refactor

The sets thing is probably slower, but it isn't run that often.

Author: Alexandru Scvortov

src/rabbit_mnesia.erl

@@ -772,8 +772,9 @@ on_node_down(Node) ->
     end.
 
 is_only_disc_node(Node, _MnesiaRunning = true) ->
-    OfflineDiscNodes = nodes_of_type(disc_copies) -- running_clustered_nodes(),
-    [Node] =:= nodes_of_type(disc_copies) -- OfflineDiscNodes;
+    RunningSet = sets:from_list(running_clustered_nodes()),
+    DiscSet = sets:from_list(nodes_of_type(disc_copies)),
+    [Node] =:= sets:to_list(sets:intersection(RunningSet, DiscSet));
 is_only_disc_node(Node, false) ->
     start_mnesia(),
     Res = is_only_disc_node(Node, true),

src/rabbit_node_monitor.erl

@@ -67,6 +67,7 @@ handle_call(_Request, _From, State) ->
 
 handle_cast({rabbit_running_on, Node}, State) ->
     rabbit_log:info("rabbit on ~p up~n", [Node]),
+    erlang:monitor(process, {rabbit, Node}),
     ok = handle_live_rabbit(Node),
     {noreply, State};
 handle_cast(_Msg, State) ->
@@ -97,6 +98,5 @@ handle_dead_rabbit(Node) ->
     ok = rabbit_mnesia:on_node_down(Node).
 
 handle_live_rabbit(Node) ->
-    erlang:monitor(process, {rabbit, Node}),
     ok = rabbit_alarm:on_node_up(Node),
     ok = rabbit_mnesia:on_node_up(Node).