Mutlithreading hangs gui

[thahir1986]

First of all , i need to tell I'm a very newb to qt.

I want to create a multithreading program for RingBuffer. I done it, but while the thread running it hangs the gui.

I call the two thread for read from and write on ringbuffer by the push button signal. While the thread process going on , i can't access the gui ..Is anything wrong in my program.

Below i paste my program. I have the ring Buffer as a seperate class file. If u want i will give that too..


//Header file

#ifndef RING_QTHREAD_H
#define RING_QTHREAD_H
 
#include <QWidget>
#include <QtGui>
#include <QThread>
#include <QMutex>
 
#include "ringBuffer.hh"
 
#define BUFF_SIZE 10
 
namespace Ui {
    class Ring_Qthread;
}
 
class Ring_Qthread : public QWidget  {
    Q_OBJECT
public:
    Ring_Qthread(QWidget *parent = 0);
    ~Ring_Qthread();
 
 
protected:
    void changeEvent(QEvent *e);
    bool eventFilter(QObject *, QEvent *);
 
private slots:
    void slot_load_buffer();
    void slot_start_process();
    void slot_quite_me();
 
private:
    Ui::Ring_Qthread *ui;
 
    void fn_create_conn(void);
 
};
 
class Writer : public QThread
{
public:
    Writer();
    void run();
};
 
class Reader : public QThread
{
public:
    Reader();
    void run();
};
 
/*
 * Start the Structure for input and output of RingBuffer.
 */
 
typedef struct struct_buff
{
    int xval;
    int yval;
 
    float xtime;
    float ytime;
}struct_buff_t;
 
/*
 * End of strucutre.
 */
 
 
#endif // RING_QTHREAD_H

#ifndef RING_QTHREAD_H
#define RING_QTHREAD_H

#include <QWidget>
#include <QtGui>
#include <QThread>
#include <QMutex>

#include "ringBuffer.hh"

#define BUFF_SIZE 10

namespace Ui {
    class Ring_Qthread;
}

class Ring_Qthread : public QWidget  {
    Q_OBJECT
public:
    Ring_Qthread(QWidget *parent = 0);
    ~Ring_Qthread();


protected:
    void changeEvent(QEvent *e);
    bool eventFilter(QObject *, QEvent *);

private slots:
    void slot_load_buffer();
    void slot_start_process();
    void slot_quite_me();

private:
    Ui::Ring_Qthread *ui;

    void fn_create_conn(void);

};

class Writer : public QThread
{
public:
    Writer();
    void run();
};

class Reader : public QThread
{
public:
    Reader();
    void run();
};

/*
 * Start the Structure for input and output of RingBuffer.
 */

typedef struct struct_buff
{
    int xval;
    int yval;

    float xtime;
    float ytime;
}struct_buff_t;

/*
 * End of strucutre.
 */


#endif // RING_QTHREAD_H

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//Sourcefile...

#include "ring_qthread.h"
#include "ui_ring_qthread.h"
 
 
 
//Global Variables
struct_buff_t in_buff[BUFF_SIZE+1], out_buff[BUFF_SIZE+1];
QMutex mut_check;
QWaitCondition cond_check;
int i_return = 0;
long int i_tot_count = 0;
long int i_out_count = 0;
bool b_inp = false;
bool b_out = false;
//i_tot_count=i_out_count=0;
 
 
/*
 * Start of Predefined Functions
 */
 
Ring_Qthread::Ring_Qthread(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Ring_Qthread)
{
    ui->setupUi(this);
    fn_create_conn();
 
}
 
 
Ring_Qthread::~Ring_Qthread()
{
    delete ui;
}
 
void Ring_Qthread::changeEvent(QEvent *e)
{
    QWidget::changeEvent(e);
    switch (e->type())
    {
        qDebug() << "omg";
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }
}
 
