merge default

11 files changed, 344 insertions, 211 deletions

diff --git a/src/gatherer.erl b/src/gatherer.erl
index 98b36038..29d2d713 100644
--- a/src/gatherer.erl
+++ b/src/gatherer.erl
@@ -18,7 +18,7 @@
 
 -behaviour(gen_server2).
 
--export([start_link/0, stop/1, fork/1, finish/1, in/2, out/1]).
+-export([start_link/0, stop/1, fork/1, finish/1, in/2, sync_in/2, out/1]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2, code_change/3]).
@@ -32,6 +32,7 @@
 -spec(fork/1 :: (pid()) -> 'ok').
 -spec(finish/1 :: (pid()) -> 'ok').
 -spec(in/2 :: (pid(), any()) -> 'ok').
+-spec(sync_in/2 :: (pid(), any()) -> 'ok').
 -spec(out/1 :: (pid()) -> {'value', any()} | 'empty').
 
 -endif.
@@ -62,6 +63,9 @@ finish(Pid) ->
 in(Pid, Value) ->
     gen_server2:cast(Pid, {in, Value}).
 
+sync_in(Pid, Value) ->
+    gen_server2:call(Pid, {in, Value}, infinity).
+
 out(Pid) ->
     gen_server2:call(Pid, out, infinity).
 
@@ -78,19 +82,22 @@ handle_call(stop, _From, State) ->
 handle_call(fork, _From, State = #gstate { forks = Forks }) ->
     {reply, ok, State #gstate { forks = Forks + 1 }, hibernate};
 
+handle_call({in, Value}, From, State) ->
+    {noreply, in(Value, From, State), hibernate};
+
 handle_call(out, From, State = #gstate { forks   = Forks,
                                          values  = Values,
                                          blocked = Blocked }) ->
     case queue:out(Values) of
+        {empty, _} when Forks == 0 ->
+            {reply, empty, State, hibernate};
         {empty, _} ->
-            case Forks of
-                0 -> {reply, empty, State, hibernate};
-                _ -> {noreply,
-                      State #gstate { blocked = queue:in(From, Blocked) },
-                      hibernate}
-            end;
-        {{value, _Value} = V, NewValues} ->
-            {reply, V, State #gstate { values = NewValues }, hibernate}
+            {noreply, State #gstate { blocked = queue:in(From, Blocked) },
+             hibernate};
+        {{value, {PendingIn, Value}}, NewValues} ->
+            reply(PendingIn, ok),
+            {reply, {value, Value}, State #gstate { values = NewValues },
+             hibernate}
     end;
 
 handle_call(Msg, _From, State) ->
@@ -107,15 +114,8 @@ handle_cast(finish, State = #gstate { forks = Forks, blocked = Blocked }) ->
     {noreply, State #gstate { forks = NewForks, blocked = NewBlocked },
      hibernate};
 
-handle_cast({in, Value}, State = #gstate { values  = Values,
-                                           blocked = Blocked }) ->
-    {noreply, case queue:out(Blocked) of
-                  {empty, _} ->
-                      State #gstate { values = queue:in(Value, Values) };
-                  {{value, From}, NewBlocked} ->
-                      gen_server2:reply(From, {value, Value}),
-                      State #gstate { blocked = NewBlocked }
-              end, hibernate};
+handle_cast({in, Value}, State) ->
+    {noreply, in(Value, undefined, State), hibernate};
 
 handle_cast(Msg, State) ->
     {stop, {unexpected_cast, Msg}, State}.
@@ -128,3 +128,18 @@ code_change(_OldVsn, State, _Extra) ->
 
 terminate(_Reason, State) ->
     State.
+
+%%----------------------------------------------------------------------------
+
+in(Value, From,  State = #gstate { values = Values, blocked = Blocked }) ->
+    case queue:out(Blocked) of
+        {empty, _} ->
+            State #gstate { values = queue:in({From, Value}, Values) };
+        {{value, PendingOut}, NewBlocked} ->
+            reply(From, ok),
+            gen_server2:reply(PendingOut, {value, Value}),
+            State #gstate { blocked = NewBlocked }
+    end.
+
+reply(undefined, _Reply) -> ok;
+reply(From,       Reply) -> gen_server2:reply(From, Reply).
diff --git a/src/rabbit.erl b/src/rabbit.erl
index 7b417b00..93808f84 100644
--- a/src/rabbit.erl
+++ b/src/rabbit.erl
@@ -364,7 +364,7 @@ status() ->
           {running_applications, application:which_applications(infinity)},
           {os,                   os:type()},
           {erlang_version,       erlang:system_info(system_version)},
-          {memory,               erlang:memory()}],
+          {memory,               rabbit_vm:memory()}],
     S2 = rabbit_misc:filter_exit_map(
            fun ({Key, {M, F, A}}) -> {Key, erlang:apply(M, F, A)} end,
            [{vm_memory_high_watermark, {vm_memory_monitor,
diff --git a/src/rabbit_amqqueue_process.erl b/src/rabbit_amqqueue_process.erl
index f137ae91..b8aad11a 100644
--- a/src/rabbit_amqqueue_process.erl
+++ b/src/rabbit_amqqueue_process.erl
@@ -497,32 +497,21 @@ confirm_messages(MsgIds, State = #q{msg_id_to_channel = MTC}) ->
     rabbit_misc:gb_trees_foreach(fun rabbit_misc:confirm_to_sender/2, CMs),
     State#q{msg_id_to_channel = MTC1}.
 
-should_confirm_message(#delivery{msg_seq_no = undefined}, _State) ->
-    never;
-should_confirm_message(#delivery{sender     = SenderPid,
+send_or_record_confirm(#delivery{msg_seq_no = undefined}, State) ->
+    {never, State};
+send_or_record_confirm(#delivery{sender     = SenderPid,
                                  msg_seq_no = MsgSeqNo,
                                  message    = #basic_message {
                                    is_persistent = true,
                                    id            = MsgId}},
-                       #q{q = #amqqueue{durable = true}}) ->
-    {eventually, SenderPid, MsgSeqNo, MsgId};
-should_confirm_message(#delivery{sender     = SenderPid,
-                                 msg_seq_no = MsgSeqNo},
-                       _State) ->
-    {immediately, SenderPid, MsgSeqNo}.
-
-needs_confirming({eventually, _, _, _}) -> true;
-needs_confirming(_)                     -> false.
-
-maybe_record_confirm_message({eventually, SenderPid, MsgSeqNo, MsgId},
-                             State = #q{msg_id_to_channel = MTC}) ->
-    State#q{msg_id_to_channel =
-                gb_trees:insert(MsgId, {SenderPid, MsgSeqNo}, MTC)};
-maybe_record_confirm_message({immediately, SenderPid, MsgSeqNo}, State) ->
+                       State = #q{q                 = #amqqueue{durable = true},
+                                  msg_id_to_channel = MTC}) ->
+    MTC1 = gb_trees:insert(MsgId, {SenderPid, MsgSeqNo}, MTC),
+    {eventually, State#q{msg_id_to_channel = MTC1}};
+send_or_record_confirm(#delivery{sender     = SenderPid,
+                                 msg_seq_no = MsgSeqNo}, State) ->
     rabbit_misc:confirm_to_sender(SenderPid, [MsgSeqNo]),
-    State;
-maybe_record_confirm_message(_Confirm, State) ->
-    State.
+    {immediately, State}.
 
