muduo源码剖析之TcpClient客户端类-编程知识

简介

muduo用TcpClient发起连接，TcpClient有一个Connector连接器，TCPClient使用Conneccor发起连接, 连接建立成功后, 用socket创建TcpConnection来管理连接, 每个TcpClient class只管理一个TcpConnecction，连接建立成功后设置相应的回调函数。很显然，TcpClient用来管理客户端连接，真正连接交给Connector。

主要成员及属性解析

主要接口

回调setters

这些回调函数会在新连接建立时，通过newConnection内部实现方法传递给TcpConnction对象

核心实现：newConnection

在构造时将这个函数作为回调注册给connector_对象
在Connector中的Channel执行本回调后，创建一个新的TcpConnection对象

connect

调用Connector的start接口

stop

调用Connector的stop接口

主要成员

loop

所属workloop

connector

TcpClient所维护的一个连接器

retry_

重连标志

TcpConnection connection_

TcpClient所维护的一个TCP连接对象
关于连接中回调的传递，参考下面的简图：

eb602a687d5a49408a8209145c038271

源码剖析

代码已编写完整注释,

TcpClient.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 a public header file, it must only include public header files.#ifndef MUDUO_NET_TCPCLIENT_H
#define MUDUO_NET_TCPCLIENT_H#include "muduo/base/Mutex.h"
#include "muduo/net/TcpConnection.h"namespace muduo
{
namespace net
{class Connector;
typedef std::shared_ptr<Connector> ConnectorPtr;class TcpClient : noncopyable
{public:// TcpClient(EventLoop* loop);// TcpClient(EventLoop* loop, const string& host, uint16_t port);TcpClient(EventLoop* loop,const InetAddress& serverAddr,const string& nameArg);~TcpClient();  // force out-line dtor, for std::unique_ptr members.void connect();//请求连接void disconnect();//断开连接void stop();//停止连接TcpConnectionPtr connection() const{MutexLockGuard lock(mutex_);return connection_;}EventLoop* getLoop() const { return loop_; }bool retry() const { return retry_; }void enableRetry() { retry_ = true; }const string& name() const{ return name_; }/// Set connection callback./// Not thread safe.void setConnectionCallback(ConnectionCallback cb){ connectionCallback_ = std::move(cb); }/// Set message callback./// Not thread safe.void setMessageCallback(MessageCallback cb){ messageCallback_ = std::move(cb); }/// Set write complete callback./// Not thread safe.void setWriteCompleteCallback(WriteCompleteCallback cb){ writeCompleteCallback_ = std::move(cb); }private:/// Not thread safe, but in loop//新连接建立后的回调函数,将新连接封装为TcpConnection交给TcpClient来管理void newConnection(int sockfd);/// Not thread safe, but in loop释放连接void removeConnection(const TcpConnectionPtr& conn);//所属loopEventLoop* loop_;//Connector,用来处理连接阶段,ConnectorPtr connector_; // avoid revealing Connectorconst string name_;ConnectionCallback connectionCallback_;//连接回调MessageCallback messageCallback_;//消息回调WriteCompleteCallback writeCompleteCallback_;//数据发送完成回调//是否重连bool retry_;   // atomic//是否连接bool connect_; // atomic// always in loop threadint nextConnId_;mutable MutexLock mutex_;//管理连接的TcpConnectionTcpConnectionPtr connection_ GUARDED_BY(mutex_);
};}  // namespace net
}  // namespace muduo#endif  // MUDUO_NET_TCPCLIENT_H

