refactor(exclusive_sub): Export transaction

apps/emqx/src/emqx_exclusive_subscription.erl

@@ -35,6 +35,11 @@
     unsubscribe/2
 ]).
 
+%% Internal exports (RPC)
+-export([
+    try_subscribe/2
+]).
+
 -record(exclusive_subscription, {
     topic :: emqx_types:topic(),
     clientid :: emqx_types:clientid()
@@ -80,10 +85,7 @@ on_delete_module() ->
 -spec check_subscribe(emqx_types:clientinfo(), emqx_types:topic()) ->
     allow | deny.
 check_subscribe(#{clientid := ClientId}, Topic) ->
-    Fun = fun() ->
-        try_subscribe(ClientId, Topic)
-    end,
-    case mria:transaction(?EXCLUSIVE_SHARD, Fun) of
+    case mria:transaction(?EXCLUSIVE_SHARD, fun ?MODULE:try_subscribe/2, [ClientId, Topic]) of
         {atomic, Res} ->
             Res;
         {aborted, Reason} ->
@@ -94,7 +96,7 @@ check_subscribe(#{clientid := ClientId}, Topic) ->
     end.
 
 unsubscribe(Topic, #{is_exclusive := true}) ->
-    _ = mria:transaction(?EXCLUSIVE_SHARD, fun() -> mnesia:delete({?TAB, Topic}) end),
+    _ = mria:transaction(?EXCLUSIVE_SHARD, fun mnesia:delete/1, [{?TAB, Topic}]),
     ok;
 unsubscribe(_Topic, _SubOpts) ->
     ok.