 run_message_queue(State) ->
     State1 = #q{backing_queue = BQ, backing_queue_state = BQS} =
@@ -544,33 +533,27 @@ attempt_delivery(#delivery{sender = SenderPid, message = Message}, Props,
                       {{Message, Props#message_properties.delivered, AckTag},
                        true, State1#q{backing_queue_state = BQS3}}
               end, false, State#q{backing_queue_state = BQS1});
-        {Duplicate, BQS1} ->
-            %% if the message has previously been seen by the BQ then
-            %% it must have been seen under the same circumstances as
-            %% now: i.e. if it is now a deliver_immediately then it
-            %% must have been before.
-            {case Duplicate of
-                 published -> true;
-                 discarded -> false
-             end,
-             State#q{backing_queue_state = BQS1}}
+        {published, BQS1} ->
+            {true,  State#q{backing_queue_state = BQS1}};
+        {discarded, BQS1} ->
+            {false, State#q{backing_queue_state = BQS1}}
     end.
 
-deliver_or_enqueue(Delivery = #delivery{message    = Message,
-                                        sender     = SenderPid}, Delivered,
-                   State) ->
-    Confirm = should_confirm_message(Delivery, State),
+deliver_or_enqueue(Delivery = #delivery{message = Message, sender = SenderPid},
+                   Delivered, State) ->
+    {Confirm, State1} = send_or_record_confirm(Delivery, State),
     Props = message_properties(Confirm, Delivered, State),
-    case attempt_delivery(Delivery, Props, State) of
-        {true, State1} ->
-            maybe_record_confirm_message(Confirm, State1);
+    case attempt_delivery(Delivery, Props, State1) of
+        {true, State2} ->
+            State2;
         %% the next one is an optimisations
         %% TODO: optimise the Confirm =/= never case too
-        {false, State1 = #q{ttl = 0, dlx = undefined}} when Confirm == never ->
-            discard_delivery(Delivery, State1);
-        {false, State1} ->
-            State2 = #q{backing_queue = BQ, backing_queue_state = BQS} =
-                maybe_record_confirm_message(Confirm, State1),
+        {false, State2 = #q{ttl = 0, dlx = undefined,
+                            backing_queue = BQ, backing_queue_state = BQS}}
+          when Confirm == never ->
+            BQS1 = BQ:discard(Message, SenderPid, BQS),
+            State2#q{backing_queue_state = BQS1};
+        {false, State2 = #q{backing_queue = BQ, backing_queue_state = BQS}} ->
             BQS1 = BQ:publish(Message, Props, SenderPid, BQS),
             ensure_ttl_timer(Props#message_properties.expiry,
                              State2#q{backing_queue_state = BQS1})
@@ -690,15 +673,9 @@ subtract_acks(ChPid, AckTags, State, Fun) ->
             Fun(State)
     end.
 
-discard_delivery(#delivery{sender = SenderPid,
-                           message = Message},
-                 State = #q{backing_queue = BQ,
-                            backing_queue_state = BQS}) ->
-    State#q{backing_queue_state = BQ:discard(Message, SenderPid, BQS)}.
-
 message_properties(Confirm, Delivered, #q{ttl = TTL}) ->
     #message_properties{expiry           = calculate_msg_expiry(TTL),
-                        needs_confirming = needs_confirming(Confirm),
+                        needs_confirming = Confirm == eventually,
                         delivered        = Delivered}.
 
 calculate_msg_expiry(undefined) -> undefined;
diff --git a/src/rabbit_backing_queue.erl b/src/rabbit_backing_queue.erl
index d69a6c3b..c6d17785 100644
--- a/src/rabbit_backing_queue.erl
+++ b/src/rabbit_backing_queue.erl
@@ -24,6 +24,7 @@
 -type(ack()   :: any()).
 -type(state() :: any()).
 
+-type(msg_ids() :: [rabbit_types:msg_id()]).
 -type(fetch_result(Ack) ::
         ('empty' |
          %% Message,                  IsDelivered, AckTag, Remaining_Len
@@ -117,7 +118,7 @@
 %% first time the message id appears in the result of
 %% drain_confirmed. All subsequent appearances of that message id will
 %% be ignored.
--callback drain_confirmed(state()) -> {[rabbit_guid:guid()], state()}.
+-callback drain_confirmed(state()) -> {msg_ids(), state()}.
 
 %% Drop messages from the head of the queue while the supplied predicate returns
 %% true. Also accepts a boolean parameter that determines whether the messages
@@ -136,7 +137,7 @@
 
 %% Acktags supplied are for messages which can now be forgotten
 %% about. Must return 1 msg_id per Ack, in the same order as Acks.
--callback ack([ack()], state()) -> {[rabbit_guid:guid()], state()}.
+-callback ack([ack()], state()) -> {msg_ids(), state()}.
 
 %% Acktags supplied are for messages which should be processed. The
 %% provided callback function is called with each message.
@@ -144,7 +145,7 @@
 
 %% Reinsert messages into the queue which have already been delivered
 %% and were pending acknowledgement.
--callback requeue([ack()], state()) -> {[rabbit_guid:guid()], state()}.
+-callback requeue([ack()], state()) -> {msg_ids(), state()}.
 
