muduo源码剖析之Acceptor监听类

简介

Acceptor类用于创建套接字，设置套接字选项，调用socket()->bind()->listen()->accept()函数，接受连接，然后调用TcpServer设置的connect事件的回调。

listen()//在TcpServer::start中调用

封装了一个listen fd相关的操作,用于mainLoop

成员及属性解析

Acceptor - 逻辑上的内部类

接受器封装，实质上就是对Channel的多一层封装

主要接口

listen

监听连接
当新连接进入时，调用Socket::accept创建套接字，触发TcpServer的回调

setNewConnectionCallback

TcpServer通过该接口设置回调，当新连接套接字创建后，创建TcpConnection对象

核心实现：

通过socket::accept接受新连接，获得套接字fd
这个fd作为参数调用TcpServer注册的回调

主要成员

• loop
• channel
• idlefd
  非常巧妙的设计，在服务器压力过大，无法新建文件描述符时，通过这个idlefd拒绝连接
  来自libevent的设计

源码剖析

Acceptor.h

#ifndef MUDUO_NET_ACCEPTOR_H
#define MUDUO_NET_ACCEPTOR_H#include <functional>#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 : noncopyable
{public:typedef std::function<void (int sockfd, const InetAddress&)> NewConnectionCallback;Acceptor(EventLoop* loop, const InetAddress& listenAddr, bool reuseport);~Acceptor();void setNewConnectionCallback(const NewConnectionCallback& cb){ newConnectionCallback_ = cb; }void listen();bool listening() const { return listening_; }// Deprecated, use the correct spelling one above.// Leave the wrong spelling here in case one needs to grep it for error messages.// bool listenning() const { return listening(); }private:void handleRead();EventLoop* loop_;Socket acceptSocket_;Channel acceptChannel_;NewConnectionCallback newConnectionCallback_;bool listening_;int idleFd_;
};}  // namespace net
}  // namespace muduo#endif  // MUDUO_NET_ACCEPTOR_H

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/base/Logging.h"
#include "muduo/net/EventLoop.h"
#include "muduo/net/InetAddress.h"
#include "muduo/net/SocketsOps.h"#include <errno.h>
#include <fcntl.h>
//#include <sys/types.h>
//#include <sys/stat.h>
#include <unistd.h>using namespace muduo;
using namespace muduo::net;Acceptor::Acceptor(EventLoop* loop, const InetAddress& listenAddr, bool reuseport): loop_(loop),acceptSocket_(sockets::createNonblockingOrDie(listenAddr.family())),//创建一个非阻塞的socket fdacceptChannel_(loop, acceptSocket_.fd()),//创建socket fd的channellistening_(false),//是否处于监听状态idleFd_(::open("/dev/null", O_RDONLY | O_CLOEXEC))
{assert(idleFd_ >= 0);acceptSocket_.setReuseAddr(true);			//设置ip地址复用acceptSocket_.setReusePort(reuseport);	//设置端口复用acceptSocket_.bindAddress(listenAddr);	//bind()函数封装,绑定ip和端口acceptChannel_.setReadCallback(std::bind(&Acceptor::handleRead, this));//设置accept的回调函数
}Acceptor::~Acceptor()
{acceptChannel_.disableAll();//将mainloop poller监听集合中移除,取消所有事件的监听acceptChannel_.remove();//在events_删除channel::close(idleFd_);//关闭文件
}void Acceptor::listen()//开始监听fd
{loop_->assertInLoopThread();//判断是不是和创建时的io线程处于同一个线程listening_ = true;//是否监听acceptSocket_.listen();//真正的监听函数acceptChannel_.enableReading();//设置监听读事件
}void Acceptor::handleRead()//当有client connnect时,则会调用
{loop_->assertInLoopThread();InetAddress peerAddr;//FIXME loop until no moreint connfd = acceptSocket_.accept(&peerAddr);//接收client connect,返回值==accept()返回值if (connfd >= 0){// string hostport = peerAddr.toIpPort();// LOG_TRACE << "Accepts of " << hostport;if (newConnectionCallback_)//如果设置了connect cb,则调用,否则则关闭这个连接{newConnectionCallback_(connfd, peerAddr);}else{sockets::close(connfd);}}else{LOG_SYSERR << "in Acceptor::handleRead";// Read the section named "The special problem of// accept()ing when you can't" in libev's doc.// By Marc Lehmann, author of libev.if (errno == EMFILE){::close(idleFd_);idleFd_ = ::accept(acceptSocket_.fd(), NULL, NULL);::close(idleFd_);idleFd_ = ::open("/dev/null", O_RDONLY | O_CLOEXEC);}}
}