陈硕《Linux多线程服务端编程》中的EventLoop Reactor 的 c++11 版本

把原书第8章的例子《设计Reactor——如何从头开始编写非阻塞网络库》

地址： https://github.com/chenshuo/recipes/tree/master/reactor

用 c++11 搞了一遍，并且简化到全部代码放在一个文件中，方便察看。

步骤0：什么都不做的 event loop 事件循环

EventLoop, assertInLoopThread()

这个步骤里，作者只想强调如何保证每个线程中只能创建一个EventLoop对象，而且如何保证此对象中的loop函数只能在本线程中被调用。

test1: poll 5秒钟，创建两个线程，每个线程都有一个 EventLoop 对象

#include 
#include 
#include 
#include 
#include 

class EventLoop;

__thread EventLoop* t_loopInThisThread = nullptr;

class EventLoop
{
public:
    EventLoop() : looping_(false), threadId_(std::this_thread::get_id())
    {
        std::cout << "EventLoop created " << this << " in thread " << threadId_ << std::endl;
        if (t_loopInThisThread) {
            std::cout << "Another EventLoop " << t_loopInThisThread << " exists in this thread " << threadId_ << std::endl;
            abort();
        } else {
            t_loopInThisThread = this;
        }
    }

    ~EventLoop()
    {
        assert(!looping_);
        t_loopInThisThread = nullptr;
    }

    static EventLoop* getEventLoopOfCurrentThread()
    {
        return t_loopInThisThread;
    }

    void loop()
    {
        assert(!looping_);
        assertInLoopThread();
        looping_ = true;
        ::poll(NULL, 0, 5*1000);
        std::cout << "EventLoop " << this << " stop looping in thread " << std::this_thread::get_id() << std::endl;
        looping_ = false;
    }
    void assertInLoopThread()
    {
        if (!isInLoopThread()) {
            abortNotInLoopThread();
        }
    }
    bool isInLoopThread() const
    {
        return threadId_ == std::this_thread::get_id();
    }

private:
    EventLoop(const EventLoop&) = delete;
    EventLoop& operator=(const EventLoop&) = delete;

    void abortNotInLoopThread()
    {
        std::cout << "EventLoop::abortNotInLoopThread - EventLoop " << this
                  << " was created in threadId_ = " << threadId_
                  << ", current thread id = " << std::this_thread::get_id() << std::endl;
        abort();
    }

    bool looping_;
    const std::thread::id threadId_;
};

void threadFunc()
{
    std::cout << "threadFunc(): pid = " << getpid() << ", tid = " << std::this_thread::get_id() << std::endl;
    EventLoop loop;
    loop.loop();
}

int main()
{
    std::cout << "main(): pid = " << getpid() << ", tid = " << std::this_thread::get_id() << std::endl;

    EventLoop loop;
    std::thread t(threadFunc);
    loop.loop();
    t.join();
}

运行结果

test2: 当从其它线程访问EventLoop时调用abort()退出

#include 
#include 
#include 
#include 
#include 

class EventLoop;

__thread EventLoop* t_loopInThisThread = nullptr;

class EventLoop
{
public:
    EventLoop() : looping_(false), threadId_(std::this_thread::get_id())
    {
        std::cout << "EventLoop created " << this << " in thread " << threadId_ << std::endl;
        if (t_loopInThisThread) {
            std::cout << "Another EventLoop " << t_loopInThisThread << " exists in this thread " << threadId_ << std::endl;
            abort();
        } else {
            t_loopInThisThread = this;
        }
    }

    ~EventLoop()
    {
        assert(!looping_);
        t_loopInThisThread = nullptr;
    }

    static EventLoop* getEventLoopOfCurrentThread()
    {
        return t_loopInThisThread;
    }

    void loop()
    {
        assert(!looping_);
        assertInLoopThread();
        looping_ = true;
        ::poll(NULL, 0, 5*1000);
        std::cout << "EventLoop " << this << " stop looping in thread " << std::this_thread::get_id() << std::endl;
        looping_ = false;
    }
    void assertInLoopThread()
    {
        if (!isInLoopThread()) {
            abortNotInLoopThread();
        }
    }
    bool isInLoopThread() const
    {
        return threadId_ == std::this_thread::get_id();
    }

private:
    EventLoop(const EventLoop&) = delete;
    EventLoop& operator=(const EventLoop&) = delete;

    void abortNotInLoopThread()
    {
        std::cout << "EventLoop::abortNotInLoopThread - EventLoop " << this
                  << " was created in threadId_ = " << threadId_
                  << ", current thread id = " << std::this_thread::get_id() << std::endl;
        abort();
    }

    bool looping_;
    const std::thread::id threadId_;
};

EventLoop* g_loop;

void threadFunc()
{
    g_loop->loop();
}

int main()
{
    EventLoop loop;
    g_loop = &loop;
    std::thread t(threadFunc);
    t.join();
}

运行结果

步骤1：Reactor原型

Channel, Poller, updateChannel()

test1: 永不退出的poll, 创建2个线程，每个线程中都有一个EventLoop

本例子中，EventLoop对象只创建了一个 Poller 对象（在初始化列表中 new 的）存放在智能指针 poller_ 内，还没有涉及 Channel 的对象操作。所以只是对空的 pollfds_ 进行 poll 系统调用，实际上就是什么描述符都没有观察，当然也不会poll到任何事件。

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

运行结果

test2: 当从其它线程访问EventLoop时调用abort()退出

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

运行结果

test3: poll一个会在5秒钟超时的timerfd描述符

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

运行结果