other request-using frameworks.
- Rather than having mpi/c/* functions allocate requests explicitly,
pass the MPI_Request* down to the I/O component and have it
perform the allocation.
- While the I/O base provides a base request which can be used,
it is not required and all request management occurs within
the component.
- Push progress management into the component, rather than having it
happen in the base. Progress functions are now easily registered,
and not all (ie, the one existing) components use progress functions
in any rational way.
ROMIO switched to generalized requests instead of MPIO_Requests many
moons ago, and Open MPI now uses ROMIO's generalized requests, so there
is no reason to wrap those requests (which are OMPI requests) in another
level of request.
Now the file function passes the MPI_Request* to the ROMIO component,
which passes it to the underlying ROMIO function, which calls
MPI_Grequest_start to create an OMPI request, which is what gets set
as the request to the user. Much cleaner.
This patch has two motivations. One, a whole heck of a lot of code
just got removed, and request handling is now much cleaner for I/O
components. Two, by adding support for Argonne's proposed generalized
request extensions, we can allow ROMIO to provide async I/O through
generalized requests, which we couldn't rationally do in the old
setup due to the crazy request completion rules.
This commit was SVN r22235.
b57b8c5b3f