QUrlOperator doesn't emit finished signal

[hayati]

I want to get a php page via QUrlOperator, but url should be entered by end users. So url may belong to unreachable host. QT Docs states that QUrlOperator always - whether operation succeeds or fails - emits a finished signal. But amazingly i don't get always. Actually after a while i don't get anymore.
More info to repliers:
1- qInitNetwork... function is in the main so it's called.
2- I get finished signals at least once.

i'll also give you some source code to test it or find what's wrong with it.
the program works as; one widget (which is mainwidget of application) opens another widget with a timeout continuously, then the opened widget tries to reach a url which is unreachable. When it gets finished signal it closes itself.

So it works for five or more times, but after an unknown times of timer timeout program does not get finished signals.

Notes:
FileReader_ and MainUI_ are subclasses of QWidget it doesn't have any other subwidgets or operations.

// header which uses qurloperator
#ifndef FILEREADER_H
#define FILEREADER_H
 
#include "FileReader_.h"
 
class QUrlOperator;
class QNetworkOperation;
 
class FileReader : public FileReader_
{
  	Q_OBJECT
 
	public:
	FileReader(QWidget* parent = 0, const char* name = 0, WFlags fl = 0 );
        ~FileReader();
 
	public slots:
		void stateChangedSlot(int state,const QString&);
		void finishedSlot(QNetworkOperation *operation);
 
	private:
		QUrlOperator* m_op;
};
 
#endif
 
// qurloperator using class's imp.
#include <qurloperator.h>
#include <qnetwork.h>
 
#include <iostream>
 
#include "filereader.h"
 
using namespace std;
 
FileReader::FileReader(QWidget* parent, const char* name, WFlags fl)
: FileReader_(parent,name,fl)
{
	// host part of url, which is here asdfasdf, should be unreachable. So host should not exist on network
	m_op = new QUrlOperator("http://asdfasdf/asdf/abcd.php");
 
	connect(m_op, SIGNAL(connectionStateChanged(int,const QString&)), SLOT(stateChangedSlot(int,const QString&)));
	connect( m_op, SIGNAL(finished(QNetworkOperation*)), SLOT(finishedSlot(QNetworkOperation*)));
 
	m_op->get();
}
 
void FileReader::stateChangedSlot(int state,const QString& data)
{
	cout << "conn state changed to: " << data.ascii() << endl;
 
	switch( state ){
		case QNetworkProtocol::ConConnected:
			cout << "CONNECTED" << endl;
			break;
		case QNetworkProtocol::ConClosed:
			cout << "CONNECTION CLOSED" << endl;
			break;
	}
}
 
void FileReader::finishedSlot(QNetworkOperation *operation)
{
	switch( operation->operation() ){
		case QNetworkProtocol::OpGet:
			if ( operation->state() == QNetworkProtocol::StFailed ) {
				cerr << "finished but there is an error..." << endl;
			}
			else if ( operation->state() == QNetworkProtocol::StDone ) {
				cout << "connection successfully finished..." << endl;
			}
	}
 
	close(true);
}
 
FileReader::~FileReader()
{
       delete m_op;
}
 
// header of opening widget
#ifndef MAINUI_H
#define MAINUI_H
 
#include "MainUI_.h"
 
class QTimer;
class FileReader;
 
class MainUI : public Form1
{
  Q_OBJECT
 
public:
  MainUI(QWidget* parent = 0, const char* name = 0, WFlags fl = 0 );
 
public slots:
	void refreshInfo();
 
protected:
	QTimer* m_timer;
	FileReader*  fileReader;
};
 
#endif
 
// imp.
#include <qtimer.h>
 
#include "mainui.h"
#include "filereader.h"
 
MainUI::MainUI(QWidget* parent, const char* name, WFlags fl)
: Form1(parent,name,fl)
{
	m_timer = new QTimer(this);
 
	connect(m_timer, SIGNAL(timeout()), SLOT(refreshInfo()));
 
	m_timer->start( 30000 );
 
	fileReader = new FileReader();
	fileReader->show();
}
 
void MainUI::refreshInfo()
{
	fileReader = new FileReader();
	fileReader->show();
}
 
 
// main.cpp
#include <qapplication.h>
#include <qnetwork.h>
#include <stdio.h>
#include <stdlib.h>
 
#include "mainui.h"
 
int main(int argc, char *argv[])
{
	QApplication app(argc,argv);
 
	qInitNetworkProtocols();
 
	MainUI fr;
	app.setMainWidget( &fr );
	fr.show();
 
	app.exec();
}

// header which uses qurloperator
#ifndef FILEREADER_H
#define FILEREADER_H

#include "FileReader_.h"

class QUrlOperator;
class QNetworkOperation;

class FileReader : public FileReader_
{
  	Q_OBJECT

	public:
	FileReader(QWidget* parent = 0, const char* name = 0, WFlags fl = 0 );
        ~FileReader();

	public slots:
		void stateChangedSlot(int state,const QString&);
		void finishedSlot(QNetworkOperation *operation);

	private:
		QUrlOperator* m_op;
};

#endif

// qurloperator using class's imp.
#include <qurloperator.h>
#include <qnetwork.h>

#include <iostream>

#include "filereader.h"

using namespace std;

