MPI_File_read_at_all_begin(3) Open MPI MPI_File_read_at_all_begin(3)
NAME
MPI_File_read_at_all_begin - Reads a file at explicitly specified off-
sets; beginning part of a split collective routine (nonblocking).
SYNTAX
C Syntax
#include <mpi.h>
int MPI_File_read_at_all_begin(MPI_File fh, MPI_Offset
offset, void *buf, int count, MPI_Datatype
datatype)
Fortran Syntax (see FORTRAN 77 NOTES)
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_READ_AT_ALL_BEGIN(FH, OFFSET, BUF,
COUNT, DATATYPE, IERROR)
<type> BUF(*)
INTEGER FH, COUNT, DATATYPE, IERROR
INTEGER(KIND=MPI_OFFSET_KIND) OFFSET
Fortran 2008 Syntax
USE mpi_f08
MPI_File_read_at_all_begin(fh, offset, buf, count, datatype, ierror)
TYPE(MPI_File), INTENT(IN) :: fh
INTEGER(KIND=MPI_OFFSET_KIND), INTENT(IN) :: offset
TYPE(*), DIMENSION(..), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count
TYPE(MPI_Datatype), INTENT(IN) :: datatype
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
C++ Syntax
#include <mpi.h>
void MPI::File::Read_at_all_begin(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.
OUTPUT PARAMETERS
buf Initial address of buffer (choice).
IERROR Fortran only: Error status (integer).
DESCRIPTION
MPI_File_read_at_all_begin is the beginning part of a split 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.
FORTRAN 77 NOTES
The MPI standard prescribes portable Fortran syntax for the OFFSET ar-
gument 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.
NOTES
All the nonblocking collective routines for data access are "split"
into two routines, each with _begin or _end as a suffix. These split
collective routines are subject to the semantic rules described in Sec-
tion 9.4.5 of the MPI-2 standard.
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++ func-
tions 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_ER-
RORS_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.
4.1.2 Nov 24, 2021 MPI_File_read_at_all_begin(3)
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