How can i stop a thread running in my Dialog Class from my mainWindow

learnist

My mainwindow looks like this

it is a qlistwidget with some Job items, whenever any job item is clicked , it shows up the QDialogbox which looks like this.

The QDialog has a listwidget and a show button, whenever the show button is clicked , a list of 10000 possible employees will show up in the Qlistwidget and these employees are calculated by this function which is in a thread3.

```

void KeyComd::Print_Descendants_key(IUIAutomation* pUIAutomation, IUIAutomationElement* pParent, int indent)
{
///Function which appends 1000 list-items in a QListWidget called "elements_listwidget" in my QDialog.
}

The usual flow is:

1) i click an item(Carwash job) in Mainwindow
2) the QDialog box shows-up,i press showbutton and list of 10000 possible employees show up
3) i select an employee jack in QDialog and click okay.
4) the Mainwindow item gets changed to "Car washing job assigned to: Jack, height 5'10, weight 86"

My question is that in step-3 , even when entire 10000 elements are not loaded yet and i find my preferred employee in first 500 list items, i select it and click 'ok' on dialog box , the item in mainwindow still doesnt change until the thread3 finishes running, can i force stop or terminate thread3 ?? such that when i click okay thread3 stops, and the item in main window changes.

This is my Dialog cpp file named Keycomd.cpp

#include "KeyComd.h"
#include "ui_KeyComd.h"
#include <QtCore>
#include <QtGui>
#include <vector>
#include<QDebug>
#include "ExecutionContext.h"
#include "XMLParser.h"
#include "Logger.h"
#include "BlockCommand.h"
#include "UIAElementUtils.h"

ExecutionContext exc;
QStringList refreshed_elements;

KeyComd::KeyComd(QWidget *parent)
: QDialog(parent)
{
ui.setupUi(this);
HRESULT hr = exc.init();
}

KeyComd::~KeyComd()
{
}
void KeyComd::on_showbutton_clicked()
{
ui.elements_listwidget->clear();
desktop_elements.clear();

std::thread thread3(&KeyComd::Print_step, this); // Here it calls a thread, because of this thread ,the execution of "Print_Descendants_key" function happens in a separate thread from main thread
thread3.detach();

}

void KeyComd::Print_step()
{
Print_Descendants_key(exc.pUIAutomation, nullptr, 0);
}

void KeyComd::Print_Descendants_key(IUIAutomation* pUIAutomation, IUIAutomationElement* pParent, int indent)
{
///Function which appends 10000 list-items in a QListWidget called "elements_listwidget" in my QDialog.
}


my mainwindow.cpp code is

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "XMLParser.h"
#include "ExecutionContext.h"
#include "Logger.h"
#include "BlockCommand.h"
#include "UIAElementUtils.h"
#include <thread>
#include <iostream>
#include <QtWidgets/qapplication.h>
#include <QtCore>
#include <QtGui>
#include <sstream>
#include <QtWidgets/qmessagebox.h>
#include <QtWidgets/qlistwidget.h>
#include <string>
#include <string.h>
#include <cstring>
#include <chrono>
#include <QCloseEvent>
#include "Header.h"
#include <map>
#include <QtWidgets/qinputdialog.h>
#include <vector>
#include "dragsupport.h"
#include "KeyComd.h"

ExecutionContext exContext;

using namespace std;

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

HRESULT hr = CoInitializeEx(NULL, NULL);
ExecutionContext exContext;
hr = exContext.init();

}

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

void MainWindow::on_xml_scripts_textbox_itemDoubleClicked(QListWidgetItem* item)
{
KeyComd keyComd;
keyComd.exec();

    if (keyComd.result() == QDialog::Accepted) //when i click okay,the code inside this block gets executed
    {                   
       // Here when okay is clicked, i want to check if thread3 is still running and if it is then stop/terminate the thread3 which is in KeyComd.cpp file 
       
       ui->qlistwidget->additem("Car washing Job assigned to: Jack , height 5'10, weight 86, age 21");
    }

}

Kent-Dorfman

Signals and slots, Mrs. Langdon, signals and slots.

www.classicmoviehub.com - John Wayne quote

And no, you shouldn't force-terminate a thread. You should build in preemption points that check for an exit flag and exit the thread function gracefully if the flag is set.

jsulm

@learnist Why does your dialog start a thread in the first place? Also, you are detaching from the thread: how do you want to check then whether it is running and stop it if it does? Do not detach and make the thread object member variable.

learnist

@jsulm Thanks sounds like that would would work. i changed it slightly but getting some errors

is this what u are saying ??
code for mainwindow.cpp

#include <QThread>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "XMLParser.h"
#include "ExecutionContext.h"
#include "Logger.h"
#include "BlockCommand.h"
#include "UIAElementUtils.h"
#include <thread>
#include <iostream>
#include <QtWidgets/qapplication.h>
#include <QtCore>
#include <QtGui>
#include <sstream>
#include <QtWidgets/qmessagebox.h>
#include <QtWidgets/qlistwidget.h>
#include <string>
#include <string.h>
#include <cstring>
#include <chrono>
#include <QCloseEvent>
#include "Header.h"
#include <map>
#include <QtWidgets/qinputdialog.h>
#include <vector> 
#include "dragsupport.h"
#include "KeyComd.h"


ExecutionContext exContext;

using namespace std; 

MainWindow::MainWindow(QWidget* parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    populatemaps();
