如何实现线程的频繁启动/停止(QThread) [英] How to implement frequent start/stop of a thread (QThread)

问题描述

我需要非常频繁地使用按钮启动和停止线程.我正在使用Qt.最近，我学习了如何创建worker的QObject并将其移至QThread的对象，作为在Qt中实现线程的正确方法.以下是我的实现...

I need to start and stop a thread very frequently using push button..I am using Qt. Recently I learned to create a QObject of the worker and move it to the object of the QThread as the correct way of implementing threads in Qt. Following is my implementation...

Worker.h

class worker : public QObject
{
    Q_OBJECT
public:
    explicit worker(QObject *parent = 0);
    void StopWork();
    void StartWork();
    bool IsWorkRunning();

signal:
    void SignalToObj_mainThreadGUI();

public slots:
    void do_Work();

private:
    void Sleep();

    volatile bool running,stopped;
    QMutex mutex;
    QWaitCondition waitcondition;
};

Worker.cpp

 worker::worker(QObject *parent) :
    QObject(parent),stopped(false),running(false)
{
}

void worker::do_Work()
{
    running = true;
    while(!stopped)
    {
        emit SignalToObj_mainThreadGUI();
        Sleep();
    }
}

void worker::Sleep()
{
    mutex.lock();
    waitcondition.wait(&mutex,10);
    mutex.unlock();
}

void worker::StopWork()
{
    mutex.lock();
    stopped = true;
    running = false;
    mutex.unlock();
}

void worker::StartWork()
{
    mutex.lock();
    stopped = false;
    running = true;
    mutex.unlock();
}

bool worker::IsWorkRunning()
{
    return running;
}

MainWindow.h

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

public slots:

private slots:
    void on_pushButton_push_to_start_clicked();

    void on_pushButton_push_to_stop_clicked();

private:

    Ui::MainWindow *ui;
    worker *myWorker;
    QThread *WorkerThread;
};

MainWindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    myWorker = new worker;
    WorkerThread = new QThread;
    myWorker.moveToThread(WorkerThread);

    QObject::connect(WorkerThread,SIGNAL(started()),myWorker,SLOT(do_Work()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_push_to_start_clicked()
{
    if(!myWorker.IsWorkRunning())
       {
         myWorker->StartWork();
         WorkerThread->start();
       }
}

void MainWindow::on_pushButton_push_to_stop_clicked()
{
  if(myWorker.IsWorkRunning())
     {
       myWorker->StopWork();
       WorkerThread->quit();
     }
}

最初，该应用程序运行正常，但是在对按钮进行一些操作以打开和关闭线程的工作之后，出现了以下错误...

Initially the application works fine but after some operations of the push button to turn the working of the thread on and off the following error comes up...

QObject :: killTimers():无法从另一个线程停止计时器

我很困惑这个错误...我需要将启动/停止功能实现为信号和插槽，而不是类的成员函数吗?

I am quite puzzled at this error...do I need to implement the start/stop functions as signals and slots rather than member functions of the class?

推荐答案

请勿启动和停止WorkerThread.只是让它运行.同样，将您的StartWork()和StopWork()方法移动到公共插槽部分.您真的根本不需要互斥体.

Don't start and stop WorkerThread. Just leave it running. Also, move your StartWork() and StopWork() methods to the public slots section. You really don't need the mutex at all.

Worker.h

class worker : public QObject
{
  Q_OBJECT
public:
  explicit worker(QObject *parent = 0);

signal:
  void SignalToObj_mainThreadGUI();
  void running();
  void stopped();

public slots:
  void StopWork();
  void StartWork();

private slots:
  void do_Work();

private:
  volatile bool running,stopped;
};

Worker.cpp

worker::worker(QObject *parent) :
  QObject(parent), stopped(false), running(false)
{}

void worker::do_Work()
{
  emit SignalToObj_mainThreadGUI();

  if ( !running || stopped ) return;

  // do important work here

  // allow the thread's event loop to process other events before doing more "work"
  // for instance, your start/stop signals from the MainWindow
  QMetaObject::invokeMethod( this, "do_Work", Qt::QueuedConnection );
}

void worker::StopWork()
{
  stopped = true;
  running = false;
  emit stopped();
}

void worker::StartWork()
{
  stopped = false;
  running = true;
  emit running();
  do_Work();
}

MainWindow.h

namespace Ui {
  class MainWindow;
}

class MainWindow : public QMainWindow
{
  Q_OBJECT
public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();

signals:
  void startWork();
  void stopWork();

private slots:
  void on_pushButton_push_to_start_clicked();
  void on_pushButton_push_to_stop_clicked();

private:
  Ui::MainWindow *ui;
  worker *myWorker;
  QThread *WorkerThread;

};

MainWindow.cpp

MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);

  myWorker = new worker;
  WorkerThread = new QThread;
  myWorker.moveToThread(WorkerThread);

  connect( this, SIGNAL(startWork()), myWorker, SLOT(StartWork()) );
  connect( this, SIGNAL(stopWork()), myWorker, SLOT(StopWork()) );
}

void MainWindow::on_pushButton_push_to_start_clicked()
{
  emit startWork();
}

void MainWindow::on_pushButton_push_to_stop_clicked()
{
  emit stopWork();
}

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