Add emqx_trie:empty/0 and optimize match_routes/1

src/emqx_router.erl

@@ -101,9 +101,13 @@ do_add_route(Topic, Dest) when is_binary(Topic) ->
 %% @doc Match routes
 -spec(match_routes(emqx_topic:topic()) -> [emqx_types:route()]).
 match_routes(Topic) when is_binary(Topic) ->
+    case emqx_trie:empty() of
+        true -> lookup_routes(Topic);
+        false ->
             %% Optimize: routing table will be replicated to all router nodes.
             Matched = mnesia:ets(fun emqx_trie:match/1, [Topic]),
-    lists:append([lookup_routes(To) || To <- [Topic | Matched]]).
+            lists:append([lookup_routes(To) || To <- [Topic | Matched]])
+    end.
 
 -spec(lookup_routes(emqx_topic:topic()) -> [emqx_types:route()]).
 lookup_routes(Topic) ->

src/emqx_trie.erl

@@ -24,6 +24,7 @@
 
 %% Trie APIs
 -export([insert/1, match/1, lookup/1, delete/1]).
+-export([empty/0]).
 
 %% Mnesia tables
 -define(TRIE, emqx_trie).
@@ -100,6 +101,11 @@ delete(Topic) when is_binary(Topic) ->
         [] -> ok
     end.
 
+%% @doc Is the trie empty?
+-spec(empty() -> boolean()).
+empty() ->
+    ets:info(?TRIE, size) == 0.
+
 %%------------------------------------------------------------------------------
 %% Internal functions
 %%------------------------------------------------------------------------------