FileReader::FileReader(QWidget* parent, const char* name, WFlags fl)
: FileReader_(parent,name,fl)
{
	// host part of url, which is here asdfasdf, should be unreachable. So host should not exist on network
	m_op = new QUrlOperator("http://asdfasdf/asdf/abcd.php");

	connect(m_op, SIGNAL(connectionStateChanged(int,const QString&)), SLOT(stateChangedSlot(int,const QString&)));
	connect( m_op, SIGNAL(finished(QNetworkOperation*)), SLOT(finishedSlot(QNetworkOperation*)));

	m_op->get();
}

void FileReader::stateChangedSlot(int state,const QString& data)
{
	cout << "conn state changed to: " << data.ascii() << endl;

	switch( state ){
		case QNetworkProtocol::ConConnected:
			cout << "CONNECTED" << endl;
			break;
		case QNetworkProtocol::ConClosed:
			cout << "CONNECTION CLOSED" << endl;
			break;
	}
}

void FileReader::finishedSlot(QNetworkOperation *operation)
{
	switch( operation->operation() ){
		case QNetworkProtocol::OpGet:
			if ( operation->state() == QNetworkProtocol::StFailed ) {
				cerr << "finished but there is an error..." << endl;
			}
			else if ( operation->state() == QNetworkProtocol::StDone ) {
				cout << "connection successfully finished..." << endl;
			}
	}

	close(true);
}

FileReader::~FileReader()
{
       delete m_op;
}

// header of opening widget
#ifndef MAINUI_H
#define MAINUI_H

#include "MainUI_.h"

class QTimer;
class FileReader;

class MainUI : public Form1
{
  Q_OBJECT

public:
  MainUI(QWidget* parent = 0, const char* name = 0, WFlags fl = 0 );

public slots:
	void refreshInfo();

protected:
	QTimer* m_timer;
	FileReader*  fileReader;
};

#endif

// imp.
#include <qtimer.h>

#include "mainui.h"
#include "filereader.h"

MainUI::MainUI(QWidget* parent, const char* name, WFlags fl)
: Form1(parent,name,fl)
{
	m_timer = new QTimer(this);

	connect(m_timer, SIGNAL(timeout()), SLOT(refreshInfo()));

	m_timer->start( 30000 );

	fileReader = new FileReader();
	fileReader->show();
}

void MainUI::refreshInfo()
{
	fileReader = new FileReader();
	fileReader->show();
}


// main.cpp
#include <qapplication.h>
#include <qnetwork.h>
#include <stdio.h>
#include <stdlib.h>

#include "mainui.h"

int main(int argc, char *argv[])
{
	QApplication app(argc,argv);

	qInitNetworkProtocols();

	MainUI fr;
	app.setMainWidget( &fr );
	fr.show();

	app.exec();
}

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thanks for all replys...

[jacek]

Maybe it's because of a memory leak? Where do you delete m_op?

[hayati]

yeh i know there is (or are) memory leak. but the problem isn't the memory leak. As you see from the code it just shows the skeleton, in actual program it is deleted but there is no change.
After all even there is a memory leak m_op is created from the beginning. so newly created m_op should get finished signal either way. I applied with the delete m_op but this didn't changed any thing
everbody is free to change the code to make it worked. As skeleton shows there isn't any magic operation took place. Amazingly it doesn't emit finished.

i also edited the source code to fix the leak.

what i also tried to stop get progres before to delete m_op with

m_op->stop();

m_op->stop();

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at the destructor but it also makes no sense

[hayati]

Unfortunately i get neither descriptive reason of the problem nor solution to it.
As the code part of my problem shows, it should be worked but it isn't.
Any help is wellcome.

here is what i get at the console output:
conn state changed to: host asdfasdf found
finished but there is an error...
conn state changed to: host asdfasdf found
finished but there is an error...
conn state changed to: host asdfasdf found
finished but there is an error...
conn state changed to: host asdfasdf found
finished but there is an error...
conn state changed to: host asdfasdf found
conn state changed to: host asdfasdf found
conn state changed to: host asdfasdf found
conn state changed to: host asdfasdf found
conn state changed to: host asdfasdf found
conn state changed to: host asdfasdf found

this goes forever...

as output shows after a while finished signal is not emitted

[jacek]

as output shows after a while finished signal is not emitted

How long does this "while" take? Which Qt version do you use?

[hayati]

i use qt3
and from the output it could be said that it's about 120 to 210 seconds at least but it could take long of course because there is no clue about the error. I'm using just the code i've posted to test the situation but even this little code makes the same error.
i think it's goint to a qt bug
because it works perfectly when requested web pages are found.

[jacek]

i use qt3

There are over 20 versions of Qt3. Which one do you use?

[hayati]

right it's v3.3.6

and v3.3.3 gives the same result

[jacek]

right it's v3.3.6

and v3.3.3 gives the same result

Try Qt 3.3.8. There was some problem with QDns fixed. On my system finished() is always emitted, but the application crashes after a while (it has something to do with event delivery).

[hayati]

thanks for the reply,
yes it's obvious that it has some problems internally.
unfortunately i can't use v3.3.8
even so, as you said it gets errors with internal SIGSEGV errors.
I'll use libcurl library for that purpose for now
thanks for help.

[jacek]

even so, as you said it gets errors with internal SIGSEGV errors.

I didn't say that they are internal errors.