Qt网络开发以及QTcpSocket::waitForBytesWritten()的问题
开发一个包含较重的网络传输(发送)负载的程序时,在一个QThread辅助线程中使用QTcpSocket::waitForBytesWritten()等待发送操作完成。发现时常诱发QAbstractSocket::SocketTimeoutError,甚至出现难以调试的崩溃问题。
一种处理措施:将QTcpSocket::waitForBytesWritten()调用替换为QTcpSocket::flush()调用。或仅执行QTcpSocket::write()写操作,由Qt事件循环处理所有工作。使用此方法时,可能需要跨线程共享QTcpSocket对象,此时对QTcpSocket对象的定义和引用应全部通过指针在堆区完成,并进行加锁保护(有助于在一定程度上避免高速调用时的栈错误)。
另一种处理措施:使用一个继承自QObject工作者子对象将对QTcpSocket的初始化和引用全部置于QThread辅助线程中进行。使用一个同时包含了工作者子对象和QThread辅助线程的、继承自QObject的控制类进行管理。子类被控制类通过moveToThread()函数整体移入QThread线程内并做好信号与槽之间的连接,启动线程后,即可使用子线程自己的事件循环进行调度和管理。
#include <QVector> #include <QQueue> #include <QString> #include <QMap> #include <QTcpSocket> #include <QThread> #include <QMutex> #include <QMutexLocker> #include <QReadWriteLock> #include <QTimer> #include <QApplication> #include <QHostAddress> /* HEADER FILE */ /* TCP Networking Data Sending Thread Worker Object */ //This object is moved to a child thread to have its own event loop class TCPClientDataSender : public QTcpSocket{ Q_OBJECT public: explicit TCPClientDataSender(); ~TCPClientDataSender(); /* Data Sending Status Indicator */ bool IsDataSending() const; public slots: /* Connection Management Command Handlers */ void ConnectToServerRequestedEventHandler(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay, bool WairForOperationToComplete); void DisconnectFromServerRequestedEventHandler(bool WairForOperationToComplete); void SetAutoReconnectOptionsRequestedEventHandler(bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay); void SendDataToServerRequestedEventHandler(); /* TCP Socket Event Handler Slots */ void TCPClientDataSender_Connected(); void TCPClientDataSender_Disconnected(); void TCPClientDataSender_Error(QAbstractSocket::SocketError errErrorInfo); void TCPClientDataSender_ReadyRead(); /* Functional Slots */ void TryReconnect(); signals: void SocketResponseReceivedFromServerEvent(QString sResponse); private: QString _sServerIP; //INTERNAL: Remote IP Address quint16 _iPort; //INTERNAL: Remote port bool _IsAutoReconnectEnabled; //INTERNAL: Is auto reconnect function on unsigned int _iAutoReconnectDelay; //INTERNAL: Auto reconnect retry interval bool _IsUserInitiatedDisconnection; //INTERNAL: Marks if user has initiated a disconnection, to avoid unexpected TryReconnect() flooding bool _IsReconnecting; //INTERNAL: Marks if we are alreading waiting a reconnection, to avoid unexpected TryReconnect() flooding bool _IsDataSending; //INTERNAL: Marks if we are sending data, avoid recursive calling of SendDataToServerRequestedEventHandler() and segmentation faults }; /* TCP Networking Client Wrapper */ class TCPClient : public QObject{ Q_OBJECT public: TCPClient(); //Default constructor, loads options from ini file or default values TCPClient(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay); //Constructor with options. Will update options saved in ini file ~TCPClient(); /* Options Management */ void LoadSettings(); //Load settings from persistent storage void SaveSettings() const; //Save settings to persistent storage /* TCP Socket Object Management */ bool IsConnected() const; //Get if we have connected to a remote server /* Connection Management */ void SetServerParameters(const QString sServerIP, quint16 iPort); //Host information (IP & Port) const QString & GetServerIP() const; quint16 GetServerPort() const; void ConnectToServer(bool WairForOperationToComplete = false); //Connect to remote server with saved values void ConnectToServer(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled=false, unsigned int iAutoReconnectDelay=0, bool WairForOperationToComplete = false); //Connect to remote server with given address and port. Will update options saved in ini file void DisconnectFromServer(bool WairForOperationToComplete = false); //Disconnect void SendDataToServer(); /* Options */ void SetAutoReconnectMode(bool IsAutoReconnectEnabled); //Set & Get auto reconnect function (handles error events) bool GetIsAutoReconnectEnabled() const; void SetAutoReconnectDelay(unsigned int iAutoReconnectDelay); //Set & Get auto reconnect retry interval unsigned int GetAutoReconnectDelay() const; /* Validators */ bool IsValidIPAddress(const QString sIPAddress) const; //Check if the given address is valid bool IsValidTCPPort(quint16 iPort, bool UseRegisteredPortsOnly=true) const; //Check if the given port ID is valid (typically in the range of [1,65535], or [1024,32767] if RegisteredPortsOnly is true) /* Threads & Worker Objects */ QThread * trdTCPDataSender; //Thread which is used to host and control worker thread TCPClientDataSender * tcpDataSender; //Worker object public slots: /* Worker Object Event Handler */ void SocketResponseReceivedFromServerEventHandler(QString sResponse); signals: /* Signals to Communicate with Worker Object */ void ConnectToServerRequestedEvent(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay, bool WairForOperationToComplete); void DisconnectFromServerRequestedEvent(bool WairForOperationToComplete); void SetAutoReconnectOptionsRequestedEvent(bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay); void SendDataToServerRequestedEvent(); void ConnectedToServerEvent(); void DisconnectedFromServerEvent(); void NetworkingErrorEvent(QAbstractSocket::SocketError errErrorInfo); /* Signals to Communicate with Upper Layer */ void ResponseReceivedFromServerEvent(QString sResponse); private: /* Connection Management */ //volatile bool _IsConnected; //INTERNAL: Get if we have connected to remote server. Not used, use tcpDataSender->state() instead. /* Options Var */ QString _sServerIP; //INTERNAL: Remote IP Address quint16 _iPort; //INTERNAL: Remote port bool _IsAutoReconnectEnabled; //INTERNAL: Is auto reconnect function on unsigned int _iAutoReconnectDelay; //INTERNAL: Auto reconnect retry interval }; /* TCP Client */ extern TCPClient * tcpDataClient; /* IMPLEMENTATION */ /* TCP Client */ TCPClient * tcpDataClient; /* TCP Networking Data Sending Thread Worker Object */ TCPClientDataSender::TCPClientDataSender(){ //Initialize internal variables _IsDataSending=false; _IsUserInitiatedDisconnection=false; _IsReconnecting=false; //Create TCP socket object and connect events connect(this, SIGNAL(connected()), this, SLOT(TCPClientDataSender_Connected())); connect(this, SIGNAL(disconnected()), this, SLOT(TCPClientDataSender_Disconnected())); qRegisterMetaType<QAbstractSocket::SocketError>("QAbstractSocket::SocketError"); //Register QAbstractSocket::SocketError type for QueuedConnection connect(this, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(TCPClientDataSender_Error(QAbstractSocket::SocketError))); connect(this, SIGNAL(readyRead()), this, SLOT(TCPClientDataSender_ReadyRead())); } TCPClientDataSender::~TCPClientDataSender(){ } /* Data Sending Status Indicator */ bool TCPClientDataSender::IsDataSending() const{ return _IsDataSending; } /* Connection Management Command Handlers */ void TCPClientDataSender::ConnectToServerRequestedEventHandler(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay, bool WairForOperationToComplete){ _sServerIP=sServerIP; _iPort=iPort; _IsAutoReconnectEnabled=IsAutoReconnectEnabled; _iAutoReconnectDelay=iAutoReconnectDelay; _IsUserInitiatedDisconnection=false; connectToHost(sServerIP, iPort); if (WairForOperationToComplete){ waitForConnected(); } return; } void TCPClientDataSender::DisconnectFromServerRequestedEventHandler(bool WairForOperationToComplete){ disconnectFromHost(); _IsUserInitiatedDisconnection=true; _IsReconnecting=false; if (WairForOperationToComplete){ waitForDisconnected(); } return; } void TCPClientDataSender::SetAutoReconnectOptionsRequestedEventHandler(bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay){ _IsAutoReconnectEnabled=IsAutoReconnectEnabled; _iAutoReconnectDelay=iAutoReconnectDelay; return; } void TCPClientDataSender::SendDataToServerRequestedEventHandler(){ //Check if SendDataToServerRequestedEventHandler() is running, avoid recursive calling of SendDataToServerRequestedEventHandler() and segmentation faults if (_IsDataSending){ //If this is a recursive calling, simply returns return; } else{ //Marks SendDataToServerRequestedEventHandler() is running _IsDataSending=true; } //Send data to remote //It's suggested that you maintain a data queue to cache data panding sending _IsDataSending=false; return; } /* TCP Socket Event Handler Slots */ void TCPClientDataSender::TCPClientDataSender_Connected(){ qDebug()<<"TCPClient: Connected to"<<_sServerIP<<":"<<_iPort; _IsReconnecting=false; return; } void TCPClientDataSender::TCPClientDataSender_Disconnected(){ qDebug()<<"TCPClient: Disconnected from"<<_sServerIP<<":"<<_iPort; return; } void TCPClientDataSender::TCPClientDataSender_Error(QAbstractSocket::SocketError errErrorInfo){ qDebug()<<"TCPClient: Error"<<errErrorInfo<<": "<<errorString(); if (state() != QTcpSocket::UnconnectedState){ disconnectFromHost(); waitForDisconnected(245000); } if (_IsAutoReconnectEnabled && !