Channel类详解[1-3]

Channel.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_CHANNEL_H
#define MUDUO_NET_CHANNEL_H


#include <boost/function.hpp>
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/weak_ptr.hpp>


#include <muduo/base/Timestamp.h>


namespace muduo
{
namespace net
{


class EventLoop;


///
/// A selectable I/O channel.
///
/// This class doesn't own the file descriptor.
/// The file descriptor could be a socket,
/// an eventfd, a timerfd, or a signalfd
class Channel : boost::noncopyable
{
 public:
  /*
EventCallback 为指向Channel 类的成员函数void();
ReadEventCallback 为指向Channel 类的成员函数void(Timestamp)
  */
  typedef boost::function<void()> EventCallback;
  typedef boost::function<void(Timestamp)> ReadEventCallback;


  Channel(EventLoop* loop, int fd);
  ~Channel();


  void handleEvent(Timestamp receiveTime);


  /*
将ReadEventCallback 指向的函数赋给对象成员
将EventCallback 指向的函数赋给对象成员
  */
  void setReadCallback(const ReadEventCallback& cb)
  { readCallback_ = cb; }
  void setWriteCallback(const EventCallback& cb)
  { writeCallback_ = cb; }
  void setCloseCallback(const EventCallback& cb)
  { closeCallback_ = cb; }
  void setErrorCallback(const EventCallback& cb)
  { errorCallback_ = cb; }


  /// Tie this channel to the owner object managed by shared_ptr,
  /// prevent the owner object being destroyed in handleEvent.
  void tie(const boost::shared_ptr<void>&);


  int fd() const { return fd_; }
  int events() const { return events_; }
  void set_revents(int revt) { revents_ = revt; } // used by pollers
  // 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; }


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


  // for debug
  string reventsToString() const;


  void doNotLogHup() { logHup_ = false; }


  EventLoop* ownerLoop() { return loop_; }
  void remove();


 private:
  void update();
  void handleEventWithGuard(Timestamp receiveTime);


  static const int kNoneEvent;
  static const int kReadEvent;
  static const int kWriteEvent;


  EventLoop* loop_;
  const int  fd_;
  int        events_;
  int        revents_;
  int        index_; // used by Poller.
  bool       logHup_;


  boost::weak_ptr<void> tie_;
  bool tied_;
  bool eventHandling_;
  ReadEventCallback readCallback_;
  EventCallback writeCallback_;
  EventCallback closeCallback_;
  EventCallback errorCallback_;
};


}
}
#endif  // MUDUO_NET_CHANNEL_H

Channel.cpp

// 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/base/Logging.h>
#include <muduo/net/Channel.h>
#include <muduo/net/EventLoop.h>


#include <sstream>


#include <poll.h>


using namespace muduo;
using namespace muduo::net;


const int Channel::kNoneEvent = 0;
const int Channel::kReadEvent = POLLIN | POLLPRI;
const int Channel::kWriteEvent = POLLOUT;


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


Channel::~Channel()
{
  assert(!eventHandling_);
}




/*弱函数指针tie_ 指向了强函数指针obj, 
tied_ = true表明弱函数指针tie_  已经被赋值*/
void Channel::tie(const boost::shared_ptr<void>& obj)
{
  tie_ = obj;
  tied_ = true;
}


void Channel::update()
{
  loop_->updateChannel(this);
}


void Channel::remove()
{
  assert(isNoneEvent());
  loop_->removeChannel(this);
}



void Channel::handleEvent(Timestamp receiveTime)
{
  boost::shared_ptr<void> guard;
  if (tied_)
  {
    guard = tie_.lock();
    if (guard)
    {
      handleEventWithGuard(receiveTime);
    }
  }
  else
  {
    handleEventWithGuard(receiveTime);
  }
}




/*根据当前socketfd 对应的revents_ 发生的事件调用
设置好的不同的回调函数
readCallback_;
writeCallback_;
closeCallback_;
errorCallback_;
*/
void Channel::handleEventWithGuard(Timestamp receiveTime)
{
  eventHandling_ = true;
  if ((revents_ & POLLHUP) && !(revents_ & POLLIN))
  {
    if (logHup_)
    {
      LOG_WARN << "Channel::handle_event() POLLHUP";
    }
    if (closeCallback_) closeCallback_();
  }


  if (revents_ & POLLNVAL)
  {
    LOG_WARN << "Channel::handle_event() POLLNVAL";
  }


  if (revents_ & (POLLERR | POLLNVAL))
  {
    if (errorCallback_) errorCallback_();
  }
  if (revents_ & (POLLIN | POLLPRI | POLLRDHUP))
  {
    if (readCallback_) readCallback_(receiveTime);
  }
  if (revents_ & POLLOUT)
  {
    if (writeCallback_) writeCallback_();
  }
  eventHandling_ = false;
}


string Channel::reventsToString() const
{
  std::ostringstream oss;
  oss << fd_ << ": ";
  if (revents_ & POLLIN)
    oss << "IN ";
  if (revents_ & POLLPRI)
    oss << "PRI ";
  if (revents_ & POLLOUT)
    oss << "OUT ";
  if (revents_ & POLLHUP)
    oss << "HUP ";
  if (revents_ & POLLRDHUP)
    oss << "RDHUP ";
  if (revents_ & POLLERR)
    oss << "ERR ";
  if (revents_ & POLLNVAL)
    oss << "NVAL ";


  return oss.str().c_str();
}

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