MPI::Request MPI::File::Iread(void* \fIbuf\fP, int \fIcount\fP,
const MPI::Datatype& \fIdatatype\fP)
.SHINPUT/OUTPUTPARAMETER
.ftR
.TP1i
fh
File handle (handle).
.SHINPUTPARAMETERS
.ftR
.TP1i
count
Number of elements in the buffer (integer).
.ftR
.TP1i
datatype
Data type of each buffer element (handle).
.SHOUTPUTPARAMETERS
.ftR
.TP1i
buf
Initial address of buffer (choice).
.ftR
.TP1i
request
Request object (handle).
.TP1i
IERROR
Fortran only: Error status (integer).
.SHDESCRIPTION
.ftR
MPI_File_iread is a nonblocking version of MPI_File_read. It attempts to read from the file associated with
.Ifh
at the current individual file pointer position maintained by the system in which a total number of
.Icount
data items having
.Idatatype
type are read into the user's buffer
.Ibuf.
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
.Istatus.
All other fields of
.Istatus
are undefined. It is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified when the file was opened.
.SHERRORS
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.
.sp
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.