简介
Connector负责主动发起连接,不负责创建socket,只负责连接的建立,外部调用Connector::start就可以发起连接,Connector具有重连的功能和停止连接的功能,连接成功建立后返回到TcpClient。
主要成员及属性解析
主要接口
setNewConnectionCallback
设置TcpClient交给的回调函数
start
最后通过loop的runInLoop调用
调用connect内部实现
stop
最终通过loop的queueInLoop调用
回收Channel控制的套接字(如果有的话)
设置connect_标记为false
retry
若connect_标记为true,则重连
核心实现:connect
调用Socket::connect方法连接服务端
连接成功后,创建一个Channel
将自身的handleWrite回调注册到Channel上,并激活可写事件关注
核心实现:handleWrite
根据getSockError的情况决定调用创建连接回调,或是错误回调,或retry操作
其中包含了TcpClient注册的回调newConnection
主要成员
loop
所属的workloop
channel
unique_ptr指针,仅在连接建立时动态创建Channel对象
当channel触发可写事件时,执行handleWrite
并在handleWrite中执行TcpClient的newConnection
serverAddr
服务端的inetaddr地址信息
connect_
非常重要的一个标记,决定了是否retry
源码剖析
代码已编写完整注释,
Connector.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_CONNECTOR_H
#define MUDUO_NET_CONNECTOR_H#include "muduo/base/noncopyable.h"
#include "muduo/net/InetAddress.h"#include <functional>
#include <memory>namespace muduo
{
namespace net
{class Channel;
class EventLoop;//负责主动发起连接,不负责创建socket,只负责连接的建立
class Connector : noncopyable,public std::enable_shared_from_this<Connector>
{public:typedef std::function<void (int sockfd)> NewConnectionCallback;Connector(EventLoop* loop, const InetAddress& serverAddr);~Connector();//设置新连接到来时的回调函数void setNewConnectionCallback(const NewConnectionCallback& cb){ newConnectionCallback_ = cb; }void start(); // can be called in any threadvoid restart(); // must be called in loop threadvoid stop(); // can be called in any thread//返回服务器的地址信息const InetAddress& serverAddress() const { return serverAddr_; }private:enum States { kDisconnected, kConnecting, kConnected };static const int kMaxRetryDelayMs = 30*1000;static const int kInitRetryDelayMs = 500;//设置连接状态void setState(States s) { state_ = s; }//在loop中执行的start启动操作void startInLoop();//在loop中执行的stop暂停操作void stopInLoop();//请求连接服务器void connect();//连接服务器成功后设置channel事件void connecting(int sockfd);//写事件回调void handleWrite();//错误发生回调void handleError();//重连void retry(int sockfd);//移除并释放channelint removeAndResetChannel();//释放channelvoid resetChannel();//所属的EventLoopEventLoop* loop_;//要连接的server地址InetAddress serverAddr_;//是否连接服务器标志bool connect_; // atomic//连接状态States state_; // FIXME: use atomic variable//对应的channelstd::unique_ptr<Channel> channel_;//连接成功时的回调函数NewConnectionCallback newConnectionCallback_;//重连间隔时间int retryDelayMs_;
};} // namespace net
} // namespace muduo#endif // MUDUO_NET_CONNECTOR_H
Connector.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)
//#include "muduo/net/Connector.h"#include "muduo/base/Logging.h"
#include "muduo/net/Channel.h"
#include "muduo/net/EventLoop.h"
#include "muduo/net/SocketsOps.h"#include <errno.h>using namespace muduo;
using namespace muduo::net;const int Connector::kMaxRetryDelayMs;Connector::Connector(EventLoop* loop, const InetAddress& serverAddr): loop_(loop),serverAddr_(serverAddr),connect_(false),state_(kDisconnected),retryDelayMs_(kInitRetryDelayMs)
{LOG_DEBUG << "ctor[" << this << "]";
}Connector::~Connector()
{LOG_DEBUG << "dtor[" << this << "]";assert(!channel_);
}void Connector::start()
{connect_ = true;//在所属IO线程Lloop中调用该函数,连接服务器loop_->runInLoop(std::bind(&Connector::startInLoop, this)); // FIXME: unsafe
}void Connector::startInLoop()
{loop_->assertInLoopThread();assert(state_ == kDisconnected);if (connect_){connect();//请求连接}else{LOG_DEBUG << "do not connect";}
}void Connector::stop()
{connect_ = false;loop_->queueInLoop(std::bind(&Connector::stopInLoop, this)); // FIXME: unsafe// FIXME: cancel timer
}void Connector::stopInLoop()
