realtime design

[Will Stuyvesant]

> [Tim Daneliuk] 
> ...
> There is an inherent problem with the term "realtime" if it is
> not further qualified.  
> ...
> 1) "Hard" realtime - ...
> ...
> 2) "Soft" realtime - ...
> ...

I was looking for a primitive that can be used for modeling *hard*
realtime, but without the ``service completed'' requirement.  ``I
cannot do this in time'' is also acceptable at timeout.  The point
is that the caller should be able to carry on.

> ...
>                  http://www.tundraware.com/Technology/Bullet/
> ...

And you have more interesting stuff there.

> HOWEVER, you said you wanted to "prototype" such a system.
> Depending on how functional your prototype needs to be, Python
> may well be a good choice.  It is relatively easy and quite
> appropriate to *model* realtime systems, hard and soft, in other
> languages.  

Well as you can see in this thread I failed using Python!  Maybe
my requirements are too strict.  For modeling ``ordinary''
function calls a combination of Queue.Queue and
threading.Thread.join(timeout=...) can be used.  But if the
function call winds up doing cpu intensive stuff (for example
pow()) at the C level then the Python threading timeout fails, so
the caller can not carry on in time.  And *that* is essential for
the realtime modeling primitive.  Performance is no issue, the
simulation is allowed to be very slow, as long as it does
implement the primitive correctly.  

If I have more time I am going to look into doing this with
processes instead of threads.  

Thank you for your comments!


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