muduo学习笔记(六) 多线程的TcpServer

前言
多线程TcpServer
- EventLoopThreadPool
- 线程池设计模式
muduo中的使用
简单透传服务实现

前言

前面文章介绍了muduo网络库的单线程设计方式，即一个EventLoop 处理所有的事件，包括链接的建立、IO、计算、以及链接的销毁，本文介绍下muduo中的多线程设计方法。

多线程TcpServer

EventLoopThreadPool

多线程的muduo::TcpServer，主要通过添加一个EventLoopThreadPool 事件循环线程池实现，新建TcpConnection时从event loop pool里挑选一个loop给TcpConnection用。也就是说多线程TcpServer自己的EventLoop只用来接受新连接，而新连接会用其他EventLoop来执行IO。（单线程TcpServer的EventLoop是与TcpConnection共享的。）

EventLoopThreadPooll 按one loop per thread的思想实现多线程TcpServer，此时主线程循环只负责TCP链接的建立，及任务的分配，需要让哪个线程干活，就把timer或IO（如TCP连接）注册到那个线程的循环里即可；对实时性有要求的connection可以单独用一个线程；数据量大的connection可以独占一个线程；并把数据处理任务分摊到另几个计算线程中（用线程池）；其他次要的辅助性connections共享一个线程。

线程池设计模式

池是一种设计模式，线程是是一种资源，线程池设计模式通常是事先申请一定的资源，当需要使用时，去资源池中申请资源，用完后再放回资源池中。EventLoopThreadPool 正是借鉴了这种设计模式，虽然使用的线程并不会放回资源池中，但是本身的一个EventLoop即一个Reactor，本身就具备等待机制了。

muduo中的使用

TcpServer每次新建一条TcpConnection就会通过EventLoopThreadPool::getNextLoop()方法来取一个EventLoop，目前的getNextLoop()只是循环的从池中取一条loop，如果提供给每条TcpConncetion的是均等的服务，那么这样就能很均匀的分配系统的资源了。

TcpServer的工作方式取决于EventLoopThreadPool中线程的创建数量。

0 意味着所有的I/O 都在TcpServer的主事件循环中，不会创建新的线程。

1 意味着所有的 I/O 在另一个线程中，TcpServer的主线程只负责建立连接。

N 意味着新的连接会被循环的分配到N条线程中工作。

连接的建立、消息、销毁

on_connection

1、对于新的连接new connection 会在 TcpServer的Loop 中由Acceptor建立，

void Acceptor::handleRead()

{

  LOG_TRACE << "Acceptor::handleRead()";

  p_loop->assertInLoopThread();

  InetAddress peerAddr;

  int connfd = m_acceptSocket.accept(&peerAddr);

2、之后从loop_thread_pool中取一个loop将新的connection注册上去。

void TcpServer::newConnetion(int sockfd, const InetAddress& peerAddr)

{

	InetAddress localAddr(sockets::getLocalAddr(sockfd));

    EventLoop* loop;

    loop = ex_event_loop_thread_pool->getNextLoop();

    TcpConnectionPtr conn(new TcpConnection(loop,

               connName, sockfd, localAddr, peerAddr));

    conn->setConnectionCallBack(m_connectionCallBack);

    conn->setMessageCallBack(m_messageCallBack);

    conn->setCloseCallBack(std::bind(&TcpServer::removeConnection, this, std::placeholders::_1));

    loop->runInLoop(std::bind(&TcpConnection::connectEstablished, conn));

on_message

1、message将在connection自己所处的loop中处理，无需多言。

on_close

1、连接的销毁稍微复杂一点，connection会在自己的loop中调用Tcp:Server::removeConnection，我们需要将他移动到TcpServer的Loop线程中先解除TcpServer对connection的使用，然后在回到connection自己的loop中销毁连接connectDestroyed()。

void TcpServer::removeConnection(const TcpConnectionPtr& conn)

{

  // FIXME: unsafe

  p_loop->runInLoop(std::bind(&TcpServer::removeConnectionInLoop, this, conn));

}

void TcpServer::removeConnectionInLoop(const TcpConnectionPtr& conn)

{

  p_loop->assertInLoopThread();

  LOG_INFO << "TcpServer::removeConnectionInLoop [" << m_name

           << "] - connection " << conn->name();

  m_closeCallBack(conn);

