,Thread and Mutex - C / C++ / MFC Discussion Boards

tjkrz25-Nov-02 10:44

25-Nov-02 10:44

Yes, I am looking to make the window topmost, activated and
prevent activation of other windows until mine is dismissed. I didn't mean keyboard focus. Sorry.

File Preview !!

Mash25-Nov-02 8:35

Mash

25-Nov-02 8:35

Hey All,

I have a SDI application.
Using the default print and preview messages (ID_FILE_PRINT & ID_FILE_PREVIEW) I am able to successfully Print and Preview my document.
I have a problem though...
When my application is in Preview Mode and I try to close the Preview window by clicking 'x' in the system menu (upper right hand corner) instead of using the 'close' button in the preview window, my entire application closes. I don't desire that. I just want to get my preview window closed. Any suggestions?? (It works fine by using the 'close' button)

Thanks,

-Mahesh Shimpi
Ideas multiply by sharing!!

Socket TIME_WAIT questions..

RobJones25-Nov-02 8:32

RobJones

25-Nov-02 8:32

Hello,
I am having a little problems with sockets.. Heres a break down.. I have a server application running on two machines.. The servers send and receive each others status every 60 seconds..

Both servers are listening.. One server will spawn a UI thread and do a connect. If the connect is successful it sends it's own status (like.. "ON_LINE") after it sends it's status, the other server receiving the status turns around and sends it's status through the same socket..

This all works fine except I don't know how to close the socket with out leaving a TIME_WAIT behind.. (I am using sysinternals TCPView to view my end points).. I have tried to issue a shutdown(s,SD_SEND) after my sends then after a FD_READ i do a shutdown(s, SD_RECEIVE) but no matter what I do I allways see a TIME_WAIT hanging around for a few minutes.. I'm not really sure if this is a bad thing but I plan on running this software on quite a few pc's and if these TIME_WAITS are using up resources I could have a big problem..

Any ideas?

Thanks!!
Rob

Re: Socket TIME_WAIT questions..

valikac25-Nov-02 8:58

valikac

25-Nov-02 8:58

Consider Shutdown(). Another solution is to set the LINGER structure to 0 and use setsockopt() to instruct the socket to close immediately.

Kuphryn

Re: Socket TIME_WAIT questions..

RobJones25-Nov-02 9:59

RobJones

25-Nov-02 9:59

Thanks for the reply.. I have been trying to use the SO_LINGER but it doesn't seem to be working.. here's what I'm trying..

First create.. then

linger m_linger;
m_linger.l_onoff = 1; // Turn linger on
m_linger.l_linger = 0; // Set time to ZERO
s.SetSockOpt(SO_LINGER, &m_linger, sizeof(m_linger),SOL_SOCKET);

This isn't working, am I doing this wrong?

Thanks,
Rob

Re: Socket TIME_WAIT questions..

valikac25-Nov-02 10:57

valikac

25-Nov-02 10:57

No. Your solution looks okay. What happens when you set the time to greater than 0?

Kuphryn

Re: Socket TIME_WAIT questions..

RobJones25-Nov-02 11:03

RobJones

25-Nov-02 11:03

I think I found the problem.. I was using API then I switched to using CAsyncSocket then to CSocket.. Just found out that SO_LINGER doesnt work with CSocket so I'm going to go back to either CAsync or straight API (if thats what you call it)..

Any way .. Thanks,
Rob

,Thread and Mutex

Anonymous25-Nov-02 7:45

Anonymous

25-Nov-02 7:45

Hi everyone,

I have a thread. The function that keeps this thread alive contains a while loop. The while loop is true while a boolean variable is maintained true. When the thread has to terminate, the boolean value is modified to false and the thread dies. This boolean variable is global. I am using a Mutex to control access to this global value.

I would like to know if it is necessary to control global variables with a Mutex when one is just reading the value? Or does one only control the global variable when one is going to modify its value?

This one depends on the previous question. How does one manage something like:
while ( g_bGlobal_Variable )
{
}
How does one apply a mutex object to the above case. Because I cannot do
dwWait = ::WaitForSingleObject();
if ( dwWait == 0 )
{
while ( g_bGlobal_Variable )
{
}
}

Otherwise this implies that the thread always has control over the Mutex object while alive.

Thanks and excuse the ignorance

Regards

Re: ,Thread and Mutex

Scott H. Settlemier25-Nov-02 8:10

Scott H. Settlemier

25-Nov-02 8:10

First, if you're going to use a synhcronization object to
protect a flag, use the synchronization object as the flag.
i.e. Use an Event whose state is checked as a condition to exit
the thread. (better yet use two events.. one to signal work to
be done, the other to exit. wait (WaitForMultipleObjects) on both
and then react appropriately.. that way your work thread won't
waste cycles running through loops pointlessly.)

