Support per-vhost stop/start API for backing queue behaviour.

src/rabbit_amqqueue.erl

@@ -16,7 +16,8 @@
 
 -module(rabbit_amqqueue).
 
--export([recover/0, stop/0, start/1, declare/6, declare/7,
+-export([warn_file_limit/0]).
+-export([recover/1, stop/1, start/1, declare/6, declare/7,
          delete_immediately/1, delete_exclusive/2, delete/4, purge/1,
          forget_all_durable/1, delete_crashed/1, delete_crashed/2,
          delete_crashed_internal/2]).
@@ -70,8 +71,8 @@
                            {'absent', rabbit_types:amqqueue(),absent_reason()}.
 -type not_found_or_absent() ::
         'not_found' | {'absent', rabbit_types:amqqueue(), absent_reason()}.
--spec recover() -> [rabbit_types:amqqueue()].
--spec stop() -> 'ok'.
+-spec recover(rabbit_types:vhost()) -> [rabbit_types:amqqueue()].
+-spec stop(rabbit_types:vhost()) -> 'ok'.
 -spec start([rabbit_types:amqqueue()]) -> 'ok'.
 -spec declare
         (name(), boolean(), boolean(), rabbit_framing:amqp_table(),
@@ -210,10 +211,7 @@
         [queue_name, channel_pid, consumer_tag, ack_required, prefetch_count,
          arguments]).
 
-recover() ->
-    %% Clear out remnants of old incarnation, in case we restarted
-    %% faster than other nodes handled DOWN messages from us.
-    on_node_down(node()),
+warn_file_limit() ->
     DurableQueues = find_durable_queues(),
     L = length(DurableQueues),
 
@@ -226,27 +224,23 @@ recover() ->
               [L, file_handle_cache:get_limit(), L]);
         false ->
             ok
-    end,
+    end.
 
+recover(VHost) ->
+    Queues = find_durable_queues(VHost),
     {ok, BQ} = application:get_env(rabbit, backing_queue_module),
-
     %% We rely on BQ:start/1 returning the recovery terms in the same
     %% order as the supplied queue names, so that we can zip them together
     %% for further processing in recover_durable_queues.
     {ok, OrderedRecoveryTerms} =
-        BQ:start([QName || #amqqueue{name = QName} <- DurableQueues]),
-    {ok,_} = supervisor:start_child(
-               rabbit_sup,
-               {rabbit_amqqueue_sup_sup,
-                {rabbit_amqqueue_sup_sup, start_link, []},
-                transient, infinity, supervisor, [rabbit_amqqueue_sup_sup]}),
-    recover_durable_queues(lists:zip(DurableQueues, OrderedRecoveryTerms)).
-
-stop() ->
-    ok = supervisor:terminate_child(rabbit_sup, rabbit_amqqueue_sup_sup),
-    ok = supervisor:delete_child(rabbit_sup, rabbit_amqqueue_sup_sup),
+        BQ:start(VHost, [QName || #amqqueue{name = QName} <- Queues]),
+    {ok, _} = rabbit_amqqueue_sup_sup:start_for_vhost(VHost),
+    recover_durable_queues(lists:zip(Queues, OrderedRecoveryTerms)).
+
+stop(VHost) ->
+    ok = rabbit_amqqueue_sup_sup:stop_for_vhost(VHost),
     {ok, BQ} = application:get_env(rabbit, backing_queue_module),
-    ok = BQ:stop().
+    ok = BQ:stop(VHost).
 
 start(Qs) ->
     %% At this point all recovered queues and their bindings are
@@ -256,6 +250,24 @@ start(Qs) ->
     [Pid ! {self(), go} || #amqqueue{pid = Pid} <- Qs],
     ok.
 
