Re: re-use and concurrency

[telesoft!rlk@uunet.uu.net (Bob Kitzberger @midnight)]

In <1697@sicsun.epfl.ch> brossard@sic.epfl.ch (Alain Brossard EPFL-SIC/SII) wri
tes:


>    Specificaly, suppose you are re-using a stack package and
>create a really usefull package out of this.  Next week/month/year,
>another collegue wants to re-use your neat package and doesn't
>realize there is this hidden requirement to be sequential.
>    
>    To me it seems the only solution would be to design
>every package to be "concurrent" proof.  What is the cost
>of such a decision?

If the solution involves using a task to implement something like
a Hoare monitor to serialize access to the package, then the cost is 
that the compiler's tasking support must be linked into the executable 
image regardless of whether or not the application is concurrent.
In addition, there is the run-time overhread of performing rendezvous
to implement the monitor.

Wrapping a task around a package to act as a monitor is as simple
as can be.  Personally, I'd leave the package libraries serial, and
if I need them to handle concurrency then I'd wrap a task around them
as needed.

	.Bob.
-- 
Bob Kitzberger               Internet : rlk@telesoft.com
TeleSoft                     uucp     : ...!ucsd.ucsd.edu!telesoft!rlk
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