muduo源码剖析之EventLoopThread

源码剖析之EventLoopThread"/>

muduo源码剖析之EventLoopThread

简介

EventLoopThread类包装了一个thread类和一个EventLoop类,(one loop per thread)是封装了一个EventLoop的独立线程

主要成员及属性解析

意为I/O线程类，EventLoopThread可以创建一个IO线程，通过startLoop返回一个IO线程的loop，threadFunc中开启loop循环，

源码剖析

这个类比较简单,代码都写了注释,不多说

EventLoopThread.h

#ifndef MUDUO_NET_EVENTLOOPTHREAD_H
#define MUDUO_NET_EVENTLOOPTHREAD_H#include "muduo/base/Condition.h"
#include "muduo/base/Mutex.h"
#include "muduo/base/Thread.h"namespace muduo
{
namespace net
{class EventLoop;class EventLoopThread : noncopyable
{public:typedef std::function<void(EventLoop*)> ThreadInitCallback;EventLoopThread(const ThreadInitCallback& cb = ThreadInitCallback(),const string& name = string());~EventLoopThread();EventLoop* startLoop();//通过此接口启动io线程,返回subloopprivate:void threadFunc();//线程调用函数,进入loopEventLoop* loop_ GUARDED_BY(mutex_);//subloopbool exiting_;//loop退出标志Thread thread_;MutexLock mutex_;Condition cond_ GUARDED_BY(mutex_);ThreadInitCallback callback_;//线程初始化时调用的函数,不设置则不会调用
};}  // namespace net
}  // namespace muduo#endif  // MUDUO_NET_EVENTLOOPTHREAD_H

EventLoopThread

// Copyright 2010, Shuo Chen.  All rights reserved.
// /
//
// Use of this source code is governed by a BSD-style license
// that can be found in the License file.// Author: Shuo Chen (chenshuo at chenshuo dot com)#include "muduo/net/EventLoopThread.h"#include "muduo/net/EventLoop.h"using namespace muduo;
using namespace muduo::net;EventLoopThread::EventLoopThread(const ThreadInitCallback& cb,const string& name): loop_(NULL),      //loop未启动为NULLexiting_(false),	//thread_(std::bind(&EventLoopThread::threadFunc, this), name),   //绑定线程运行函数mutex_(),cond_(mutex_),callback_(cb)
{
}EventLoopThread::~EventLoopThread()
{exiting_ = true;if (loop_ != NULL) // not 100% race-free, eg. threadFunc could be running callback_.{// still a tiny chance to call destructed object, if threadFunc exits just now.// but when EventLoopThread destructs, usually programming is exiting anyway.loop_->quit();thread_.join();   //等待线程退出}
}EventLoop* EventLoopThread::startLoop()
{assert(!thread_.started());thread_.start(); //调用pthread_create创建线程,此时有两个线程在运行//一个是调用EventLoopThread::startLoop()的线程，一个是执行EventLoopThread::threadFunc()的线程（IO线程）EventLoop* loop = NULL;{MutexLockGuard lock(mutex_);while (loop_ == NULL){cond_.wait();     //须要等待EventLoop对象的创建}loop = loop_;       //IO线程创建loop_赋给主线程}return loop;          //主线程返回IO线程创建的EventLoop对象
}void EventLoopThread::threadFunc()            //创建线程时会调用这个函数
{EventLoop loop;       //IO线程也要创建EventLoop对象,还要通知主线程已经创建完毕if (callback_)//如果设置了cb则diao'y{callback_(&loop);     //将定义好的loop传入回调}{MutexLockGuard lock(mutex_);// loop_指针指向了一个栈上的对象，threadFunc函数退出之后。这个指针就失效了// threadFunc函数退出，就意味着线程退出了，EventLoopThread对象也就没有存在的价值了// 因而不会有什么大的问题loop_ = &loop;cond_.notify();     //创建好，发送通知}loop.loop();          // 会在这里循环，直到EventLoopThread析构。此后不再使用loop_訪问EventLoop了//assert(exiting_);MutexLockGuard lock(mutex_);loop_ = NULL;
}