Second, yes. Even access to resources should be protected (generally)
since you want to ensure that the resource is not being modified while
you are reading it. (or whatever)

That said, some types of resources (small register-sized variables
generally) can be read/written without the need of a protecting
synchronization object. Check out the Interlocked_______ functions
in win32.

Re: ,Thread and Mutex

Ruca26-Nov-02 1:11

Ruca

26-Nov-02 1:11

Thanks Scott
I am sorry for the anonymous that was an error.

Rui

Re: ,Thread and Mutex

Scott H. Settlemier28-Nov-02 16:14

Scott H. Settlemier

28-Nov-02 16:14

Here's a code sample:

// these handles are created and passed out to whoever'll
// let the thread know when to work and when to quit

HANDLE hWorkToBeDone=CreateEvent(0,FALSE,FALSE,0); // resets on wait
HANDLE hTimeToQuit=CreateEvent(0,TRUE,FALSE,0); // once signalled, stays so

// Basic thread loop

HANDLE Waitables[]={hTimeToQuit,hWorkToBeDone};
for (DWORD W=~WAIT_OBJECT_0;W!=WAIT_OBJECT_0;)
{
	switch (W=WaitForMultipleObjects(2,Waitables,FALSE,INFINITE))
	{
	case WAIT_FAILED:
		// use GetLastError and handle this
		break;
	case WAIT_OBJECT_0: // It is time to quit
		break;
	case WAIT_OBJECT_0+1: // There is work to be done
		; // Do some work
		break;
	case WAIT_TIMEOUT: // impossible? we specified no timeout
	default: // there should be no other cases. (e.g. for abandoned mutexes)
		ASSERT(FALSE);
	}
}

,Thread and Mutex

Anonymous25-Nov-02 7:34

Anonymous

25-Nov-02 7:34

Hi everyone

Animation Control

Brigg Thorp25-Nov-02 7:28

Brigg Thorp

25-Nov-02 7:28

I have an animation control on a dialog box that displays an AVI file while some processing is taking place. I create the animation control and play it from my WM_INITDIALOG handler. However, sometimes I notice that the animation takes a second or two to start playing. Any suggestions on what I can do to make sure this animation comes up all the time?

Brigg Thorp
Software Engineer
Timex Corporation

Re: Animation Control

Scott H. Settlemier25-Nov-02 10:16

Scott H. Settlemier

25-Nov-02 10:16

Hmm, never used that control before.
Can you create the hosting dialog as a hidden
modeless dialog (some time before ever
needed) and just pop it up, disabling
the main window, when needed? (Call animation
control's Seek method when creating dialog,
and Play in you OnShowWindow handler)
That way, hopefully the animation is ready to
play when you need it.

Basic MFC question

will138325-Nov-02 5:54

will1383

25-Nov-02 5:54

Hello all,

This is a basic question in MFC, but for some odd reason I can't figure out how to do it. I want to be able to specify the size of the main window when it comes up, and would like to be able to save this information (via .ini file I suppose). I thought that by modifying the CreateStruct in the OnCreate or the OnPreCreate would handle this setting the initiail size of the main window, but it does not work. Any suggestions on how to do this, and could anyone point me in the right direction to "save" this window information so when it comes up again I can use the last position/size information.

Thank you in advance.

Dan

Re: Basic MFC question

Rob Caldecott25-Nov-02 5:58

Rob Caldecott

25-Nov-02 5:58

There are some articles on how to do this somewhere on this very site...

When I am king, you will be first against the wall.

Re: Basic MFC question

Roman Fadeyev25-Nov-02 6:04

Roman Fadeyev

25-Nov-02 6:04

This site contains some examples of how to save and restore window position. I saw an article http://www.codeproject.com/docview/persistframes.asp[^] about storing and loading positions of SDI/MDI ChildFrame, MainFrame and so on more recently.

Re: Basic MFC question

Stephane Rodriguez.25-Nov-02 6:39

Stephane Rodriguez.

