Two threads in a console application

[msr]

Hello,

Im developing a console application in which the main thread is continuously reading and parsing user input commands. One of that commands is called "loop" and with that I want to start loop after the user press ENTER and stops it when the user press ENTER again.

So I have something like this:

(MainThread)

while(getchar() != '\n') QCoreApplication::processEvents();
loop->start(); 
while(getchar() != '\n') QCoreApplication::processEvents();
loop->stop();

while(getchar() != '\n') QCoreApplication::processEvents();
loop->start(); 
while(getchar() != '\n') QCoreApplication::processEvents();
loop->stop();

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(ReadLoopThread)

while(condition)
{
   // read data from a serial device
   // print data on console
   // sleep 'x' miliseconds
}

while(condition)
{
   // read data from a serial device
   // print data on console
   // sleep 'x' miliseconds
}

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What's the correct way to implement this?

I tried many solutions (none worked well):
1) create a thread with a timer that emits a signal every 'x' miliseconds (avoiding the use of sleep()) and connected to a slot that reads data from serial device and print data in console if a global boolean variable is 'true' (meaning Im on the "loop" command); not efficient - timer is always emitting the signal
2) two mutexes to control/block the loop as needed; it works but if I call QThread::sleep() it the thread blocks (why?)

Now Im thinking on using .moveToThread() of QObject class but I really need to control the periodicity of loop and that way I guess I can't use QThread::sleep().

The code in main():

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    Commander *commander = new Commander();
    QObject::connect(commander, SIGNAL(end()), &a, SLOT(quit()));
    QTimer::singleShot(0, commander, SLOT(start())); // start the thread
    QTimer::singleShot(10, commander, SLOT(console())); // start console's loop
 
    return a.exec();
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    Commander *commander = new Commander();
    QObject::connect(commander, SIGNAL(end()), &a, SLOT(quit()));
    QTimer::singleShot(0, commander, SLOT(start())); // start the thread
    QTimer::singleShot(10, commander, SLOT(console())); // start console's loop

    return a.exec();
}

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Commander inherits QThread. console() is the where I get (getline()) and parse user input.

The ReadLoopThread:

class ReadLoop : public QThread
{
    Q_OBJECT
public:
    ReadLoop(Commander *commander) {m_commander = commander;}
public slots:
    void run();
private:
    Commander *m_commander;
};

class ReadLoop : public QThread
{
    Q_OBJECT
public:
    ReadLoop(Commander *commander) {m_commander = commander;}
public slots:
    void run();
private:
    Commander *m_commander;
};

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Control implemented with mutexes:

void ReadLoop::run()
{
    forever
    {
        qDebug() << "readLoop is waiting to start";
        start_mutex.lock();
        start_mutex.unlock();
        while(!stop_mutex.tryLock())
        {
            qDebug() << "readLoop'ing";
            //QThread::sleep(1000); // DOESN'T WORK! Block the thread.
                                               // Without it, qDebug() executes "as fast as possible" - not acceptable
        }
        stop_mutex.unlock();
    }
}

void ReadLoop::run()
{
    forever
    {
        qDebug() << "readLoop is waiting to start";
        start_mutex.lock();
        start_mutex.unlock();
        while(!stop_mutex.tryLock())
        {
            qDebug() << "readLoop'ing";
            //QThread::sleep(1000); // DOESN'T WORK! Block the thread.
                                               // Without it, qDebug() executes "as fast as possible" - not acceptable
        }
        stop_mutex.unlock();
    }
}

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Any help is GREATLY appreciated.