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Date: 15 Sep 93 17:32:39 GMT
From: dst17!mab@ford-wdl1.arpa  (Mark A Biggar)
Subject: Re: Tasking in Ada
Message-ID: <1993Sep15.173239.2471@wdl.loral.com>
List-Id: <comp.lang.ada>

In article <1993Sep15.094745.16963@jarvis.csri.toronto.edu> blaak@csri.toronto.
edu (Raymond Blaak) writes:
>kgatlin@galaxy.csc.calpoly.edu (Kang Su Gatlin) writes:
>>I have hit a snag with Ada.  I need to create dynamic tasks that know which
>>task they are.
>...
>>I can't seem to find a way to pass information to tasks efficiently.  I want
>>all the tasks to run simultaneously so that the creation and execution of
>>the tasks can be done in t(1) time.  
>>The only way I can think of how to do it is to loop through and create the 
>>tasks but that is O(n) time.  Or I can create an array of tasks (if that is
>>possible) but then how do I get information to the tasks with using the
>>rendezvous mechanism (again O(n)).
>If n is small, then looping through is probably the best way. If n is large
>then consider the array of tasks as a tree (i.e. the children of task i are
>tasks 2i and 2i+1) and have each task communicate the identities to its
>children. This would give you O(log n) time. To start things off you would
>need only to tell task 1 its identity.
>At any rate, if your code is running on a serial machine, then simply looping
>through is faster anyway, for there would be less parallelism being simulated
>to assign the identities.

The above is all you can do in Ada83, but there will be relief in Ada9x.
Ada9x allows for discriminants ob task types, which can be used in the obvious
way to parameterize tasks at creation time.

--
Mark Biggar
mab@wdl.loral.com