  EventLoop* ioLoop = conn->getLoop();

  ioLoop->queueInLoop(

      std::bind(&TcpConnection::connectDestroyed, conn));

}

简单透传服务实现

利用muduo多线程TcpServer 实现一个简单的透传服务，从connection中收到的消息直接转发给所有的其他connection。

//ws_tcp_server.hpp

#pragma once

#include <async_logging>

#include <muduo_server>

namespace ws {

extern std::unique_ptr<muduo::EventLoop> active_event_loop;

class tcp_server{

public:

  //! ctor

  tcp_server(void);

  //! dtor

  ~tcp_server(void) = default;

  //! copy ctor

  tcp_server(const tcp_server&) = delete;

  //! assignment operator

  tcp_server& operator=(const tcp_server&) = delete;

public:

  //! listen_and_serve

  //! start server and listened on port

  void listen_and_serve(std::size_t port);

private:

  void on_connection(const muduo::TcpConnectionPtr&);

  void on_message(const muduo::TcpConnectionPtr& , muduo::Buffer*, ssize_t );

  void on_close(const muduo::TcpConnectionPtr&);

private:

  //!

  //typedef std::vector<muduo::TcpConnectionPtr> connections_t;

  //!

  typedef std::map<std::string, muduo::TcpConnectionPtr> connections_map_t;

private:

  //! master connection

  //muduo::TcpConnectionPtr m_master_connection;

  //! slave connection

  //connections_t m_connections;

  //! muduo tcp server

  std::unique_ptr<muduo::TcpServer> m_tcp_server;

  //! connections map

  connections_map_t m_connections_map;

  std::size_t cnt_connetions;

};

}

//ws_tcp_server.cpp

#include "ws_tcp_server.hpp"

#include <assert.h>

static muduo::EventLoopThread static_event_loop;

std::unique_ptr<muduo::EventLoop> ws::active_event_loop = std::unique_ptr<muduo::EventLoop>(static_event_loop.startLoop());

using namespace ws;

tcp_server::tcp_server()

  :cnt_connetions(0)

{

}

void tcp_server::listen_and_serve(std::size_t port)

{

  assert(active_event_loop);

  muduo::ex_event_loop_thread_pool = std::unique_ptr<muduo::EventLoopThreadPool>(new muduo::EventLoopThreadPool(ws::active_event_loop.get(), "event_loop", 3));

  active_event_loop->runInLoop(std::bind(&muduo::EventLoopThreadPool::start, muduo::ex_event_loop_thread_pool.get()));

  m_tcp_server = std::unique_ptr<muduo::TcpServer>(new muduo::TcpServer(active_event_loop.get(), InetAddress(port)));

  m_tcp_server->setConnectionCallBack(std::bind(&tcp_server::on_connection, this, std::placeholders::_1));

  m_tcp_server->setMessageCallBack(std::bind(&tcp_server::on_message, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));

  m_tcp_server->setCloseCallBack(std::bind(&tcp_server::on_close, this, std::placeholders::_1));

  m_tcp_server->start();

}

void tcp_server::on_connection(const muduo::TcpConnectionPtr& conn)

{

  cnt_connetions++;

  std::string conn_name = "tcp connection " + std::to_string(cnt_connetions);

  conn->setConnectionName(conn_name);

  m_connections_map[conn_name] = std::move(conn);

}

void tcp_server::on_message(const muduo::TcpConnectionPtr& conn, muduo::Buffer* buf, ssize_t size)

{

  connections_map_t::iterator iter;

  for(iter = m_connections_map.begin(); iter != m_connections_map.end(); iter++)

  {

    if(iter->second != conn){

      LOG_DEBUG << "con " << conn->name() << " send to " << iter->second->name();

      iter->second->send(buf->peek(), size);

    }

  }

  buf->retrieve(size);

}

void tcp_server::on_close(const muduo::TcpConnectionPtr& conn)

{

  size_t n = m_connections_map.erase(conn->name());

  (void)n;

  assert(n == 1);

}

// main.cpp

#include <async_logging>

#include "ws_tcp_server.hpp"

int main()

{

  Logger::setLogLevel(Logger::DEBUG);

  ws::tcp_server tcp_server;

  tcp_server.listen_and_serve(8008);

  getchar();

}

../bin/ws_server

2019-03-19 16:22:17.202112 [TRACE] [EventLoopThread.cpp:41] [startLoop] EventLoopThread::startLoop() wait()

