From 4230a3c535a5b2fb13d11507699f25de7f306cc5 Mon Sep 17 00:00:00 2001
From: Feng Lee <feng@emqx.io>
Date: Fri, 4 Jan 2019 17:49:55 +0800
Subject: [PATCH] Optimize the trie match

---
 src/emqx_router.erl | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/emqx_router.erl b/src/emqx_router.erl
index 793735d55..f01db0d52 100644
--- a/src/emqx_router.erl
+++ b/src/emqx_router.erl
@@ -101,14 +101,20 @@ 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]),
+    case match_trie(Topic) of
+        [] -> lookup_routes(Topic);
+        Matched ->
             lists:append([lookup_routes(To) || To <- [Topic | Matched]])
     end.
 
+%% @private
+%% Optimize: routing table will be replicated to all router nodes.
+match_trie(Topic) ->
+    case emqx_trie:empty() of
+        true -> [];
+        false -> mnesia:ets(fun emqx_trie:match/1, [Topic])
+    end.
+
 -spec(lookup_routes(emqx_topic:topic()) -> [emqx_types:route()]).
 lookup_routes(Topic) ->
     ets:lookup(?ROUTE, Topic).