giving a user permission to kill their processes only

Hey all,

So the pg_cancel_backend() function by default is only available to super users, so I decided
to write a wrapper function around, use a SECURITY DEFINER, and GRANT my user privilege to use
the wrapper.

BEGIN;
CREATE FUNCTION kill_process(integer) RETURNS boolean AS 'select pg_cancel_backend($1);'
LANGUAGE SQL SECURITY DEFINER;
REVOKE EXECUTE ON FUNCTION kill_process(integer) FROM PUBLIC;
COMMIT;
GRANT EXECUTE ON FUNCTION kill_process(integer) TO gnychis;

The problem with this is I can now kill other users postgresql processes.  I was wondering if
anyone knows a way in which i can check that the postgres process being killed is running a
query for that user?  Therefore, they can't kill queries in postgres processes started by other
users.

Thanks!
George