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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: About task-safeness
Date: Thu, 03 Feb 2011 09:53:03 +0100
Organization: Tidorum Ltd
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Date: 2011-02-03T09:53:03+01:00
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Randy Brukardt wrote:
> "mockturtle" <framefritti@gmail.com> wrote in message 
> news:06ecb5ab-a9e5-4a5d-9370-6bbe137d3693@glegroupsg2000goo.googlegroups.com...
> ...
>> (For example, a package defining some type of object could keep the number 
>> of allocated
>> objects, so it can give to each object a unique ID.)  If such a package was 
>> used  by two
>> different tasks, and the counter was not protected, obscure bugs can arise. 
>> This type of
>> structure maybe is not very recommended, but it happens... :-(
> 
> Note that "protection" may simply be declaring the object Atomic. Presuming 
> the compiler supports that, there isn't a problem with multiple tasks 
> accessing the same counter.

Randy, could you be more explicit about your suggested use of Atomic? As 
I understand it, even if a counter variable N is Atomic, two tasks 
concurrently executing an assignment of the form

    N := N + 1;

can interleave their actions so that N is increased by only 1, not by 2 
as intended.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .