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MPI_File_read_ordered(3OpenMPI)                                              MPI_File_read_ordered(3OpenMPI)



NAME
       MPI_File_read_ordered - Reads a file at a location specified by a shared file pointer (blocking, col-lective). collective).
       lective).


SYNTAX
       C Syntax
           #include <mpi.h>
           int MPI_File_read_ordered(MPI_File fh, void *buf,
                         int count, MPI_Datatype datatype,
                         MPI_Status *status)

       Fortran Syntax
           INCLUDE 'mpif.h'
           MPI_FILE_READ_ORDERED(FH, BUF, COUNT, DATATYPE,
                         STATUS, IERROR)
                  <type>     BUF(*)
                  INTEGER    FH, COUNT, DATATYPE, STATUS(MPI_STATUS_SIZE), IERROR


C++ Syntax
       #include <mpi.h>
       void MPI::File::Read_ordered(void* buf, int count,
            const MPI::Datatype& datatype, MPI::Status& status)

       void MPI::File::Read_ordered(void* buf, int count,
            const MPI::Datatype& datatype)


INPUT PARAMETERS
       fh        File handle (handle).

       count     Number of elements in buffer (integer).

       datatype  Data type of each buffer element (handle).


OUTPUT PARAMETERS
       buf       Initial address of buffer (choice).

       status    Status object (Status).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_File_read_ordered is a collective routine. This routine must be called by all  processes  in  the
       communicator group associated with the file handle fh.  Each process may pass different argument val-ues values
       ues for the datatype and count arguments. Each process attempts to read,  from  the  file  associated
       with  fh,  a  total  number of count data items having datatype type into the user's buffer buf.  For
       each process, the location in the file at which data is read is the position at which the shared file
       pointer  would be after all processes whose ranks within the group are less than that of this process
       had read their data. MPI_File_read_ordered returns the actual number of  datatype  elements  read  in
       status.   The shared file pointer is updated by the amounts of data requested by all processes of the
       group.


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. If the default error handler is
       set to MPI::ERRORS_THROW_EXCEPTIONS, 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. For MPI I/O function
       errors, the default error handler is set to MPI_ERRORS_RETURN. The error handler may be changed  with
       MPI_File_set_errhandler;  the  predefined  error handler MPI_ERRORS_ARE_FATAL may be used to make I/O
       errors fatal. Note that MPI does not guarantee that an MPI program can continue past an error.




Open MPI 1.2                                   September 2006                MPI_File_read_ordered(3OpenMPI)