Ignore exceptions on the msg store while terminating a client on

queue shutdown.

When the msg store has crashed and the supervisor is trying to stop
all its sibilings, the variable queue termination might crash as the store
is not available. This would prevent the supervisor to restart the vhost,
as it stops at the second crash.

Author: dcorbacho

src/rabbit_variable_queue.erl

@@ -579,7 +579,7 @@ terminate(_Reason, State) ->
         purge_pending_ack(true, State),
     PRef = case MSCStateP of
                undefined -> undefined;
-               _         -> ok = rabbit_msg_store:client_terminate(MSCStateP),
+               _         -> ok = maybe_client_terminate(MSCStateP),
                             rabbit_msg_store:client_ref(MSCStateP)
            end,
     ok = rabbit_msg_store:client_delete_and_terminate(MSCStateT),
@@ -2943,3 +2943,14 @@ log_upgrade_verbose(Msg) ->
 
 log_upgrade_verbose(Msg, Args) ->
     rabbit_log_upgrade:info(Msg, Args).
+
+maybe_client_terminate(MSCStateP) ->
+    %% Queue might have been asked to stop by the supervisor, it needs a clean
+    %% shutdown in order for the supervising strategy to work - if it reaches max
+    %% restarts might bring the vhost down.
+    try
+        rabbit_msg_store:client_terminate(MSCStateP)
+    catch
+        _:_ ->
+            ok
+    end.