Re: caching on MPI handles

Nick Nevin (nevin@osc.edu)
Fri, 18 Oct 1996 17:34:07 -0400 (EDT)

>>>>> " " == Eric Salo <salo@mrjones.engr.sgi.com> writes:

> I'll pass on the question of file handles, since I don't claim to
> understand anything about the I/O chapter. But in general, adding
> dedicated routines for each object class to support attribute
> caching feels like a much better solution to me, so this is an
> approach that I would personally favor.

> Regarding datatypes, it does seem like this would be a useful bit
> of functionality, but I'm a bit concerned about the effect on
> derived datatypes. Consider the following sequence of events:

> 1) An attribute is cached on Datatype A Datatype A is used to
> create Datatype B The value of the attribute on Datatype A is
> altered.

> What is the defined behavior? Perhaps there is a simple solution
> to this problem, but if so it's not yet obvious to me.

I don't see a problem if we make it so that A and B's attributes are
distinct, i.e. new datatypes always start out with no attributes and
there is no inheritance via copy functions.

Any changes to attributes on A have no effect on B and vice-versa.

We might also want to consider restricting caching to committed types
only.

---nick.

-=-
Nick Nevin nevin@osc.edu
Ohio Supercomputer Center http://www.osc.edu/lam.html