 %% How long is my queue?
 -callback len(state()) -> non_neg_integer().
diff --git a/src/rabbit_mirror_queue_coordinator.erl b/src/rabbit_mirror_queue_coordinator.erl
index 40359da3..6cd71fc3 100644
--- a/src/rabbit_mirror_queue_coordinator.erl
+++ b/src/rabbit_mirror_queue_coordinator.erl
@@ -101,19 +101,25 @@
 %% channel during a publish, only some of the mirrors may receive that
 %% publish. As a result of this problem, the messages broadcast over
 %% the gm contain published content, and thus slaves can operate
-%% successfully on messages that they only receive via the gm. The key
-%% purpose of also sending messages directly from the channels to the
-%% slaves is that without this, in the event of the death of the
-%% master, messages could be lost until a suitable slave is promoted.
+%% successfully on messages that they only receive via the gm.
 %%
-%% However, that is not the only reason. For example, if confirms are
-%% in use, then there is no guarantee that every slave will see the
-%% delivery with the same msg_seq_no. As a result, the slaves have to
-%% wait until they've seen both the publish via gm, and the publish
-%% via the channel before they have enough information to be able to
-%% perform the publish to their own bq, and subsequently issue the
-%% confirm, if necessary. Either form of publish can arrive first, and
-%% a slave can be upgraded to the master at any point during this
+%% The key purpose of also sending messages directly from the channels
+%% to the slaves is that without this, in the event of the death of
+%% the master, messages could be lost until a suitable slave is
+%% promoted. However, that is not the only reason. A slave cannot send
+%% confirms for a message until it has seen it from the
+%% channel. Otherwise, it might send a confirm to a channel for a
+%% message that it might *never* receive from that channel. This can
+%% happen because new slaves join the gm ring (and thus receive
+%% messages from the master) before inserting themselves in the
+%% queue's mnesia record (which is what channels look at for routing).
+%% As it turns out, channels will simply ignore such bogus confirms,
+%% but relying on that would introduce a dangerously tight coupling.
+%%
+%% Hence the slaves have to wait until they've seen both the publish
+%% via gm, and the publish via the channel before they issue the
+%% confirm. Either form of publish can arrive first, and a slave can
+%% be upgraded to the master at any point during this
 %% process. Confirms continue to be issued correctly, however.
 %%
 %% Because the slave is a full process, it impersonates parts of the
@@ -344,10 +350,9 @@ handle_cast({gm_deaths, Deaths},
             State = #state { q  = #amqqueue { name = QueueName, pid = MPid } })
   when node(MPid) =:= node() ->
     case rabbit_mirror_queue_misc:remove_from_queue(QueueName, Deaths) of
-        {ok, MPid, DeadPids, ExtraNodes} ->
+        {ok, MPid, DeadPids} ->
             rabbit_mirror_queue_misc:report_deaths(MPid, true, QueueName,
                                                    DeadPids),
-            rabbit_mirror_queue_misc:add_mirrors(QueueName, ExtraNodes),
             noreply(State);
         {error, not_found} ->
             {stop, normal, State}
@@ -398,8 +403,6 @@ members_changed([_CPid], _Births, []) ->
 members_changed([CPid], _Births, Deaths) ->
     ok = gen_server2:cast(CPid, {gm_deaths, Deaths}).
 
-handle_msg([_CPid], _From, master_changed) ->
-    ok;
 handle_msg([CPid], _From, request_depth = Msg) ->
     ok = gen_server2:cast(CPid, Msg);
 handle_msg([CPid], _From, {ensure_monitoring, _Pids} = Msg) ->
diff --git a/src/rabbit_mirror_queue_master.erl b/src/rabbit_mirror_queue_master.erl
index 15ab9424..6dac2808 100644
--- a/src/rabbit_mirror_queue_master.erl
+++ b/src/rabbit_mirror_queue_master.erl
@@ -88,18 +88,19 @@ stop() ->
     %% Same as start/1.
     exit({not_valid_for_generic_backing_queue, ?MODULE}).
 
-init(Q, Recover, AsyncCallback) ->
+init(Q = #amqqueue{name = QName}, Recover, AsyncCallback) ->
     {ok, BQ} = application:get_env(backing_queue_module),
     BQS = BQ:init(Q, Recover, AsyncCallback),
-    init_with_existing_bq(Q, BQ, BQS).
+    State = #state{gm = GM} = init_with_existing_bq(Q, BQ, BQS),
+    {_MNode, SNodes} = rabbit_mirror_queue_misc:suggested_queue_nodes(Q),
+    rabbit_mirror_queue_misc:add_mirrors(QName, SNodes),
+    ok = gm:broadcast(GM, {depth, BQ:depth(BQS)}),
+    State.
 
-init_with_existing_bq(#amqqueue { name = QName } = Q, BQ, BQS) ->
+init_with_existing_bq(Q, BQ, BQS) ->
     {ok, CPid} = rabbit_mirror_queue_coordinator:start_link(
                    Q, undefined, sender_death_fun(), depth_fun()),
     GM = rabbit_mirror_queue_coordinator:get_gm(CPid),
-    {_MNode, SNodes} = rabbit_mirror_queue_misc:suggested_queue_nodes(Q),
-    rabbit_mirror_queue_misc:add_mirrors(QName, SNodes),
-    ok = gm:broadcast(GM, {depth, BQ:depth(BQS)}),
     #state { gm                  = GM,
              coordinator         = CPid,
              backing_queue       = BQ,
@@ -148,7 +149,17 @@ stop_all_slaves(Reason, #state{gm = GM}) ->
     MRefs = [erlang:monitor(process, S) || S <- Slaves],
     ok = gm:broadcast(GM, {delete_and_terminate, Reason}),
     [receive {'DOWN', MRef, process, _Pid, _Info} -> ok end || MRef <- MRefs],
-    ok = gm:forget_group(proplists:get_value(group_name, Info)).
+    %% Normally when we remove a slave another slave or master will
+    %% notice and update Mnesia. But we just removed them all, and
+    %% have stopped listening ourselves. So manually clean up.
+    QName = proplists:get_value(group_name, Info),
+    rabbit_misc:execute_mnesia_transaction(
+      fun () ->
+              [Q] = mnesia:read({rabbit_queue, QName}),
+              rabbit_mirror_queue_misc:store_updated_slaves(
+                Q #amqqueue { slave_pids = [] })
+      end),
+    ok = gm:forget_group(QName).
 
 purge(State = #state { gm                  = GM,
                        backing_queue       = BQ,
@@ -368,8 +379,10 @@ discard(Msg = #basic_message { id = MsgId }, ChPid,
     case dict:find(MsgId, SS) of
         error ->
             ok = gm:broadcast(GM, {discard, ChPid, Msg}),
-            State #state { backing_queue_state = BQ:discard(Msg, ChPid, BQS),
-                           seen_status         = dict:erase(MsgId, SS) };
+            ensure_monitoring(
+              ChPid, State #state {
+                       backing_queue_state = BQ:discard(Msg, ChPid, BQS),
+                       seen_status         = dict:erase(MsgId, SS) });
         {ok, discarded} ->
             State
     end.
diff --git a/src/rabbit_mirror_queue_misc.erl b/src/rabbit_mirror_queue_misc.erl
index 453f2f2c..b6c229aa 100644
--- a/src/rabbit_mirror_queue_misc.erl
+++ b/src/rabbit_mirror_queue_misc.erl
@@ -31,11 +31,12 @@
 
