17.2.247. MPI_Isendrecv_replace

MPI_Isendrecv_replace - Sends and receives a message using a single buffer.

17.2.247.1. SYNTAX

17.2.247.1.1. C Syntax

#include <mpi.h>

int MPI_Isendrecv_replace(void *buf, int count, MPI_Datatype datatype,
    int dest, int sendtag, int source, int recvtag, MPI_Comm comm,
    MPI_Request *request)

17.2.247.1.2. Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_ISENDRECV_REPLACE(BUF, COUNT, DATATYPE, DEST, SENDTAG, SOURCE,
        RECVTAG, COMM, REQUEST, IERROR)
    <type>    BUF(*)
    INTEGER    COUNT, DATATYPE, DEST, SENDTAG
    INTEGER    SOURCE, RECVTAG, COMM
    INTEGER    REQUEST, IERROR

17.2.247.1.3. Fortran 2008 Syntax

USE mpi_f08
MPI_Isendrecv_replace(buf, count, datatype, dest, sendtag, source, recvtag,
        comm, request, ierror)
    TYPE(*), DIMENSION(..) :: buf
    INTEGER, INTENT(IN) :: count, dest, sendtag, source, recvtag
    TYPE(MPI_Datatype), INTENT(IN) :: datatype
    TYPE(MPI_Comm), INTENT(IN) :: comm
    TYPE(MPI_Request) :: request
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

17.2.247.2. INPUT/OUTPUT PARAMETER

  • buf: Initial address of send and receive buffer (choice).

17.2.247.3. INPUT PARAMETERS

  • count: Number of elements in send and receive buffer (integer).

  • datatype: Type of elements to send and receive (handle).

  • dest: Rank of destination (integer).

  • sendtag: Send message tag (integer).

  • source: Rank of source (integer).

  • recvtag: Receive message tag (integer).

  • comm: Communicator (handle).

17.2.247.4. OUTPUT PARAMETERS

  • request: Communication request (handle).

  • IERROR: Fortran only: Error status (integer).

17.2.247.5. DESCRIPTION

The non-blocking send-receive operations combine in one call the sending of a message to one destination and the receiving of another message, from another process. The two (source and destination) are possibly the same. A send-receive operation is useful for executing a shift operation across a chain of processes. The send-receive operation can be used in conjunction with the functions described in the “Process Topologies” chapter of the MPI Standard in order to perform shifts on various logical topologies. Also, a send-receive operation is useful for implementing remote procedure calls.

A message sent by a send-receive operation can be received by a regular receive operation or probed by a probe operation; a send-receive operation can receive a message sent by a regular send operation.

MPI_Isendrecv_replace executes a non-blocking send and receive. The same buffer is used both for the send and for the receive, so that the message sent is replaced by the message received.

A non-blocking send-receive request can be determined to be completed by calling the MPI_Wait, MPI_Waitany, MPI_Test, or MPI_Testany with the request returned by this function.

17.2.247.6. ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

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.