2019-03-19 16:22:17.203199 [TRACE] [TimerQueue.cpp:20] [createTimerfd] createTimerfd() fd : 4

2019-03-19 16:22:17.203376 [TRACE] [Epoll.cpp:115] [updateChannel] fd= 4 events 3

2019-03-19 16:22:17.203549 [TRACE] [EventLoop.cpp:23] [createEventfd] createEventfd() fd : 5

2019-03-19 16:22:17.203711 [INFO ] [EventLoop.cpp:43] EventLoop Create 0x7F1E72371B30 in thread 44057

2019-03-19 16:22:17.203872 [TRACE] [Epoll.cpp:115] [updateChannel] fd= 5 events 3

2019-03-19 16:22:17.204188 [TRACE] [EventLoopThread.cpp:65] [threadFunc] EventLoopThread::threadFunc() notify()

2019-03-19 16:22:17.204332 [TRACE] [EventLoop.cpp:74] [loop] EventLoop 0x7F1E72371B30 start loopig

2019-03-19 16:22:17.204477 [TRACE] [Epoll.cpp:72] [poll] Epoll::poll() maxConcurrencySize 2

2019-03-19 16:22:17.204794 [TRACE] [EventLoopThread.cpp:46] [startLoop] EventLoopThread::startLoop() wakeup

2019-03-19 16:22:17.210324 [INFO ] [EventLoop.cpp:43] EventLoop Create 0x7F1E71B70B30 in thread 44058

2019-03-19 16:22:17.212173 [INFO ] [EventLoop.cpp:43] EventLoop Create 0x7F1E7136FB30 in thread 44059

2019-03-19 16:22:17.212725 [INFO ] [EventLoop.cpp:43] EventLoop Create 0x7F1E70B6EB30 in thread 44060

2019-03-19 16:22:22.399790 [INFO ] [TcpServer.cpp:52] TcpServer::newConnetion() [Serv ] - new connection [Serv #1] from 127.0.0.1:51400

2019-03-19 16:22:22.399833 [INFO ] [TcpServer.cpp:61] Loop 0x7F1E71B70B30

2019-03-19 16:22:22.399842 [DEBUG] [TcpConnection.cpp:27] [TcpConnection] TcpConnection::ctor[Serv #1] at 0x7F1E6C0046F0 fd=17

2019-03-19 16:22:24.901612 [INFO ] [TcpServer.cpp:52] TcpServer::newConnetion() [Serv ] - new connection [Serv #2] from 127.0.0.1:51402

2019-03-19 16:22:24.901625 [INFO ] [TcpServer.cpp:61] Loop 0x7F1E7136FB30

2019-03-19 16:22:24.901635 [DEBUG] [TcpConnection.cpp:27] [TcpConnection] TcpConnection::ctor[Serv #2] at 0x7F1E6C006A30 fd=18

2019-03-19 16:22:25.903035 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 2 send to tcp connection 1

2019-03-19 16:22:32.499161 [INFO ] [TcpServer.cpp:52] TcpServer::newConnetion() [Serv ] - new connection [Serv #3] from 127.0.0.1:51404

2019-03-19 16:22:32.499174 [INFO ] [TcpServer.cpp:61] Loop 0x7F1E70B6EB30

2019-03-19 16:22:32.499183 [DEBUG] [TcpConnection.cpp:27] [TcpConnection] TcpConnection::ctor[Serv #3] at 0x7F1E6C008D80 fd=19

2019-03-19 16:22:33.499744 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 3 send to tcp connection 1

2019-03-19 16:22:33.499771 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 3 send to tcp connection 2

2019-03-19 16:22:35.986563 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 2 send to tcp connection 1

2019-03-19 16:22:35.986670 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 2 send to tcp connection 3

2019-03-19 16:22:36.982713 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 2 send to tcp connection 1

2019-03-19 16:22:36.982759 [DEBUG] [ws_tcp_server.cpp:58] [on_message] con tcp connection 2 send to tcp connection 3

2019-03-19 16:22:38.244229 [INFO ] [TcpServer.cpp:90] TcpServer::removeConnectionInLoop [Serv ] - connection tcp connection 2

2019-03-19 16:22:38.244281 [DEBUG] [TcpConnection.cpp:36] [~TcpConnection] TcpConnection::dtor[tcp connection 2] at 0x7F1E6C006A30 fd=18 state=kDisConnected