/*
 * End of Pre-defined Functions
 */
 
 
/*
 * Event filter function for get call after mouse click on all buttons.
 */
 
 
bool Ring_Qthread::eventFilter(QObject *_obj, QEvent *_event)
{
 
    if(_event->type() == QEvent::MouseButtonPress)// && ((QMouseEvent*)_event)->button() == Qt::LeftButton)
    {
        qDebug() << "This is Event filter to help u\n";
        if(_obj->objectName() == "btn_quit")
        {
            qDebug() << "btn_quit";
            emit slot_quite_me();
        }
        else if (_obj->objectName() == "btn_process")
        {
            qDebug() << "btn_process";
            emit slot_start_process();
        }
        else if (_obj->objectName() == "btn_load")
        {
            qDebug() << "btn_load";
            emit slot_load_buffer();
        }
        return true;
 
    }
    else
        return false;
}
 
 
/*
 * Start of create connections Functions.
 */
void Ring_Qthread::fn_create_conn()
{
 
      //Use the below commented code if u r gonna use slot and signals
 
    connect(ui->btn_load, SIGNAL(clicked()), this, SLOT(slot_load_buffer()));
    connect(ui->btn_process, SIGNAL(clicked()), this, SLOT(slot_start_process()));
    connect(ui->btn_quit, SIGNAL(clicked()), this, SLOT(slot_quite_me()));
 
  /*
    ui->btn_process->installEventFilter(this);
    ui->btn_quit->installEventFilter(this);
    ui->btn_load->installEventFilter(this);
   */
}
 
/*
 * End of Create connections Functions
 */
 
/*
 * Start of Slot Functions.
 */
 
void Ring_Qthread::slot_load_buffer()
{
    for (int i=0; i<BUFF_SIZE; ++i)
    {
        in_buff[i].xval = rand() % 10;
        in_buff[i].yval = rand() % 10;
 
        in_buff[i].xtime = rand() % 500;
        in_buff[i].ytime = rand() % 500;
    }
    in_buff[BUFF_SIZE].xval = -1;
    in_buff[BUFF_SIZE].yval = -1;
 
    in_buff[BUFF_SIZE].xtime = -1;
    in_buff[BUFF_SIZE].ytime = -1;
 
    QFile *in_file;
            in_file = new QFile("input_buffer.txt");
    if(!in_file->open(QIODevice::WriteOnly | QIODevice::Text))
        qDebug() << "Error in open the input Buffer file";
    QTextStream stream_in(in_file);
    for (int j=0;j<=BUFF_SIZE;j++)
    {
        stream_in << in_buff[j].xval << " " << in_buff[j].yval << " " << in_buff[j].xtime << " " << in_buff[j].ytime << "\n";
 
    }
 
}
 
void Ring_Qthread::slot_start_process()
{
 
    Writer writer1;
    Reader reader1;
 
    writer1.start();
    reader1.start();
 
    writer1.wait();
    reader1.wait();
 
    return (void)NULL;
 
 
 
}
 
void Ring_Qthread::slot_quite_me()
{
    exit(0);
}
 
///////////////////////////////////////////////////////////////
/*
 * Start of Class Writer Functions.
 */
 
Writer::Writer() :  QThread()
{
    //Code if u want.
}
 
void Writer::run()
{
    //i_return = 3;
    for (int j=0; j<=BUFF_SIZE; j++)
    {
        qDebug() << in_buff[j].xval << " " << in_buff[j].yval << " " << in_buff[j].xtime << " " << in_buff[j].ytime << "\n";
    }
 
    forever
    {
        mut_check.lock();
        if (i_return !=4)
        {
        i_return = fn_process(1, &in_buff[i_tot_count].xval, &in_buff[i_tot_count].yval, &in_buff[i_tot_count].xtime, &in_buff[i_tot_count].ytime);
        if (i_return == 4)
        {
            cond_check.wait(&mut_check);
        }
        else if (i_return == 2)
        {
            //qDebug() << "Writer \n";
 
            i_tot_count++;
            //cond_check.wait(&mut_check);
        }
        if(in_buff[i_tot_count-1].xval == -1)
            b_inp = true;
    }
        mut_check.unlock();
 
        if (b_inp && b_out)
            return (void) NULL;
    }
 
}
 
/*
 * End of Class Writer Functions.
 */
 
 
 
