Re: CEvent & WaitForSingleObject (auto-reset)
Thanks Joe,
I wouldn't trust an MFC synchronization primitive as far as I
could throw a 1960s mainframe.
That's rich! ;-)
I'm going to assume that you're not a recent gym rat convert benching 350
lbs. Therefore, I should see the MFC sync thing as BAAAADDDDD.
I did get it working by using the handle as Alexander suggested. An
oversight on my part even after looking at it 100 times. I will look into
using ATL or Win32 instead.
It does amaze me though that a library that was a cornerstone in Windows
development can have so many flaws, in such an important concept, that
everyone with experience knows to avoid it.
Regards,
Jim
"Joseph M. Newcomer" wrote:
I wouldn't trust an MFC synchronization primitive as far as I could throw a 1960s
mainframe.
You are correct in your perception of what should happen. Have you considered trying it
with a simple Event object (HANDLE h = ::CreateEvent(NULL, FALSE, FALSE, NULL)?
I would consider a semaphore a better choice. Each click increments it, each iteration
decrements it.
joe
On Thu, 2 Jul 2009 06:16:02 -0700, Jimbo_Jimbob_Jiminator
<JimboJimbobJiminator@discussions.microsoft.com> wrote:
Haven't been here in a while. Haven't been doing any Windows programming for
some time.
I have an issue with CEvent & WaitForSingleObject. The likely issue is that
I have no idea what I'm doing but, if we put that aside and pretend that I
have a clue, it goes like this:
The default implementation for CEvent is auto-reset. That is how I want to
use it. I have only a main tread and a second thread so I do not have several
threads waiting.
I have looked in books and all over the web and all of the examples seem to
show how to start a thread or stop a thread with an event. In this case,
auto-reset is not that useful if you only have one worker thread anyway.
I am trying to control when a loop runs with the event. The issue is that
once the user clicks the button to allow the progress bar to be updated once,
it just keeps updating through completion. I figure that the state of the
CEvent should auto-reset and it should not run another iteration until the
user intiates it.
Regards,
Jim
Here are some code snips that show it:
//This is primarily from an example I found on the web. I added the
//WaitForSingleObject as a test case.
UINT TestThread(LPVOID lParam)
{
AfxMessageBox("Bite Me");
PTHREADINFOSTRUCT pTis = (PTHREADINFOSTRUCT)lParam;
pTis->pEvent->Lock();
for(int i=0;i<100;i++)
{
::WaitForSingleObject(pTis->pEvent, INFINITE) == WAIT_OBJECT_0;
//This sends a message to the main thread to update the status bar
PostMessage(pTis->hWnd,UWM_USER_THRD_UPPRG,i,100);
Sleep(100);
}
PostMessage(pTis->hWnd,UWM_USER_THRD_FIN,0,0);
delete pTis;
return 0;
}
void CPPage1::OnBnClickedButton1()
{
//Testing Wait Single Object. Sends message to main dlg that user clicked
//the button
LRESULT Rslt = ::SendMessage(m_pMainWnd->m_hWnd , UWM_TEST_WSO, 0, 0);
}
LRESULT CMainDlg::OnWSO(WPARAM wParam, LPARAM lParam)
{
//User clicked the button set event to allow progress bar another tick.
pTis->pEvent->SetEvent();
return 0;
}
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
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