 -spec(remove_from_queue/2 ::
         (rabbit_amqqueue:name(), [pid()])
-        -> {'ok', pid(), [pid()], [node()]} | {'error', 'not_found'}).
+        -> {'ok', pid(), [pid()]} | {'error', 'not_found'}).
 -spec(on_node_up/0 :: () -> 'ok').
 -spec(add_mirrors/2 :: (rabbit_amqqueue:name(), [node()]) -> 'ok').
 -spec(add_mirror/2 ::
-        (rabbit_amqqueue:name(), node()) -> rabbit_types:ok_or_error(any())).
+        (rabbit_amqqueue:name(), node()) ->
+                           {'ok', atom()} | rabbit_types:error(any())).
 -spec(store_updated_slaves/1 :: (rabbit_types:amqqueue()) ->
                                      rabbit_types:amqqueue()).
 -spec(suggested_queue_nodes/1 :: (rabbit_types:amqqueue()) ->
@@ -59,7 +60,6 @@
 
 remove_from_queue(QueueName, DeadGMPids) ->
     DeadNodes = [node(DeadGMPid) || DeadGMPid <- DeadGMPids],
-    ClusterNodes = rabbit_mnesia:cluster_nodes(running) -- DeadNodes,
     rabbit_misc:execute_mnesia_transaction(
       fun () ->
               %% Someone else could have deleted the queue before we
@@ -73,49 +73,52 @@ remove_from_queue(QueueName, DeadGMPids) ->
                       {QPid1, SPids1} = promote_slave(Alive),
                       case {{QPid, SPids}, {QPid1, SPids1}} of
                           {Same, Same} ->
-                              {ok, QPid1, [], []};
+                              {ok, QPid1, []};
                           _ when QPid =:= QPid1 orelse node(QPid1) =:= node() ->
                               %% Either master hasn't changed, so
                               %% we're ok to update mnesia; or we have
                               %% become the master.
-                              Q1 = store_updated_slaves(
-                                     Q #amqqueue { pid        = QPid1,
-                                                   slave_pids = SPids1 }),
-                              %% Sometimes a slave dying means we need
-                              %% to start more on other nodes -
-                              %% "exactly" mode can cause this to
-                              %% happen.
-                              {_, OldNodes} = actual_queue_nodes(Q1),
-                              {_, NewNodes} = suggested_queue_nodes(
-                                                Q1, ClusterNodes),
-                              {ok, QPid1, [QPid | SPids] -- Alive,
-                               NewNodes -- OldNodes};
+                              store_updated_slaves(
+                                Q #amqqueue { pid        = QPid1,
+                                              slave_pids = SPids1 }),
+                              {ok, QPid1, [QPid | SPids] -- Alive};
                           _ ->
                               %% Master has changed, and we're not it,
                               %% so leave alone to allow the promoted
                               %% slave to find it and make its
                               %% promotion atomic.
-                              {ok, QPid1, [], []}
+                              {ok, QPid1, []}
                       end
               end
       end).
 
 on_node_up() ->
-    ClusterNodes = rabbit_mnesia:cluster_nodes(running),
     QNames =
         rabbit_misc:execute_mnesia_transaction(
           fun () ->
                   mnesia:foldl(
-                    fun (Q = #amqqueue{name = QName}, QNames0) ->
+                    fun (Q = #amqqueue{name       = QName,
+                                       pid        = Pid,
+                                       slave_pids = SPids}, QNames0) ->
+                            %% We don't want to pass in the whole
+                            %% cluster - we don't want a situation
+                            %% where starting one node causes us to
+                            %% decide to start a mirror on another
+                            PossibleNodes0 = [node(P) || P <- [Pid | SPids]],
+                            PossibleNodes =
+                                case lists:member(node(), PossibleNodes0) of
+                                    true  -> PossibleNodes0;
+                                    false -> [node() | PossibleNodes0]
+                                end,
                             {_MNode, SNodes} = suggested_queue_nodes(
-                                                 Q, ClusterNodes),
+                                                 Q, PossibleNodes),
                             case lists:member(node(), SNodes) of
                                 true  -> [QName | QNames0];
                                 false -> QNames0
                             end
                     end, [], rabbit_queue)
           end),
-    [ok = add_mirror(QName, node()) || QName <- QNames],
+    [{ok, _} = add_mirror(QName, node()) || QName <- QNames],
     ok.
 
 drop_mirrors(QName, Nodes) ->
@@ -141,7 +144,7 @@ drop_mirror(QName, MirrorNode) ->
       end).
 
 add_mirrors(QName, Nodes) ->
-    [ok = add_mirror(QName, Node)  || Node <- Nodes],
+    [{ok, _} = add_mirror(QName, Node)  || Node <- Nodes],
     ok.
 
 add_mirror(QName, MirrorNode) ->
@@ -154,8 +157,7 @@ add_mirror(QName, MirrorNode) ->
                   [SPid] ->
                       case rabbit_misc:is_process_alive(SPid) of
                           true ->
-                              {error,{queue_already_mirrored_on_node,
-                                      MirrorNode}};
+                              {ok, already_mirrored};
                           false ->
                               start_child(Name, MirrorNode, Q)
                       end
@@ -171,20 +173,20 @@ start_child(Name, MirrorNode, Q) ->
         {ok, undefined} ->
             %% this means the mirror process was
             %% already running on the given node.
-            ok;
+            {ok, already_mirrored};
         {ok, down} ->
             %% Node went down between us deciding to start a mirror
             %% and actually starting it. Which is fine.
-            ok;
+            {ok, node_down};
         {ok, SPid} ->
             rabbit_log:info("Adding mirror of ~s on node ~p: ~p~n",
                             [rabbit_misc:rs(Name), MirrorNode, SPid]),
-            ok;
+            {ok, started};
         {error, {{stale_master_pid, StalePid}, _}} ->
             rabbit_log:warning("Detected stale HA master while adding "
                                "mirror of ~s on node ~p: ~p~n",
                                [rabbit_misc:rs(Name), MirrorNode, StalePid]),
-            ok;
+            {ok, stale_master};
         {error, {{duplicate_live_master, _}=Err, _}} ->
             Err;
         Other ->
@@ -235,14 +237,14 @@ suggested_queue_nodes(Q) ->
 %% This variant exists so we can pull a call to
 %% rabbit_mnesia:cluster_nodes(running) out of a loop or
 %% transaction or both.
-suggested_queue_nodes(Q, ClusterNodes) ->
+suggested_queue_nodes(Q, PossibleNodes) ->
     {MNode0, SNodes} = actual_queue_nodes(Q),
     MNode = case MNode0 of
                 none -> node();
                 _    -> MNode0
             end,
     suggested_queue_nodes(policy(<<"ha-mode">>, Q), policy(<<"ha-params">>, Q),
-                          {MNode, SNodes}, ClusterNodes).
+                          {MNode, SNodes}, PossibleNodes).
 
