multiple reactors(35 -1 )

---

---

• muduo库如何支持多线程
  EventLoopThread（IO线程类）
  EventLoopThreadPool（IO线程池类）
  IO线程池的功能是开启若干个IO线程，并让这些IO线程处于事件循环的状态

---

下面的这些代码可能和前面给出的源代码有些不一样，阅读的同学请注意了

---

---

EventLoopThreadPool头文件

eventloopthreadpool.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_EVENTLOOPTHREADPOOL_H#define MUDUO_NET_EVENTLOOPTHREADPOOL_H#include <muduo/base/Condition.h>#include <muduo/base/Mutex.h>#include <vector>#include <boost/function.hpp>#include <boost/noncopyable.hpp>#include <boost/ptr_container/ptr_vector.hpp>namespace muduo{namespace net{class EventLoop;class EventLoopThread;class EventLoopThreadPool : boost::noncopyable{ public:  typedef boost::function<void(EventLoop*)> ThreadInitCallback;  EventLoopThreadPool(EventLoop* baseLoop);  ~EventLoopThreadPool();  void setThreadNum(int numThreads) { numThreads_ = numThreads; }  void start(const ThreadInitCallback& cb = ThreadInitCallback());  EventLoop* getNextLoop(); private:  EventLoop* baseLoop_; // 与Acceptor所属EventLoop相同  bool started_;        /*是否启动*/  int numThreads_;      // 线程数  int next_;            // 新连接到来，所选择的EventLoop对象下标  boost::ptr_vector<EventLoopThread> threads_;        // IO线程列表  std::vector<EventLoop*> loops_;                 // EventLoop列表};}}#endif  // MUDUO_NET_EVENTLOOPTHREADPOOL_H

EventLoopThreadPool源文件

eventloopthreadpool.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/EventLoopThreadPool.h>#include <muduo/net/EventLoop.h>#include <muduo/net/EventLoopThread.h>#include <boost/bind.hpp>using namespace muduo;using namespace muduo::net;EventLoopThreadPool::EventLoopThreadPool(EventLoop* baseLoop)  : baseLoop_(baseLoop),  // 与Acceptor所属EventLoop相同    started_(false),    numThreads_(0),    next_(0){}EventLoopThreadPool::~EventLoopThreadPool(){  // Don't delete loop, it's stack variable}/*每个线程初始化时的回调函数cb*/void EventLoopThreadPool::start(const ThreadInitCallback& cb){  assert(!started_);  baseLoop_->assertInLoopThread();  started_ = true;  for (int i = 0; i < numThreads_; ++i)  {    EventLoopThread* t = new EventLoopThread(cb);    threads_.push_back(t);    loops_.push_back(t->startLoop());    // 启动EventLoopThread线程，在进入事件循环之前，会调用cb  }  if (numThreads_ == 0 && cb)  {    // 只有一个EventLoop，在这个EventLoop进入事件循环之前，调用cb    cb(baseLoop_);  }}EventLoop* EventLoopThreadPool::getNextLoop(){  baseLoop_->assertInLoopThread();  EventLoop* loop = baseLoop_;  // 如果loops_为空，则loop指向baseLoop_  // 如果不为空，按照round-robin（RR，轮叫）的调度方式选择一个EventLoop  if (!loops_.empty())  {    // round-robin    loop = loops_[next_];    ++next_;    if (implicit_cast<size_t>(next_) >= loops_.size())    {      next_ = 0;    }  }  return loop;}