_IsReconnecting && !_IsUserInitiatedDisconnection){ //Check if we need to reconnect qDebug()<<"TCPClient: Will retry connect after"<<_iAutoReconnectDelay<<"ms"; QTimer::singleShot(_iAutoReconnectDelay, this, SLOT(TryReconnect())); _IsReconnecting=true; } return; } void TCPClientDataSender::TCPClientDataSender_ReadyRead(){ while (bytesAvailable()){ //Read a command line and emit a signal emit SocketResponseReceivedFromServerEvent(readLine()); //Process events QApplication::processEvents(); } return; } /* Functional Slots */ void TCPClientDataSender::TryReconnect(){ if (_IsUserInitiatedDisconnection){ return; } if (state() != QTcpSocket::ConnectingState && state() != QTcpSocket::ConnectedState){ qDebug()<<"TCPClient: Retrying to connect to"<<_sServerIP<<":"<<_iPort; connectToHost(_sServerIP, _iPort); waitForConnected(245000); } if (state() != QTcpSocket::ConnectedState){ qDebug()<<"TCPClient: Will retry connect after"<<_iAutoReconnectDelay<<"ms"; if (state() != QTcpSocket::UnconnectedState){ disconnectFromHost(); waitForDisconnected(245000); } QTimer::singleShot(_iAutoReconnectDelay, this, SLOT(TryReconnect())); } return; } /* TCP Networking Client Wrapper */ TCPClient::TCPClient(){ //Load settings TCPClient::LoadSettings(); //Create worker object tcpDataSender = new TCPClientDataSender; //Creat thread object trdTCPDataSender = new QThread; tcpDataSender->moveToThread(trdTCPDataSender); //Connect events and handlers connect(this, SIGNAL(ConnectToServerRequestedEvent(QString,quint16,bool,unsigned int,bool)), tcpDataSender, SLOT(ConnectToServerRequestedEventHandler(QString,quint16,bool,unsigned int,bool))); connect(this, SIGNAL(DisconnectFromServerRequestedEvent(bool)), tcpDataSender, SLOT(DisconnectFromServerRequestedEventHandler(bool))); connect(this, SIGNAL(SetAutoReconnectOptionsRequestedEvent(bool,uint)), tcpDataSender, SLOT(SetAutoReconnectOptionsRequestedEventHandler(bool,uint))); connect(this, SIGNAL(SendDataToServerRequestedEvent()), tcpDataSender, SLOT(SendDataToServerRequestedEventHandler())); connect(tcpDataSender, SIGNAL(SocketResponseReceivedFromServerEvent(QString)), this, SLOT(SocketResponseReceivedFromServerEventHandler(QString))); connect(tcpDataSender, SIGNAL(connected()), this, SIGNAL(ConnectedToServerEvent())); connect(tcpDataSender, SIGNAL(disconnected()), this, SIGNAL(DisconnectedFromServerEvent())); connect(tcpDataSender, SIGNAL(error(QAbstractSocket::SocketError)), this, SIGNAL(NetworkingErrorEvent(QAbstractSocket::SocketError))); //Start child thread's own event loop trdTCPDataSender->start(); } TCPClient::TCPClient(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay){ //Save settings _sServerIP=sServerIP; _iPort=iPort; _IsAutoReconnectEnabled=IsAutoReconnectEnabled; _iAutoReconnectDelay=iAutoReconnectDelay; TCPClient::SaveSettings(); //Create worker object tcpDataSender = new TCPClientDataSender; //Creat thread object and move worker object (and all of it's child objects) to this thread trdTCPDataSender = new QThread; tcpDataSender->moveToThread(trdTCPDataSender); //Connect events and handlers connect(this, SIGNAL(ConnectToServerRequestedEvent(QString,quint16,bool,unsigned int,bool)), tcpDataSender, SLOT(ConnectToServerRequestedEventHandler(QString,quint16,bool,unsigned