+find_durable_queues(VHost) ->
+    Node = node(),
+    mnesia:async_dirty(
+      fun () ->
+              qlc:e(qlc:q([Q || Q = #amqqueue{name = Name,
+                                              vhost = VH,
+                                              pid  = Pid}
+                                    <- mnesia:table(rabbit_durable_queue),
+                                VH =:= VHost,
+                                node(Pid) == Node andalso
+                                %% Terminations on node down will not remove the rabbit_queue
+                                %% record if it is a mirrored queue (such info is now obtained from
+                                %% the policy). Thus, we must check if the local pid is alive
+                                %% - if the record is present - in order to restart.
+                                (mnesia:read(rabbit_queue, Name, read) =:= []
+                                orelse not erlang:is_process_alive(Pid))]))
+      end).
+
 find_durable_queues() ->
     Node = node(),
     mnesia:async_dirty(
@@ -268,8 +280,8 @@ find_durable_queues() ->
                                 %% record if it is a mirrored queue (such info is now obtained from
                                 %% the policy). Thus, we must check if the local pid is alive
                                 %% - if the record is present - in order to restart.
-                                                    (mnesia:read(rabbit_queue, Name, read) =:= []
-                                                     orelse not erlang:is_process_alive(Pid))]))
+                                (mnesia:read(rabbit_queue, Name, read) =:= []
+                                orelse not erlang:is_process_alive(Pid))]))
       end).
 
 recover_durable_queues(QueuesAndRecoveryTerms) ->

src/rabbit_backing_queue.erl

@@ -54,19 +54,19 @@
 
 -spec info_keys() -> rabbit_types:info_keys().
 
-%% Called on startup with a list of durable queue names. The queues
-%% aren't being started at this point, but this call allows the
+%% Called on startup with a vhost and a list of durable queue names on this vhost.
+%% The queues aren't being started at this point, but this call allows the
 %% backing queue to perform any checking necessary for the consistency
 %% of those queues, or initialise any other shared resources.
 %%
 %% The list of queue recovery terms returned as {ok, Terms} must be given
 %% in the same order as the list of queue names supplied.
--callback start([rabbit_amqqueue:name()]) -> rabbit_types:ok(recovery_terms()).
+-callback start(rabbit_types:vhost(), [rabbit_amqqueue:name()]) -> rabbit_types:ok(recovery_terms()).
 
-%% Called to tear down any state/resources. NB: Implementations should
+%% Called to tear down any state/resources for vhost. NB: Implementations should
 %% not depend on this function being called on shutdown and instead
 %% should hook into the rabbit supervision hierarchy.
--callback stop() -> 'ok'.
+-callback stop(rabbit_types:vhost()) -> 'ok'.
 
 %% Initialise the backing queue and its state.
 %%

src/supervisor2.erl

@@ -142,6 +142,14 @@
            [ChildSpec :: child_spec()]}}
     | ignore.
 
+%% Optional callback prep_stop/0. It cannot be exported as Erlang/OTP doesn't
+%% support definition of optional callbacks.
+%%
+%% Currently used to stop application dependencies.
+%%
+%% -callback prep_stop() -> ok.
+%%
+
 -define(restarting(_Pid_), {restarting,_Pid_}).
 
 %%% ---------------------------------------------------
@@ -629,6 +637,7 @@ handle_info({'EXIT', Pid, Reason}, State) ->
 	{ok, State1} ->
 	    {noreply, State1};
 	{shutdown, State1} ->
+            prep_stop(State1),
 	    {stop, shutdown, State1}
     end;
 
@@ -801,7 +810,8 @@ restart_child(Pid, Reason, State) ->
 try_restart(RestartType, Reason, Child, State) ->
     case handle_restart(RestartType, Reason, Child, State) of
         {ok, NState}       -> {noreply, NState};
-        {shutdown, State2} -> {stop, shutdown, State2}
+        {shutdown, State2} -> prep_stop(State2),
+                              {stop, shutdown, State2}
     end.
 
 do_restart(RestartType, Reason, Child, State) ->
@@ -1504,3 +1514,16 @@ report_progress(Child, SupName) ->
     Progress = [{supervisor, SupName},
 		{started, extract_child(Child)}],
     error_logger:info_report(progress, Progress).
+
+prep_stop(#state{module = Mod}) ->
+    %% Catch any exception - including non-existing prep_stop -
+    %% and continue stopping the supervision tree.
+    %% This is only executed when children are terminating,
+    %% because any other call from a top supervisor or application
+    %% will cause a deadlock stopping applications within prep_stop.
+    try
+        Mod:prep_stop()
+    catch
+        _:_ ->
+            ok
+    end.