mp_probe Subroutine

   SUBROUTINE mp_probe(source, comm, tag)
      !! probes for an incoming message with any tag

      INTEGER                                  :: source
         !! the source of the possible incoming message, if MP_ANY_SOURCE it is a blocking one and return value is the source of the
         !! next incoming message if source is a different value it is a non-blocking probe retuning MP_ANY_SOURCE if there is no
         !! incoming message
      TYPE(mp_comm_type), INTENT(IN)           :: comm
         !! the communicator
      INTEGER, INTENT(OUT)                     :: tag
         !! the tag of the incoming message

      CHARACTER(LEN=*), PARAMETER :: routineN = 'mp_probe'

      INTEGER                                  :: handle, ierr
#if defined(__parallel)
      MPI_STATUS_TYPE                          :: status_single
      LOGICAL                                  :: flag
#endif

!   ---------------------------------------------------------------------------

      CALL timeset(routineN, handle)

      ierr = 0
#if defined(__parallel)
      IF (source .EQ. mp_any_source) THEN
         CALL mpi_probe(mp_any_source, mp_any_tag, comm%handle, status_single, ierr)
         IF (ierr /= 0) CALL mp_stop(ierr, "mpi_probe @ "//routineN)
         source = status_single MPI_STATUS_EXTRACT(MPI_SOURCE)
         tag = status_single MPI_STATUS_EXTRACT(MPI_TAG)
      ELSE
         flag = .FALSE.
         CALL mpi_iprobe(source, mp_any_tag, comm%handle, flag, status_single, ierr)
         IF (ierr /= 0) CALL mp_stop(ierr, "mpi_iprobe @ "//routineN)
         IF (flag .EQV. .FALSE.) THEN
            source = mp_any_source
            tag = -1 !status_single MPI_STATUS_EXTRACT(MPI_TAG) ! in case of flag==false status is undefined
         ELSE
            tag = status_single MPI_STATUS_EXTRACT(MPI_TAG)
         END IF
      END IF
#else
      tag = -1
      MARK_USED(comm)
      MARK_USED(source)
#endif
      CALL timestop(handle)
   END SUBROUTINE mp_probe