oracular (3) MPI_Imrecv.openmpi.3.gz

Provided by: openmpi-doc_4.1.6-13.3ubuntu2_all bug

NAME
       MPI_Imrecv - Non-blocking receive for a matched message


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Imrecv(void *buf, int count, MPI_Datatype type,
            MPI_Message *message, MPI_Request *request)


Fortran Syntax
       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_IMRECV(BUF, COUNT, DATATYPE, MESSAGE, REQUEST, IERROR)
            <type>    BUF(*)
            INTEGER   COUNT, DATATYPE, MESSAGE, REQUEST, IERROR


Fortran 2008 Syntax
       USE mpi_f08
       MPI_Imrecv(buf, count, datatype, message, request, ierror)
            TYPE(*), DIMENSION(..), ASYNCHRONOUS :: buf
            INTEGER, INTENT(IN) :: count
            TYPE(MPI_Datatype), INTENT(IN) :: datatype
            TYPE(MPI_Message), INTENT(INOUT) :: message
            TYPE(MPI_Request), INTENT(OUT) :: request
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror


C++ Syntax
       There is no C++ binding for this function.


INPUT PARAMETERS
       count     Number of elements to receive (nonnegative integer).

       datatype  Datatype of each send buffer element (handle).

       message   Message (handle).


OUTPUT PARAMETERS
       buf       Initial address of receive buffer (choice).

       request   Request (handle).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       The  functions  MPI_Mrecv and MPI_Imrecv receive messages that have been previously matched by a matching
       probe.

       The request returned from MPI_Imrecv can be used with any of the MPI_Test and MPI_Wait variants, like any
       non-blocking receive request.

       If  MPI_Imrecv  is called with MPI_MESSAGE_NULL as the message argument, a call to one of the MPI_Test or
       MPI_Wait variants will return immediately with the status object set to source  =  MPI_PROC_NULL,  tag  =
       MPI_ANY_TAG, and count = 0, as if a receive from MPI_PROC_NULL was issued.

       If  reception of a matched message is started with MPI_Imrecv, then it is possible to cancel the returned
       request with MPI_Cancel. If MPI_Cancel succeeds, the matched  message  must  be  found  by  a  subsequent
       message  probe  (MPI_Probe,  MPI_Iprobe,  MPI_Mprobe,  or  MPI_Improbe), received by a subsequent receive
       operation or canceled by the sender.

       Note, however, that is it possible for the cancellation of operations initiated with MPI_Imrecv to  fail.
       An  example  of  a  failing  case is when canceling the matched message receive would violate MPI message
       ordering rules (e.g., if another message matching the same message signature has matched -- and  possible
       received -- before this MPI_Imrecv is canceled).


NOTE
       This is an MPI-3 function and has no C++ binding.


ERRORS
       Almost  all  MPI  routines  return  an  error  value; C routines as the value of the function and Fortran
       routines in the last argument. C++ functions do not return errors.

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.


SEE ALSO
       MPI_Mprobe
       MPI_Improbe
       MPI_Probe
       MPI_Iprobe
       MPI_Imrecv
       MPI_Cancel