 policy(Policy, Q) ->
     case rabbit_policy:get(Policy, Q) of
@@ -250,11 +252,11 @@ policy(Policy, Q) ->
         _       -> none
     end.
 
-suggested_queue_nodes(<<"all">>, _Params, {MNode, _SNodes}, All) ->
-    {MNode, All -- [MNode]};
-suggested_queue_nodes(<<"nodes">>, Nodes0, {MNode, _SNodes}, All) ->
+suggested_queue_nodes(<<"all">>, _Params, {MNode, _SNodes}, Possible) ->
+    {MNode, Possible -- [MNode]};
+suggested_queue_nodes(<<"nodes">>, Nodes0, {MNode, _SNodes}, Possible) ->
     Nodes = [list_to_atom(binary_to_list(Node)) || Node <- Nodes0],
-    Unavailable = Nodes -- All,
+    Unavailable = Nodes -- Possible,
     Available = Nodes -- Unavailable,
     case Available of
         [] -> %% We have never heard of anything? Not much we can do but
@@ -265,16 +267,26 @@ suggested_queue_nodes(<<"nodes">>, Nodes0, {MNode, _SNodes}, All) ->
                   false -> promote_slave(Available)
               end
     end;
-suggested_queue_nodes(<<"exactly">>, Count, {MNode, SNodes}, All) ->
+%% When we need to add nodes, we randomise our candidate list as a
+%% crude form of load-balancing. TODO it would also be nice to
+%% randomise the list of ones to remove when we have too many - but
+%% that would fail to take account of synchronisation...
+suggested_queue_nodes(<<"exactly">>, Count, {MNode, SNodes}, Possible) ->
     SCount = Count - 1,
     {MNode, case SCount > length(SNodes) of
-                true  -> Cand = (All -- [MNode]) -- SNodes,
+                true  -> Cand = shuffle((Possible -- [MNode]) -- SNodes),
                          SNodes ++ lists:sublist(Cand, SCount - length(SNodes));
                 false -> lists:sublist(SNodes, SCount)
             end};
 suggested_queue_nodes(_, _, {MNode, _}, _) ->
     {MNode, []}.
 
+shuffle(L) ->
+    {A1,A2,A3} = now(),
+    random:seed(A1, A2, A3),
+    {_, L1} = lists:unzip(lists:keysort(1, [{random:uniform(), N} || N <- L])),
+    L1.
+
 actual_queue_nodes(#amqqueue{pid = MPid, slave_pids = SPids}) ->
     {case MPid of
          none -> none;
@@ -310,13 +322,6 @@ update_mirrors0(OldQ = #amqqueue{name = QName},
     All = fun ({A,B}) -> [A|B] end,
     OldNodes = All(actual_queue_nodes(OldQ)),
     NewNodes = All(suggested_queue_nodes(NewQ)),
-    %% When a mirror dies, remove_from_queue/2 might have to add new
-    %% slaves (in "exactly" mode). It will check mnesia to see which
-    %% slaves there currently are. If drop_mirror/2 is invoked first
-    %% then when we end up in remove_from_queue/2 it will not see the
-    %% slaves that add_mirror/2 will add, and also want to add them
-    %% (even though we are not responding to the death of a
-    %% mirror). Breakage ensues.
     add_mirrors(QName, NewNodes -- OldNodes),
     drop_mirrors(QName, OldNodes -- NewNodes),
     ok.
diff --git a/src/rabbit_mirror_queue_slave.erl b/src/rabbit_mirror_queue_slave.erl
index 307f2b4f..f4679184 100644
--- a/src/rabbit_mirror_queue_slave.erl
+++ b/src/rabbit_mirror_queue_slave.erl
@@ -173,7 +173,6 @@ handle_call({deliver, Delivery, true}, From, State) ->
 
 handle_call({gm_deaths, Deaths}, From,
             State = #state { q          = #amqqueue { name = QueueName },
-                             gm         = GM,
                              master_pid = MPid }) ->
     %% The GM has told us about deaths, which means we're not going to
     %% receive any more messages from GM
@@ -181,32 +180,21 @@ handle_call({gm_deaths, Deaths}, From,
         {error, not_found} ->
             gen_server2:reply(From, ok),
             {stop, normal, State};
-        {ok, Pid, DeadPids, ExtraNodes} ->
+        {ok, Pid, DeadPids} ->
             rabbit_mirror_queue_misc:report_deaths(self(), false, QueueName,
                                                    DeadPids),
             if node(Pid) =:= node(MPid) ->
                     %% master hasn't changed
                     gen_server2:reply(From, ok),
-                    rabbit_mirror_queue_misc:add_mirrors(QueueName, ExtraNodes),
                     noreply(State);
                node(Pid) =:= node() ->
                     %% we've become master
                     QueueState = promote_me(From, State),
-                    rabbit_mirror_queue_misc:add_mirrors(QueueName, ExtraNodes),
                     {become, rabbit_amqqueue_process, QueueState, hibernate};
                true ->
                     %% master has changed to not us.
                     gen_server2:reply(From, ok),
-                    %% assertion, we don't need to add_mirrors/2 in this
-                    %% branch, see last clause in remove_from_queue/2
-                    [] = ExtraNodes,
                     erlang:monitor(process, Pid),
-                    %% GM is lazy. So we know of the death of the
-                    %% slave since it is a neighbour of ours, but
-                    %% until a message is sent, not all members will
-                    %% know. That might include the new master. So
-                    %% broadcast a no-op message to wake everyone up.
-                    ok = gm:broadcast(GM, master_changed),
                     noreply(State #state { master_pid = Pid })
             end
     end;
@@ -257,8 +245,8 @@ handle_info(timeout, State) ->
     noreply(backing_queue_timeout(State));
 
 handle_info({'DOWN', _MonitorRef, process, MPid, _Reason},
-           State = #state { gm = GM, master_pid = MPid }) ->
-    ok = gm:broadcast(GM, {process_death, MPid}),
+            State = #state { gm = GM, master_pid = MPid }) ->
+    ok = gm:broadcast(GM, process_death),
     noreply(State);
 
 handle_info({'DOWN', _MonitorRef, process, ChPid, _Reason}, State) ->
@@ -345,16 +333,21 @@ joined([SPid], _Members) -> SPid ! {joined, self()}, ok.
 members_changed([_SPid], _Births,     []) -> ok;
 members_changed([ SPid], _Births, Deaths) -> inform_deaths(SPid, Deaths).
 
