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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Getting the index for an element in mutually referencing
 containers
Date: Sun, 12 Mar 2017 00:37:01 +0200
Organization: Tidorum Ltd
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Xref: news.eternal-september.org comp.lang.ada:27843
Date: 2017-03-12T00:37:01+02:00
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On 17-03-11 23:46 , Simon Wright wrote:

> Basically, I (Simon, now) am having trouble thinking of an application
> where reference counting would be an appropriate solution.

How about this one: the SW generates messages (telemetry packets) 
reporting various sorts of data and events.

Depending on the kind of the message, the same message may have to be 
distributed within the SW to several destinations: a radio link, a log 
file (mass memory), a message-monitoring service (for possible 
autonomous action), etc.

Each destination has a queue of incoming messages, and the queueing and 
processing time for a given message varies accordingly. Rather than copy 
the (possibly long) message into each destination's queue, the queues 
hold references to a single, shared instance of the message, dynamically 
allocated in a memory pool. These references are counted. When, finally, 
all destinations have processed the message, the message's reference 
count reaches zero, and the message can be deallocated.

This use of reference counting is a typical design in satellite on-board SW.

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