- 6if (s.ok()) *dbptr = impl;
- 7return s;
- </code></pre><p>以上就是DB::Open的主题逻辑。</p>
- <p><strong>12.2 DBImpl::DBImpl()</strong></p>
- <p>构造函数做的都是初始化操作，</p>
- <pre class="language-"><code>DBImpl::DBImpl(const Options& options, const std::string&dbname)
- </code></pre><p>首先是初始化列表中，直接根据参数赋值，或者直接初始化。Comparator和filter policy都是参数传入的。在传递option时会首先将option中的参数合法化，<strong>logfile<em>number</em></strong>初始化为0，指针初始化为NULL。
- 创建MemTable，并增加引用计数，创建WriteBatch。</p>
- <pre class="language-"><code>1mem_(newMemTable(internal_comparator_)),
- 2tmp_batch_(new WriteBatch),
- 3mem_->Ref();
- 4// 然后在函数体中，创建TableCache和VersionSet。
- 5// 为其他预留10个文件，其余的都给TableCache.
- 6const int table_cache_size = options.max_open_files - 10;
- 7table_cache_ = newTableCache(dbname_, &options_, table_cache_size);
- 8versions_ = newVersionSet(dbname_, &options_, table_cache_, &internal_comparator_);
- </code></pre><h3 id=""> </h3>
- <h3 id="123-dbimpnewdb"><a name="123-dbimpnewdb" class="anchor-navigation-ex-anchor" href="#123-dbimpnewdb"><i class="fa fa-link" aria-hidden="true"></i></a>12.3 DBImp::NewDB()</h3>
- <p>当外部在调用DB::Open()时设置了option指定如果db不存在就创建，如果db不存在leveldb就会调用函数创建新的db。判断db是否存在的依据是<strong><db name="">/CURRENT</db></strong>文件是否存在。其逻辑很简单。</p>
- <pre class="language-"><code> 1// S1首先生产DB元信息，设置comparator名，以及log文件编号、文件编号，以及seq no。
- 2VersionEdit new_db;
- 3new_db.SetComparatorName(user_comparator()->Name());
- 4new_db.SetLogNumber(0);
- 5new_db.SetNextFile(2);
- 6new_db.SetLastSequence(0);
- 7// S2 生产MANIFEST文件，将db元信息写入MANIFEST文件。
- 8const std::string manifest = DescriptorFileName(dbname_, 1);
- 9WritableFile* file;
- 10Status s = env_->NewWritableFile(manifest, &file);
- 11if (!s.ok()) return s;
- 12{
- 13 log::Writer log(file);
- 14 std::string record;
- 15 new_db.EncodeTo(&record);
- 16 s = log.AddRecord(record);
- 17 if (s.ok()) s = file->Close();
- 18}
- 19delete file;
- 20// S3 如果成功，就把MANIFEST文件名写入到CURRENT文件中
- 21if (s.ok()) s = SetCurrentFile(env_, dbname_, 1);
- 22elseenv_->DeleteFile(manifest);
- 23return s;
- </code></pre><p>这就是创建新DB的逻辑，很简单。</p>
- <p><strong>12.4 DBImpl::Recover()</strong></p>
- <p>函数声明为：</p>
- <pre class="language-"><code>StatusDBImpl::Recover(VersionEdit* edit)
- </code></pre><p>如果调用成功则设置VersionEdit。Recover的基本功能是：首先是处理创建flag，比如存在就返回失败等等；然后是尝试从已存在的sstable文件恢复db；最后如果发现有大于原信息记录的log编号的log文件，则需要回放log，更新db数据。回放期间db可能会dump新的level 0文件，因此需要把db元信息的变动记录到edit中返回。函数逻辑如下：</p>
- <p>S1 创建目录，目录以db name命名，忽略任何创建错误，然后尝试获取d<strong>b name/LOCK</strong>文件锁，失败则返回。</p>
- <pre class="language-"><code>1env_->CreateDir(dbname_);
- 2Status s = env_->LockFile(LockFileName(dbname_), &db_lock_);
- 3if (!s.ok()) return s;
- </code></pre><p>S2 根据CURRENT文件是否存在，以及option参数执行检查。
