OpenEuphoria

Re: Multitasking Preview Release

• Posted by "Juergen Luethje" <j.lue at gmx.de> Sep 22, 2005
• 599 views

Robert Craig wrote:

> Jonas Temple wrote:
>> Will this handle the following (in Windows):
>>
>> * Routine "a" is executed when a user clicks a button
>> * "a" starts task "b"
>> * task "b" calls a routine in a .DLL that extracts information from another
>> computer.
>>  Sometimes the answer comes back quickly and sometimes the answer comes back
>>  in minutes
>> (i.e. SQL query).  For this example, let's say 5 minutes.
>> * user can't wait for answer and wants to cancel the query.  I add a button
>> to the
>> window that lets the user cancel the query.  User clicks button and I use
>> task_kill()
>> against task "b".
>>
>> Since task "b" is still waiting for the routine in the DLL to return, would
>> taks "b"
>> be cancelled immediately or when the DLL returns control to task "b"?
>
> With cooperative multitasking, task b can't call a routine in a .dll
> and then wait inside that call, without holding up all the other tasks.
>
> What you need is some kind of asynchronous (non-blocking) I/O call,
> that will let task b return from the call immediately, and then
> check periodically to see if the I/O is complete. You could set up
> task b to check, say, every 2 or 3 seconds to see if the I/O is complete.
> While it's doing that, other tasks could handle the user interface,
> and any other processing that you want to do in parallel with task b.
> If the user wants to stop the I/O, you could let task b know via
> a global variable that it should quit, or you could call
> task_kill() on task b to force it to stop the periodic checking.

<snip>

I wrote a plugin (a Windows DLL) for Total Commander. Sometimes, when
the DLL reads/writes huge files, obviously Total Commander is not able
to update the optical appearance of its main window, until the DLL has
finished its work.

Can I do something to solve the problem now, without the new
multitasking system? Can the new multitasking system help to write
"more cooperative" DLLs?

TIA,
   Juergen

-- 
Have you read a good program lately?