我从 QThread 调用 QTcpSocket 类的写入函数时出现错误

Posted 2023-02-16

【中文标题】我从 QThread 调用 QTcpSocket 类的写入函数时出现错误

【英文标题】：An error ouucrred while I calling the write function of the QTcpSocket class from a QThread

【发布时间】：2016-07-19 03:39:05

【问题描述】：

我正在学习 Qt 中的多线程编程，然后当我从 QThread 调用 QTcpSocket 类的 write 函数时，函数输出为：

QObject: Cannot create children for a parent that is in a different thread.
(Parent is QNativeSocketEngine(0x6f1840), parent's thread is QThread(0x624e90), current thread is QThread(0x716ed0)

我调用 write 函数的代码：

QString Processor::GetSystemInfoOfClient() const

    QString result;
    const char *send_buffer = "GSIOC";
    char receive_buffer[100];
    this->cli_sock->write(send_buffer);
    this->cli_sock->waitForBytesWritten();
    this->cli_sock->waitForReadyRead(100000);
    this->cli_sock->read(receive_buffer, 100);
    result = QString(receive_buffer);
    return result;

我接受连接的代码：

void Processor::Accept()

    this->cli_sock = m_server->nextPendingConnection();
    this->cli_addr = this->cli_sock->peerAddress();
    this->cli_port = this->cli_sock->peerPort();

连接处理器的定义：

class Processor : public QObject

    Q_OBJECT
public:
    explicit Processor(QObject *parent = 0, QTcpServer *server = nullptr);
private:
    QTcpServer *m_server = nullptr;
    QTcpSocket *cli_sock = nullptr;
    QHostAddress cli_addr;
    quint16 cli_port;

    QString GetSystemInfoOfClient() const;
signals:
   void GetDetailedFinished(const QString &address,const QString &port, const QString &SystemInfo);
public slots:
   void GetClientDetail();
   void Accept();
;

然后我将处理器移动到QThread

    Processor *processor = new Processor(0, server);
    processor->moveToThread(&processor_thread);
    connect(&processor_thread, &QThread::finished, processor, &QObject::deleteLater);
    connect(this, &Processor_Controller::Accept, processor, &Processor::Accept);
    connect(this, &Processor_Controller::GetClientDetail, processor, &Processor::GetClientDetail);
    connect(processor, &Processor::GetDetailedFinished, this, &Processor_Controller::PassClientDetail);
    processor_thread.start();

我在主线程中创建了QTcpServer。

    // The address of the server
    QHostAddress srv_addr("127.0.0.1");

    // The server listen port
    quint16 srv_port = 9895;

    Processor_Controller *controller = new Processor_Controller(0, &server);

    connect(&server, &QTcpServer::newConnection, controller, &Processor_Controller::BeginProcess);

    connect(controller, &Processor_Controller::DisplayClientDetail, this, &MainWindow::DisplayClientDetail);

    // BeginListen
    if(!server.listen(srv_addr, srv_port))
        emit statusBar()->showMessage("Listen Failed");
    else
        emit statusBar()->showMessage("Listen Success");

调用GetSystemInfoOfClient函数的函数：

void Processor::GetClientDetail()

    QString address    = this->cli_addr.toString();
    QString port       = QString::number(this->cli_port);
    QString SystemInfo = this->GetSystemInfoOfClient();
    emit this->GetDetailedFinished(address, port, SystemInfo);

处理器的构造函数：

Processor::Processor(QObject *parent, QTcpServer *server) : QObject(parent)

    this->m_server = server;

我只想在主线程中创建一个服务器并在处理器类中处理连接。如何在不改变这种想法的情况下避免这个错误？

【问题讨论】：

当您初始化cli_sock 变量时，尝试将封闭的Processor 对象设置为父对象

我已经尝试过这样做，但没有太大区别

更多的想法：1）在堆上创建cli_addr，而不是在堆栈上2）向我们展示Processor构造函数的代码。此错误与线程关联性有关，即您在一个线程中创建了一些 QObject 并在另一个线程中使用

GetSystemInfoOfClient 的电话在哪里？

处理器构造函数只有一行代码： Processor::Processor(QObject *parent, QTcpServer *server) : QObject(parent) this->m_server = server;

【参考方案1】：

我在Processor::Accept函数中使用这两行代码就解决了这个问题

QTcpSocket *m_socket = m_server->nextPendingConnection();
this->cli_sock->setSocketDescriptor(m_socket->socketDescriptor(), m_socket->state(), m_socket->openMode());

【讨论】：

请查看Qt Threaded Fortune Server Example 以及他们实现多线程服务器的方式并遵循他们的模式。

见setSocketDescriptor的documentation末尾的注释，不可能用相同的本机套接字描述符初始化两个抽象套接字。。在您的代码中，您在cli_sock 和m_socket 中使用相同的套接字描述符。你迟早会遇到问题。 . .

我会看到示例，而m_socket 就像一个临时对象一样，我将一无所获。