[Mpi3-tools] MPI handles interface

[Jeff Squyres]

Per feedback from the last time we discussed the handles interface, I  
changed the communicator query interface to return an opaque handle  
that can subsequently be queried for all the communicator's specific  
information.  This design allows (but does not require) the DLL to  
probe/obtain all the communicator information from the MPI process  
once and cache it locally (presumably on the opaque handle) such that  
if the debugger queries more than just one piece of information,  
queries can be satisfied locally without needing to probe the MPI  
process again.

I also removed the f2c and cxx2c query functions, replacing them with  
a bitmask on the main _query() function indicating what the type is of  
the communicator being queried.

Note that I have *only* updated communicator stuff; I have not yet  
updated the other types, pending feedback from this group.

Any further feedback before I actually go implement this interface?   
Please reply by the end of this week (COB, Friday, 22 May, 2009).

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Here's the new file (interesting stuff starts around line 675):

     http://www.open-mpi.org/hg/hgwebdir.cgi/jsquyres/mpi3-tools-handles/file/tip/ompi/debuggers/mpihandles_interface.h

Here's the commit showing the diff of the changes I made:

     http://www.open-mpi.org/hg/hgwebdir.cgi/jsquyres/mpi3-tools-handles/rev/f6f329f9ec41

-- 
Jeff Squyres
Cisco Systems