muduo库net源码分析十（muduo库如何支持多线程）

muduo库如何支持one loop per thread

由以下类实现

EventLoopThread&＃xff08;IO线程类&＃xff09;

EventLoopThreadPool&＃xff08;IO线程池类&＃xff09;

IO线程池的功能是开启若干个IO线程&＃xff0c;并让这些IO线程处于事件循环的状态

#ifndef MUDUO_NET_EVENTLOOPTHREADPOOL_H
#define MUDUO_NET_EVENTLOOPTHREADPOOL_H#include
#include #include
#include
#include
#include namespace muduo
{namespace net
{class EventLoop;
class EventLoopThread;class EventLoopThreadPool : boost::noncopyable
{public:typedef boost::function ThreadInitCallback;EventLoopThreadPool(EventLoop* baseLoop);~EventLoopThreadPool();void setThreadNum(int numThreads) { numThreads_ &＃61; numThreads; }void start(const ThreadInitCallback& cb &＃61; ThreadInitCallback());EventLoop* getNextLoop();private:EventLoop* baseLoop_; // 与Acceptor所属EventLoop相同bool started_;int numThreads_; // 线程数int next_; // 新连接到来&＃xff0c;所选择的EventLoop对象下标boost::ptr_vector threads_; // IO线程列表&＃xff0c;ptr_vector 对象销毁的时候管理的对象也销毁std::vector loops_; // EventLoop列表 &＃xff0c;这些对象都是线程中的栈上对象&＃xff0c;不用销毁
};}
}#endif // MUDUO_NET_EVENTLOOPTHREADPOOL_H


#include #include
#include #include using namespace muduo;
using namespace muduo::net;EventLoopThreadPool::EventLoopThreadPool(EventLoop* baseLoop): baseLoop_(baseLoop),started_(false),numThreads_(0),next_(0)
{
}EventLoopThreadPool::~EventLoopThreadPool()
{// Don&＃39;t delete loop, it&＃39;s stack variable
}void EventLoopThreadPool::start(const ThreadInitCallback& cb)
{assert(!started_);baseLoop_->assertInLoopThread();started_ &＃61; true;for (int i &＃61; 0; i startLoop()); // 启动EventLoopThread线程&＃xff0c;在进入事件循环之前&＃xff0c;会调用cb}if (numThreads_ &＃61;&＃61; 0 && cb){// 只有一个EventLoop&＃xff0c;在这个EventLoop进入事件循环之前&＃xff0c;调用cbcb(baseLoop_);}
}EventLoop* EventLoopThreadPool::getNextLoop()
{baseLoop_->assertInLoopThread();EventLoop* loop &＃61; baseLoop_;// 如果loops_为空&＃xff0c;则loop指向baseLoop_// 如果不为空&＃xff0c;按照round-robin&＃xff08;RR&＃xff0c;轮叫&＃xff09;的调度方式选择一个EventLoopif (!loops_.empty()){// round-robinloop &＃61; loops_[next_];&＃43;&＃43;next_;if (implicit_cast(next_) >&＃61; loops_.size()){next_ &＃61; 0;}}return loop;
}