///////////////////////////////////////////////////////////////
/*
 * Start of Reader Class Functions
 */
 
Reader::Reader() :  QThread()
{
    //Code if u want
}
 
void Reader::run()
{
    forever
    {
        mut_check.lock();
     if(i_return !=1)
     {
        i_return = fn_process(2, &out_buff[i_out_count].xval, &out_buff[i_out_count].yval, &out_buff[i_out_count].xtime, &out_buff[i_out_count].ytime);
 
        if(i_return == 3)
        {
            //qDebug() << "reader\n";
 
            i_out_count++;
            //cond_check.wakeOne();
        }
        else if (i_return == 1)
        {
            qDebug() << "go man go\n";
            cond_check.wakeOne();
        }
        if (out_buff[i_out_count-1].xval == -1)
            b_out = true;
    }
        mut_check.unlock();
 
        if (b_inp && b_out)
        {
            qDebug() << "\nOutPut man.\n";
            for (int j=0; j<=BUFF_SIZE; j++)
            {
                qDebug() << out_buff[j].xval << " " << out_buff[j].yval << " " << out_buff[j].xtime << " " << out_buff[j].ytime << "\n";
            }
            return (void)NULL;
        }
    }
}
 
/*
 * End of Reader Class functions.
 */
 
///////////////////////////////////////////////////////////////

#include "ring_qthread.h"
#include "ui_ring_qthread.h"



//Global Variables
struct_buff_t in_buff[BUFF_SIZE+1], out_buff[BUFF_SIZE+1];
QMutex mut_check;
QWaitCondition cond_check;
int i_return = 0;
long int i_tot_count = 0;
long int i_out_count = 0;
bool b_inp = false;
bool b_out = false;
//i_tot_count=i_out_count=0;


/*
 * Start of Predefined Functions
 */

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

}


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

void Ring_Qthread::changeEvent(QEvent *e)
{
    QWidget::changeEvent(e);
    switch (e->type())
    {
        qDebug() << "omg";
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }
}

/*
 * End of Pre-defined Functions
 */


/*
 * Event filter function for get call after mouse click on all buttons.
 */


bool Ring_Qthread::eventFilter(QObject *_obj, QEvent *_event)
{

    if(_event->type() == QEvent::MouseButtonPress)// && ((QMouseEvent*)_event)->button() == Qt::LeftButton)
    {
        qDebug() << "This is Event filter to help u\n";
        if(_obj->objectName() == "btn_quit")
        {
            qDebug() << "btn_quit";
            emit slot_quite_me();
        }
        else if (_obj->objectName() == "btn_process")
        {
            qDebug() << "btn_process";
            emit slot_start_process();
        }
        else if (_obj->objectName() == "btn_load")
        {
            qDebug() << "btn_load";
            emit slot_load_buffer();
        }
        return true;

    }
    else
        return false;
}


/*
 * Start of create connections Functions.
 */
void Ring_Qthread::fn_create_conn()
{

      //Use the below commented code if u r gonna use slot and signals

    connect(ui->btn_load, SIGNAL(clicked()), this, SLOT(slot_load_buffer()));
    connect(ui->btn_process, SIGNAL(clicked()), this, SLOT(slot_start_process()));
    connect(ui->btn_quit, SIGNAL(clicked()), this, SLOT(slot_quite_me()));

  /*
    ui->btn_process->installEventFilter(this);
    ui->btn_quit->installEventFilter(this);
    ui->btn_load->installEventFilter(this);
   */
}

