-spec cached_unlinked_count() -> non_neg_integer() | unknown.

-spec handle_call(term(), gen_server:from(), map()) -> {reply, term(), map()}.

-spec handle_cast(term(), map()) -> {noreply, map()}.

-spec handle_info(term(), map()) -> {noreply, map()}.

-spec init([]) -> {ok, map()}.

-spec start_link() -> {ok, pid()} | {error, term()}.

-spec sweep_now() -> {ok, non_neg_integer()}.