Hibernate process if not activated

Author: SimonUnge

deps/rabbit/priv/schema/rabbit.schema

@@ -2492,6 +2492,10 @@ end}.
 %% Queue membership evaluation
 %%
 
+{mapping, "queue_membership_evaluation.enabled", "rabbit.member_eval_enabled", [
+    {datatype, {enum, [true, false]}}]}.
+
+
 {mapping, "queue_membership_evaluation.default_timeout", "rabbit.member_eval_default_timeout", [
     {datatype, integer}, {validators, ["non_negative_integer"]}
 ]}.

deps/rabbit/src/rabbit_queue_member_eval.erl

@@ -26,7 +26,7 @@
 
 -define(EVAL_MSG, member_eval).
 
--record(state, {timer_ref :: reference(),
+-record(state, {timer_ref :: reference() | undefined,
                 default_interval :: non_neg_integer(),
                 short_interval :: non_neg_integer(),
                 target_group_size :: non_neg_integer() | undefined}).
@@ -59,15 +59,24 @@ init([]) ->
                                         ?SHORT_INTERVAL),
     TargetGroupSize = rabbit_misc:get_env(rabbit, member_eval_target_group_size,
                                           undefined),
-    Ref = erlang:send_after(DefaultInterval, self(), ?EVAL_MSG),
-    {ok, #state{timer_ref = Ref,
-                default_interval = DefaultInterval,
-                short_interval = ShortInterval,
-                target_group_size = TargetGroupSize}}.
+    Enabled = rabbit_misc:get_env(rabbit, member_eval_enabled,
+                                  false),
+    State = #state{default_interval = DefaultInterval,
+                   short_interval = ShortInterval,
+                   target_group_size = TargetGroupSize},
+    case Enabled of
+        true ->
+            Ref = erlang:send_after(DefaultInterval, self(), ?EVAL_MSG),
+            {ok, State#state{timer_ref = Ref}};
+        false ->
+            {ok, State, hibernate}
+    end.
 
 handle_call(_Request, _From, State) ->
     {reply, ok, State}.
 
+handle_cast(nodechange, #state{timer_ref = undefined} = State) ->
+    {noreply, State, hibernate};
 handle_cast(nodechange, #state{timer_ref = OldRef,
                                short_interval = Time} = State) ->
     _ = erlang:cancel_timer(OldRef),