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MPI_File_iread - Reads a file starting at the location specified
by the individual file pointer (nonblocking, noncollective).
C Syntax
#include <mpi.h>
int MPI_File_iread(MPI_File fh, void *buf, int count,
MPI_Datatype datatype, MPI_Request *request)
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_FILE_IREAD(FH, BUF, COUNT, DATATYPE, REQUEST, IERROR)
<type> BUF(*)
INTEGER FH, COUNT, DATATYPE, REQUEST, IERROR
USE mpi_f08
MPI_File_iread(fh, buf, count, datatype, request, ierror)
TYPE(MPI_File), INTENT(IN) :: fh
TYPE(*), DIMENSION(..), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
- fh
- File handle (handle).
- count
- Number
of elements in the buffer (integer).
- datatype
- Data type of each buffer element
(handle).
- buf
- Initial address of buffer (choice).
- request
- Request object (handle).
- IERROR
- Fortran only: Error status (integer).
MPI_File_iread
is a nonblocking version of MPI_File_read. It attempts to read from the
file associated with fh at the current individual file pointer position
maintained by the system in which a total number of count data items having
datatype type are read into the user’s buffer buf. The data is taken out
of those parts of the file specified by the current view. MPI_File_iread
stores the number of data-type 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.
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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