MPI_Comm_get_attr(3)               Open MPI               MPI_Comm_get_attr(3)



NAME
       MPI_Comm_get_attr - Retrieves attribute value by key.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval,
            void *attribute_val, int *flag)


Fortran Syntax (see FORTRAN 77 NOTES)
       INCLUDE 'mpif.h'
       MPI_COMM_GET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, IERROR)
            INTEGER   COMM, COMM_KEYVAL, IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
            LOGICAL FLAG


C++ Syntax
       #include <mpi.h>
       bool MPI::Comm::Get_attr(int comm_keyval, void* attribute_val)
            const


INPUT PARAMETERS
       comm      Communicator to which the attribute is attached (handle).

       comm_keyval
                 Key value (integer).


OUTPUT PARAMETER
       attribute_val
                 Attribute value, unless flag = false.

       flag      False if no attribute is associated with the key (logical).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_Comm_get_attr retrieves an attribute value by key. The call is
       erroneous if there is no key with value keyval. On the other hand, the
       call is correct if the key value exists, but no attribute is attached
       on comm for that key; in that case, the call returns flag = false. In
       particular, MPI_KEYVAL_INVALID is an erroneous key value.

       This function replaces MPI_Attr_get, the use of which is deprecated.
       The C binding is identical. The Fortran binding differs in that
       attribute_val is an address-sized integer.


FORTRAN 77 NOTES
       The MPI standard prescribes portable Fortran syntax for the
       ATTRIBUTE_VAL argument only for Fortran 90. Sun FORTRAN 77 users may
       use the non-portable syntax

            INTEGER*MPI_ADDRESS_KIND ATTRIBUTE_VAL

       where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the
       length of the declared integer in bytes.


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. By default, this error handler aborts the MPI job, except for
       I/O function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
       may be used to cause error values to be returned. Note that MPI does
       not guarantee that an MPI program can continue past an error.




1.4.1                            Jan 14, 2010             MPI_Comm_get_attr(3)
