itaps-parallel Proposal for handling queries with parts, sets, and partitions

[Onkar Sahni]

>>> So again, I go back to asking: what are the core needs that prevent us
>>> from using sets as both parts and partitions?  The entity set mechanism
>>> was designed with this specific usage in mind.
>>
>> If "sets as both parts and partitions" mean using entity-sets then we
>> have
>> already discussed this in great detail. I think the question in
>> discussion
>> is irrespective of how one implements parts and partitions? If I
>> understood the question right then we need to answer queries which
>> involve
>> a specific part and a specific entity-set (where entity-set may span
>> more
>> than one part, may be local to a process). Now, if it is implied that
>> choosing entity-sets for both parts and partitions allows to use set
>> operations (booleans), outside the interface explicitly by applications,
>> to answer such queries well then applications might as well do it in
>> other
>> equivalent ways (for example, loop over entities in set and ask
>> residence
>> parts to get entities in the entity-sey belonging to a specific part).
>>
>
> Sure, but the implication in the current discussion is that doing
> booleans in the applications themselves is undesirable.  Therefore we
> are looking for a way to represent these questions in the interface.  To
> that I assert that there are lots of other set booleans that are also
> likely and possibly more common, and therefore we should design these
> functions to be more general than just applying to parts and partitions.
>   Examples of these queries include:
> - boundary condition faces which are owned locally
> - vertices in a set being smoothed which are also on a model face
> - elements at one refinement level with faces on the skin

These general queries are not (at least to me) related to "core needs that
prevent us from using sets as both parts and partitions".

Infact, applications can also ask for intersection (i.e., this+this+that)
of all examples queries listed above. I would consider these more
"utility" type functions which I hope is not confused with parallel
interface ("parts and partitions") and may even be separate form mesh
interface (iMesh, serial one) as one can ask these general questions at
geometric model level too (iGeom)? Do we use "entity-sets" in iGeom
(sorry, I am not familiar with iGeom)?

For "utility" type functions, we can easily deal with them by following
similar concepts as STL algorithms, like find, sort etc., that take
iterators and some operators (may be we can pass in iMesh entity iterators
and some iMesh boolean operators). For example,

numBCFacesOwned = count(bcFaceIterBegin,bcFaceIterEnd,&iPart_isEntOwned);

- Onkar