缩略版muduo网络库（2）：事件处理器 Chanel

#pragma once

#include "nocopyable.hpp"
#include "timestamp.hpp"

#include <functional>
#include <memory>   //智能指针需要

class EventLoop;    //前置声明，避免过多的头文件包含

class Channel:nocpoyable{
public:
    using EventCallback = std::function<void()>;    //设置事件回调名称
    using ReadEventCallback = std::function<void(timestamp)>; 

    Channel(EventLoop* loop,int fd);    //这里只需要个指针，前置声明无伤大雅
    ~Channel();

    //fd得到poller事件通知后，处理事件
    void handleEvent(timestamp receiveTime);    //这里需要初始化了，不能仅仅前置声明，需要包头文件了
    
    //设置回调函数对象
    void setReadCallback(ReadEventCallback cb){ readCallback_ = std::move(cb); }
    void setWriteCallback(EventCallback cb){ writeCallback_ = std::move(cb); }
    void setCloseCallback(EventCallback cb){ closeCallback_ = std::move(cb); }
    void setErrorCallback(EventCallback cb){ errorCallback_ = std::move(cb); }

    //防止手动remove channel之后，channel还在执行回调操作  
    void tie(const std::shared_ptr<void>&);

    int fd() const { return fd_; }
    int events() const { return events_; }
    void set_revents(int revt) { revents_ = revt; }
  
    // int revents() const { return revents_; }
    bool isNoneEvent() const { return events_ == kNoneEvent; }

    void enableReading() { events_ |= kReadEvent; update(); }
    void disableReading() { events_ &= ~kReadEvent; update(); }
    void enableWriting() { events_ |= kWriteEvent; update(); }
    void disableWriting() { events_ &= ~kWriteEvent; update(); }
    void disableAll() { events_ = kNoneEvent; update(); }
    bool isWriting() const { return events_ & kWriteEvent; }
    bool isReading() const { return events_ & kReadEvent; }

    // for Poller
    int index() { return index_; }
    void set_index(int idx) { index_ = idx; }

    //one loop per thread
    EventLoop* ownerLoop() { return loop_; }
    void remove();

private:

    void update();
    void handleEventWithGuard(timestamp receiveTime);

    //事件状态标志
    static const int kNoneEvent;
    static const int kReadEvent;
    static const int kWriteEvent;

    EventLoop* loop_;   //  事件循环
    const int fd_;      //poller监听对象
    int events_;        //注册fd感兴趣的事件
    int revents_;       //poller返回的具体发生的事情
    int index_;
    bool       logHup_;
    
    std::weak_ptr<void> tie_;
    int tied_;
    bool eventHandling_;
    bool addedToLoop_;

    //channel通道可以获知fd最终发生的具体时间revents，所以它负责调用具体事件的回调操作
    ReadEventCallback readCallback_;
    EventCallback writeCallback_;
    EventCallback closeCallback_;
    EventCallback errorCallback_;

    
};

#include"channel.hpp"
#include"eventloop.hpp"
#include"logger.hpp"

#include<sys/epoll.h>

//事件状态标志
const int kNoneEvent = 0;
const int kReadEvent = EPOLLIN | EPOLLPRI;
const int kWriteEvent = EPOLLOUT;

Channel::Channel(EventLoop* loop,int fd)
    : loop_(loop),fd_(fd),events_(0),revents_(0),index_(-1),
    logHup_(true),tied_(false),eventHandling_(false),addedToLoop_(false)
{
}

Channel::~Channel(){}

void Channel::tie(const std::shared_ptr<void> &obj){
    tie_ = obj;
    tied_ = true;
}

//当改变了channel所表示的fd的events事件后，update负责在poller中修改fd相应事件的epoll_ctl
void Channel::update(){
    /*
        当channel所属的EventLoop调用poller的相应方法，注册fd的events事件
        add code...
    */
}
    
//用完了把自己咔嚓了
void Channel::remove(){
    //add code...
}

void Channel::handleEvent(timestamp receiveTime){
    
    if (tied_){     //对于tied_的在哪里被修改使用目前是个未知数
        std::shared_ptr<void> guard = tie_.lock();
        if (guard){
            handleEventWithGuard(receiveTime);
        }
    }
    else{
        handleEventWithGuard(receiveTime);
    }

}

//根据具体接收到的事件，执行相应的回调操作
void Channel::handleEventWithGuard(timestamp receiveTime){
    LOG_INFO("channel handleEvent revents:%d",revents_);

    if((revents_ & EPOLLHUP) && !(revents_ & EPOLLIN)){ //发生异常
        if(closeCallback_){
            closeCallback_();
        }
    }

    if(revents_ & EPOLLERR){    //发生错误
        if(errorCallback_){
            errorCallback_();
        }
    }

    //有可读事件
    if(revents_ & (EPOLLIN | EPOLLPRI)){
        if(readCallback_){
            readCallback_(receiveTime);
        }
    }

    //有可写事件
    if(revents_ & EPOLLOUT){
        if(writeCallback_){
            writeCallback_();
        }
    }
}