How to pause processing?

Dustin Henry

I have an application with a main processing loop ( while(true){} ). When the application is running normally it eats up about 2% of the CPU. Whenever focus is taken away from the application window however, the CPU usage jumps to about 50%. This also happens when I comment out all of my code in the loop except the windows message queue processing and my app jumps from 60fps to about 2000fps. My question is, how do I 'pause' processing when focus is taken away, but still have the abilty to get window messages so I know when focus is given back? Thanks in advance, Dustin

Johan Pretorius

When your application receives the WM_KILLFOCUS message then set the thread priority to BelowNormal or Lowest or make the application thread sleep. Hope it helps

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Dustin Henry

That doesn't seem to work. Am I doing this correctly? I have never created/manipulated threads before.

case WM_ACTIVATE:
{
	// See if we lost or gained focus
	if (LOWORD(wParam) == WA_ACTIVE)
	{
		HANDLE thread = GetCurrentThread();
		SetThreadPriority(thread, THREAD_PRIORITY_NORMAL);
	}
	else
	{
		HANDLE thread = GetCurrentThread();
		SetThreadPriority(thread, THREAD_PRIORITY_LOWEST);
	}
}
break;

I also tried doing it on the WM_KILLFOCUS event but with the same results. Thanks, Dustin

Johan Pretorius

Something i forgot when you posted was that you wanted to pause the processing not lower it. try this if it does not work try send me an demo so i can test.

//add global variable to main.cpp
static bool g_bRunning = true;

//Modify case statement
case WM_ACTIVATE:
{
   //See if we lost or gained focus
   if (LOWORD(wParam) == WA_ACTIVE)
   {
     g_bRunning = true;
   }
   else
   {
     g_bRunning = false;
   }
}
break;

//add to main loop
while (!g_bRunning){/*leave empty*/};//this should pause it.

//just add an mutex and !!

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Mark Salsbery

Dustin Henry wrote:

I comment out all of my code in the loop except the windows message queue processing and my app jumps from 60fps to about 2000fps.

What do you mean by "fps"? Typically a Windows message loop uses virtually no CPU until a message is received. What's going on in your message loop? Mark

Dustin Henry

fps = Frames per second. It is a Direct3D application. Typically a Windows message loop uses virtually no CPU until a message is received I thought the same thing, but if I comment out all of my processing except for the message peek and dispatch, the app still eats the CPU when focus is lost. Here is my entire WindowProc:

LRESULT CALLBACK WindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{	 
	switch(msg)
	{	
		case WM_CREATE: 
		{  
			// do initialization stuff here
			// return success
			return(0);
		} 
		break;
		case WM_LBUTTONDOWN:
		{
			// get the position of the mouse
			POINT ptMouse = {(int)LOWORD(lParam),(int)HIWORD(lParam)};
			g_pInterface->UpdateMouse(ptMouse, true);
		}
		break;
		case WM_LBUTTONUP:
		{
			// get the position of the mouse
			POINT ptMouse = {(int)LOWORD(lParam),(int)HIWORD(lParam)};
			g_pInterface->UpdateMouse(ptMouse, false);
		}
		break;
		case WM_MOUSEMOVE:
		{
			// get the position of the mouse
			POINT ptMouse = {(int)LOWORD(lParam),(int)HIWORD(lParam)};
			g_pInterface->UpdateMouse(ptMouse);

			CString stMove;
			stMove.Format("(%d,%d)",(int)LOWORD(lParam),(int)HIWORD(lParam));
			//SetWindowText(g_hWND, stMove);
		}
		break;
		case WM_DESTROY: 
		{
			// kill the application, this sends a WM_QUIT message 
			PostQuitMessage(0);
			// return success
			return(0);
		} 
		break;
		case WM_GRAPHNOTIFY:
		{
			g_pInterface->GetDirectShow()->OnGraphEvent();
		}
		break;
		default:break;

	} // end switch
	// process any messages that we didn't take care of 
	return (DefWindowProc(hWnd, msg, wParam, lParam));
} // end WinProc

And my main loop: (the message part)

while(TRUE)
{
	// Get the time this function began executing
	//DWORD dwStartTime = GetTickCount();
	// test if there is a message in queue, if so get it
	if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
	{ 
		// test if this is a quit
		if (msg.message == WM_QUIT)
		   break;
		// translate any accelerator keys
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			// send the message to the window proc
			DispatchMessage(&msg);
		}
	} // end if
/* Other processing... */
}

Dustin

Dustin Henry

Since my message peek is in the main loop, if I do that it will no longer look for messages and will not tell me when focus has been restored.

Johan Pretorius

Mark Salsbery wrote:

What do you mean by "fps"?

Well i am guessing he is writing a game/game engine. Applications also lose focus when they are minimized. That is why he probaly needs the application to stop processing.

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Johan Pretorius

Well you could put a copy of the messagepeek functions to the while (!m_bRunning) {}; then there should be no problems

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Johan Pretorius

Sorry his reply was not there when i posted mine

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Dustin Henry

Well I think I fixed it. I basically used CaveFox's idea of a running boolean but in the main loop placed:

if (!g_bRunning)
	Sleep(1000);

I believe this was happening because I allow the program to basically sit and spin in an infinite loop. Even if I commented out everything in the while(), the same thing happened. I guess the program just needed something to do. Any idea why this is? Thanks for your help guys. Dustin

Mark Salsbery

Try GetMessage instead of PeekMessage You shouldn't have to sleep or mess with thread priority for user interface thread :) Mark

Mark Salsbery

No SLEEP()!!! ;)

while(GetMessage(&msg,NULL,0,0))
{
// translate any accelerator keys
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
// send the message to the window proc
DispatchMessage(&msg);
}
}

Johan Pretorius

This should stop all processing (except the messages).

case WM_ACTIVATE:
{
   //See if we lost or gained focus
   if (LOWORD(wParam) == WA_ACTIVE)
   {
     g_bRunning = true;
   }
   else
   {
     g_bRunning = false;
   }
}
break;


static bool m_bRunning = true;

while(TRUE)
{
	// Get the time this function began executing
	//DWORD dwStartTime = GetTickCount();
	// test if there is a message in queue, if so get it
        do
        {
             if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
             { 
		// test if this is a quit
		if (msg.message == WM_QUIT)
		   break;
		// translate any accelerator keys
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			// send the message to the window proc
			DispatchMessage(&msg);
		}
	     } // end if
        } while(!m_bRunning)
 /* Other processing... */
}

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Mark Salsbery

Really, I BEG you guys...pleeeease leave the poor UI thread alone :(( What did it ever do to you??? :)

Johan Pretorius

Yea it was a little overkill (by me X|) ... im sleep deprived and are not thinking strait. Should have solved it with the first post :^)

Artificial Intelligence is no match for Natural Stupidity
No one can understand the truth until he drinks of coffee's frothy goodness. ~Sheik Abd-al-Kadir
I can't always be wrong ... or can I?

Mark Salsbery

:laugh: It looked right to me - I had to test it before I saw it! As soon as Sleep() comes up, it's time for an intervention :)