-handle_msg([_SPid], _From, master_changed) ->
-    ok;
 handle_msg([_SPid], _From, request_depth) ->
     %% This is only of value to the master
     ok;
 handle_msg([_SPid], _From, {ensure_monitoring, _Pid}) ->
     %% This is only of value to the master
     ok;
-handle_msg([SPid], _From, {process_death, Pid}) ->
-    inform_deaths(SPid, [Pid]);
+handle_msg([_SPid], _From, process_death) ->
+    %% Since GM is by nature lazy we need to make sure there is some
+    %% traffic when a master dies, to make sure we get informed of the
+    %% death. That's all process_death does, create some traffic. We
+    %% must not take any notice of the master death here since it
+    %% comes without ordering guarantees - there could still be
+    %% messages from the master we have yet to receive. When we get
+    %% members_changed, then there will be no more messages.
+    ok;
 handle_msg([CPid], _From, {delete_and_terminate, _Reason} = Msg) ->
     ok = gen_server2:cast(CPid, {gm, Msg}),
     {stop, {shutdown, ring_shutdown}};
@@ -413,16 +406,16 @@ confirm_messages(MsgIds, State = #state { msg_id_status = MS }) ->
                           %% If it needed confirming, it'll have
                           %% already been done.
                           Acc;
-                      {ok, {published, ChPid}} ->
+                      {ok, published} ->
                           %% Still not seen it from the channel, just
                           %% record that it's been confirmed.
-                          {CMsN, dict:store(MsgId, {confirmed, ChPid}, MSN)};
+                          {CMsN, dict:store(MsgId, confirmed, MSN)};
                       {ok, {published, ChPid, MsgSeqNo}} ->
                           %% Seen from both GM and Channel. Can now
                           %% confirm.
                           {rabbit_misc:gb_trees_cons(ChPid, MsgSeqNo, CMsN),
                            dict:erase(MsgId, MSN)};
-                      {ok, {confirmed, _ChPid}} ->
+                      {ok, confirmed} ->
                           %% It's already been confirmed. This is
                           %% probably it's been both sync'd to disk
                           %% and then delivered and ack'd before we've
@@ -454,9 +447,6 @@ promote_me(From, #state { q                   = Q = #amqqueue { name = QName },
                    rabbit_mirror_queue_master:depth_fun()),
     true = unlink(GM),
     gen_server2:reply(From, {promote, CPid}),
-    %% TODO this has been in here since the beginning, but it's not
-    %% obvious if it is needed. Investigate...
-    ok = gm:confirmed_broadcast(GM, master_changed),
 
     %% Everything that we're monitoring, we need to ensure our new
     %% coordinator is monitoring.
@@ -492,18 +482,18 @@ promote_me(From, #state { q                   = Q = #amqqueue { name = QName },
     %%
     %% MS contains the following three entry types:
     %%
-    %% a) {published, ChPid}:
+    %% a) published:
     %%   published via gm only; pending arrival of publication from
     %%   channel, maybe pending confirm.
     %%
     %% b) {published, ChPid, MsgSeqNo}:
     %%   published via gm and channel; pending confirm.
     %%
-    %% c) {confirmed, ChPid}:
+    %% c) confirmed:
     %%   published via gm only, and confirmed; pending publication
     %%   from channel.
     %%
-    %% d) discarded
+    %% d) discarded:
     %%   seen via gm only as discarded. Pending publication from
     %%   channel
     %%
@@ -521,22 +511,18 @@ promote_me(From, #state { q                   = Q = #amqqueue { name = QName },
     %% this does not affect MS, nor which bits go through to SS in
     %% Master, or MTC in queue_process.
 
-    MSList = dict:to_list(MS),
-    SS = dict:from_list(
-           [E || E = {_MsgId, discarded} <- MSList] ++
-               [{MsgId, Status}
-                || {MsgId, {Status, _ChPid}} <- MSList,
-                   Status =:= published orelse Status =:= confirmed]),
+    St = [published, confirmed, discarded],
+    SS = dict:filter(fun (_MsgId, Status) -> lists:member(Status, St) end, MS),
     AckTags = [AckTag || {_MsgId, AckTag} <- dict:to_list(MA)],
 
     MasterState = rabbit_mirror_queue_master:promote_backing_queue_state(
                     CPid, BQ, BQS, GM, AckTags, SS, MPids),
 
-    MTC = lists:foldl(fun ({MsgId, {published, ChPid, MsgSeqNo}}, MTC0) ->
-                              gb_trees:insert(MsgId, {ChPid, MsgSeqNo}, MTC0);
-                          (_, MTC0) ->
-                              MTC0
-                      end, gb_trees:empty(), MSList),
+    MTC = dict:fold(fun (MsgId, {published, ChPid, MsgSeqNo}, MTC0) ->
+                            gb_trees:insert(MsgId, {ChPid, MsgSeqNo}, MTC0);
+                        (_Msgid, _Status, MTC0) ->
+                            MTC0
+                    end, gb_trees:empty(), MS),
     Deliveries = [Delivery || {_ChPid, {PubQ, _PendCh}} <- dict:to_list(SQ),
                               Delivery <- queue:to_list(PubQ)],
     rabbit_amqqueue_process:init_with_backing_queue_state(
@@ -647,16 +633,12 @@ maybe_enqueue_message(
             MQ1 = queue:in(Delivery, MQ),
             SQ1 = dict:store(ChPid, {MQ1, PendingCh}, SQ),
             State1 #state { sender_queues = SQ1 };
-        {ok, {confirmed, ChPid}} ->
-            %% BQ has confirmed it but we didn't know what the
-            %% msg_seq_no was at the time. We do now!
+        {ok, confirmed} ->
             ok = rabbit_misc:confirm_to_sender(ChPid, [MsgSeqNo]),
             SQ1 = remove_from_pending_ch(MsgId, ChPid, SQ),
             State1 #state { msg_id_status = dict:erase(MsgId, MS),
                             sender_queues = SQ1 };
-        {ok, {published, ChPid}} ->
-            %% It was published to the BQ and we didn't know the
-            %% msg_seq_no so couldn't confirm it at the time.
+        {ok, published} ->
             {MS1, SQ1} =
                 case needs_confirming(Delivery, State1) of
                     never       -> {dict:erase(MsgId, MS),
@@ -700,20 +682,17 @@ process_instruction(
                    msg_id_status       = MS }) ->
 