- 如果文件不存在<strong>&create_is_missing=true</strong>，则调用函数NewDB()创建；否则报错。
- 如果文件存在& error_if_exists=true，则报错。
- S3 调用VersionSet的<strong>Recover()</strong>函数，就是从文件中恢复数据。如果出错则打开失败，成功则向下执行S4。</p>
- <pre class="language-"><code>s = versions_->Recover();
- </code></pre><p>S4尝试从所有比manifest文件中记录的log要新的log文件中恢复（前一个版本可能会添加新的log文件，却没有记录在manifest中）。另外，函数PrevLogNumber()已经不再用了，仅为了兼容老版本。</p>
- <pre class="language-"><code> 1// S4.1 这里先找出所有满足条件的log文件：比manifest文件记录的log编号更新。
- 2SequenceNumber max_sequence(0);
- 3const uint64_t min_log = versions_->LogNumber();
- 4const uint64_t prev_log = versions_->PrevLogNumber();
- 5std::vector<span class="token tag"><span class="token tag"><span class="token punctuation"><</span><span class="token namespace">std:</span>:string</span><span class="token punctuation">></span></span>filenames;
- 6s = env_->GetChildren(dbname_, &filenames); // 列出目录内的所有文件
- 7uint64_t number;
- 8FileType type;
- 9std::vector<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>uint64_t</span><span class="token punctuation">></span></span>logs;
- 10for (size_t i = 0; i < filenames.size(); i++) { // 检查log文件是否比min log更新
- 11 if (ParseFileName(filenames[i], &number, &type) && type == kLogFile
- 12 && ((number >= min_log) || (number == prev_log))) {
- 13 logs.push_back(number);
- 14 }
- 15}
- 16// S4.2 找到log文件后，首先排序，保证按照生成顺序，依次回放log。并把DB元信息的变动（sstable文件的变动）追加到edit中返回。
- 17std::sort(logs.begin(), logs.end());
- 18for (size_t i = 0; i < logs.size(); i++) {
- 19 s = RecoverLogFile(logs[i], edit, &max_sequence);
- 20 // 前一版可能在生成该log编号后没有记录在MANIFEST中，
- 21 //所以这里我们手动更新VersionSet中的文件编号计数器
- 22 versions_->MarkFileNumberUsed(logs[i]);
- 23}
- 24// S4.3 更新VersionSet的sequence
- 25if (s.ok()) {
- 26 if (versions_->LastSequence() < max_sequence)
- 27 versions_->SetLastSequence(max_sequence);
- 28}
- </code></pre><p>上面就是Recover的执行流程。</p>
- <h3 id="125-dbimpldeleteobsoletefiles"><a name="125-dbimpldeleteobsoletefiles" class="anchor-navigation-ex-anchor" href="#125-dbimpldeleteobsoletefiles"><i class="fa fa-link" aria-hidden="true"></i></a>12.5 DBImpl::DeleteObsoleteFiles()</h3>
- <p>这个是垃圾回收函数，如前所述，每次compaction和recovery之后都会有文件被废弃。DeleteObsoleteFiles就是删除这些垃圾文件的，它在每次compaction和recovery完成之后被调用。
- 其调用点包括：<strong>DBImpl::CompactMemTable,DBImpl::BackgroundCompaction,</strong> 以及DB::Open的<strong>recovery</strong>步骤之后。
- 它会删除所有过期的log文件，没有被任何level引用到、或不是正在执行的compaction的output的sstable文件。
- 该函数没有参数，其代码逻辑也很直观，就是列出db的所有文件，对不同类型的文件分别判断，如果是过期文件，就删除之，如下：</p>
- <pre class="language-"><code> 1// S1 首先，确保不会删除pending文件，将versionset正在使用的所有文件加入到live中。
- 2std::set<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>uint64_t</span><span class="token punctuation">></span></span> live = pending_outputs_;