---

---

TcpServer头文件

TcpServer.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_TCPSERVER_H#define MUDUO_NET_TCPSERVER_H#include <muduo/base/Types.h>#include <muduo/net/TcpConnection.h>#include <map>#include <boost/noncopyable.hpp>#include <boost/scoped_ptr.hpp>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 : boost::noncopyable{ public:  typedef boost::function<void(EventLoop*)> ThreadInitCallback;  //TcpServer(EventLoop* loop, const InetAddress& listenAddr);  TcpServer(EventLoop* loop,            const InetAddress& listenAddr,            const string& nameArg);  ~TcpServer();  // force out-line dtor, for scoped_ptr members.  const string& hostport() const { return hostport_; }  const string& name() const { return name_; }  /// 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);  void setThreadInitCallback(const ThreadInitCallback& cb)  { threadInitCallback_ = cb; }  /// Starts the server if it's not listenning.  ///  /// It's harmless to call it multiple times.  /// Thread safe.  void start();  /// Set connection callback.  /// Not thread safe.  // 设置连接到来或者连接关闭回调函数  void setConnectionCallback(const ConnectionCallback& cb)  { connectionCallback_ = cb; }  /// Set message callback.  /// Not thread safe.  // 设置消息到来回调函数  void setMessageCallback(const MessageCallback& cb)  { messageCallback_ = cb; } private:  /// Not thread safe, but in loop  void newConnection(int sockfd, const InetAddress& peerAddr);  /// Thread safe.  void removeConnection(const TcpConnectionPtr& conn);  /// Not thread safe, but in loop  void removeConnectionInLoop(const TcpConnectionPtr& conn);  typedef std::map<string, TcpConnectionPtr> ConnectionMap;  EventLoop* loop_;  // the acceptor loop  const string hostport_;       // 服务端口  const string name_;           // 服务名  boost::scoped_ptr<Acceptor> acceptor_; // avoid revealing Acceptor  boost::scoped_ptr<EventLoopThreadPool> threadPool_; //线程池  ConnectionCallback connectionCallback_;  MessageCallback messageCallback_;  ThreadInitCallback threadInitCallback_;   // IO线程池中的线程在进入事件循环前，会回调用此函数  bool started_;  // always in loop thread  int nextConnId_;              // 下一个连接ID  ConnectionMap connections_;   // 连接列表};}}#endif  // MUDUO_NET_TCPSERVER_H

