Re: Winsock - FD_WRITE - C / C++ / MFC Discussion Boards

Re: Type Conversion happens while writing to Logfile in VC++

aruzhere29-Jun-16 2:42

aruzhere

29-Jun-16 2:42

Found out the way to do that without actually removing Hex. Used <

openMP loop and exception

Joerg Michels27-Jun-16 23:38

Joerg Michels

27-Jun-16 23:38

Hi all,

I have a for loop parallelized with openMP. Inside I want to catch possible exceptions. My idea is that the caught exception should be a private variable, as it is possible that several exception occur parallel. But I cannot express this.

example:

#pragma omp parallel for default(none)
for ( int i = 0; i < 10; ++ i )
{
	try
	{
		// do something ...
	}
	catch ( const std::exception&	e )
	{
		e;
		// handle exception ...
	}
}

This yields to compiler error:

error C3052: 'e' : variable doesn't appear in a data-sharing clause under a default(none) clause

But I cannot mark the exception variable as private, as I is not known at that scope.

I can bypass the compiler error by changing the default sharing behaviour to shared, but I think this could lead to a runtime error, if two exceptions occur at the same time.

What is the correct way to deal with this?

Thanks in advance,
Joerg

Heap Corruption issue

Ben Aldhouse21-Jun-16 10:27

Ben Aldhouse

21-Jun-16 10:27

I've got an application which has two dialogs, I use a deque and Direct2D in one dialog within a thread. Now, if I close the application via handling WM_CLOSE I have no problem but when I try and close it by clicking on 'Close Window' in the task bar or using Alt F4 I get a breakpoint triggered on

C++

if (!HeapFree(select_heap(block), 0, block))

I know it's a long shot since I have given so little detail - but seeing as the difference seems to be in the way I close the app down I was hoping there might be a quick and easy fix for this.

Yours hopefully,

Ben

*Update since I posted in this it the next door forum, this morning, by mistake: I still get the same error if the thread (and hence the direct2d drawing) isn't running. Perhaps it is something to do with the way I set up the dialogs.

Re: Heap Corruption issue

David Crow21-Jun-16 10:47

David Crow

21-Jun-16 10:47

Isn't the WM_CLOSE message being sent whether you terminate the app via Task Manager or by using Alt+F4?

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

Re: Heap Corruption issue

Ben Aldhouse21-Jun-16 12:45

Ben Aldhouse

21-Jun-16 12:45

Thanks for your reply!

I don't know, to be honest. The problem was occurring when I AltF4ed or clicked on Close Window but not when I clicked on my 'Exit' button. However, it looks like it was a corrupt memory problem I had with a member variable I'd assigned to the heap and was using to pass data between threads.

I've changed the communication to the following:

In the sending thread:

ControlDlg * pParent = (ControlDlg *) this->GetParent();
ColourAlphaEnvelope * s = new ColourAlphaEnvelope;
*s = m_ColourEnvelope;
pParent->PostMessage(CM_COLOURBOUNDS, reinterpret_cast<WPARAM>(s));

and in the recieving dialog I used

afx_msg LRESULT CRectArtDlg::OnCmColourbounds(WPARAM wParam, LPARAM lParam)
{
	std::auto_ptr<ColourAlphaEnvelope> s(reinterpret_cast<ColourAlphaEnvelope*>(wParam));
	m_colourEnvelope = *s;
	return 0;
}

I bet there are dozens of better ways of doing this (not least since a quick Google reveals that auto_ptr is depracated) but I haven't had a crash and the compiler isn't telling me there is a memory leak.

Winsock - FD_WRITE

Vijjuuu.21-Jun-16 4:54

Vijjuuu.

21-Jun-16 4:54

Hi all,

i am developing client program using WSAAsyncselect() in Winsock2.
i have few queries regarding FD_WRITE.
i understood that when client is connected to server. There will be FD_WRITE event posted stating that we can send the data to server. However, i want to send data to server based on some other events that the application is interested in. i am not quite sure how the FD_WRITE event will be fired when i want send data to server.

here is the pseudo.

