C++深入刨析muduo中的抽象类Poller

#include <map>
#include <vector>
#include "muduo/base/Timestamp.h"
#include "muduo/net/EventLoop.h"
namespace muduo
{
namespace net
{
class Channel;
class Poller : noncopyable
{
 public:
  typedef std::vector<Channel*> ChannelList;
  Poller(EventLoop* loop);
  virtual ~Poller();
  virtual Timestamp poll(int timeoutMs, ChannelList* activeChannels) = 0;
  virtual void updateChannel(Channel* channel) = 0;
  virtual void removeChannel(Channel* channel) = 0;
  virtual bool hasChannel(Channel* channel) const;
  static Poller* newDefaultPoller(EventLoop* loop);
  void assertInLoopThread() const
  {
    ownerLoop_->assertInLoopThread();
  }
 protected:
  typedef std::map<int, Channel*> ChannelMap;
  ChannelMap channels_;
 private:
  EventLoop* ownerLoop_;
};
}  // namespace net
}  // namespace muduo

 protected:
  typedef std::map<int, Channel*> ChannelMap;
  ChannelMap channels_;
 private:
  EventLoop* ownerLoop_;  // 表示Poller所属的事件循环EventLoop

#pragma once
#include "noncopyable.h"
#include "Timestamp.h"
#include <vector>
#include <unordered_map>
class Channel;  //只用到指针类型，如果需要用到实例就要包含相应头文件，类型声明是没用的
class EventLoop;
// muduo库中多路事件分发器的核心IO复用模块
class Poller : noncopyable{
    public:
        using ChannelList = std::vector<Channel*>;
        Poller(EventLoop *loop);
        virtual ~Poller();
        // 给所有IO复用保留统一的接口  epoll_wait
        virtual Timestamp poll(int timeoutMs, ChannelList* activeChannels) = 0;
        // 更新感兴趣的事件  epoll_ctl  EPOLL_CTL_ADD  EPOLL_CTL_MOD
        virtual void updateChannel(Channel* channel) = 0;
        // eventloop中删除channel  epoll_ctl  EPOLL_CTL_DEL
        virtual void removeChannel(Channel* channel) = 0;
        // 判断Poller里是否包含某个channel
        bool hasChannel(Channel* channel) const;
        // EventLoop可以通过newDefaultPoller获取一个Poller实例
        static Poller* newDefaultPoller(EventLoop* loop);
    protected:
        // key:sockfd，value:sockfd所属的Channel
        using ChannelMap = std::unordered_map<int, Channel*>;
        ChannelMap channels_;
    private:
        EventLoop* ownerLoop_;  // Poller所属的事件循环
};

#include "Poller.h"
#include "Channel.h"
Poller::Poller(EventLoop *loop)
    : ownerLoop_(loop)
{}
Poller::~Poller() = default;
bool Poller::hasChannel(Channel* channel) const{
    auto iter = channels_.find(channel->fd());
    return iter != channels_.end() && iter->second == channel;  // 找到fd且channel相等
}

#include "muduo/net/Poller.h"
#include "muduo/net/poller/PollPoller.h"
#include "muduo/net/poller/EPollPoller.h"
#include <stdlib.h>
using namespace muduo::net;
Poller* Poller::newDefaultPoller(EventLoop* loop)
{
  if (::getenv("MUDUO_USE_POLL"))
  {
    return new PollPoller(loop);  // 环境变量中有MUDUO_USE_POLL，则返回PollPoller实例
  }
  else
  {
    return new EPollPoller(loop); // 默认返回EPollPoller实例
  }
}

#include <stdlib.h>
#include "Poller.h"
#include "EPollPoller.h"
Poller* Poller::newDefaultPoller(EventLoop* loop){
    if(std::getenv("MUDUO_USE_POLL")){
        // new poll的实例
        return nullptr;
    }else{
        return new EPollPoller(loop);
    }
}