     %% We really are going to do the publish right now, even though we
-    %% may not have seen it directly from the channel. As a result, we
-    %% may know that it needs confirming without knowing its
-    %% msg_seq_no, which means that we can see the confirmation come
-    %% back from the backing queue without knowing the msg_seq_no,
-    %% which means that we're going to have to hang on to the fact
-    %% that we've seen the msg_id confirmed until we can associate it
-    %% with a msg_seq_no.
+    %% may not have seen it directly from the channel. But we cannot
+    %% issues confirms until the latter has happened. So we need to
+    %% keep track of the MsgId and its confirmation status in the
+    %% meantime.
     State1 = ensure_monitoring(ChPid, State),
     {MQ, PendingCh} = get_sender_queue(ChPid, SQ),
     {MQ1, PendingCh1, MS1} =
         case queue:out(MQ) of
             {empty, _MQ2} ->
                 {MQ, sets:add_element(MsgId, PendingCh),
-                 dict:store(MsgId, {published, ChPid}, MS)};
+                 dict:store(MsgId, published, MS)};
             {{value, Delivery = #delivery {
                        msg_seq_no = MsgSeqNo,
                        message    = #basic_message { id = MsgId } }}, MQ2} ->
diff --git a/src/rabbit_queue_index.erl b/src/rabbit_queue_index.erl
index 6d6c648a..21f58154 100644
--- a/src/rabbit_queue_index.erl
+++ b/src/rabbit_queue_index.erl
@@ -537,7 +537,7 @@ queue_index_walker_reader(QueueName, Gatherer) ->
     State = blank_state(QueueName),
     ok = scan_segments(
            fun (_SeqId, MsgId, _MsgProps, true, _IsDelivered, no_ack, ok) ->
-                   gatherer:in(Gatherer, {MsgId, 1});
+                   gatherer:sync_in(Gatherer, {MsgId, 1});
                (_SeqId, _MsgId, _MsgProps, _IsPersistent, _IsDelivered,
                 _IsAcked, Acc) ->
                    Acc
diff --git a/src/rabbit_tests.erl b/src/rabbit_tests.erl
index 11f280bb..2e26837d 100644
--- a/src/rabbit_tests.erl
+++ b/src/rabbit_tests.erl
@@ -886,38 +886,49 @@ test_arguments_parser() ->
 test_dynamic_mirroring() ->
     %% Just unit tests of the node selection logic, see multi node
     %% tests for the rest...
-    Test = fun ({NewM, NewSs}, Policy, Params, {OldM, OldSs}, All) ->
+    Test = fun ({NewM, NewSs, ExtraSs}, Policy, Params, {OldM, OldSs}, All) ->
                    {NewM, NewSs0} =
                        rabbit_mirror_queue_misc:suggested_queue_nodes(
                          Policy, Params, {OldM, OldSs}, All),
-                   NewSs = lists:sort(NewSs0)
+                   NewSs1 = lists:sort(NewSs0),
+                   case dm_list_match(NewSs, NewSs1, ExtraSs) of
+                       ok    -> ok;
+                       error -> exit({no_match, NewSs, NewSs1, ExtraSs})
+                   end
            end,
 
-    Test({a,[b,c]},<<"all">>,'_',{a,[]},   [a,b,c]),
-    Test({a,[b,c]},<<"all">>,'_',{a,[b,c]},[a,b,c]),
-    Test({a,[b,c]},<<"all">>,'_',{a,[d]},  [a,b,c]),
+    Test({a,[b,c],0},<<"all">>,'_',{a,[]},   [a,b,c]),
+    Test({a,[b,c],0},<<"all">>,'_',{a,[b,c]},[a,b,c]),
+    Test({a,[b,c],0},<<"all">>,'_',{a,[d]},  [a,b,c]),
 
     %% Add a node
-    Test({a,[b,c]},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{a,[b]},[a,b,c,d]),
-    Test({b,[a,c]},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{b,[a]},[a,b,c,d]),
+    Test({a,[b,c],0},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{a,[b]},[a,b,c,d]),
+    Test({b,[a,c],0},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{b,[a]},[a,b,c,d]),
     %% Add two nodes and drop one
-    Test({a,[b,c]},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{a,[d]},[a,b,c,d]),
+    Test({a,[b,c],0},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{a,[d]},[a,b,c,d]),
     %% Promote slave to master by policy
-    Test({a,[b,c]},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{d,[a]},[a,b,c,d]),
+    Test({a,[b,c],0},<<"nodes">>,[<<"a">>,<<"b">>,<<"c">>],{d,[a]},[a,b,c,d]),
     %% Don't try to include nodes that are not running
-    Test({a,[b]},  <<"nodes">>,[<<"a">>,<<"b">>,<<"f">>],{a,[b]},[a,b,c,d]),
+    Test({a,[b],  0},<<"nodes">>,[<<"a">>,<<"b">>,<<"f">>],{a,[b]},[a,b,c,d]),
     %% If we can't find any of the nodes listed then just keep the master
-    Test({a,[]},   <<"nodes">>,[<<"f">>,<<"g">>,<<"h">>],{a,[b]},[a,b,c,d]),
+    Test({a,[],   0},<<"nodes">>,[<<"f">>,<<"g">>,<<"h">>],{a,[b]},[a,b,c,d]),
 
-    Test({a,[b]},  <<"exactly">>,2,{a,[]},   [a,b,c,d]),
-    Test({a,[b,c]},<<"exactly">>,3,{a,[]},   [a,b,c,d]),
-    Test({a,[c]},  <<"exactly">>,2,{a,[c]},  [a,b,c,d]),
-    Test({a,[b,c]},<<"exactly">>,3,{a,[c]},  [a,b,c,d]),
-    Test({a,[c]},  <<"exactly">>,2,{a,[c,d]},[a,b,c,d]),
-    Test({a,[c,d]},<<"exactly">>,3,{a,[c,d]},[a,b,c,d]),
+    Test({a,[],   1},<<"exactly">>,2,{a,[]},   [a,b,c,d]),
+    Test({a,[],   2},<<"exactly">>,3,{a,[]},   [a,b,c,d]),
+    Test({a,[c],  0},<<"exactly">>,2,{a,[c]},  [a,b,c,d]),
+    Test({a,[c],  1},<<"exactly">>,3,{a,[c]},  [a,b,c,d]),
+    Test({a,[c],  0},<<"exactly">>,2,{a,[c,d]},[a,b,c,d]),
+    Test({a,[c,d],0},<<"exactly">>,3,{a,[c,d]},[a,b,c,d]),
 
     passed.
 
