Access violation when closing report during generation

rbuser

I'm still new to working with ReportBuilder but we've experienced an issue
where users are clicking the close button while a large report is being
generated, resulting in an access violation.

Is there a clean way of preventing or handling this exception?

Using Delphi 2007 with ReportBuilder 11.08.

Thanks in advance,

A.J. van de Ven

rbuser

> Is there a clean way of preventing or handling this exception?

I have cancelled reports during generation and not received an AV.

Do you at least have a call stack? (It may or may not provide clues).

Ed Dressel
Team DM

nicocizik

Hi A.J.,

As Ed mentioned, are you able to check your call stack and trace into the RB
source and see where the exception is occurring? We are not aware of any
specific issues that occur when closing a report so any information you can
give us would be very helpful in tracking it down.

--
Regards,

Nico Cizik
Digital Metaphors
http://www.digital-metaphors.com

rbuser

We've asked our support department to recreate it and they're able to by
closing the application itself when the report is being generated.

I did as you suggested and looked at the call stack generated by
madException (see below) but don't see anything that gives an indication of
where the problem is occurring other than the exception message itself.

Perhaps we need to cancel the report generation as soon as the user clicks
the application's close button?

compiled with : Delphi 2006/07
madExcept version : 3.0k
callstack crc : $8a3865db, $0f13b540, $0dfc8d4a
exception number : 1
exception class : EInvalidOperation
exception message : Control '' has no parent window.

Main ($1654):
004caadf +0a7 MyApp.exe Controls 6750 +9 TWinControl.CreateWnd
0049f725 +005 MyApp.exe StdCtrls 3791 +1 TButton.CreateWnd
004caf46 +016 MyApp.exe Controls 6883 +3 TWinControl.CreateHandle
00613b07 +017 MyApp.exe cxButtons TcxCustomButton.CreateHandle
004ce970 +01c MyApp.exe Controls 8894 +4 TWinControl.HandleNeeded
004ce97d +005 MyApp.exe Controls 8900 +1 TWinControl.GetHandle
00613398 +0ac MyApp.exe cxButtons TcxCustomButton.MouseUp
004c86f4 +02c MyApp.exe Controls 5355 +2 TControl.DoMouseUp
004c8776 +076 MyApp.exe Controls 5367 +8 TControl.WMLButtonUp
004c7a78 +024 MyApp.exe Controls 5021 +5 TControl.Perform
004c7deb +2bb MyApp.exe Controls 5146 +83 TControl.WndProc
004cbde3 +4fb MyApp.exe Controls 7304 +111 TWinControl.WndProc
0049f4f4 +06c MyApp.exe StdCtrls 3684 +13 TButtonControl.WndProc
006127c6 +06e MyApp.exe cxButtons TcxCustomButton.WndProc
004cb50c +02c MyApp.exe Controls 7073 +3 TWinControl.MainWndProc
0047f86c +014 MyApp.exe Classes 11583 +8 StdWndProc
76b08b77 +00a USER32.dll DispatchMessageA
004e888c +0fc MyApp.exe Forms 8105 +23 TApplication.ProcessMessage
004e88c6 +00a MyApp.exe Forms 8124 +1 TApplication.HandleMessage
004e8bbb +0b3 MyApp.exe Forms 8223 +20 TApplication.Run
012813af +347 MyApp.exe MyApp 170 +43 initialization
76a5d0e7 +010 kernel32.dll BaseThreadInitThunk

rbuser

> exception message : Control '' has no parent window.

that's not an AV :-)--- but I have always related that exception to using
Dev Express controls (which I use extensively) though I have not seen it in
a while. I have never seen it with RB.

If you are closing the app, how are you telling it to close? Also, did you
cancel the report generation before closing the application?

Ed Dressel
Team DM

rbuser

Besides setting some variables, this is how we close the application:

for i := 0 to MDIChildCount - 1 do
begin
MDIChildren[0].Close;
Application.ProcessMessages;
end;

Currently, we don't cancel the report generation prior to closing the
application.

However, we do set a variable ShuttingDown := True. We use this in a number
of places, such as form-specific OnActivate and OnClose routines, to prevent
certain actions from taking place if the software is being closed.

rbuser

> for i := 0 to MDIChildCount - 1 do


This is similar to what I use to do but I took it over the chin a few times
by other users for calling the .ProcessMessages. I've been told that it is
not a good idea, and removing it has fixed various issues in my application.

I would recommend changing that to something like:

for I := MDICHildCount-1 downto 0 do
PostMessage(MDICHildren[I].Handle, WM_CLOSE, 0, 0);

that may take care of the problem, but you will have to test.

Ed Dressel

rbuser

Thanks, Ed.

We'll give it a shot and see what happens.

Doing so permantently will require quite a bit of testing, but we'll
definitely look into it.

rbuser

> Doing so permantently will require quite a bit of testing, but we'll

Definately. Best wishes

Ed Dressel