Cause some traffic on master hibernation, and explain why.

2 files changed, 13 insertions, 1 deletions

diff --git a/src/rabbit_mirror_queue_coordinator.erl b/src/rabbit_mirror_queue_coordinator.erl
index 3d4605280f..d328488298 100644
--- a/src/rabbit_mirror_queue_coordinator.erl
+++ b/src/rabbit_mirror_queue_coordinator.erl
@@ -19,7 +19,7 @@
 -export([start_link/4, get_gm/1, ensure_monitoring/2]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
-         code_change/3]).
+         code_change/3, handle_pre_hibernate/1]).
 
 -export([joined/2, members_changed/3, handle_msg/3, handle_terminate/2]).
 
@@ -389,6 +389,15 @@ terminate(_Reason, #state{}) ->
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
+handle_pre_hibernate(State = #state { gm = GM }) ->
+    %% Since GM notifications of deaths are lazy we might not get a
+    %% timely notification of slave death if policy changes when
+    %% everything is idle. So cause some activity just before we
+    %% sleep. This won't cause us to go into perpetual motion as the
+    %% heartbeat does not wake up coordinator or slaves.
+    gm:broadcast(GM, hibernate_heartbeat),
+    {hibernate, State}.
+
 %% ---------------------------------------------------------------------------
 %% GM
 %% ---------------------------------------------------------------------------
diff --git a/src/rabbit_mirror_queue_slave.erl b/src/rabbit_mirror_queue_slave.erl
index 92e1cc2736..c64e35599c 100644
--- a/src/rabbit_mirror_queue_slave.erl
+++ b/src/rabbit_mirror_queue_slave.erl
@@ -421,6 +421,9 @@ members_changed([ SPid], _Births, Deaths) ->
         {promote, CPid} -> {become, rabbit_mirror_queue_coordinator, [CPid]}
     end.
 
+handle_msg([_SPid], _From, hibernate_heartbeat) ->
+    %% See rabbit_mirror_queue_coordinator:handle_pre_hibernate/1
+    ok;
 handle_msg([_SPid], _From, request_depth) ->
     %% This is only of value to the master
     ok;