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MPI_File_iread_at - Reads a file at an explicitly specified offset
(nonblocking, noncollective).
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)
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
#include <mpi.h>
MPI::Request MPI::File::Iread_at(MPI::Offset offset, void* buf,
int count, const MPI::Datatype& datatype)
- fh
- File handle (handle).
- offset
- File offset (integer).
- count
- Number of elements in the buffer (integer).
- datatype
- Data type of each buffer
element (handle).
- buf
- Initial address of the buffer (choice).
- request
- Request object (handle).
- IERROR
- Fortran only: Error status (integer).
MPI_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.
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.
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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