MMORPG大型游戏设计与开发（part3 of net）

　　这一部分需要向大家介绍的是服务器的select以及收发包的具体流程，从核心代码功能上分析网络交互具体过程。

　　首先大家要看第二部分（part2 of net）的代码结构图，因为在接下来的流程过程中会用到其中模块的名称，若是不知道大致的功能那么接下来的解说可能就成为天书了。

　　总体流程为：服务器管理器初始化并创建主套接字连接，进入主循环等待新连接（select），如果有新的连接则将新连接加入连接管理器。不管有没有新的连接，循环会依次处理连接的异常->输入流->输出流->命令处理。其中异常即连接包发送错误的处理，输入流即套接字输入流中如果大小长度不为空则重新拼接包，输出流进行包的拼接，并将未发送的流进行发送，命令处理其实是对输入流的处理，处理（handler）发送过来的包。

　　以下详细说明这几个流程从代码上的实现，以及所在的模块。

　　1、  服务器管理器初始化（servermanager）

bool ServerManager::init() {
  __ENTER_FUNCTION
    serversocket_ = 
      new pap_server_common_net::Socket(g_config.billing_info_.port_);
    Assert(serversocket_);
    serversocket_->set_nonblocking();
    socketid_ = serversocket_->getid();
    Assert(socketid_ != SOCKET_INVALID);
    FD_SET(socketid_, &readfds_[kSelectFull]);
    FD_SET(socketid_, &exceptfds_[kSelectFull]);
    minfd_ = maxfd_ = socketid_;
    timeout_[kSelectFull].tv_sec = 0;
    timeout_[kSelectFull].tv_usec = 0;
    threadid_ = pap_common_sys::get_current_thread_id();
    uint16_t i;
    for (i = 0; i < OVER_SERVER_MAX; ++i) {
      serverhash_[i] = ID_INVALID;
    }
    return true;
  __LEAVE_FUNCTION
    return false;
}

　　2、  服务器管理器进入主循环（servermanager）

void ServerManager::loop() {
  __ENTER_FUNCTION
    while (isactive()) {
      bool result = false;
      try {
        result = select();
        Assert(result);
        //ERRORPRINTF("select");
        result = processexception();
        Assert(result);
        //ERRORPRINTF("processexception");
        result = processinput();
        Assert(result);
        //ERRORPRINTF("processinput");
        result = processoutput();
        Assert(result); 
        //ERRORPRINTF("processoutput");
      }
      catch(...) {
        
      }
      try {
        result = processcommand();
        Assert(result);
        //ERRORPRINTF("processcommand");
      }
      catch(...) {
        
      }

      try {
        result = heartbeat();
        Assert(result);
      }
      catch(...) {
      }
    }
  __LEAVE_FUNCTION
}

　　3、  服务器线程进入select模式

bool ServerManager::select() {
  __ENTER_FUNCTION
    timeout_[kSelectUse].tv_sec = timeout_[kSelectFull].tv_sec;
    timeout_[kSelectUse].tv_usec = timeout_[kSelectFull].tv_usec;
    readfds_[kSelectUse] = readfds_[kSelectFull];
    writefds_[kSelectUse] = writefds_[kSelectFull];
    exceptfds_[kSelectUse] = exceptfds_[kSelectFull];
    pap_common_base::util::sleep(100);
    int32_t result = SOCKET_ERROR;
    try {
      result = pap_common_net::socket::Base::select(
          maxfd_ + 1,
          &readfds_[kSelectUse],
          &writefds_[kSelectUse],
          &exceptfds_[kSelectUse],
          &timeout_[kSelectUse]);
      Assert(result != SOCKET_ERROR);
    }
    catch(...) {
      g_log->fast_save_log(kBillingLogFile, 
                           "ServerManager::select have error, result: %d", 
                           result);
    }
    return true;
  __LEAVE_FUNCTION
    return false;
}

