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MPI_File_iread(3OpenMPI)                                                            MPI_File_iread(3OpenMPI)



NAME
       MPI_File_iread - Reads a file starting at the location specified by the individual file pointer (non-blocking, (nonblocking,
       blocking, 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  associ-ated associated
       ated  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 num-ber number
       ber 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.




Open MPI 1.2                                   September 2006                       MPI_File_iread(3OpenMPI)