muduo源码剖析之EventLoopThreadPool

本文主要是介绍muduo源码剖析之EventLoopThreadPool，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

简介

EventLoopThreadPool是EventLoopThread类的线程池类

封装了若干个EventLoopThread的线程池，所有者是一个外部的EventLoop

EventLoopThreadPool == EventLoopThread + vector

主要成员及属性解析

通过调用start函数来new EventLoopThread创建对应的线程和其loop,并将创建的保存在vector中

源码剖析

这个类比较简单,代码都写了注释,不多说

EventLoopThreadPool.h

// Copyright 2010, Shuo Chen.  All rights reserved.
// http://code.google.com/p/muduo/
//
// 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)
//
// This is an internal header file, you should not include this.#ifndef MUDUO_NET_EVENTLOOPTHREADPOOL_H
#define MUDUO_NET_EVENTLOOPTHREADPOOL_H#include "muduo/base/noncopyable.h"
#include "muduo/base/Types.h"#include <functional>
#include <memory>
#include <vector>namespace muduo
{namespace net
{class EventLoop;
class EventLoopThread;class EventLoopThreadPool : noncopyable
{public:typedef std::function<void(EventLoop*)> ThreadInitCallback;EventLoopThreadPool(EventLoop* baseLoop, const string& nameArg);~EventLoopThreadPool();//设置subloop的数量void setThreadNum(int numThreads) { numThreads_ = numThreads; }//线程池启动,会创建设置好的EventLoopThread数量,并保存threads_中void start(const ThreadInitCallback& cb = ThreadInitCallback());// valid after calling start()/// round-robin//通过next变量保存下标,每调用一次就会获取下一个loopEventLoop* getNextLoop();/// with the same hash code, it will always return the same EventLoop//使用相同的哈希码，它将始终返回相同的事件循环,//通过hash码获取相应的loopEventLoop* getLoopForHash(size_t hashCode);//获取所有的subloopstd::vector<EventLoop*> getAllLoops();bool started() const{ return started_; }const string& name() const{ return name_; }private:EventLoop* baseLoop_;     //主线程的事件驱动循环，TcpServer所在的事件驱动循环，创建TcpServer传入的EventLoopstring name_;bool started_;//线程池启动标志int numThreads_;          //线程数 int next_;                //标记下次应该取出哪个线程，采用round_robinstd::vector<std::unique_ptr<EventLoopThread>> threads_;     //线程池中所有的线程 //线程池中每个线程对应的事件驱动循环，从线程池取出线程实际上返回的是事件驱动循环//每个事件驱动循环运行在一个线程中std::vector<EventLoop*> loops_;
};}  // namespace net
}  // namespace muduo#endif  // MUDUO_NET_EVENTLOOPTHREADPOOL_H

EventLoopThreadPool.cc

// Copyright 2010, Shuo Chen.  All rights reserved.
// http://code.google.com/p/muduo/
//
// 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/EventLoopThreadPool.h"#include "muduo/net/EventLoop.h"
#include "muduo/net/EventLoopThread.h"#include <stdio.h>using namespace muduo;
using namespace muduo::net;//EventLoopThreadPool loop对应的线程池
EventLoopThreadPool::EventLoopThreadPool(EventLoop* baseLoop, const string& nameArg): baseLoop_(baseLoop),//设置mainloopname_(nameArg),started_(false),numThreads_(0),next_(0)
{
}EventLoopThreadPool::~EventLoopThreadPool()
{// Don't delete loop, it's stack variable
}void EventLoopThreadPool::start(const ThreadInitCallback& cb)   //开启线程池，创建线程
{assert(!started_);baseLoop_->assertInLoopThread();started_ = true;for (int i = 0; i < numThreads_; ++i){char buf[name_.size() + 32];snprintf(buf, sizeof buf, "%s%d", name_.c_str(), i);EventLoopThread* t = new EventLoopThread(cb, buf);threads_.push_back(std::unique_ptr<EventLoopThread>(t));loops_.push_back(t->startLoop());}if (numThreads_ == 0 && cb){cb(baseLoop_);}
}EventLoop* EventLoopThreadPool::getNextLoop()        //获取一个线程（事件驱动循环），通常在创建TcpConnection时调用 
{baseLoop_->assertInLoopThread();assert(started_);EventLoop* loop = baseLoop_;if (!loops_.empty()){// round-robinloop = loops_[next_];++next_;if (implicit_cast<size_t>(next_) >= loops_.size()){next_ = 0;}}return loop;
}EventLoop* EventLoopThreadPool::getLoopForHash(size_t hashCode)
{baseLoop_->assertInLoopThread();EventLoop* loop = baseLoop_;if (!loops_.empty()){loop = loops_[hashCode % loops_.size()];}return loop;
}std::vector<EventLoop*> EventLoopThreadPool::getAllLoops()
{baseLoop_->assertInLoopThread();assert(started_);if (loops_.empty()){return std::vector<EventLoop*>(1, baseLoop_);}else{return loops_;}
}