25-Nov-02 6:39

add this in CMainFrame::OnCreate() :

SetWindowPos(NULL, 0,0, 600,350,SWP_NOZORDER|SWP_NOMOVE);

Re: Basic MFC question

Jeff Patterson26-Nov-02 3:26

Jeff Patterson

26-Nov-02 3:26

In addition to S.Rod.'s answer you can also use

MoveWindow(200,100,450,300,TRUE);
This will change the size and move it around the screen

Also,

GetClientRect(&rcClient); // get size of client area
m_cyClient = rcClient.bottom-rcClient.top; // only the 'y' length

Will get the size of the window.
To get the left and right sides you can rcClient.Right-rcClien.Right

Jeff Patterson

Programmers speak in Code.
www.anti-dmca.org

CFileDialog problem under win 98

lbc25-Nov-02 5:50

lbc

25-Nov-02 5:50

Hello all
I have a VC7 dialog based application.
Basically one dialog with

an edit box
IDC_EDIT

and 2 buttons
IDC_READ_MYFILE
IDC_CANCEL

when I press the IDC_READ_MYFILE button i want to open a standard File Open Dialog, managed by the message_map entry, something like this:

ON_BN_CLICKED(IDC_READ_MYFILE, OnReadMyfile)

...

void CMyAppDlg::OnReadMyfile()
{
// TODO: Add your control notification handler code here

static CString szFilter = "DXF Files (*.dxf)|*.dxf||";
CFileDialog fileDialog(TRUE, "dxf", NULL, OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT, szFilter, NULL );

if(fileDialog.DoModal() == IDOK)

{
CString sDXF_FileName;
sDXF_FileName = fileDialog.GetPathName();

... do some processing on this file

UpdateData(FALSE);
}

}

Tested under windows XP it *works fine* (opening the File Dialog and processing the selected file as needed) but under windows 98 it works but when pressing on the IDC_READ_MYFILE button nothing happens (the File Open dialog is not open) while the close button works and also the about message box works (called inside the dialog top left System menu)

By the way I have checked the resources IDs and there isn't any conflict

any help/tips will be greatly appreciated

thanks in advance!

best regards

Re: CFileDialog problem under win 98

Rob Caldecott25-Nov-02 5:57

Rob Caldecott

25-Nov-02 5:57

This is an MFC7 bug I'm afraid. There is an MSDN article on this I think (you'll get the same problem on Win95 and older versions of NT4).

The fix is to pass zero as the last param, e.g.:

CFileDialog fileDialog(TRUE, "dxf", NULL, OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT, szFilter, NULL, 0);

When I am king, you will be first against the wall.

Re: CFileDialog problem under win 98

lbc25-Nov-02 22:06

lbc

25-Nov-02 22:06

thank you very much!
i was getting crazy finding out which reasons could be causing that strange behaviour

best regards

MDI Splitter problems

Bjornarsen25-Nov-02 5:43

Bjornarsen

25-Nov-02 5:43

Hi, i am making a MDI application and i am trying to add some splitters to it.
I want two splitters to divide the Frame/MDICLIENT window into tree panes/views and i want all views to show the same view-class.

Below is a clip of my code where i make the splitters :

if (!m_wndSplitter.CreateStatic(this,2,1))
{
TRACE(_T("failed to create the splitter"));
return FALSE;
}
if (!m_wndSplitter.CreateView(1,0,RUNTIME_CLASS(CAPecc2View),CSize(200, 200), pContext))
{
TRACE(_T("failed to create view in second pane"));
return FALSE;
}
// add the second splitter pane - which is a nested splitter with 2 rows
if (!m_wndSplitter2.CreateStatic(&m_wndSplitter,1,2))
{
TRACE0("Failed to create nested splitter\n");
return FALSE;
}
if (!m_wndSplitter2.CreateView(0,0,RUNTIME_CLASS(CAPecc2View),CSize(200, 200), pContext))
{
TRACE(_T("failed to create view in second pane"));
return FALSE;
}
if (!m_wndSplitter2.CreateView(0,1,RUNTIME_CLASS(CAPecc2View),CSize(200, 200), pContext))
{
TRACE(_T("failed to create view in second pane"));
return FALSE;
}

the problem i get is an assert in the following code :
CAPecc2Doc* CAPecc2View::GetDocument() const // non-debug version is inline
{
ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CAPecc2Doc))); //NB, HERE is the problem???
return (CAPecc2Doc*)m_pDocument;
}

I did the same for a SDI application and i worked fine there, so i don't have a clue why it doesen't work for this application.

I hope there is someone who can help me, cause i am really stucked Frown | :-(

.

best regards

Bjørnar Skogseth

Re: MDI Splitter problems

dima_t25-Nov-02 18:02

dima_t

25-Nov-02 18:02

I'm not sure, maybe CDocument::AddView will help you. Try to add your views to document manually.

Dmitry Timin

Re: Sockets and Threads

georgiek5025-Nov-02 5:34

georgiek50

25-Nov-02 5:34

Try this for a start: www.sockets.com

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.