itaps-parallel A question about iMeshP interface functions

[Devine, Karen D]

I admit I don¹t understand the issue, either, but I'm not in the middle of
implementing it as you are.  We have a phone conf scheduled for 9am PDT on
Monday, Aug 25.  Lori, can we use a few minutes at the end of the conf to
talk about this issue?  Thanks.

Karen



On 8/14/08 9:45 AM, "Onkar Sahni" <osahni at scorec.rpi.edu> wrote:

>
>
>> There's simply no way to
>> pass a remote entity handle --- that would require both a handle and a
>> part ID.
>
>   In iMeshP_getCopies(), copies_entity_handles (of type
> iBase_EntityHandle) can have handles that are off-proc. (if handle is a
> pointer then off-proc. pointer/memory). What if user took one such
> handle and pass it in iMeshP_getEntOwnerPart().
>
>>
>> Second, because a partition is a covering of the entire contents of a
>> parallel mesh, checking whether an entity is in a partition reduces to
>> checking whether the entity handle is valid in the local root set, a
>> test that iMesh requires routinely.
>
>   There should be routine test but we do not want to exercise such routine
> test in very basic functions.
>
> - Onkar
>
>
>
>
>> Onkar Sahni wrote:
>>>> I had assumed that if one had a handle for an entity at all, that the
>>>> local
>>>> processor knew enough about that entity to answer such questions (e.g.
>>>> that
>>>> it is an interface or ghost entity.)  But I missed several discussions.
>>>> Are
>>>> we back to considering entity handles to be globally unique across all
>>>> processors?
>>>
>>>   If entity-handle is local (on local part/proc.) then one can ask such
>>> questions (ghost entity etc.), but if entity is not local, i.e,
>>> remote-handle or remote-copt then it is not valid to ask such questions.
>>> How do we return reasonable error message/code in this case of
>>> remote-handle. There are no globally unique entity handles.
>>
>> I'm a bit confused about what the problem is here.
>>
>> First, I agree that we're certain to be looking at a local entity handle
>> here (though it could be a ghost or copy).  There's simply no way to
>> pass a remote entity handle --- that would require both a handle and a
>> part ID.
>>
>> Second, because a partition is a covering of the entire contents of a
>> parallel mesh, checking whether an entity is in a partition reduces to
>> checking whether the entity handle is valid in the local root set, a
>> test that iMesh requires routinely.
>>
>>>> It seems to me that the iMeshP_getEntOwnerPart and
>>>> iMeshP_getEntOwnerPartArr
>>>> are inherently expensive, and those are the only two for which I see a
>>>> requirement to return an error if the passed entity is not contained in
>>>> the
>>>> partition.  I'm looking at the draft spec Karen sent on July 24th.  Is
>>>> there
>>>> a more recent one?
>>>
>>>   I do not see why these will be expensive, at least they are not in
>>> FMDB
>>> implementation.
>>
>> If those are cheap, then surely checking for partition membership is too
>> (if it belongs to a part, the entity surely belongs to the partition...).
>>
>> Maybe I'm being incredibly naive here, but I don't see this as being
>> terribly difficult or time consuming.  Am I missing something here?
>>
>> Carl
>>
>> --
>> ------------------------------------------------------------------------
>> Dr. Carl Ollivier-Gooch, P.Eng.                   Voice: +1-604-822-1854
>> Associate Professor                                 Fax: +1-604-822-2403
>> Department of Mechanical Engineering             email: cfog at mech.ubc.ca
>> University of British Columbia              http://www.mech.ubc.ca/~cfog
>> Vancouver, BC  V6T 1Z4                  http://tetra.mech.ubc.ca/ANSLab/
>> ------------------------------------------------------------------------
>>
>>
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