int,bool))); connect(this, SIGNAL(DisconnectFromServerRequestedEvent(bool)), tcpDataSender, SLOT(DisconnectFromServerRequestedEventHandler(bool))); connect(this, SIGNAL(SetAutoReconnectOptionsRequestedEvent(bool,uint)), tcpDataSender, SLOT(SetAutoReconnectOptionsRequestedEventHandler(bool,uint))); connect(this, SIGNAL(SendDataToServerRequestedEvent()), tcpDataSender, SLOT(SendDataToServerRequestedEventHandler())); connect(tcpDataSender, SIGNAL(SocketResponseReceivedFromServerEvent(QString)), this, SLOT(SocketResponseReceivedFromServerEventHandler(QString))); connect(tcpDataSender, SIGNAL(connected()), this, SIGNAL(ConnectedToServerEvent())); connect(tcpDataSender, SIGNAL(disconnected()), this, SIGNAL(DisconnectedFromServerEvent())); connect(tcpDataSender, SIGNAL(error(QAbstractSocket::SocketError)), this, SIGNAL(NetworkingErrorEvent(QAbstractSocket::SocketError))); //Start child thread's own event loop trdTCPDataSender->start(); } TCPClient::~TCPClient(){ //Save settings if (TCPClient::IsConnected()){ TCPClient::DisconnectFromServer(); } TCPClient::SaveSettings(); //Quit child thread trdTCPDataSender->quit(); if (!trdTCPDataSender->wait(1000)){ trdTCPDataSender->terminate(); } //Delete worker object tcpDataSender->deleteLater(); tcpDataSender=NULL; //Delete child thread trdTCPDataSender->deleteLater(); trdTCPDataSender=NULL; } /* Options Management */ void TCPClient::LoadSettings(){ //Load settings return; } void TCPClient::SaveSettings() const{ //Save settings return; } /* TCP Socket Object Management */ bool TCPClient::IsConnected() const{ return (tcpDataSender->state()==QTcpSocket::ConnectedState); } /* Connection Management */ void TCPClient::SetServerParameters(const QString sServerIP, quint16 iPort){ if (TCPClient::IsValidIPAddress(sServerIP) && TCPClient::IsValidTCPPort(iPort)){ //Save settings _sServerIP=sServerIP; _iPort=iPort; TCPClient::SaveSettings(); } return; } const QString & TCPClient::GetServerIP() const{ return _sServerIP; } quint16 TCPClient::GetServerPort() const{ return _iPort; } void TCPClient::ConnectToServer(bool WairForOperationToComplete){ emit ConnectToServerRequestedEvent(_sServerIP,_iPort,_IsAutoReconnectEnabled,_iAutoReconnectDelay,WairForOperationToComplete); return; } void TCPClient::ConnectToServer(const QString sServerIP, quint16 iPort, bool IsAutoReconnectEnabled, unsigned int iAutoReconnectDelay, bool WairForOperationToComplete){ //Save settings _sServerIP=sServerIP; _iPort=iPort; _IsAutoReconnectEnabled=IsAutoReconnectEnabled; _iAutoReconnectDelay=iAutoReconnectDelay; TCPClient::SaveSettings(); //Connect emit ConnectToServerRequestedEvent(_sServerIP,_iPort,_IsAutoReconnectEnabled,_iAutoReconnectDelay,WairForOperationToComplete); return; } void TCPClient::DisconnectFromServer(bool WairForOperationToComplete){ emit DisconnectFromServerRequestedEvent(WairForOperationToComplete); return; } void TCPClient::SendDataToServer(){ //In high frame rate mode, avoid SendDataToServerRequestedEvent() signal flooding if (tcpDataSender->IsDataSending()){ return; } emit SendDataToServerRequestedEvent(); return; } /* Options */ void TCPClient::SetAutoReconnectMode(bool IsAutoReconnectEnabled){ _IsAutoReconnectEnabled=IsAutoReconnectEnabled; TCPClient::SaveSettings(); emit SetAutoReconnectOptionsRequestedEvent(_IsAutoReconnectEnabled,_iAutoReconnectDelay); return; } bool TCPClient::GetIsAutoReconnectEnabled() const{ return _IsAutoReconnectEnabled; } void TCPClient::SetAutoReconnectDelay(unsigned int iAutoReconnectDelay){ _iAutoReconnectDelay=iAutoReconnectDelay; TCPClient::SaveSettings(); emit SetAutoReconnectOptionsRequestedEvent(_IsAutoReconnectEnabled,_iAutoReconnectDelay); return; } unsigned int TCPClient::GetAutoReconnectDelay() const{ return _iAutoReconnectDelay; } /* Worker Object Event Handler */ void TCPClient::SocketResponseReceivedFromServerEventHandler(QString sResponse){ qDebug()<<"TCPClient: Response"<<sResponse<<"received from the remote"; emit ResponseReceivedFromServerEvent(sResponse); return; } /* Validators */ bool TCPClient::IsValidIPAddress(const QString sIPAddress) const{ QHostAddress hstTestAddr; return hstTestAddr.setAddress(sIPAddress); } bool TCPClient::IsValidTCPPort(quint16 iPort, bool UseRegisteredPortsOnly) const{ quint16 iPortIDMin = 1, iPortIDMax = 65535; if (UseRegisteredPortsOnly){ iPortIDMin=1024; iPortIDMax=32767; } return ((iPort >= iPortIDMin) && (iPort <= iPortIDMax)); }
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