Shut down the object and notify any onfini() coroutines.

        Returns:
            Remaining ref count

async def fini(self):
        '''
        Shut down the object and notify any onfini() coroutines.

        Returns:
            Remaining ref count
        '''
        assert self.anitted, f'{self.__class__.__name__} initialized improperly.  Must use Base.anit class method.'

        if self.isfini:
            return

        if __debug__:
            import synapse.lib.threads as s_threads  # avoid import cycle
            assert s_threads.iden() == self.tid

        self._syn_refs -= 1
        if self._syn_refs > 0:
            return self._syn_refs

        self.isfini = True

        fevt = self.finievt

        if fevt is not None:
            fevt.set()

        for base in list(self.tofini):
            await base.fini()

        try:
            await self._kill_active_tasks()
        except:
            logger.exception(f'{self} - Exception during _kill_active_tasks')

        for fini in self._fini_funcs:
            try:
                await s_coro.ornot(fini)
            except asyncio.CancelledError:
                raise
            except Exception:
                logger.exception(f'{self} - fini function failed: {fini}')

        self._syn_funcs.clear()
        self._fini_funcs.clear()
        return 0