Use ets table size instead of count the elements

Author: SimonUnge

deps/rabbit/src/rabbit_channel_tracking.erl

@@ -25,6 +25,7 @@
          shutdown_tracked_items/2]).
 
 -export([list/0, list_of_user/1, list_on_node/1,
+         channel_count_on_node/1,
          tracked_channel_table_name_for/1,
          tracked_channel_per_user_table_name_for/1,
          ensure_tracked_tables_for_this_node/0,
@@ -185,8 +186,18 @@ list_on_node(Node) ->
             []
     end.
 
--spec tracked_channel_table_name_for(node()) -> atom().
+channel_count_on_node(Node) when Node == node() ->
+    ets:info(?TRACKED_CHANNEL_TABLE, size);
+channel_count_on_node(Node) ->
+    case rabbit_misc:rpc_call(Node, ?MODULE, ?FUNCTION_NAME, [Node]) of
+        Int when is_integer(Int) ->
+            Int;
+        _ ->
+            0
+    end.
 
+
+-spec tracked_channel_table_name_for(node()) -> atom().
 tracked_channel_table_name_for(Node) ->
     list_to_atom(rabbit_misc:format("tracked_channel_on_node_~ts", [Node])).
 
@@ -220,8 +231,8 @@ get_tracked_channels_by_connection_pid(ConnPid) ->
 
 get_tracked_channel_by_id(ChId) ->
     rabbit_tracking:match_tracked_items(
-        ?TRACKED_CHANNEL_TABLE,
-        #tracked_channel{id = ChId, _ = '_'}).
+      ?TRACKED_CHANNEL_TABLE,
+      #tracked_channel{id = ChId, _ = '_'}).
 
 delete_tracked_channel_user_entry(Username) ->
     rabbit_tracking:delete_tracked_entry(

deps/rabbit/src/rabbit_reader.erl

@@ -947,7 +947,7 @@ is_over_node_channel_limit() ->
             false;
         NodeLimit ->
             %% Only fetch this if a limit is set
-            CurrNodeChannels = length(rabbit_channel_tracking:list_on_node(node())),
+            CurrNodeChannels = rabbit_channel_tracking:channel_count_on_node(node()),
             case CurrNodeChannels < NodeLimit of
                 true ->
                     false;

deps/rabbit/test/per_node_limit_SUITE.erl

@@ -168,7 +168,7 @@ open_channel(Conn) when is_pid(Conn) ->
 
 count_channels_per_node(Config)  ->
     NodeConfig = rabbit_ct_broker_helpers:get_node_config(Config, 0),
-    length(rabbit_ct_broker_helpers:rpc(Config, 0,
-                                        rabbit_channel_tracking,
-                                        list_on_node,
-                                        [?config(nodename, NodeConfig)])).
+    rabbit_ct_broker_helpers:rpc(Config, 0,
+                                 rabbit_channel_tracking,
+                                 channel_count_on_node,
+                                 [?config(nodename, NodeConfig)]).