/*
 * End of Create connections Functions
 */

/*
 * Start of Slot Functions.
 */

void Ring_Qthread::slot_load_buffer()
{
    for (int i=0; i<BUFF_SIZE; ++i)
    {
        in_buff[i].xval = rand() % 10;
        in_buff[i].yval = rand() % 10;

        in_buff[i].xtime = rand() % 500;
        in_buff[i].ytime = rand() % 500;
    }
    in_buff[BUFF_SIZE].xval = -1;
    in_buff[BUFF_SIZE].yval = -1;

    in_buff[BUFF_SIZE].xtime = -1;
    in_buff[BUFF_SIZE].ytime = -1;

    QFile *in_file;
            in_file = new QFile("input_buffer.txt");
    if(!in_file->open(QIODevice::WriteOnly | QIODevice::Text))
        qDebug() << "Error in open the input Buffer file";
    QTextStream stream_in(in_file);
    for (int j=0;j<=BUFF_SIZE;j++)
    {
        stream_in << in_buff[j].xval << " " << in_buff[j].yval << " " << in_buff[j].xtime << " " << in_buff[j].ytime << "\n";

    }

}

void Ring_Qthread::slot_start_process()
{

    Writer writer1;
    Reader reader1;

    writer1.start();
    reader1.start();

    writer1.wait();
    reader1.wait();

    return (void)NULL;



}

void Ring_Qthread::slot_quite_me()
{
    exit(0);
}

///////////////////////////////////////////////////////////////
/*
 * Start of Class Writer Functions.
 */

Writer::Writer() :  QThread()
{
    //Code if u want.
}

void Writer::run()
{
    //i_return = 3;
    for (int j=0; j<=BUFF_SIZE; j++)
    {
        qDebug() << in_buff[j].xval << " " << in_buff[j].yval << " " << in_buff[j].xtime << " " << in_buff[j].ytime << "\n";
    }

    forever
    {
        mut_check.lock();
        if (i_return !=4)
        {
        i_return = fn_process(1, &in_buff[i_tot_count].xval, &in_buff[i_tot_count].yval, &in_buff[i_tot_count].xtime, &in_buff[i_tot_count].ytime);
        if (i_return == 4)
        {
            cond_check.wait(&mut_check);
        }
        else if (i_return == 2)
        {
            //qDebug() << "Writer \n";

            i_tot_count++;
            //cond_check.wait(&mut_check);
        }
        if(in_buff[i_tot_count-1].xval == -1)
            b_inp = true;
    }
        mut_check.unlock();

        if (b_inp && b_out)
            return (void) NULL;
    }

}

/*
 * End of Class Writer Functions.
 */



///////////////////////////////////////////////////////////////
/*
 * Start of Reader Class Functions
 */

Reader::Reader() :  QThread()
{
    //Code if u want
}

void Reader::run()
{
    forever
    {
        mut_check.lock();
     if(i_return !=1)
     {
        i_return = fn_process(2, &out_buff[i_out_count].xval, &out_buff[i_out_count].yval, &out_buff[i_out_count].xtime, &out_buff[i_out_count].ytime);

        if(i_return == 3)
        {
            //qDebug() << "reader\n";

            i_out_count++;
            //cond_check.wakeOne();
        }
        else if (i_return == 1)
        {
            qDebug() << "go man go\n";
            cond_check.wakeOne();
        }
        if (out_buff[i_out_count-1].xval == -1)
            b_out = true;
    }
        mut_check.unlock();

        if (b_inp && b_out)
        {
            qDebug() << "\nOutPut man.\n";
            for (int j=0; j<=BUFF_SIZE; j++)
            {
                qDebug() << out_buff[j].xval << " " << out_buff[j].yval << " " << out_buff[j].xtime << " " << out_buff[j].ytime << "\n";
            }
            return (void)NULL;
        }
    }
}

/*
 * End of Reader Class functions.
 */

///////////////////////////////////////////////////////////////

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[tbscope]

Try debugging your program. Set some breakpoints and see where it loops infinitly.

What the #@* is this?

return (void)NULL;

return (void)NULL;

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By the way: asking the same question on multiple forums is considered rude by me.

[wysota]

You are starting a thread and immediately calling wait() which blocks the calling thread (your gui thread) until the thread it is waiting for exits.