muduo网络库之Acceptor、TcpServer

本篇博客针对Acceptor类和TcpServer类做下小结。

博客代码来自于陈硕的muduo网络库，github地址https://github.com/chenshuo/muduo

学习笔记：

Acceptor类专注于做一件事情，就是在服务端接收所有的客户端请求，将连接成功的客户端交给TcpServer进一步处理。当服务端处于“1+N”多线程模式时，Acceptor的所有IO事件在“1”代表的线程中执行，连接进来的多个客户端在“N”代表的线程池中执行IO事件。

TcpServer类作为用户可见类，用户可以设置线程池中子线程数量，当有新连接进来时，TcpServer循环抽取一个子线程处理该连接的IO事件，从而保证各子线程的负载平衡。

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();//设置新连接回调，Acceptor把新连接交给上层的TcpServer处理void setNewConnectionCallback(const NewConnectionCallback& cb){ newConnectionCallback_ = cb; }bool listenning() const { return listenning_; }void listen();//监听服务端private:void handleRead();//acceptSocket_有新来的连接EventLoop* loop_;      //通过loop_将acceptSocket_监听读事件注册到Poller中Socket acceptSocket_;  //等待socket等待客户端连接Channel acceptChannel_;//监听acceptSocket_描述符上的读事件NewConnectionCallback newConnectionCallback_;//TcpServer的新连接回调bool listenning_;int idleFd_;//预留空文件描述符，预防客户端连接数太多导致服务端无法连接
};}  // namespace net
}  // namespace muduo#endif  // MUDUO_NET_ACCEPTOR_H

Acceptor.cpp

#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())),//创建非阻塞socketacceptChannel_(loop, acceptSocket_.fd()),listenning_(false),idleFd_(::open("/dev/null", O_RDONLY | O_CLOEXEC))//打开一个空文件
{assert(idleFd_ >= 0);acceptSocket_.setReuseAddr(true);acceptSocket_.setReusePort(reuseport);acceptSocket_.bindAddress(listenAddr);acceptChannel_.setReadCallback(std::bind(&Acceptor::handleRead, this));//当acceptSocket_有新连接时会调用该回调
}Acceptor::~Acceptor()
{//注销Poller中的acceptChannel_acceptChannel_.disableAll();acceptChannel_.remove();//关闭空文件描述符::close(idleFd_);
}void Acceptor::listen()
{loop_->assertInLoopThread();listenning_ = true;//acceptSocket_监听新连接acceptSocket_.listen();//当acceptSocket_监听到了新连接，acceptChannel_同时也获取到了读事件acceptChannel_.enableReading();
}void Acceptor::handleRead()
{loop_->assertInLoopThread();InetAddress peerAddr;//FIXME loop until no moreint connfd = acceptSocket_.accept(&peerAddr);if (connfd >= 0){// string hostport = peerAddr.toIpPort();// LOG_TRACE << "Accepts of " << hostport;if (newConnectionCallback_){//把新连接丢给TcpServer处理，Acceptor继续执行监听新连接的工作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){//描述符已经耗尽，把空文件描述符释放出来连接当前接进来的客户端::close(idleFd_);idleFd_ = ::accept(acceptSocket_.fd(), NULL, NULL);//把客户端接进来后立马关闭连接释放仅剩的1个描述符::close(idleFd_);//让这个描述符重新占用空文件idleFd_ = ::open("/dev/null", O_RDONLY | O_CLOEXEC);}}
}

TcpServer.h

#ifndef MUDUO_NET_TCPSERVER_H
#define MUDUO_NET_TCPSERVER_H#include "muduo/base/Atomic.h"
#include "muduo/base/Types.h"
#include "muduo/net/TcpConnection.h"#include <map>namespace muduo
{
namespace net
{class Acceptor;
class EventLoop;
class EventLoopThreadPool;///
/// TCP server, supports single-threaded and thread-pool models.
///
/// This is an interface class, so don't expose too much details.
class TcpServer : noncopyable
{public:typedef std::function<void(EventLoop*)> ThreadInitCallback;enum Option{kNoReusePort,kReusePort,};//TcpServer(EventLoop* loop, const InetAddress& listenAddr);TcpServer(EventLoop* loop,const InetAddress& listenAddr,const string& nameArg,Option option = kNoReusePort);~TcpServer();  // force out-line dtor, for std::unique_ptr members.const string& ipPort() const { return ipPort_; }const string& name() const { return name_; }EventLoop* getLoop() const { return loop_; }/// Set the number of threads for handling input.////// Always accepts new connection in loop's thread./// Must be called before @c start/// @param numThreads/// - 0 means all I/O in loop's thread, no thread will created.///   this is the default value./// - 1 means all I/O in another thread./// - N means a thread pool with N threads, new connections///   are assigned on a round-robin basis.void setThreadNum(int numThreads);  //设置线程池IO线程个数void setThreadInitCallback(const ThreadInitCallback& cb)//设置初始回调{ threadInitCallback_ = cb; }/// valid after calling start()std::shared_ptr<EventLoopThreadPool> threadPool(){ return threadPool_; }/// Starts the server if it's not listenning.////// It's harmless to call it multiple times./// Thread safe.void start(); //开启服务端监听/// Set connection callback./// Not thread safe.void setConnectionCallback(const ConnectionCallback& cb){ connectionCallback_ = cb; }/// Set message callback./// Not thread safe.void setMessageCallback(const MessageCallback& cb){ messageCallback_ = cb; }/// Set write complete callback./// Not thread safe.void setWriteCompleteCallback(const WriteCompleteCallback& cb){ writeCompleteCallback_ = cb; }private:/// Not thread safe, but in loopvoid newConnection(int sockfd, const InetAddress& peerAddr);/// Thread safe.void removeConnection(const TcpConnectionPtr& conn);/// Not thread safe, but in loopvoid removeConnectionInLoop(const TcpConnectionPtr& conn);typedef std::map<string, TcpConnectionPtr> ConnectionMap;EventLoop* loop_;  //处理acceptor_的IO事件const string ipPort_;const string name_;std::unique_ptr<Acceptor> acceptor_; //循环监听所有客户端的连接请求std::shared_ptr<EventLoopThreadPool> threadPool_;//线程池，已连接客户端的IO事件ConnectionCallback connectionCallback_;          //连接回调MessageCallback messageCallback_;                //消息回调WriteCompleteCallback writeCompleteCallback_;    //写完成回调ThreadInitCallback threadInitCallback_;          //线程初始回调AtomicInt32 started_;//启动标志// always in loop threadint nextConnId_;//记录客户端个数ConnectionMap connections_;//保存客户端连接
};}  // namespace net
}  // namespace muduo#endif  // MUDUO_NET_TCPSERVER_H

TcpServer.cpp

#include "muduo/net/TcpServer.h"#include "muduo/base/Logging.h"
#include "muduo/net/Acceptor.h"
#include "muduo/net/EventLoop.h"
#include "muduo/net/EventLoopThreadPool.h"
#include "muduo/net/SocketsOps.h"#include <stdio.h>  // snprintfusing namespace muduo;
using namespace muduo::net;TcpServer::TcpServer(EventLoop* loop,const InetAddress& listenAddr,const string& nameArg,Option option): loop_(CHECK_NOTNULL(loop)),ipPort_(listenAddr.toIpPort()),name_(nameArg),acceptor_(new Acceptor(loop, listenAddr, option == kReusePort)),threadPool_(new EventLoopThreadPool(loop, name_)),connectionCallback_(defaultConnectionCallback),messageCallback_(defaultMessageCallback),nextConnId_(1)
{//acceptor_每收到一个客户端的连接，就将连接转给TcpServer::newConnection()处理acceptor_->setNewConnectionCallback(std::bind(&TcpServer::newConnection, this, _1, _2));
}TcpServer::~TcpServer()
{loop_->assertInLoopThread();LOG_TRACE << "TcpServer::~TcpServer [" << name_ << "] destructing";//逐个销毁映射表里的连接for (auto& item : connections_){TcpConnectionPtr conn(item.second);/*reset后conn指向的对象引用计数减为1，待执行完for循环后conn这个栈对象被销毁，引用计数减为0，至此连接彻底被销毁*/item.second.reset();conn->getLoop()->runInLoop(std::bind(&TcpConnection::connectDestroyed, conn));}
}//设置IO线程池子线程个数
void TcpServer::setThreadNum(int numThreads)
{assert(0 <= numThreads);threadPool_->setThreadNum(numThreads);
}void TcpServer::start()
{if (started_.getAndSet(1) == 0){//开启线程池,准备处理服务端的IO事件threadPool_->start(threadInitCallback_);//acceptor_开启监听assert(!acceptor_->listenning());loop_->runInLoop(std::bind(&Acceptor::listen, get_pointer(acceptor_)));}
}void TcpServer::newConnection(int sockfd, const InetAddress& peerAddr)
{loop_->assertInLoopThread();//给新连接进来的socket分配一个loop，以后该socket上所有的IO操作都在此loop中完成EventLoop* ioLoop = threadPool_->getNextLoop();char buf[64];snprintf(buf, sizeof buf, "-%s#%d", ipPort_.c_str(), nextConnId_);++nextConnId_;string connName = name_ + buf;LOG_INFO << "TcpServer::newConnection [" << name_<< "] - new connection [" << connName<< "] from " << peerAddr.toIpPort();InetAddress localAddr(sockets::getLocalAddr(sockfd));// FIXME poll with zero timeout to double confirm the new connection// FIXME use make_shared if necessary//至此conn与ioLoop绑定，conn上的IO事件都将在ioLoop中执行TcpConnectionPtr conn(new TcpConnection(ioLoop,connName,sockfd,localAddr,peerAddr));connections_[connName] = conn;//给新连接进来的socket设置回调conn->setConnectionCallback(connectionCallback_);conn->setMessageCallback(messageCallback_);conn->setWriteCompleteCallback(writeCompleteCallback_);conn->setCloseCallback(std::bind(&TcpServer::removeConnection, this, _1)); // FIXME: unsafeioLoop->runInLoop(std::bind(&TcpConnection::connectEstablished, conn));
}void TcpServer::removeConnection(const TcpConnectionPtr& conn)
{// FIXME: unsafeloop_->runInLoop(std::bind(&TcpServer::removeConnectionInLoop, this, conn));
}void TcpServer::removeConnectionInLoop(const TcpConnectionPtr& conn)
{loop_->assertInLoopThread();LOG_INFO << "TcpServer::removeConnectionInLoop [" << name_<< "] - connection " << conn->name();//删除映射表的连接size_t n = connections_.erase(conn->name());(void)n;assert(n == 1);EventLoop* ioLoop = conn->getLoop();//注销socket在Poller中的监听ioLoop->queueInLoop(std::bind(&TcpConnection::connectDestroyed, conn));
}

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