TcpServer源文件

TcpServer.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/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 <boost/bind.hpp>#include <stdio.h>  // snprintfusing namespace muduo;using namespace muduo::net;TcpServer::TcpServer(EventLoop* loop, /*这是main reactor*/                     const InetAddress& listenAddr,                     const string& nameArg)  : loop_(CHECK_NOTNULL(loop)),    hostport_(listenAddr.toIpPort()),    name_(nameArg),    acceptor_(new Acceptor(loop, listenAddr)),    threadPool_(new EventLoopThreadPool(loop)),    /*connectionCallback_(defaultConnectionCallback),    messageCallback_(defaultMessageCallback),*/    started_(false),    nextConnId_(1){  // Acceptor::handleRead函数中会回调用TcpServer::newConnection  // _1对应的是socket文件描述符，_2对应的是对等方的地址(InetAddress)  acceptor_->setNewConnectionCallback(      boost::bind(&TcpServer::newConnection, this, _1, _2));}TcpServer::~TcpServer(){  loop_->assertInLoopThread();  LOG_TRACE << "TcpServer::~TcpServer [" << name_ << "] destructing";  for (ConnectionMap::iterator it(connections_.begin());      it != connections_.end(); ++it)  {    TcpConnectionPtr conn = it->second;    it->second.reset();      // 释放当前所控制的对象，引用计数减一    conn->getLoop()->runInLoop(      boost::bind(&TcpConnection::connectDestroyed, conn));    conn.reset();           // 释放当前所控制的对象，引用计数减一  }}void TcpServer::setThreadNum(int numThreads){  /*numThreads不包含main reactor thread*/  assert(0 <= numThreads);  threadPool_->setThreadNum(numThreads);}// 该函数多次调用是无害的// 该函数可以跨线程调用void TcpServer::start(){  if (!started_)  {    started_ = true;    /*启动线程池*/    threadPool_->start(threadInitCallback_);  }  if (!acceptor_->listenning())  {    // get_pointer返回原生指针    loop_->runInLoop(        boost::bind(&Acceptor::listen, get_pointer(acceptor_)));  }}void TcpServer::newConnection(int sockfd, const InetAddress& peerAddr){  loop_->assertInLoopThread();  // 按照轮叫的方式选择一个EventLoop  EventLoop* ioLoop = threadPool_->getNextLoop();  char buf[32];  snprintf(buf, sizeof buf, ":%s#%d", hostport_.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  /*TcpConnectionPtr conn(new TcpConnection(loop_,                                          connName,                                          sockfd,                                          localAddr,                                          peerAddr));*/  TcpConnectionPtr conn(new TcpConnection(ioLoop,                                          connName,                                          sockfd,                                          localAddr,                                          peerAddr));  LOG_TRACE << "[1] usecount=" << conn.use_count();  connections_[connName] = conn;  LOG_TRACE << "[2] usecount=" << conn.use_count();  conn->setConnectionCallback(connectionCallback_);  conn->setMessageCallback(messageCallback_);  conn->setCloseCallback(      boost::bind(&TcpServer::removeConnection, this, _1));  // conn->connectEstablished(); 这个表示直接在当前线程中调用  ioLoop->runInLoop(boost::bind(&TcpConnection::connectEstablished, conn));  LOG_TRACE << "[5] usecount=" << conn.use_count();}void TcpServer::removeConnection(const TcpConnectionPtr& conn){    /*  loop_->assertInLoopThread();  LOG_INFO << "TcpServer::removeConnectionInLoop [" << name_           << "] - connection " << conn->name();  LOG_TRACE << "[8] usecount=" << conn.use_count();  size_t n = connections_.erase(conn->name());  LOG_TRACE << "[9] usecount=" << conn.use_count();  (void)n;  assert(n == 1);  loop_->queueInLoop(      boost::bind(&TcpConnection::connectDestroyed, conn));  LOG_TRACE << "[10] usecount=" << conn.use_count();  */  loop_->runInLoop(boost::bind(&TcpServer::removeConnectionInLoop, this, conn));}void TcpServer::removeConnectionInLoop(const TcpConnectionPtr& conn){  loop_->assertInLoopThread();  LOG_INFO << "TcpServer::removeConnectionInLoop [" << name_           << "] - connection " << conn->name();  LOG_TRACE << "[8] usecount=" << conn.use_count();  size_t n = connections_.erase(conn->name());  LOG_TRACE << "[9] usecount=" << conn.use_count();  (void)n;  assert(n == 1);  EventLoop* ioLoop = conn->getLoop();  ioLoop->queueInLoop(      boost::bind(&TcpConnection::connectDestroyed, conn));  //loop_->queueInLoop(  //    boost::bind(&TcpConnection::connectDestroyed, conn));  LOG_TRACE << "[10] usecount=" << conn.use_count();}

---

---

测试程序

#include <muduo/net/TcpServer.h>#include <muduo/net/EventLoop.h>#include <muduo/net/InetAddress.h>#include <boost/bind.hpp>#include <stdio.h>using namespace muduo;using namespace muduo::net;class TestServer{ public:  TestServer(EventLoop* loop,             const InetAddress& listenAddr, int numThreads)    : loop_(loop),      server_(loop, listenAddr, "TestServer"),      numThreads_(numThreads)  {    server_.setConnectionCallback(        boost::bind(&TestServer::onConnection, this, _1));    server_.setMessageCallback(        boost::bind(&TestServer::onMessage, this, _1, _2, _3));    server_.setThreadNum(numThreads);  }  void start()  {      server_.start();  } private:  void onConnection(const TcpConnectionPtr& conn)  {    if (conn->connected())    {      printf("onConnection(): new connection [%s] from %s\n",             conn->name().c_str(),             conn->peerAddress().toIpPort().c_str());    }    else    {      printf("onConnection(): connection [%s] is down\n",             conn->name().c_str());    }  }  void onMessage(const TcpConnectionPtr& conn,                   const char* data,                   ssize_t len)  {    printf("onMessage(): received %zd bytes from connection [%s]\n",           len, conn->name().c_str());  }  EventLoop* loop_;  TcpServer server_;  int numThreads_;};int main(){  printf("main(): pid = %d\n", getpid());  InetAddress listenAddr(8888);  EventLoop loop;  TestServer server(&loop, listenAddr,4);  server.start();  loop.loop();}

---

---

---