File access issue

[knarfin]

I'm trying to read a log file as it's being updated by another program. The log file is being written to 2x per second, and the script read it 2x/sec. Right now the script will read it once, and the file will cease to be written to until the script is closed. I've followed all the FileOpens with FileCloses, but it seems like the script freezes the file's access as long as it's running. Ideas?

CODE

$Log = "C:\myLog.log"

$LineReadA = 0

While 1

$nMsg = GUIGetMsg()

Do

$nMsg = GUIGetMsg()

If $nMsg = $GUI_EVENT_CLOSE

Exit

EndIf

$RealSec = @SEC

Sleep(1)

$RealSec2 = @SEC

Until $RealSec2 > $RealSec

$LineReadB = $LineReadA

$FileRead = FileOpen($Log,0)

$LineReadA = FileReadLine($FileRead, -1)

FileClose($Log)

GUICtrlSetData ($LastLine, $LineReadA)

WEnd

[Zedna]

Try to use _WinAPI_CreateFile() there are more options for sharing mode

Look here at example of use:

http://www.autoitscript.com/forum/index.php?showtopic=76829

[ptrex]

@all

Can this get you going ?

; In computer programming, a mutex (mutual exclusion object) is a program object that is created so that multiple program thread

; can take turns sharing the same resource, such as access to a file. Typically, when a program is started, it creates a mutex for a

; given resource at the beginning by requesting it from the system and the system returns a unique name or ID for it. After that,

; any thread needing the resource must use the mutex to lock the resource from other threads while it is using the resource.

; If the mutex is already locked, a thread needing the resource is typically queued by the system and then given control when the mutex

; becomes unlocked (when once more, the mutex is locked during the new thread's use of the resource).

Func _CreateMutex($sOccurName)
    $hMutex = DllCall("kernel32.dll", "hwnd", "CreateMutex", "int", 0, "int", 1, "str", $sOccurName)
    $hMutex = $hMutex[0]
    If $hMutex = 0 Then Exit
EndFunc

Func _Write()
    FileWriteLine("c:\write.txt", GUICtrlRead($input))
    DllCall("kernel32.dll", "int", "ReleaseMutex", "hwnd", $hMutex)
    DllCall("kernel32.dll", "int", "CloseHandle", "hwnd", $hMutex)
    $hMutex = 0
EndFunc

Regards,

Ptrex

[knarfin]

That leads me in the right direction; thanks.

The problem is that another application is creating and writing to/reading from the log file. After looking at the CreateFile entry in the MSDN library, it seems like the share attributes have to be set upon file creation (which I have no control over). Is there a way to modify the file access sharing modes of existing files?

[AdmiralAlkex]

Didn't you check the helpfile?? It does clearly say "Creates or opens a file or other device", it's just like FileOpen() but with more options!

[knarfin]

ohhhhhh. Yes, I see now. I have it returning text characters using the _WinAPI functions, but I now I need a way to locate the byte locations of the beginning and end of lines in the log, so I can extract one line of text at a time. The UDFs I've seen on here use FileOpen, CountLines, etc, to retrieve this information, which apparently don't allow for access sharing.

[ProgAndy]

It would work with FileOPen, too., but FileClose needs the HANDLE, not the Filename

$FileRead = FileOpen($Log,0)

$LineReadA = FileReadLine($FileRead, -1)

FileClose($FileRead)

[knarfin]

dummmmmmmb. And it works. THANK YOU!

[smartee]

dummmmmmmb. And it works. THANK YOU!

no question is dumb to ask