{loop_->assertInLoopThread();if (state_ == kConnecting){//将状态设置为断开连接setState(kDisconnected);//移除并释放channelint sockfd = removeAndResetChannel();retry(sockfd);}
}//连接服务器
void Connector::connect()
{//创建一个非阻塞的socket fdint sockfd = sockets::createNonblockingOrDie(serverAddr_.family());//请求连接服务器int ret = sockets::connect(sockfd, serverAddr_.getSockAddr());int savedErrno = (ret == 0) ? 0 : errno;switch (savedErrno){case 0:case EINPROGRESS:case EINTR:case EISCONN:connecting(sockfd);break;case EAGAIN:case EADDRINUSE:case EADDRNOTAVAIL:case ECONNREFUSED:case ENETUNREACH:retry(sockfd);//重连break;case EACCES:case EPERM:case EAFNOSUPPORT:case EALREADY:case EBADF:case EFAULT:case ENOTSOCK:LOG_SYSERR << "connect error in Connector::startInLoop " << savedErrno;sockets::close(sockfd);break;default:LOG_SYSERR << "Unexpected error in Connector::startInLoop " << savedErrno;sockets::close(sockfd);// connectErrorCallback_();break;}
}void Connector::restart()
{loop_->assertInLoopThread();//设置标志为断开连接setState(kDisconnected);retryDelayMs_ = kInitRetryDelayMs;connect_ = true;//启动startInLoop();
}//连接服务器成功后设置channel事件
void Connector::connecting(int sockfd)
{setState(kConnecting);//设置状态为正在连接assert(!channel_);//创建一个channelchannel_.reset(new Channel(loop_, sockfd));//设置读事件回调channel_->setWriteCallback(std::bind(&Connector::handleWrite, this)); // FIXME: unsafe//设置错误事件回调channel_->setErrorCallback(std::bind(&Connector::handleError, this)); // FIXME: unsafe// channel_->tie(shared_from_this()); is not working,// as channel_ is not managed by shared_ptr//注册可写事件channel_->enableWriting();
}//移除并释放channel
int Connector::removeAndResetChannel()
{//取消所有事件的监听channel_->disableAll();//将channel从loop中移除channel_->remove();//释放channelint sockfd = channel_->fd();// Can't reset channel_ here, because we are inside Channel::handleEventloop_->queueInLoop(std::bind(&Connector::resetChannel, this)); // FIXME: unsafereturn sockfd;
}void Connector::resetChannel()
{//释放unique_ptr所指向的资源,也就是channelchannel_.reset();
}//可写事件的回调函数
void Connector::handleWrite()
{LOG_TRACE << "Connector::handleWrite " << state_;if (state_ == kConnecting){//移除channel(Connector的channel只管理建立连接的阶段),成功建立连接后//交给TcpClient的TcpConnection来管理int sockfd = removeAndResetChannel();//可写并不一定连接建立成功//如果连接发生错误,socket会是可读可写的//所以还需要调用getsockopt检查是否出错int err = sockets::getSocketError(sockfd);if (err){LOG_WARN << "Connector::handleWrite - SO_ERROR = "<< err << " " << strerror_tl(err);retry(sockfd);//出错重连}else if (sockets::isSelfConnect(sockfd))//是否是自连接{LOG_WARN << "Connector::handleWrite - Self connect";retry(sockfd);}else{//连接成功建立,更改状态//调用TcpClient设置的回调函数,创建TcpConnection对象 setState(kConnected);//设置状态为已经成功连接if (connect_){newConnectionCallback_(sockfd);}else{sockets::close(sockfd);}}}else{// what happened?assert(state_ == kDisconnected);}
}void Connector::handleError()
{LOG_ERROR << "Connector::handleError state=" << state_;if (state_ == kConnecting){int sockfd = removeAndResetChannel();int err = sockets::getSocketError(sockfd);LOG_TRACE << "SO_ERROR = " << err << " " << strerror_tl(err);retry(sockfd);}
}//重连
void Connector::retry(int sockfd)
{//socket是一次性的,失败后需要关闭重新创建sockets::close(sockfd);//将状态设置为断开连接setState(kDisconnected);if (connect_){LOG_INFO << "Connector::retry - Retry connecting to " << serverAddr_.toIpPort()<< " in " << retryDelayMs_ << " milliseconds. ";//隔一段时间后重连,重新执行startInLooploop_->runAfter(retryDelayMs_/1000.0,std::bind(&Connector::startInLoop, shared_from_this()));//间隔时间翻倍retryDelayMs_ = std::min(retryDelayMs_ * 2, kMaxRetryDelayMs);}else{LOG_DEBUG << "do not connect";}
}