+%% Does the first list match the second where the second is required
+%% to have exactly Extra superfluous items?
+dm_list_match([],     [],      0)     -> ok;
+dm_list_match(_,      [],     _Extra) -> error;
+dm_list_match([H|T1], [H |T2], Extra) -> dm_list_match(T1, T2, Extra);
+dm_list_match(L1,     [_H|T2], Extra) -> dm_list_match(L1, T2, Extra - 1).
+
 test_user_management() ->
 
     %% lots if stuff that should fail
diff --git a/src/rabbit_vm.erl b/src/rabbit_vm.erl
new file mode 100644
index 00000000..53f3df18
--- /dev/null
+++ b/src/rabbit_vm.erl
@@ -0,0 +1,129 @@
+%% The contents of this file are subject to the Mozilla Public License
+%% Version 1.1 (the "License"); you may not use this file except in
+%% compliance with the License. You may obtain a copy of the License
+%% at http://www.mozilla.org/MPL/
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and
+%% limitations under the License.
+%%
+%% The Original Code is RabbitMQ.
+%%
+%% The Initial Developer of the Original Code is VMware, Inc.
+%% Copyright (c) 2007-2012 VMware, Inc.  All rights reserved.
+%%
+
+-module(rabbit_vm).
+
+-export([memory/0]).
+
+-define(MAGIC_PLUGINS, ["mochiweb", "webmachine", "cowboy", "sockjs",
+                        "rfc4627_jsonrpc"]).
+
+%%----------------------------------------------------------------------------
+
+-ifdef(use_specs).
+
+-spec(memory/0 :: () -> rabbit_types:infos()).
+
+-endif.
+
+%%----------------------------------------------------------------------------
+
+%% Like erlang:memory(), but with awareness of rabbit-y things
+memory() ->
+    Conns        = (sup_memory(rabbit_tcp_client_sup) +
+                        sup_memory(ssl_connection_sup) +
+                        sup_memory(amqp_sup)),
+    Qs           = (sup_memory(rabbit_amqqueue_sup) +
+                        sup_memory(rabbit_mirror_queue_slave_sup)),
+    Mnesia       = mnesia_memory(),
+    MsgIndexETS  = ets_memory(rabbit_msg_store_ets_index),
+    MsgIndexProc = (pid_memory(msg_store_transient) +
+                        pid_memory(msg_store_persistent)),
+    MgmtDbETS    = ets_memory(rabbit_mgmt_db),
+    MgmtDbProc   = sup_memory(rabbit_mgmt_sup),
+    Plugins      = plugin_memory() - MgmtDbProc,
+
+    [{total,     Total},
+     {processes, Processes},
+     {ets,       ETS},
+     {atom,      Atom},
+     {binary,    Bin},
+     {code,      Code},
+     {system,    System}] =
+        erlang:memory([total, processes, ets, atom, binary, code, system]),
+
+    OtherProc = Processes - Conns - Qs - MsgIndexProc - MgmtDbProc - Plugins,
+
+    [{total,            Total},
+     {connection_procs, Conns},
+     {queue_procs,      Qs},
+     {plugins,          Plugins},
+     {other_proc,       lists:max([0, OtherProc])}, %% [1]
+     {mnesia,           Mnesia},
+     {mgmt_db,          MgmtDbETS + MgmtDbProc},
+     {msg_index,        MsgIndexETS + MsgIndexProc},
+     {other_ets,        ETS - Mnesia - MsgIndexETS - MgmtDbETS},
+     {binary,           Bin},
+     {code,             Code},
+     {atom,             Atom},
+     {other_system,     System - ETS - Atom - Bin - Code}].
+
+%% [1] - erlang:memory(processes) can be less than the sum of its
+%% parts. Rather than display something nonsensical, just silence any
+%% claims about negative memory. See
+%% http://erlang.org/pipermail/erlang-questions/2012-September/069320.html
+
+%%----------------------------------------------------------------------------
+
+sup_memory(Sup) ->
+    lists:sum([child_memory(P, T) || {_, P, T, _} <- sup_children(Sup)]) +
+        pid_memory(Sup).
+
+sup_children(Sup) ->
+    rabbit_misc:with_exit_handler(
+      rabbit_misc:const([]), fun () -> supervisor:which_children(Sup) end).
+
+pid_memory(Pid)  when is_pid(Pid)   -> case process_info(Pid, memory) of
+                                           {memory, M} -> M;
+                                           _           -> 0
+                                       end;
+pid_memory(Name) when is_atom(Name) -> case whereis(Name) of
+                                           P when is_pid(P) -> pid_memory(P);
+                                           _                -> 0
+                                       end.
+
+child_memory(Pid, worker)     when is_pid (Pid) -> pid_memory(Pid);
+child_memory(Pid, supervisor) when is_pid (Pid) -> sup_memory(Pid);
+child_memory(_, _)                              -> 0.
+
+mnesia_memory() ->
+    case mnesia:system_info(is_running) of
+        yes -> lists:sum([bytes(mnesia:table_info(Tab, memory)) ||
+                             Tab <- mnesia:system_info(tables)]);
+        no  -> 0
+    end.
+
+ets_memory(Name) ->
+    lists:sum([bytes(ets:info(T, memory)) || T <- ets:all(),
+                                             N <- [ets:info(T, name)],
+                                             N =:= Name]).
+
+bytes(Words) ->  Words * erlang:system_info(wordsize).
+
+plugin_memory() ->
+    lists:sum([plugin_memory(App) ||
+                  {App, _, _} <- application:which_applications(),
+                  is_plugin(atom_to_list(App))]).
+
+plugin_memory(App) ->
+    case catch application_master:get_child(
+                 application_controller:get_master(App)) of
+        {Pid, _} -> sup_memory(Pid);
+        _        -> 0
+    end.
+
+is_plugin("rabbitmq_" ++ _) -> true;
+is_plugin(App)              -> lists:member(App, ?MAGIC_PLUGINS).