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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Tasking and wxWidgets
Date: Sat, 26 Nov 2005 07:46:15 +0000
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Date: 2005-11-26T07:46:15+00:00
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"Lucretia" <lucretia9@lycos.co.uk> writes:

> 2) I could also go the other way and inside the
> wx.Base.Object.Object_Type (wxObject) provide a mutex object, such
> that every call in wxAda would lock (on entry) and unlock (on exit)
> thus providing thread safety if that particular object were accessed
> via multiple tasks. The overhead of constructing/destructing a mutex
> locker object, locking/unlocking the mutex object on every call
> would be rather high and thus, would most probably slow the
> application down to a crawl (although, not tested). Use of inlining
> might make this nicer?

Not clear that inlining would help a lot here.

What would be acceptable? Using a Lock from the Booch �components
(http://booch95.sourceforge.net) takes just under 20 us on a 1.5GHz
Powerbook.

   with Ada.Text_IO; use Ada.Text_IO;
   with BC.Support.High_Resolution_Time;
   with BC.Support.Synchronization;
   procedure Time_Lock is
      Mutex : aliased BC.Support.Synchronization.Semaphore;
      Start, Finish : BC.Support.High_Resolution_Time.Time;
      use type BC.Support.High_Resolution_Time.Time;
   begin
      Start := BC.Support.High_Resolution_Time.Clock;
      declare
         L : BC.Support.Synchronization.Lock (Mutex'Access);
         pragma Unreferenced (L);
      begin
         --  Mutex now secured and will be released on block exit (even
         --  on exception)
         null;
      end;
      Finish := BC.Support.High_Resolution_Time.Clock;
      Put_Line ("took " & Duration'Image (Finish - Start));
   end Time_Lock;