fix(limiter): refresh dispatcher limiter when retainer config updated

apps/emqx/src/emqx_limiter/src/emqx_limiter_server.erl

@@ -112,6 +112,10 @@
 %% If no bucket path is set in config, there will be no limit
 connect(_Type, undefined) ->
     {ok, emqx_htb_limiter:make_infinity_limiter()};
+%% Workaround.
+%% After API updated some config, the bucket name maybe become ‘’ (converted from empty binary)
+connect(_Type, '') ->
+    {ok, emqx_htb_limiter:make_infinity_limiter()};
 connect(Type, BucketName) when is_atom(BucketName) ->
     case get_bucket_cfg(Type, BucketName) of
         undefined ->

apps/emqx_retainer/src/emqx_retainer.erl

@@ -201,6 +201,7 @@ init([]) ->
 
 handle_call({update_config, NewConf, OldConf}, _, State) ->
     State2 = update_config(State, NewConf, OldConf),
+    emqx_retainer_dispatcher:refresh_limiter(NewConf),
     {reply, ok, State2};
 handle_call(clean, _, #{context := Context} = State) ->
     clean(Context),

apps/emqx_retainer/src/emqx_retainer_dispatcher.erl

@@ -26,6 +26,7 @@
     start_link/2,
     dispatch/2,
     refresh_limiter/0,
+    refresh_limiter/1,
     wait_dispatch_complete/1,
     worker/0
 ]).
@@ -51,13 +52,16 @@
 dispatch(Context, Topic) ->
     cast({?FUNCTION_NAME, Context, self(), Topic}).
 
-%% sometimes it is necessary to reset the client's limiter after updated the limiter's config
-%% an limiter update handler maybe added later, now this is a workaround
+%% reset the client's limiter after updated the limiter's config
 refresh_limiter() ->
+    Conf = emqx:get_config([retainer]),
+    refresh_limiter(Conf).
+
+refresh_limiter(Conf) ->
     Workers = gproc_pool:active_workers(?POOL),
     lists:foreach(
         fun({_, Pid}) ->
-            gen_server:cast(Pid, ?FUNCTION_NAME)
+            gen_server:cast(Pid, {?FUNCTION_NAME, Conf})
         end,
         Workers
     ).
@@ -150,8 +154,8 @@ handle_call(Req, _From, State) ->
 handle_cast({dispatch, Context, Pid, Topic}, #{limiter := Limiter} = State) ->
     {ok, Limiter2} = dispatch(Context, Pid, Topic, undefined, Limiter),
     {noreply, State#{limiter := Limiter2}};
-handle_cast(refresh_limiter, State) ->
-    BucketName = emqx_conf:get([retainer, flow_control, batch_deliver_limiter]),
+handle_cast({refresh_limiter, Conf}, State) ->
+    BucketName = emqx_map_lib:deep_get([flow_control, batch_deliver_limiter], Conf, undefined),
     {ok, Limiter} = emqx_limiter_server:connect(batch, BucketName),
     {noreply, State#{limiter := Limiter}};
 handle_cast(Msg, State) ->