bionic (3) MPI_File_read_at_all.openmpi.3.gz

NAME

       MPI_File_read_at_all - Reads a file at explicitly specified offsets (blocking, collective).

SYNTAX

C Syntax

       #include  <mpi.h>  int  MPI_File_read_at_all(MPI_File  fh,  MPI_Offset offset,      void *buf, int count,
       MPI_Datatype datatype,      MPI_Status *status)

Fortran Syntax (see FORTRAN 77 NOTES)

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_FILE_READ_AT_ALL(FH, OFFSET, BUF, COUNT,
            DATATYPE, STATUS, IERROR)
            <type>    BUF(*)
            INTEGER   FH, COUNT, DATATYPE, STATUS(MPI_STATUS_SIZE), IERROR
            INTEGER(KIND=MPI_OFFSET_KIND) OFFSET

C++ Syntax

       #include <mpi.h>
       void MPI::File::Read_at_all(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype, MPI::Status& status)

       void MPI::File::Read_at_all(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype)

INPUT PARAMETERS

       fh        File handle (handle).

       offset    File offset (integer).

       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_at_all is a collective routine that attempts to read from the file associated with  fh  (at
       the  offset position) a total number of count data items having datatype type into the user's buffer buf.
       The offset is in etype units relative to the current view. That is, holes are not counted  when  locating
       an  offset.  The  data  is  taken  out  of  those  parts  of  the  file  specified  by  the current view.
       MPI_File_read_at_all stores the number of datatype elements actually read in status.  All other fields of
       status  are  undefined.  It  is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified
       when the file was opened.

FORTRAN 77 NOTES

       The MPI standard prescribes portable Fortran syntax for the OFFSET argument only for Fortran 90.  FORTRAN
       77 users may use the non-portable syntax

            INTEGER*MPI_OFFSET_KIND OFFSET

       where  MPI_OFFSET_KIND  is  a  constant defined in mpif.h and gives the length of the declared integer in
       bytes.

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.