MPI_File_iread_at(3) Open MPI MPI_File_iread_at(3)NAMEMPI_File_iread_at - Reads a file at an explicitly specified offset
(nonblocking, noncollective).
SYNTAX
C Syntax
#include <mpi.h>
int MPI_File_iread_at(MPI_File fh, MPI_Offset offset,
void *buf, int count, MPI_Datatype datatype,
MPI_Request *request)
Fortran Syntax (see FORTRAN 77 NOTES)
INCLUDE 'mpif.h'
MPI_FILE_IREAD_AT(FH, OFFSET, BUF, COUNT, DATATYPE, REQUEST, IERROR)
<type> BUF(*)
INTEGER FH, COUNT, DATATYPE, REQUEST, IERROR
INTEGER(KIND=MPI_OFFSET_KIND) OFFSET
C++ Syntax
#include <mpi.h>
MPI::Request MPI::File::Iread_at(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 the buffer (integer).
datatype Data type of each buffer element (handle).
OUTPUT PARAMETERS
buf Initial address of the buffer (choice).
request Request object (handle).
IERROR Fortran only: Error status (integer).
DESCRIPTIONMPI_File_iread_at is the nonblocking version of MPI_File_read_at.
MPI_File_iread_at is a nonblocking 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_iread_at
stores the number of datatype elements actually read in status. All
other fields of status are undefined.
FORTRAN 77 NOTES
The MPI standard prescribes portable Fortran syntax for the OFFSET
argument only for Fortran 90. Sun 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++ 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_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.
1.7.4 Feb 04, 2014 MPI_File_iread_at(3)
