C / C++ / MFC

19-Oct-04 4:13

Hello, I had posted a question yesterday with no responses.. I figured I would give it one more shot..

I found a article on another site that talked about my problem.. here is a little blurb from the article...

If the terminating socket has been closed, calling Flush on the CArchive will raise an exception (so will calling Close). In the previous case, before the exception is handled, CArchive goes out of scope and its destructor calls Close. Close throws another exception and all hell breaks loose. Never throw exceptions from destructors.

You will need nested try / catch blocks ... [Article^]

My problem with the exceptions is fixed but I still have a memory leak.. Any ideas why??

// Some function calls OnSend passing it a pointer to the socket
// and a string to send..
 
void CMainFrame::OnSend(CClientSocket *pSocket, CString strMsg)
{	if(*pSocket != INVALID_SOCKET)
	{		
		try		
		{			
			sendObject(pSocket, strMsg);		
		}
		catch (CException* pEx)
		{
			pEx->Delete();
		}
	}
}
 
BOOL CMainFrame::sendObject(CClientSocket *pSocket, CString strMsg)
{
	BOOL bRet = TRUE;
	CSocketFile sf(pSocket);
	CArchive ar_send(&sf, CArchive::store);
 
	try
	{		
		// Send the data
		ar_send << strMsg;
		ar_send.Flush();
		ar_send.Close();
		sf.Close();
	}
	catch (CException* pEx)	
	{		
		bRet = FALSE;
		pEx->Delete();
	}	
	return bRet;
}

Whoever said nothing's impossible never tried slamming a revolving door!

Bob Stanneveld19-Oct-04 9:18

19-Oct-04 9:18

Hello,

The exception thrown is probably allocated using new. Try calling <delete> on pEx and see if that solves anything...

Multiply it by infinity and take it beyond eternity and you'll still have no idea about what I'm talking about.

RobJones19-Oct-04 9:23

19-Oct-04 9:23

Why do you mean by call on pEx? If it was allocated using new shouldn't the pEx->Delete() clean it up?

Thanks for the response,
Rob

Whoever said nothing's impossible never tried slamming a revolving door!

Bob Stanneveld19-Oct-04 9:35

19-Oct-04 9:35

Hello,

I see, I forgot to close a <code> tag... It should read: call delete on pEx. I've just read the documentation on CException and I read that you shouldn't call delete on the object...

You can use a memory leak detect[^] mechanism to detect the leak. There are several others here on CP

Multiply it by infinity and take it beyond eternity and you'll still have no idea about what I'm talking about.

RobJones19-Oct-04 10:21

19-Oct-04 10:21

Didn't help, it ASSERTS if you try to 'delete pEx' the ASSERT says to use pEx->Delete() and not the other... Anyway I have traced the problem down some what, the Flush() causes a exception and so does the Close().. I'm not sure how I can catch both exceptions.. I can see 2 exceptions in the debug window yet my trace shows that I am only catching one of the two.. When I put another try/catch around the Close I catch it yet an extra exception occurs (3), this is just odd.. And the memory leak is still there.. weird..

I tried using AfxIsValidAddress() for the CArchive and CSocketFile and this worked like a charm in Debug mode, Said that the address wasn't valid when the connection was lost, yet said it was valid when the connection was present.. but in Release mode it fails every time, connected or not.. ever had any experence in using AfxIsValidAddress?

Rob

Whoever said nothing's impossible never tried slamming a revolving door!

Bob Stanneveld19-Oct-04 11:24

19-Oct-04 11:24

I use AfxIsValidAddress a lot, but I never experianced any problems with it.

I see that you catch exceptions, but I don't see you use the exceptions. You only delete them. What is the exception trying to tell you?

Besides that, if you application won't run for a long time and the memory leak isn't too big, I wouldn't worry about it.

Multiply it by infinity and take it beyond eternity and you'll still have no idea about what I'm talking about.

