From 4eb6ab70caa95bef3d8ed67e4d8b76ed7072a781 Mon Sep 17 00:00:00 2001
From: David Ansari <david.ansari@gmx.de>
Date: Tue, 12 Dec 2023 16:24:33 +0100
Subject: [PATCH] Avoid expensive rabbit_nodes:list_running()

for non-mirrored queues
---
 deps/rabbit/src/rabbit_mirror_queue_misc.erl | 30 +++++++++++++-------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/deps/rabbit/src/rabbit_mirror_queue_misc.erl b/deps/rabbit/src/rabbit_mirror_queue_misc.erl
index b5b0f1436149..3813daf0c8a1 100644
--- a/deps/rabbit/src/rabbit_mirror_queue_misc.erl
+++ b/deps/rabbit/src/rabbit_mirror_queue_misc.erl
@@ -609,19 +609,22 @@ promote_slave([SPid | SPids]) ->
 -spec initial_queue_node(amqqueue:amqqueue(), node()) -> node().
 
 initial_queue_node(Q, DefNode) ->
-    {MNode, _SNodes} = suggested_queue_nodes(Q, DefNode, rabbit_nodes:list_running()),
+    {MNode, _SNodes} = suggested_queue_nodes(Q, DefNode, fun rabbit_nodes:list_running/0),
     MNode.
 
 -spec suggested_queue_nodes(amqqueue:amqqueue()) ->
           {node(), [node()]}.
 
-suggested_queue_nodes(Q)      -> suggested_queue_nodes(Q, rabbit_nodes:list_running()).
+suggested_queue_nodes(Q)      -> suggested_queue_nodes(Q, fun rabbit_nodes:list_running/0).
 suggested_queue_nodes(Q, All) -> suggested_queue_nodes(Q, node(), All).
 
 %% The third argument exists so we can pull a call to
 %% rabbit_nodes:list_running() out of a loop or transaction
 %% or both.
-suggested_queue_nodes(Q, DefNode, All) when ?is_amqqueue(Q) ->
+-spec suggested_queue_nodes(amqqueue:amqqueue(), node(), Nodes | fun(() -> Nodes)) ->
+    {node(), Nodes} when
+      Nodes :: [node()].
+suggested_queue_nodes(Q, DefNode, AllNodes) when ?is_amqqueue(Q) ->
     Owner = amqqueue:get_exclusive_owner(Q),
     {MNode0, SNodes, SSNodes} = actual_queue_nodes(Q),
     MNode = case MNode0 of
@@ -629,13 +632,20 @@ suggested_queue_nodes(Q, DefNode, All) when ?is_amqqueue(Q) ->
                 _    -> MNode0
             end,
     case Owner of
-        none -> Params = policy(<<"ha-params">>, Q),
-                case module(Q) of
-                    {ok, M} -> M:suggested_queue_nodes(
-                                 Params, MNode, SNodes, SSNodes, All);
-                    _       -> {MNode, []}
-                end;
-        _    -> {MNode, []}
+        none ->
+            case module(Q) of
+                {ok, M} ->
+                    Params = policy(<<"ha-params">>, Q),
+                    All = if is_list(AllNodes) -> AllNodes;
+                             is_function(AllNodes) -> AllNodes()
+                          end,
+                    M:suggested_queue_nodes(
+                      Params, MNode, SNodes, SSNodes, All);
+                _ ->
+                    {MNode, []}
+            end;
+        _ ->
+            {MNode, []}
     end.
 
 policy(Policy, Q) ->