TcpClient.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/TcpClient.h"#include "muduo/base/Logging.h"
#include "muduo/net/Connector.h"
#include "muduo/net/EventLoop.h"
#include "muduo/net/SocketsOps.h"#include <stdio.h>  // snprintfusing namespace muduo;
using namespace muduo::net;// TcpClient::TcpClient(EventLoop* loop)
//   : loop_(loop)
// {
// }// TcpClient::TcpClient(EventLoop* loop, const string& host, uint16_t port)
//   : loop_(CHECK_NOTNULL(loop)),
//     serverAddr_(host, port)
// {
// }namespace muduo
{
namespace net
{
namespace detail
{//断开连接
void removeConnection(EventLoop* loop, const TcpConnectionPtr& conn)
{loop->queueInLoop(std::bind(&TcpConnection::connectDestroyed, conn));
}void removeConnector(const ConnectorPtr& connector)
{//connector->
}}  // namespace detail
}  // namespace net
}  // namespace muduoTcpClient::TcpClient(EventLoop* loop,const InetAddress& serverAddr,const string& nameArg): loop_(CHECK_NOTNULL(loop)),connector_(new Connector(loop, serverAddr)),name_(nameArg),connectionCallback_(defaultConnectionCallback),messageCallback_(defaultMessageCallback),retry_(false),connect_(true),nextConnId_(1)
{//设置Connector新连接建立的回调函数connector_->setNewConnectionCallback(std::bind(&TcpClient::newConnection, this, _1));// FIXME setConnectFailedCallbackLOG_INFO << "TcpClient::TcpClient[" << name_<< "] - connector " << get_pointer(connector_);
}TcpClient::~TcpClient()
{LOG_INFO << "TcpClient::~TcpClient[" << name_<< "] - connector " << get_pointer(connector_);TcpConnectionPtr conn;bool unique = false;{MutexLockGuard lock(mutex_);//检查所管理对象是否仅由当前 shared_ptr 的实例管理unique = connection_.unique();conn = connection_;}if (conn){assert(loop_ == conn->getLoop());// FIXME: not 100% safe, if we are in different thread//执行断开连接操作CloseCallback cb = std::bind(&detail::removeConnection, loop_, _1);loop_->runInLoop(std::bind(&TcpConnection::setCloseCallback, conn, cb));//如果TcpConnection只有一份,那就强行关闭连接if (unique){conn->forceClose();}}else{connector_->stop();// FIXME: HACKloop_->runAfter(1, std::bind(&detail::removeConnector, connector_));}
}//请求连接服务器
void TcpClient::connect()
{// FIXME: check stateLOG_INFO << "TcpClient::connect[" << name_ << "] - connecting to "<< connector_->serverAddress().toIpPort();connect_ = true;connector_->start();
}//断开连接
void TcpClient::disconnect()
{connect_ = false;{MutexLockGuard lock(mutex_);if (connection_){connection_->shutdown();}}
}void TcpClient::stop()
{connect_ = false;connector_->stop();
}//新连接建立后的回调函数,将新连接封装为TcpConnection交给TcpClient来管理
void TcpClient::newConnection(int sockfd)
{loop_->assertInLoopThread();//获取服务器地址并打印InetAddress peerAddr(sockets::getPeerAddr(sockfd));char buf[32];snprintf(buf, sizeof buf, ":%s#%d", peerAddr.toIpPort().c_str(), nextConnId_);++nextConnId_;string connName = name_ + buf;//获取client地址InetAddress localAddr(sockets::getLocalAddr(sockfd));// FIXME poll with zero timeout to double confirm the new connection// FIXME use make_shared if necessary//创建一个TcpConnection,并设置相关回调TcpConnectionPtr conn(new TcpConnection(loop_,connName,sockfd,localAddr,peerAddr));conn->setConnectionCallback(connectionCallback_);conn->setMessageCallback(messageCallback_);conn->setWriteCompleteCallback(writeCompleteCallback_);conn->setCloseCallback(std::bind(&TcpClient::removeConnection, this, _1)); // FIXME: unsafe{MutexLockGuard lock(mutex_);connection_ = conn;}//调用连接建立函数conn->connectEstablished();
}//释放连接
void TcpClient::removeConnection(const TcpConnectionPtr& conn)
{loop_->assertInLoopThread();assert(loop_ == conn->getLoop());{MutexLockGuard lock(mutex_);assert(connection_ == conn);//释放TcpConnectionconnection_.reset();}//在所属loop中执行连接断开释放操作loop_->queueInLoop(std::bind(&TcpConnection::connectDestroyed, conn));//如果设置了重连并且连接标志为true,那就重新连接if (retry_ && connect_){LOG_INFO << "TcpClient::connect[" << name_ << "] - Reconnecting to "<< connector_->serverAddress().toIpPort();connector_->restart();//重新启动}
}