    ui->setupUi(this);
 
    HRESULT hr = CoInitializeEx(NULL, NULL);
    ExecutionContext exContext;
    hr = exContext.init();
    QThread dialog_thread;
}


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

void MainWindow::on_xml_scripts_textbox_itemDoubleClicked(QListWidgetItem* item)
{
        KeyComd keyComd;
        keyComd.moveToThread(&dialog_thread);
        connect(&keyComd, &QDialog::Accepted, &dialog_thread, &QThread::quit);
        dialog_thread.start();
        keyComd.exec();        
        
        if (keyComd.result() == QDialog::Accepted) //when i click okay,the code inside this block gets executed
        {                   
           // Here when okay is clicked, i want to check if thread3 is still running and if it is then stop/terminate the thread3 which is in KeyComd.cpp file 
           ui->qlistwidget->additem("Car washing Job assigned to: Jack , height 5'10, weight 86, age 21");   
           emit keyComd.accepted();
        }
}

code for dialogbox

#include "KeyComd.h"
#include "ui_KeyComd.h"
#include <QtCore>
#include <QtGui>
#include <vector> 
#include<QDebug>
#include "ExecutionContext.h"
#include "XMLParser.h"
#include "Logger.h"
#include "BlockCommand.h"
#include "UIAElementUtils.h"

ExecutionContext exc;
QStringList refreshed_elements;

KeyComd::KeyComd(QWidget *parent)
    : QDialog(parent)
{
    ui.setupUi(this);
    HRESULT hr = exc.init();
}

KeyComd::~KeyComd()
{
}
void KeyComd::on_showbutton_clicked()
{
    ui.elements_listwidget->clear();
    desktop_elements.clear();
    this->Print_Descendants_key();
}

void KeyComd::Print_step()
{
    Print_Descendants_key(exc.pUIAutomation, nullptr, 0);
}

void KeyComd::Print_Descendants_key(IUIAutomation* pUIAutomation, IUIAutomationElement* pParent, int indent)
{
    ///Function which appends 10000 list-items in a QListWidget called "elements_listwidget" in my QDialog.
}

but i am getting an error in this line keyComd.moveToThread(&dialog_thread); saying identifier dialog_thread is undefined. in the mainwindow class.

jsulm

@learnist said in How can i stop a thread running in my Dialog Class from my mainWindow:

QThread dialog_thread;

? This is a local variable in the constructor! Make it MEMBER variable...

"saying identifier dialog_thread is undefined. in the mainwindow class" - of course it's undefined as you do not have such a member variable only a local variable in the constructor...

learnist

@jsulm Thanks for correcting me ,i tried making the thread member function, still it shows this error "Here its showing an error "call of an object of a class type without appropriate operator() or conversion functions to pointer-to-function type"

for reference this is my.cpp file

#include "KeyComd.h"
#include "ui_KeyComd.h"
#include <QtCore>
#include <QtGui>
#include <vector> 
#include<QDebug>
#include "ExecutionContext.h"
#include "XMLParser.h"
#include "Logger.h"
#include "BlockCommand.h"
#include "UIAElementUtils.h"

ExecutionContext exc;
QStringList refreshed_elements;

KeyComd::KeyComd(QWidget *parent)
	: QDialog(parent)
{
	ui.setupUi(this);
	HRESULT hr = exc.init();	
}

KeyComd::~KeyComd()
{
}
void KeyComd::on_showbutton_clicked()
{
	ui.elements_listwidget->clear();
	desktop_elements.clear();

	thread3(&KeyComd::Print_step, this); // Here its showing an error "call of an object of a class type without appropriate operator() or conversion functions to pointer-to-function type"
	thread3.detach(); //should i not detach here ???
}

void KeyComd::Print_step()
{
	Print_Descendants_key(exc.pUIAutomation, nullptr, 0);
}

void KeyComd::Print_Descendants_key(IUIAutomation* pUIAutomation, IUIAutomationElement* pParent, int indent)
{
	///Function which appends 1000 list-items in a QListWidget called "elements_listwidget" in my QDialog.
}




void KeyComd::closeEvent(QCloseEvent* event)
{
	std::terminate();
}

void KeyComd::accepted()
{
	std::terminate();
}

This is my .h file

#pragma once

#include<QtWidgets/qdialog.h>
#include "ui_KeyComd.h"
#include <thread>
#include "ExecutionContext.h"
#include "XMLParser.h"
#include "Logger.h"
#include "BlockCommand.h"
#include "UIAElementUtils.h"

class KeyComd : public QDialog, public Ui::KeyComd
{
	Q_OBJECT
	
public:
	KeyComd(QWidget *parent = Q_NULLPTR);
	~KeyComd();

	std::thread thread3; //Here i am creating it as a member variable.
	
	std::thread *thread3; //have even tried this, still it shows an error.


	void Print_step();

	void closeEvent(QCloseEvent* event);
	void accepted();
	void Print_Descendants_key(IUIAutomation* pUIAutomation, IUIAutomationElement* pParent, int indent = 0);
	QString PrintElement_Info_key(IUIAutomationElement* pElement);

private slots:
	void on_showbutton_clicked();

	void on_buttonBox_accepted();
	
private:



	QStringList desktop_elements;

	Ui::KeyComd ui;
};

jsulm

@learnist said in How can i stop a thread running in my Dialog Class from my mainWindow:

thread3(&KeyComd::Print_step, this);

What is this line supposed to do? This is not valid C++ code as std::thread does not have an operator() operator.
Initialisation is done in constructors:

KeyComd::KeyComd(QWidget *parent)
	: QDialog(parent),
          thread3(&KeyComd::Print_step, this)
{
	ui.setupUi(this);
	HRESULT hr = exc.init();	
}

"//should i not detach here ???" - why?

Pablo J. Rogina

@learnist please don't double post.