MPIRecv(3OpenMPI) MPIRecv(3OpenMPI)

NAME
       MMPPIIRReeccvv - Performs a standard-mode blocking receive.


SSYYNNTTAAXX
CC SSyynnttaaxx
       #include 
       int MPIRecv(void *buf, int count, MPIDatatype datatype,
            int source, int tag, MPIComm comm, MPIStatus *status)


FFoorrttrraann SSyynnttaaxx
       INCLUDE 'mpif.h'
       MPIRECV(BUF, COUNT, DATATYPE, SOURCE, TAG, COMM, STATUS, IERROR)
                BUF(*)
            INTEGER   COUNT, DATATYPE, SOURCE, TAG, COMM
            INTEGER   STATUS(MPISTATUSSIZE), IERROR


CC++++ SSyynnttaaxx
       #include 
       void Comm::Recv(void* buf, int count, const Datatype& datatype,
            int source, int tag, Status& status) const

       void Comm::Recv(void* buf, int count, const Datatype& datatype,
            int source, int tag) const


IINNPPUUTT PPAARRAAMMEETTEERRSS
       count     Maximum number of elements to receive (integer).

       datatype  Datatype of each receive buffer entry (handle).

       source    Rank of source (integer).

       tag       Message tag (integer).

       comm      Communicator (handle).


OOUUTTPPUUTT PPAARRAAMMEETTEERRSS
       buf       Initial address of receive buffer (choice).

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       This  basic  receive  operation, MPIRecv, is blocking: it returns only
       after the receive buffer contains the newly received message. A receive
       can  complete before the matching send has completed (of course, it can
       complete only after the matching send has started).

       The blocking semantics of this call are described in Section 3.4 of the
       MPI-1 Standard, "Communication Modes."

       The receive buffer contains a number (defined by the value of count) of
       consecutive elements. The first element  in  the  set  of  elements  is
       located at addressbuf. The type of each of these elements is specified
       by datatype.

       The length of the received message must be less than or  equal  to  the
       length of the receive buffer. An  MPIERRTRUNCATE is returned upon the
       overflow condition.

       If a message that is shorter than the  length  of  the  receive  buffer
       arrives,  then  only  those  locations  corresponding  to the (shorter)
       received message are modified.


NNOOTTEESS
       The count argument indicates the maximum  number  of  entries  of  type
       datatype that can be received in a message. Once a message is received,
       use the MPIGetcount  function  to  determine  the  actual  number  of
       entries within that message.

       To receive messages of unknown length, use the MPIProbe function. (For
       more information about MPIProbe and MPICancel, see  their  respective
       man pages; also, see Section 3.8 of the MPI-1 Standard, "Probe and Can-
       cel.")

       A message can be  received  by  a  receive  operation  only  if  it  is
       addressed  to the receiving process, and if its source, tag, and commu-
       nicator (comm) values match the source, tag, and comm values  specified
       by  the receive operation. The receive operation may specify a wildcard
       value for source and/or tag, indicating that any source and/or tag  are
       acceptable.  The  wildcard value for source is source = MPIANYSOURCE.
       The wildcard value for tag is tag = MPIANYTAG. There is  no  wildcard
       value for comm. The scope of these wildcards is limited to the proceses
       in the group of the specified communicator.

       The message tag is specified by the tag argument of the receive  opera-
       tion.

       The  argument source, if different from MPIANYSOURCE, is specified as
       a rank within the process group associated with that same  communicator
       (remote  process  group,  for  intercommunicators).  Thus, the range of
       valid values for the source argument is  {0,...,n-1}  {MPIANYSOURCE},
       where n is the number of processes in this group.

       Note the asymmetry between send and receive operations: A receive oper-
       ation may accept messages from an arbitrary sender; on the other  hand,
       a  send operation must specify a unique receiver. This matches a "push"
       communication mechanism, where data transfer is effected by the  sender
       (rather than a "pull" mechanism, where data transfer is effected by the
       receiver).

       Source = destination is allowed, that is, a process can send a  message
       to  itself.  However,  it is not recommended for a process to send mes-
       sages  to  itself  using  the  blocking  send  and  receive  operations
       described  above,  since  this may lead to deadlock. See Section 3.5 of
       the MPI-1 Standard, "Semantics of Point-to-Point Communication."

       If your application does not need to examine the status field, you  can
       save  resources by using the predefined constant MPISTATUSIGNORE as a
       special value for the status argument.


EERRRROORRSS
       Almost all MPI routines return an error value; C routines as the  value
       of  the  function  and Fortran routines in the last argument. C++ func-
       tions do not return errors. If the default  error  handler  is  set  to
       MPI::ERRORSTHROWEXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       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
       MPICommseterrhandler; the predefined error handler MPIERRORSRETURN
       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
       MPIIrecv
       MPIProbe






Open MPI 1.2                      March 2007                MPIRecv(3OpenMPI)