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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: How to: communication between multiple tasks using protected
 objects - with no polling?
Date: Wed, 21 Jan 2015 09:28:22 +0100
Organization: cbb software GmbH
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Date: 2015-01-21T09:28:22+01:00
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On Tue, 20 Jan 2015 14:36:20 -0800 (PST), Esa Riihonen wrote:

> Here is the problem. My typical C-process 'listens' to several FIFOs
> connected to separate processes. This is realized using a ppoll-type
> 'reactor' - so in essence the process is sleeping until there is some
> activity in any of the monitored file descriptors (I guess this is in
> essence quite basic arrangement in the 'C-world').
> 
> I first thought I can implement this by the 'select' - something like this:
> 
> PO1 and PO2 are instantiations of a protected type with entry 'Get'.
> 
> ...
> loop
>   ...
>   select
>     PO1.Get(...);
>   or
>     PO2.Get(...);
>   or 
>     ...
>   end select;
>   ...
> end loop;

The typical design of 1-n is reverse: the publisher queues request to the
consumer rather than lets the consumer to come and pick it.

The publisher may call the consumer's entry or else queue the request into
a queue. If publishers shall not be blocked (e.g. in order to prevent
priority inversion or due to time constraints), also when it is n-m, use
the blackboard instead of a queue.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de