- 3versions_->AddLiveFiles(&live); //该函数其后分析
- 4 // S2 列举db的所有文件
- 5std::vector<span class="token tag"><span class="token tag"><span class="token punctuation"><</span><span class="token namespace">std:</span>:string</span><span class="token punctuation">></span></span>filenames;
- 6env_->GetChildren(dbname_, &filenames);
- 7// S3 遍历所有列举的文件，根据文件类型，分别处理；
- 8uint64_t number;
- 9FileType type;
- 10for (size_t i = 0; i < filenames.size(); i++) {
- 11 if (ParseFileName(filenames[i], &number, &type)) {
- 12 bool keep = true; //false表明是过期文件
- 13 // S3.1 kLogFile，log文件，根据log编号判断是否过期
- 14 keep = ((number >= versions_->LogNumber()) ||
- 15 (number == versions_->PrevLogNumber()));
- 16 // S3.2 kDescriptorFile，MANIFEST文件，根据versionset记录的编号判断
- 17 keep = (number >= versions_->ManifestFileNumber());
- 18 // S3.3 kTableFile，sstable文件，只要在live中就不能删除
- 19 // S3.4 kTempFile，如果是正在写的文件，只要在live中就不能删除
- 20 keep = (live.find(number) != live.end());
- 21 // S3.5 kCurrentFile,kDBLockFile, kInfoLogFile，不能删除
- 22 keep = true;
- 23 // S3.6 如果keep为false，表明需要删除文件，如果是table还要从cache中删除
- 24 if (!keep) {
- 25 if (type == kTableFile) table_cache_->Evict(number);
- 26 Log(options_.info_log, "Delete type=%d #%lld\n", type, number);
- 27 env_->DeleteFile(dbname_ + "/" + filenames[i]);
- 28 }
- 29 }
- 30}
- </code></pre><p>这就是删除过期文件的逻辑，其中调用到了<strong>VersionSet::AddLiveFiles</strong>函数，保证不会删除active的文件。</p>
- <p>函数DbImpl::MaybeScheduleCompaction()放在Compaction一节分析，基本逻辑就是如果需要compaction，就启动后台线程执行compaction操作。</p>
- <h3 id="126-dbimplrecoverlogfile"><a name="126-dbimplrecoverlogfile" class="anchor-navigation-ex-anchor" href="#126-dbimplrecoverlogfile"><i class="fa fa-link" aria-hidden="true"></i></a>12.6 DBImpl::RecoverLogFile()</h3>
- <p>函数声明：</p>
- <pre class="language-"><code>StatusRecoverLogFile(uint64_t log_number, VersionEdit* edit,SequenceNumber* max_sequence)
- </code></pre><p>参数说明：
- @log_number是指定的log文件编号
- @edit记录db元信息的变化——sstable文件变动
- @max_sequence 返回max{log记录的最大序号, *max_sequence}
- 该函数打开指定的log文件，回放日志。期间可能会执行compaction，生产新的level 0sstable文件，记录文件变动到edit中。
- 它声明了一个局部类LogReporter以打印错误日志，没什么好说的，下面来看代码逻辑。</p>
- <pre class="language-"><code> 1// S1 打开log文件返回SequentialFile*file，出错就返回，否则向下执行S2。
- 2// S2 根据log文件句柄file创建log::Reader，准备读取log。
- 3log::Reader reader(file, &reporter, true/*checksum*/, 0/*initial_offset*/);
- 4// S3 依次读取所有的log记录，并插入到新生成的memtable中。这里使用到了批量更新接口WriteBatch，具体后面再分析。
- 5std::string scratch;
- 6Slice record;
- 7WriteBatch batch;
- 8MemTable* mem = NULL;
- 9while (reader.ReadRecord(&record, &scratch) && status.ok()) { // 读取全部log
- 10 if (record.size() < 12) { // log数据错误，不满足最小长度12
- 11 reporter.Corruption(record.size(), Status::Corruption("log recordtoo small"));
- 12 continue;
- 13 }
- 14 WriteBatchInternal::SetContents(&batch, record); // log内容设置到WriteBatch中
- 15 if (mem == NULL) { // 创建memtable
- 16 mem = new MemTable(internal_comparator_);
- 17 mem->Ref();
- 18 }
- 19 status = WriteBatchInternal::InsertInto(&batch, mem); // 插入到memtable中
- 20 MaybeIgnoreError(&status);
- 21 if (!status.ok()) break;
- 22 const SequenceNumber last_seq =
- 23 WriteBatchInternal::Sequence(&batch) + WriteBatchInternal::Count(&batch) - 1;
- 24 if (last_seq > *max_sequence) *max_sequence = last_seq; // 更新max sequence
- 25 // 如果mem的内存超过设置值，则执行compaction，如果compaction出错，
- 26 // 立刻返回错误，DB::Open失败
- 27 if (mem->ApproximateMemoryUsage() > options_.write_buffer_size) {
- 28 status = WriteLevel0Table(mem, edit, NULL);
- 29 if (!status.ok()) break;
- 30 mem->Unref(); // 释放当前memtable
- 31 mem = NULL;
- 32 }
- 33}
- 34// S4 扫尾工作，如果mem != NULL，说明还需要dump到新的sstable文件中。
- 35if (status.ok() && mem != NULL) {// 如果compaction出错，立刻返回错误
- 36 status = WriteLevel0Table(mem, edit, NULL);
- 37}
- 38if (mem != NULL)mem->Unref();
- 39delete file;
- 40return status;
- </code></pre><p>把MemTabledump到sstable是函数WriteLevel0Table的工作，其实这是compaction的一部分，准备放在compaction一节来分析。</p>
- <p><strong>12.7 小结</strong></p>
- <p>如上DB打开的逻辑就已经分析完了，打开逻辑参见DB::Open()中描述的5个步骤。此外还有两个东东：把Memtable dump到sstable的WriteLevel0Table()函数，以及批量修改WriteBatch。第一个放在后面的compaction一节，第二个放在DB更新操作中。接下来就是db的关闭。</p>
- <h2 id="_1"><a name="_1" class="anchor-navigation-ex-anchor" href="#_1"><i class="fa fa-link" aria-hidden="true"></i></a> </h2>
- <h3 id="13-db的关闭销毁"><a name="13-db的关闭销毁" class="anchor-navigation-ex-anchor" href="#13-db的关闭销毁"><i class="fa fa-link" aria-hidden="true"></i></a>13 DB的关闭&销毁</h3>
- <h3 id="131-db关闭"><a name="131-db关闭" class="anchor-navigation-ex-anchor" href="#131-db关闭"><i class="fa fa-link" aria-hidden="true"></i></a>13.1 DB关闭</h3>
- <p>外部调用者通过DB::Open()获取一个DB<em>对象，如果要关闭打开的DB</em>db对象，则直接delete db即可，这会调用到DBImpl的析构函数。
- 析构依次执行如下的5个逻辑：
- S1 等待后台compaction任务结束
- S2 释放db文件锁，<dbname>/lock文件
- S3 删除VersionSet对象，并释放MemTable对象
- S4 删除log相关以及TableCache对象
- S5 删除options的block_cache以及info_log对象</dbname></p>
- <h3 id="132-db销毁"><a name="132-db销毁" class="anchor-navigation-ex-anchor" href="#132-db销毁"><i class="fa fa-link" aria-hidden="true"></i></a>13.2 DB销毁</h3>
- <p>函数声明：</p>
- <pre class="language-"><code>StatusDestroyDB(const std::string& dbname, const Options& options)
- </code></pre><p>该函数会删除掉db的数据内容，要谨慎使用。函数逻辑为：
- S1 获取dbname目录的文件列表到filenames中，如果为空则直接返回，否则进入S2。
- S2 锁文件<dbname>/lock，如果锁成功就执行S3
- S3 遍历filenames文件列表，过滤掉lock文件，依次调用DeleteFile删除。
- S4 释放lock文件，并删除之，然后删除文件夹。
- Destory就执行完了，如果删除文件出现错误，记录之，依然继续删除下一个。最后返回错误代码。
- 看来这一章很短小。DB的打开关闭分析完毕。 </dbname></p>
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