From 6fc50d11f8025b210b6959961aabe06da38792cc Mon Sep 17 00:00:00 2001
From: JianBo He <heeejianbo@gmail.com>
Date: Tue, 6 Jun 2023 19:34:23 +0800
Subject: [PATCH] fix(mqttsn): clean pre-defined topics once gateway reloaded

---
 .../emqx_gateway_mqttsn/src/emqx_gateway_mqttsn.erl |  1 +
 .../src/emqx_mqttsn_registry.erl                    | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/apps/emqx_gateway_mqttsn/src/emqx_gateway_mqttsn.erl b/apps/emqx_gateway_mqttsn/src/emqx_gateway_mqttsn.erl
index 167ee465c..1e32c5b85 100644
--- a/apps/emqx_gateway_mqttsn/src/emqx_gateway_mqttsn.erl
+++ b/apps/emqx_gateway_mqttsn/src/emqx_gateway_mqttsn.erl
@@ -125,5 +125,6 @@ on_gateway_unload(
     },
     _GwState
 ) ->
+    emqx_mqttsn_registry:clean_predefined_topics(GwName, maps:get(predefined, Config, [])),
     Listeners = normalize_config(Config),
     stop_listeners(GwName, Listeners).
diff --git a/apps/emqx_gateway_mqttsn/src/emqx_mqttsn_registry.erl b/apps/emqx_gateway_mqttsn/src/emqx_mqttsn_registry.erl
index 9db355a9b..e0e138531 100644
--- a/apps/emqx_gateway_mqttsn/src/emqx_mqttsn_registry.erl
+++ b/apps/emqx_gateway_mqttsn/src/emqx_mqttsn_registry.erl
@@ -26,7 +26,8 @@
 
 -export([
     register_topic/3,
-    unregister_topic/2
+    unregister_topic/2,
+    clean_predefined_topics/2
 ]).
 
 -export([
@@ -118,6 +119,16 @@ lookup_element(Tab, Key, Pos) ->
 unregister_topic({_, Pid}, ClientId) ->
     gen_server:call(Pid, {unregister, ClientId}).
 
+-spec clean_predefined_topics(atom(), list()) -> ok.
+clean_predefined_topics(InstaId, PredefTopics) when is_list(PredefTopics) ->
+    Tab = name(InstaId),
+    F = fun(#{id := TopicId, topic := TopicName0}) ->
+        TopicName = iolist_to_binary(TopicName0),
+        mria:dirty_delete(Tab, {predef, TopicId}),
+        mria:dirty_delete(Tab, {predef, TopicName})
+    end,
+    lists:foreach(F, PredefTopics).
+
 lookup_name(Pid) ->
     gen_server:call(Pid, name).