ASM Community

How can I check if my application is arleady running?
I want only one instance in memory

Use a Mutex, it can only be created once until released. If you create a mutex when your app starts any subsequent versions of your app that attempt to create the same mutex will fail to create a new one.

invoke CreateMutex,NULL,TRUE,ADDR MutexString
invoke GetLastError
.IF eax != 0
invoke ExitProcess,0
.endif

dont use mutex, it uses system memory. try a shared section approtch.
first you want to add to your build.bat under the linker.

/section:share,rws

then in notepad(or whatever you use) put at the top

share segment

AppInit dd 0

share ends

then somewhere in code

	cmp AppInit,1

	je @F

	mov AppInit,1

	jmp endFFFF

	@@:

	invoke ExitProcess,0;exit!

	endFFFF:

	;code here

yes but if your program abnormally termanates without relasing the mutex, its stuck there and will prevent the program from being opend again.

not from my experance. if i didnt close it by my self i couldnt use it any more.

This is instant crash code that I tested, the mutex was destroyed on each crash:

invoke CreateMutex,NULL,TRUE,OFFSET MutexString

invoke GetLastError

.IF eax != 0

	invoke ExitProcess,0

.endif



mov eax,0

mov [eax],DWORD PTR 1

The other way added 512 bytes to the executable for one DWORD, that's quite a bit of overhead.

It's not run in a loop and at somewhere around 8700 clocks (in my tests using CreateMutex and GetLastError) it will not even be noticable during an application start. The saving is not significant as it cannot be run more than once.

Or you can use the brainless method I have used in the past.
I set a registry key in my app's section called "Running", then I toggle it from 1 to 0 based
on whether the app is running.
I needed another app to be aware of my running app, but was crunched for time.
I haven't bothered with a better solution with this app since it's hasn't failed in this regard (yet :))

EDIT: ( I also have a key "ExitSuccesful" making sure it hasn't crashed...)

RobotBob

im not talking about loading a sector, im talking about the time it takes to acccess that varable and compare from memory!
btw i have a 33 meg a second( ramdom read)(100meg bufferd) an extra 512 bytes wont matter unless its fragmented. you could have a 200k exe and it would load in approxamtly the same time a 2k exe would.

greenant,
Use the FindWindow method, it seems more reliable than the CreateMutex and CreateSemaphore techniques:


SingleInstance PROC pszAppName:DWORD
LOCAL hWin:DWORD
; Limit the application to a single instance
invoke FindWindow, 0, pszAppName
.IF eax
mov hWin, eax
invoke EnableWindow,hWin,TRUE
invoke ShowWindow,hWin,SW_RESTORE
invoke SetForegroundWindow,hWin
mov eax, FALSE
.ELSE
mov eax, TRUE
.ENDIF
ret
SingleInstance ENDP