C++

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
	case WM_SOMEOTHEREVENT:
		// collect the data. we need to send collected data to sever (right now data is stored in a list).  
		break;
	case WM_SOCKET:
		switch (WSAGETSELECTEVENT(lParam))
		{
             // how to fire this event when application wants to send data ?
		     case FD_WRITE:

		     break;
		}
		break;
	}
	return 0;
}

Thanks in advance.

Re: Winsock - FD_WRITE

David Crow21-Jun-16 7:19

David Crow

21-Jun-16 7:19

Your application will receive an FD_WRITE event shortly after a connection is made. If your "write" operation receives a WSAEWOULDBLOCK result, your application will find out that sends are again possible when an FD_WRITE network event is recorded and the associated event object is set.

Re: Winsock - FD_WRITE

Vijjuuu.21-Jun-16 8:04

Vijjuuu.

21-Jun-16 8:04

Hi David,

Thanks for your reply.

i am sorry, i couldn't get what you mean.

i understand that application will receive an FD_WRITE event shortly after a connection is made but there is no data to send at that time.

here is scenario i am trying for

1) connect to server
2) Connection established - FD_WRITE event is receive.
3) there is no data to send to server
4) some other event fired (not related to socket) -- data arrived, so store the data.
5) now data is available to send to server

in the above steps 4 and 5 will happen one after the another. how can i raise FD_Write event after the data is available (means step 4) ?

Re: Winsock - FD_WRITE

David Crow21-Jun-16 8:12

David Crow

21-Jun-16 8:12

Vijjuuu. wrote:
how can i raise FD_Write event after the data is available (means step 4) ?

Why would you need to raise the FD_WRITE event? It is sent to your application to let it know that it can now send data to the socket.

Re: Winsock - FD_WRITE

Vijjuuu.21-Jun-16 8:21

Vijjuuu.

21-Jun-16 8:21

Thanks again David,

i understood that its lets application know that it can send data to the socket, but when there is no data to send ?
and does it mean after initial FD_Write (the time after connection established) , FD_WRITE will be polled to application to let know that it can send data ?

i really appreciate your patience. Thanks.

Re: Winsock - FD_WRITE

David Crow21-Jun-16 9:19

David Crow

21-Jun-16 9:19

Vijjuuu. wrote:
...but when there is no data to send ?

Then don't send any.

Vijjuuu. wrote:

and does it mean after initial FD_Write (the time after connection established) , FD_WRITE will be polled to application to let know that it can send data ?

Did you read the documentation that goes with that event? Your application gets the initial FD_WRITE event which means it can start sending data to the socket. In the event that whatever "send" function you are using returns WSAEWOULDBLOCK, you would then have to wait for the next FD_WRITE event to resume sending data to the socket.

Re: Winsock - FD_WRITE

Member 1260667928-Jun-16 20:47

Member 12606679

28-Jun-16 20:47

As I understand it, the FD_WRITE message means you have a
connection and room in the output buffer to accept data.

After you get FD_WRITE, use send() to send data
when you have it.

modified 29-Jun-16 2:58am.

DLL files from wmi

Member 1253112919-Jun-16 22:10

Member 12531129

19-Jun-16 22:10

when i am using wmi functions "SELECT * FROM Win32_Processor", can i somehow get dll files from which is that information loaded?

Re: DLL files from wmi

Jochen Arndt19-Jun-16 22:30

Jochen Arndt

19-Jun-16 22:30

The information is not stored in a DLL. It is stored in a database file (the WMI Repository) in the directory %windir%System32\Wbem\Repository\.

See also WMI Overview[^] and Windows Management Instrumentation - Wikipedia, the free encyclopedia[^].

Print class Members?

bosfan16-Jun-16 5:29

bosfan

16-Jun-16 5:29

Hi,
is it possible to print class members, like in Visual Studio in the "Immediate Window", when i write a class name there is an output with all members/variables in the window?

Is there an API for this?

Thanks for help
bosfan

Re: Print class Members?

Maximilien16-Jun-16 5:41

Maximilien

16-Jun-16 5:41

In the debugger or as a simple output (printf/cout) ?

I'd rather be phishing!

Re: Print class Members?

David Crow16-Jun-16 6:12

David Crow

16-Jun-16 6:12