MPI_File_read_ordered(3)           Open MPI           MPI_File_read_ordered(3)



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


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 values 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.




1.4.1                            Jan 14, 2010         MPI_File_read_ordered(3)
