Acceptor （32）

1. Acceptor用于accept(2)接受TCP连接

2. Acceptor的数据成员包括Socket、Channel，Acceptor的socket是listening socket（即server socket）。Channel用于观察此socket的readable事件，并回调Accptor::handleRead()，后者调用accept(2)来接受新连接，并回调用户callback。

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Acceptor的头文件

Acceptor.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_ACCEPTOR_H
#define MUDUO_NET_ACCEPTOR_H

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

#include <muduo/net/Channel.h>
#include <muduo/net/Socket.h>

namespace muduo
{
namespace net
{

class EventLoop;
class InetAddress;

///
/// Acceptor of incoming TCP connections.
///
class Acceptor : boost::noncopyable
{
 public:
  typedef boost::function<void (int sockfd,
                                const InetAddress&)> NewConnectionCallback;

  Acceptor(EventLoop* loop, const InetAddress& listenAddr);
  ~Acceptor();

  void setNewConnectionCallback(const NewConnectionCallback& cb)
  { newConnectionCallback_ = cb; }

  bool listenning() const { return listenning_; }
  void listen();

 private:
  /*这是监听套接字的可读事件的套接字*/
  void handleRead();

  EventLoop* loop_;
  Socket acceptSocket_; /*监听套接字*/
  ;/*通道 会观察acceptSocket_监听套接字的可读事件，这个channel所属的eventloop是loop_*/
  Channel acceptChannel_;
  NewConnectionCallback newConnectionCallback_;
  /*是否处于监听的状态*/
  bool listenning_;
  int idleFd_;
};

}
}

#endif  // MUDUO_NET_ACCEPTOR_H

Acceptor源文件

Acceptor.cc

// 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/net/Acceptor.h>

#include <muduo/net/EventLoop.h>
#include <muduo/net/InetAddress.h>
#include <muduo/net/SocketsOps.h>

#include <boost/bind.hpp>

#include <errno.h>
#include <fcntl.h>
//#include <sys/types.h>
//#include <sys/stat.h>

using namespace muduo;
using namespace muduo::net;

Acceptor::Acceptor(EventLoop* loop, const InetAddress& listenAddr)
  : loop_(loop),
  /*创建一个监听套接字*/
    acceptSocket_(sockets::createNonblockingOrDie()),
  /*acceptchannel 关注acceptSocket_套接字的事件 */
    acceptChannel_(loop, acceptSocket_.fd()),
    listenning_(false),
    /*预先准备一个文件描述符*/
    idleFd_(::open("/dev/null", O_RDONLY | O_CLOEXEC))
{
  assert(idleFd_ >= 0);
  /*设置地址重复利用*/
  acceptSocket_.setReuseAddr(true);
  /*绑定地址*/
  acceptSocket_.bindAddress(listenAddr);
  /*设置监听套接字“读”的套接字*/
  acceptChannel_.setReadCallback(
      boost::bind(&Acceptor::handleRead, this));
}

/*虚构函数*/
Acceptor::~Acceptor()
{
  /*先取消 acceptSocket_的所有事件，然后才移除*/
  acceptChannel_.disableAll();
  acceptChannel_.remove();
  ::close(idleFd_);
}
/*监听 监听套接字*/
void Acceptor::listen()
{/*断言在IO线程中*/
  loop_->assertInLoopThread();

  listenning_ = true;
  acceptSocket_.listen();
  /*关注acceptSocket_的可读事件*/
  acceptChannel_.enableReading();
}

/*监听套接字的可读事件的回调函数*/
void Acceptor::handleRead()
{
  /*断言在IO线程中*/
  loop_->assertInLoopThread();
  /*创建一个对等方的地址，这是客户端的地址*/
  InetAddress peerAddr(0);
  //FIXME loop until no more
  /*对等连接套接字*/
  int connfd = acceptSocket_.accept(&peerAddr);
  if (connfd >= 0)
  {
    // string hostport = peerAddr.toIpPort();
    // LOG_TRACE << "Accepts of " << hostport;
    /*回调上层（应用层）的回调函数*/
    if (newConnectionCallback_)
    {
      newConnectionCallback_(connfd, peerAddr);
    }
    /*如果应用层没有回调函数，则直接关闭此连接套接字*/
    else
    {
      sockets::close(connfd);
    }
  }
  else
  {
    // Read the section named "The special problem of
    // accept()ing when you can't" in libev's doc.
    // By Marc Lehmann, author of livev.
    /*如果是文件符超出限制*/
    if (errno == EMFILE)
    {
      /**/
      ::close(idleFd_);
      /*因为这是电平触发，所以为了防止一直触发，可以先接受，然后关闭掉*/
      idleFd_ = ::accept(acceptSocket_.fd(), NULL, NULL);
      ::close(idleFd_);
      idleFd_ = ::open("/dev/null", O_RDONLY | O_CLOEXEC);
    }
  }
}

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测试程序

#include <muduo/net/Acceptor.h>
#include <muduo/net/EventLoop.h>
#include <muduo/net/InetAddress.h>
#include <muduo/net/SocketsOps.h>

#include <stdio.h>

using namespace muduo;
using namespace muduo::net;

void newConnection(int sockfd, const InetAddress& peerAddr)
{
  printf("newConnection(): accepted a new connection from %s\n",
         peerAddr.toIpPort().c_str());
  ::write(sockfd, "How are you?\n", 13);
  sockets::close(sockfd);
}

int main()
{
  printf("main(): pid = %d\n", getpid());

  InetAddress listenAddr(8888);
  EventLoop loop;

  Acceptor acceptor(&loop, listenAddr);
  acceptor.setNewConnectionCallback(newConnection);
  acceptor.listen();

  loop.loop();
}

程序输出

ubuntu@ubuntu-virtual-machine:~$ telnet 127.0.0.1 8888
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
How Are You ?
Connection closed by foreign host.
ubuntu@ubuntu-virtual-machine:~$ telnet 127.0.0.1 8888
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
How Are You ?
Connection closed by foreign host.
ubuntu@ubuntu-virtual-machine:~$