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Back to article list Search Articles Add Comment Printer friendly Direct link Clarion 6: Keep track of all threads 2004-03-12 -- Don Wood Newsgroups: softvelocity.public.clarion6
> Is there a way to loop through all the active threads?
> I need to know if a certain file is in use somewhere in my program before
> it continues.
I would suggest a global, non-threaded queue containing three variables.
!---------------------------------------------------------------------------
INCLUDE('CWSYNCHC.INC'),ONCE ! needed for critical sections
EVENT:CheckFileForUse EQUATE (760H)
EVENT:CheckedFileForUse EQUATE (761H)
MainThread Signed
ThreadQueue Queue, pre(TQ)
ThreadNumber Signed
FileInUse Byte
CheckedForUse Byte
End
ThreadCS CriticalSection
!---------------------------------------------------------------------------
When the App starts, save it's THREAD() in the MainThread variable.
Then, everytime you start a Proc in a new thread, you add it's Thread to the
queue:
!---------------------------------------------------------------------------
ThreadCS.wait()
clear(ThreadQueue)
TQ:ThreadNumber = Thread()
add(ThreadQueue)
ThreadCS.Release()
!---------------------------------------------------------------------------
Also in the kill embed you'll want to remove the thread number from the
queue.
Now, to find out if any of the threads are using the file, loop through the
queue and post an event to each queue, telling them to check and send a
response.
!---------------------------------------------------------------------------
ThreadCS.wait()
loop i# = 1 to records(ThreadQueue)
!first clear all the queue's flags
TQ:FileInUse = FALSE
TQ:CheckedForUse = FALSE
put(ThreadQueue)
! then tell each thread to check
post(EVENT:CheckFileForUse, ,TQ:ThreadNumber)
end
ThreadCS.Release()
!---------------------------------------------------------------------------
Then in each thread check for the event in TakeEvent() and check if the file
is in use
!---------------------------------------------------------------------------
case EVENT()
of EVENT:CheckFileForUse
ThreadCS.wait()
clear(ThreadQueue)
TQ:ThreadNmber = thread()
get(threadqueue)
if ~errorcode()
TQ:CheckedForUse = true
! check for file in use in this thread
! if file in use
TQ:FileInUse = true
else
TQ:FileInUse = false
end
put(ThreadQueue)
end
post(EVENT:CheckedFileForUse,,MainThread)
end
ThreadCS.Release()
!---------------------------------------------------------------------------
Lastly, in your Main thread you wait for the CheckedFileForUse events.
!---------------------------------------------------------------------------
ThreadCS.wait()
loop i# = 1 to records(threadQueue)
get(ThreadQueue, i#)
if TQ:CheckedForUse = FALSE
! not all threads have responded, might want to break here,
! and wait for another event
end
if TQ:FileInUse = TRUE
! do what ever you want when the file is in use
end
end
ThreadCS.Release()
!---------------------------------------------------------------------------
It's long and a little confusing, but It's the best way I know of to have
all your threads communicating.
Hope this helps,
Don Wood
VendPrint, Inc.
Today is November 21, 2024, 6:50 am This article has been viewed 35322 times. Google search has resulted in 26 hits on this article since January 25, 2004.
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