Avoid a remote call in rabbit_quorum_queue:queue_topology

Author: mkuratczyk

deps/rabbit/src/rabbit_quorum_queue.erl

@@ -2228,10 +2228,24 @@ maybe_log_leader_health_check_result(Result) ->
 -spec queue_topology(amqqueue:amqqueue()) ->
     {Leader :: undefined | node(), Replicas :: [node(),...]}.
 queue_topology(Q) ->
-    [{leader, Leader0},
-     {members, Members}] = rabbit_queue_type:info(Q, [leader, members]),
-    Leader = case Leader0 of
-                 '' -> undefined;
-                 _ -> Leader0
-             end,
+    Leader = case find_leader(Q) of
+        undefined ->
+            undefined;
+        {Name, LeaderNode} ->
+            %% double-check the leader is alive if it's supposed to be local
+            %% this avoids a remote call, while ensuring we don't claim to be
+            %% a leader, if we don't have the leader process running
+            case LeaderNode =:= node() of
+                true ->
+                    case erlang:is_pid(Name) of
+                        true ->
+                            LeaderNode;
+                        false ->
+                            undefined
+                    end;
+                false ->
+                    LeaderNode
+            end
+    end,
+    Members = get_nodes(Q),
     {Leader, Members}.