oracular (3) MPI_File_iread.openmpi.3.gz

NAME

       MPI_File_iread  -  Reads  a  file  starting  at  the  location  specified  by the individual file pointer
       (nonblocking, noncollective).

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_File_iread(MPI_File fh, void  *buf, int  count,
            MPI_Datatype  datatype, MPI_Request  *request)

Fortran Syntax

       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

Fortran 2008 Syntax

       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

C++ Syntax

       #include <mpi.h>
       MPI::Request MPI::File::Iread(void* buf, int count,
            const MPI::Datatype& datatype)

INPUT/OUTPUT PARAMETER

       fh        File handle (handle).

INPUT PARAMETERS

       count     Number of elements in the buffer (integer).

       datatype  Data type of each buffer element (handle).

OUTPUT PARAMETERS

       buf       Initial address of buffer (choice).

       request   Request object (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       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.

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++ 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.