　　4、  服务器线程进行异常处理

bool ServerManager::processexception() {
  __ENTER_FUNCTION
    if (SOCKET_INVALID == minfd_ && SOCKET_INVALID == maxfd_)
      return true;
    uint16_t connectioncount = billingconnection::Manager::getcount();
    billingconnection::Server* serverconnection = NULL;
    uint16_t i;
    for (i = 0; i < connectioncount; ++i) {
      if (ID_INVALID == connectionids_[i]) continue;
      serverconnection = g_connectionpool->get(connectionids_[i]);
      Assert(serverconnection);
      int32_t socketid = serverconnection->getsocket()->getid();
      if (socketid_ == socketid) {
        Assert(false);
        continue;
      }
      if (FD_ISSET(socketid, &exceptfds_[kSelectUse])) {
        removeconnection(serverconnection);
      }
    }
    return true;
  __LEAVE_FUNCTION
    return false;
}

　　5、  服务器线程进行输入流处理

bool ServerManager::processinput() {
  __ENTER_FUNCTION
    if (SOCKET_INVALID == minfd_ && SOCKET_INVALID == maxfd_)
      return true; //no connection
    uint16_t i;
    if (FD_ISSET(socketid_, &readfds_[kSelectUse])) {
      for (i = 0; i < kOneStepAccept; ++i) {
        if (!accept_newconnection()) break;
      }
    }
    uint16_t connectioncount = billingconnection::Manager::getcount();
    for (i = 0; i < connectioncount; ++i) {
      if (ID_INVALID == connectionids_[i]) continue;
      billingconnection::Server* serverconnection = NULL;
      serverconnection = g_connectionpool->get(connectionids_[i]);
      Assert(serverconnection);
      int32_t socketid = serverconnection->getsocket()->getid();
      if (socketid_ == socketid) continue;
      if (FD_ISSET(socketid, &readfds_[kSelectUse])) { //read information
        if (serverconnection->getsocket()->iserror()) {
          removeconnection(serverconnection);
        }
        else {
          try {
            if (!serverconnection->processinput()) 
              removeconnection(serverconnection);
          }
          catch(...) {
            removeconnection(serverconnection);
          }
        }
      }
    }
    return true;
  __LEAVE_FUNCTION
    return false;
}

　　6、  服务器线程进行输出流处理

bool ServerManager::processoutput() {
  __ENTER_FUNCTION
    if (SOCKET_INVALID == maxfd_&& SOCKET_INVALID == minfd_)
      return false;
    uint16_t i;
    uint16_t connectioncount = billingconnection::Manager::getcount();
    for (i = 0; i < connectioncount; ++i) {
      if (ID_INVALID == connectionids_[i]) continue;
      billingconnection::Server* serverconnection = NULL;
      serverconnection = g_connectionpool->get(connectionids_[i]);
      Assert(serverconnection);
      int32_t socketid = serverconnection->getsocket()->getid();
      if (socketid_ == socketid) continue;
      if (FD_ISSET(socketid, &writefds_[kSelectUse])) {
        if (serverconnection->getsocket()->iserror()) {
          removeconnection(serverconnection);
        }
        else {
          try {
            if (!serverconnection->processoutput()) 
              removeconnection(serverconnection);
          }
          catch(...) {
            removeconnection(serverconnection);
          }
        }
      }
    }
    return true;
  __LEAVE_FUNCTION
    return false;
}

　　7、  服务器线程进行命令处理

bool ServerManager::processcommand() {
  __ENTER_FUNCTION
    if (SOCKET_INVALID == maxfd_&& SOCKET_INVALID == minfd_)
      return false;
    uint16_t i;
    uint16_t connectioncount = billingconnection::Manager::getcount();
    for (i = 0; i < connectioncount; ++i) {
      if (ID_INVALID == connectionids_[i]) continue;
      billingconnection::Server* serverconnection = NULL;
      serverconnection = g_connectionpool->get(connectionids_[i]);
      //serverconnection = &billing_serverconnection_;
      Assert(serverconnection);
      int32_t socketid = serverconnection->getsocket()->getid();
      if (socketid_ == socketid) continue;
      if (serverconnection->getsocket()->iserror()) {
        removeconnection(serverconnection);
      }
      else { //connection is ok
        try {
          if (!serverconnection->processcommand(false)) 
            removeconnection(serverconnection);
        }
        catch(...) {
          removeconnection(serverconnection);
        }
      }
    }
    return true;
  __LEAVE_FUNCTION
    return false;
}

　　下一部分，我将讲解在网络部分一些重要的代码块。