RobJones19-Oct-04 16:48

Machines in LAN connected to my machine

19-Oct-04 16:48

Just to simplify the code i didn't show what i do with the exception, actually I do a ...

char szError[4096];
pEx->GetErrorMessage(szError, sizeof(szError));
TRACE("sendObject Error: %s\n", szError);

pEx->Delete();

... For testing I sometimes used a AfxMessageBox..

anyway, the memory leak is super small, and actually the application will never get that far unless the super un-natural happens, but it still bothers me that I can't figure it out so I just wanted to see if anyone had any ideas..

Thanks for all your help!
Rob

Whoever said nothing's impossible never tried slamming a revolving door!

tgprakash19-Oct-04 4:10

tgprakash

19-Oct-04 4:10

Hello All,
It is well know that other systems in my LAN can connect to my machine by typing "\\User\d$" at the Start Menu->RUN... command and entering the password.

Q) Is there any way i could get the list of machine(Ip or Name) connected to mine. Does the sytem registry keep track of all the machines which have/are connected.

please get me some code if possible.

Regards,
Prax

Re: Machines in LAN connected to my machine

RobJones19-Oct-04 4:54

Re: Machines in LAN connected to my machine

19-Oct-04 4:54

From a command prompt you can type 'net sessions'..

Rob

Whoever said nothing's impossible never tried slamming a revolving door!

rromerot19-Oct-04 5:59

rromerot

19-Oct-04 5:59

"NET VIEW" will give you a list of machines that can access yours.

WNetEnumResource is a win32 windows networking API that will let you iterate through the same list as with the above command.

Ray

Re: Machines in LAN connected to my machine

David Crow19-Oct-04 8:00

David Crow

19-Oct-04 8:00

Try NetSessionEnum(NULL, ...).

"Opinions are neither right nor wrong. I cannot change your opinion of me. I can, however, change what influences your opinion." - David Crow

Callback ?

madretierra19-Oct-04 3:44

madretierra

19-Oct-04 3:44

hello,

I have two .exe, the main application (in mfc) and a directshow filter crossed by a video stream.

From the directshow filter code, when a certain value is detected I have to send it (to the main application) and to make start a method in the main application.

How can I realise such a thing ? Is Callback a possible solution ?

Thanks a lot for your help and have a nice day,
alain

There is no way to happiness, happiness is the way !

Re: SendMessage/PostMessage

Budric B.19-Oct-04 8:19

Budric B.

19-Oct-04 8:19

I don't believe callback is possible. Here are some high level suggestions you can research.

You can try the function FindWindow(..) to get a handle on your MFC window and then SendMessage() to send a message to this window. It's a win32 function.

Otherwise you may need to use some other method (interprocess communication). I suppose you can try network communication using sockets. Maybe send/receive on 127.0.0.1. Or I believe Windows should provide some functions to send/receive messages between processes.

There are tutorials on codeproject.
http://www.codeproject.com/threads/[^]

Re: SendMessage/PostMessage

madretierra19-Oct-04 22:30

madretierra

19-Oct-04 22:30

Thanks a lot for your answer.

I am triing to use the BEGIN_MESSAGE_MAP of MFC to realise what I need :

BEGIN_MESSAGE_MAP(CPatchingMPEG2Dlg, CDialog)

ON_MESSAGE(WM_USER+1, OnMyMessage)

END_MESSAGE_MAP()

I think it's the right direction, but now I get the difficult of paasing m_hwnd variable to my direcshow code. I am going to try your solution with 'FindWindow' which seems very good !

I wish you a nice day,

thanks, alain

There is no way to happiness, happiness is the way !

And don't pass pointers between processes

Budric B.19-Oct-04 8:24

Budric B.

19-Oct-04 8:24

Windows uses virtual memory so an address in one process is meaningless in another. I read it in:
http://www.codeproject.com/threads/int64_memsteal.asp[^]

among other places.

Re: Callback ?

Bob Stanneveld19-Oct-04 9:26