Question

我知道我无法在线程之间与QTcpSocket通信，但我找不到我做错了什么。

一旦我将数据发送信号发送到另一个线程中的QTcpSocket，QSocketNotifier应该禁用它自己让QTcpSocket读取数据。因为我遇到上述错误，所以不会被禁用，并且不会发出readyRead（）信号。

我使用QEventLoop实现阻塞机制（同步通信 - ModBus协议）而不锁定主循环。我不能使用waitReadyRead（）因为我以前遇到过该函数的问题（超时）：

https://bugreports.qt-project.org/browse/QTBUG-24451

和

https://bugreports.qt-project.org/browse/QTBUG-14975

有人可能好奇为什么我设置了这么多线程：

Thread1：每个新通信都会创建一个新线程，并使用“全局”互斥锁将其锁定，以确保没有其他函数执行并行通信。在该线程内部 - 在准备和锁定互斥锁之后，我通过Qt :: QueuedConnection信号与QTcpSocket通信，该信号位于Thread2中（与设备持续通信）。

Thread2：创建QTcpSocket对象并移动到线程。一旦我连接设备，我不想关闭插座。因为Im阻塞主事件循环，我需要其他事件循环来运行来自QTcpSocket的信号。

代码：

void someFunctionThatWantToSendData( void ) // Main Thread
{
    ElfKernel::KernelSingleton::Instance().getGUIcontrol()->getCtrlUnitPtr()->execModbusCommand( someParameters, someCommunicationFunction );
}

ElfKernel::FrameReceived ControlUnit::execModbusCommand( std::list<unsigned int> paramsToCommand, FunctionStringList execCommand ) // Main Thread
{
    ModbusCommandReply* mcr = new ModbusCommandReply(); // THREAD_1!!!!!! this object run in a Thread -> ModbusCommandReply : public QThread
    auto timeout = ElfKernel::CommunicationManagerSingleton::Instance().getTimeout();
    mcr->execute( paramsToCommand, execCommand );  // executes THREAD_1
    bool hasFinishedWithoutTimeout = mcr->wait(timeout);  // waiting for THREAD_1 to finish
    FrameReceived ret = mcr->getData();
    delete mcr;
    return ret;
}

// this method is executed after preparations done by: mcr->execute( paramsToCommand, execCommand );
ElfKernel::FrameReceived CommunicationManager::getData( std::string data )  // THREAD_1
{
    emit signalTcpSocketWriteData( data );
    loop.exec();    // QEventLoop declared in a header; program loops until QTcpSocket::readyRead() signal will hit the slot TcpSocketClient::readyRead()
    FrameReceived fr = tcpSocket->readDataString();
}

// executed by: emit signalTcpSocketWriteData( data );
void TcpSocketClient::writeDataSlot( std::string data ) // THREAD_2!!!!!
{
    tcpSocket_->write( data );
    tcpSocket_->flush();
}

void TcpSocketClient::readyRead( void ) // should be executed in THREAD_2 but signal readyRead() never arrives here because a get error on Output: "QSocketNotifier: socket notifiers cannot be disabled from another thread"
{
    ElfKernel::CommunicationManagerSingleton::Instance().loop.quit();   // breaks loop.exec() in CommunicationManager::getData()
}

// constructor
CommunicationManager::CommunicationManager( void )  // Main Thread
{
    tcpSocket = new TcpSocketClient();
    tcpSocketThread = new QThread();
    tcpSocket->moveToThread( tcpSocketThread );
    QObject::connect( tcpSocketThread, SIGNAL(started()), tcpSocket, SLOT(prepare()) );
    tcpSocketThread->start();   // CREATED THREAD_2!!!!!

    QObject::connect(this, SIGNAL(signalTcpSocketWriteData(std::string)), tcpSocket, SLOT(writeDataSlot(std::string)), Qt::QueuedConnection );
    QObject::connect(this, SIGNAL(signalTcpSocketReadData(std::string *)), tcpSocket, SLOT(readDataSlot(std::string *)), Qt::QueuedConnection);

    // and other stuff
}

// constructor
TcpSocketClient::TcpSocketClient(QObject *parent)   // Main Thread - before it is moved to THREAD_2
{
    parent;

    //prepare();    // it is executed after signal QThread::started() is emitted
}

// method run after thread started
void TcpSocketClient::prepare( void )   // THREAD_2
{
    tcpSocket_ = new QTcpSocket(this);
    QObject::connect(tcpSocket_, SIGNAL(disconnected()), this, SLOT(hostHaveDisconnected()));
    QObject::connect(tcpSocket_, SIGNAL(readyRead()), this, SLOT(readyRead()));
}

因为我说插槽TcpSocketClient :: readyRead（）将不会被调用并且我在输出中得到消息：“QSocketNotifier：无法从另一个线程禁用套接字通知程序”。

如果我替换此代码：

ElfKernel::FrameReceived ControlUnit::execModbusCommand( std::list<unsigned int> paramsToCommand, FunctionStringList execCommand ) // Main Thread
{
    ModbusCommandReply* mcr = new ModbusCommandReply(); // THREAD_1!!!!!! this object run in a Thread -> ModbusCommandReply : public QThread
    auto timeout = ElfKernel::CommunicationManagerSingleton::Instance().getTimeout();
    mcr->execute( paramsToCommand, execCommand );  // executes THREAD_1
    bool hasFinishedWithoutTimeout = mcr->wait(timeout);  // waiting for THREAD_1 to finish
    FrameReceived ret = mcr->getData();
    delete mcr;
    return ret;
}

使用：

ElfKernel::FrameReceived ControlUnit::execModbusCommand( std::list<unsigned int> paramsToCommand, FunctionStringList execCommand ) // Main Thread
{
    FrameReceived ret = execCommand( paramsToCommand );  // Main Thread
    return ret;
}

所以程序没有被推送到主线程但只在主线程中运行（只有差异！）然后一切正常工作 - readyRead槽工作循环中断，我得到数据。我需要将ModbusCommandReply作为线程运行，因为我在mcr-> gt执行中设置了一个mutex.lock（），所以每当我的程序的其他部分运行方法execModbusCommand时，它将被停止，直到其他线程将释放资源来建立通信。

我不明白为什么它说“QSocketNotifier：套接字通知程序无法从另一个线程禁用” - 我在线程启动后通过将新对象放在堆上来在THREAD_2内设置QTcpSocket：tcpSocket_ = new QTcpSocket（this）; < / p>

我将不胜感激，谢谢！

Answer 1

在主线程中我建立了连接：

tcpSocket->connect( ... );

在主线程中生成子对象而不是在tcpSocketThread中。

另外建议：

tpcSocket->setParent(0);
// before
tcpSocket->moveToThread( tcpSocketThread );

QSocketNotifier：无法从另一个线程禁用套接字通知程序

1 个答案: