[fpc-pascal] QueueUserAPC Similar Cross platform Functionality

[Andrew Brunner]

In theory that's what I'm planning to do to emulate the functionality.
 I'm going to create a queue using a FIFO technique and empty out the
queue executing the callbacks for each item in the queue - from a
manager thread.

Thanks for the advice.  -Andrew

On Fri, Oct 9, 2009 at 11:40 AM, David Emerson <dle3ab at angelbase.com> wrote:
> Hi Andrew,
>
> I don't really understand your question as well as I'd like to (in
> particular, I don't understand the difference between a "callback" and
> any other sort of procedure; as well as other confusions) So this might
> be bunk advice, but here it is...
>
> Have you considered making your own thread function wrapper that could
> duplicate the functionality you need?
>
> type
>  thread_param_and_callback_func = record
>    thread_func : function (p : pointer) : ptrint;  // as required
>    thread_param : pointer;  // the parameter to the main thread func
>    callback_proc : procedure (...);
>    callback_param : ???;
>    end;
>  p_thread_param_and_callback_func = ^thread_param_and_callback_func;
>
> function thread_proc_wrapper (p : pointer) : ptrint;
> begin
>  with thread_param_and_callback_func (p^) do begin
>    thread_func (thread_param);
>    callback_proc (callback_param);
>    end;
> end;
>
> I've only made one multithreaded program at this point, but it was a
> huge success, and I used something similar to this-- a thread handling
> function that would repeatedly request tasks and execute them, until
> the tasks were all complete. (I added a repeat loop...)
>
> Hope this helps... (or inspires you to think of something that will
> work :)
>
> ~David.
>
>
> On Thu 8 Oct 2009, Andrew Brunner wrote:
>> Hi there,
>>
>> I've got a unit I'm porting from Windows to Linux and I came across a
>> QueueUserAPC (Kernel32 Windows) I make to add a callback method that
>> gets executed by the thread I added this to.
>>
>> function QueueUserAPC(Callback: Pointer; hThread: THandle;
>> dwData:DWORD): boolean; stdcall;
>>
>> When the Thread gets around to it, it processes the callback function
>> I passed in during the queue call.
>>
>> Judging by the performance of this method I would say that the Windows
>> Kernel maintains a queue of events to process for each thread.  And
>> this function allows me to attach a callback to that queue so I can
>> allocate memory within that stack rather than the stack of the calling
>> thread.  This feature is important as I want to keep memory allocation
>> to specific threads.
>>
>> Does Threading under Linux have anything like this?  Have any of you
>> done anything like this under *nix?
>>
>> Thanks for any feedback.
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>>
>
>
>
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