這一部分需要向大家介紹的是服務器的select以及收發包的具體流程，從核心代碼功能上分析網絡交互具體過程。

　　首先大家要看第二部分（part2 of net）的代碼結構圖，因為在接下來的流程過程中會用到其中模塊的名稱，若是不知道大致的功能那么接下來的解說可能就成為天書了。

　　總體流程為：服務器管理器初始化并創建主套接字連接，進入主循環等待新連接（select），如果有新的連接則將新連接加入連接管理器。不管有沒有新的連接，循環會依次處理連接的異常->輸入流->輸出流->命令處理。其中異常即連接包發送錯誤的處理，輸入流即套接字輸入流中如果大小長度不為空則重新拼接包，輸出流進行包的拼接，并將未發送的流進行發送，命令處理其實是對輸入流的處理，處理（handler）發送過來的包。

　　以下詳細說明這幾個流程從代碼上的實現，以及所在的模塊。

　　1、? 服務器管理器初始化（servermanager）

bool ServerManager::init() {__ENTER_FUNCTIONserversocket_ = 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、? 服務器管理器進入主循環（servermanager）

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void ServerManager::loop() {__ENTER_FUNCTIONwhile (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 } loop

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　　3、? 服務器線程進入select模式

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bool ServerManager::select() {__ENTER_FUNCTIONtimeout_[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; } select

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　　4、? 服務器線程進行異常處理

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bool ServerManager::processexception() {__ENTER_FUNCTIONif (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; } processexception

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　　5、? 服務器線程進行輸入流處理

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bool ServerManager::processinput() {__ENTER_FUNCTIONif (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; } processinput

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　　6、? 服務器線程進行輸出流處理

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bool ServerManager::processoutput() {__ENTER_FUNCTIONif (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; } processoutput

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　　7、? 服務器線程進行命令處理

bool ServerManager::processcommand() {__ENTER_FUNCTIONif (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; } processcommand

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　　下一部分，我將講解在網絡部分一些重要的代碼塊。

轉載于:https://www.cnblogs.com/liuzhi/p/4084565.html

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