[Mpi3-ft] MPI_ANY_SOURCE

[Darius Buntinas]

I think we can do this without a warning, just by using an error:  If a wait (or wait_all, test, etc) is called with an anysource request while the req's communicator is anysource disabled, then the function will return an error (maybe something like MPI_ERR_ANYSOURCE_DISABLED).

Of course in the wait_all case the app needs to be able to determine which req is the anysource on a disabled communicator.  We may be able to help the user here by using the status array.

-d

On Oct 11, 2011, at 3:16 PM, Darius Buntinas wrote:

> 
> I think you're right Josh, the blocking version wouldn't need to be changed.
> 
> For the nonblocking version, wouldn't we only need to lock around the Wait, not between the Recv and Wait?  If we're worried about hanging in a blocking Wait, I think we just need to check for all-clients-failed before calling Wait.  If anysources are reenabled by another thread before this thread calls Wait, that's OK, so long as the thread checks first.
> 
> Here's a function a user could implement to use whenever waiting on an anysource:
> 
> int My_AS_MPI_Wait(MPI_Request *req, MPI_Status *status)
> {
>    while(1) {
>        reader_lock();
>        if (my_cnt != recognize_cnt) {
>            /* New failures were detected */
>            /* check failed_group and decide if ok to continue */
>            if (ok_to_continue(req, failed_group) == FALSE) {
>                reader_unlock();
>                return MPI_ERR_PROC_FAIL_STOP;
>            }
>            my_cnt == recognize_cnt;
>        }
>        err = MPI_Wait(req, status);
>        if (err == MPI_WARN_PROC_FAIL_STOP) {
>            /* Failure case */
>            reader_unlock();
>            writer_lock();
>            if (my_cnt != recognize_cnt) {
>                /* another thread has already re-enabled wildcards */
>                writer_unlock();
>                continue;
>            }
>            MPI_Comm_reenable_any_source(comm, &failed_group);
>            ++recognize_cnt;
>            writer_unlock();
>            continue;
>        } else {
>            reader_unlock();
>            return MPI_ERR_PROC_FAIL_STOP;
>        }
>        reader_unlock();
>    }
> }
> 
> -d
>