MPI_File_read_ordered(3) 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.

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