MPI_File_iread(3)                  Open MPI                  MPI_File_iread(3)



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
           INCLUDE 'mpif.h'
           MPI_FILE_IREAD(FH, BUF, COUNT, DATATYPE, REQUEST, IERROR)
                 <type>         BUF(*)
                 INTEGER        FH, COUNT, DATATYPE, REQUEST, 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.




1.4.1                            Jan 14, 2010                MPI_File_iread(3)
