Merge bug 24926

17 files changed, 487 insertions, 175 deletions

diff --git a/docs/rabbitmq-plugins.1.xml b/docs/rabbitmq-plugins.1.xml
index 8ecb4fc8..e891969f 100644
--- a/docs/rabbitmq-plugins.1.xml
+++ b/docs/rabbitmq-plugins.1.xml
@@ -40,6 +40,7 @@
   <refsynopsisdiv>
     <cmdsynopsis>
       <command>rabbitmq-plugins</command>
+      <arg choice="opt">-n <replaceable>node</replaceable></arg>
       <arg choice="req"><replaceable>command</replaceable></arg>
       <arg choice="opt" rep="repeat"><replaceable>command options</replaceable></arg>
     </cmdsynopsis>
@@ -97,12 +98,14 @@
           </variablelist>
           <para>
             Lists all plugins, their versions, dependencies and
-            descriptions. Each plugin is prefixed with a status
-            indicator - [ ] to indicate that the plugin is not
-            enabled, [E] to indicate that it is explicitly enabled,
-            [e] to indicate that it is implicitly enabled, and [!] to
-            indicate that it is enabled but missing and thus not
-            operational.
+            descriptions. Each plugin is prefixed with two status
+            indicator characters inside [ ]. The first indicator can
+            be " " to indicate that the plugin is not enabled, "E" to
+            indicate that it is explicitly enabled, "e" to indicate
+            that it is implicitly enabled, or "!" to indicate that it
+            is enabled but missing and thus not operational. The
+            second indicator can be " " to show that the plugin is not
+            running, or "*" to show that it is.
           </para>
           <para>
             If the optional pattern is given, only plugins whose
@@ -130,17 +133,31 @@
       </varlistentry>
 
       <varlistentry>
-        <term><cmdsynopsis><command>enable</command> <arg choice="req"><replaceable>plugin</replaceable> ...</arg></cmdsynopsis></term>
+        <term><cmdsynopsis><command>enable</command> <arg choice="opt">--offline</arg> <arg choice="opt">--online</arg> <arg choice="req"><replaceable>plugin</replaceable> ...</arg></cmdsynopsis></term>
         <listitem>
           <variablelist>
             <varlistentry>
+              <term>--offline</term>
+              <listitem><para>Just modify the enabled plugins file.</para></listitem>
+            </varlistentry>
+            <varlistentry>
+              <term>--online</term>
+              <listitem><para>Treat failure to connect to the running broker as fatal.</para></listitem>
+            </varlistentry>
+            <varlistentry>
               <term>plugin</term>
               <listitem><para>One or more plugins to enable.</para></listitem>
             </varlistentry>
           </variablelist>
           <para>
             Enables the specified plugins and all their
-            dependencies.
+            dependencies. This will update the enabled plugins file
+            and then attempt to connect to the broker and ensure it is
+            running all enabled plugins. By default if it is not
+            possible to connect to the running broker (for example if
+            it is stopped) then a warning is displayed. Specify
+            <command>--online</command> or
+            <command>--offline</command> to change this.
           </para>
 
           <para role="example-prefix">For example:</para>
@@ -154,17 +171,31 @@
       </varlistentry>
 
       <varlistentry>
-        <term><cmdsynopsis><command>disable</command> <arg choice="req"><replaceable>plugin</replaceable> ...</arg></cmdsynopsis></term>
+        <term><cmdsynopsis><command>disable</command> <arg choice="opt">--offline</arg> <arg choice="opt">--online</arg> <arg choice="req"><replaceable>plugin</replaceable> ...</arg></cmdsynopsis></term>
         <listitem>
           <variablelist>
             <varlistentry>
+              <term>--offline</term>
+              <listitem><para>Just modify the enabled plugins file.</para></listitem>
+            </varlistentry>
+            <varlistentry>
+              <term>--online</term>
+              <listitem><para>Treat failure to connect to the running broker as fatal.</para></listitem>
+            </varlistentry>
+            <varlistentry>
               <term>plugin</term>
               <listitem><para>One or more plugins to disable.</para></listitem>
             </varlistentry>
           </variablelist>
           <para>
-            Disables the specified plugins and all plugins that
-            depend on them.
+            Disables the specified plugins and all their
+            dependencies. This will update the enabled plugins file
+            and then attempt to connect to the broker and ensure it is
+            running all enabled plugins. By default if it is not
+            possible to connect to the running broker (for example if
+            it is stopped) then a warning is displayed. Specify
+            <command>--online</command> or
+            <command>--offline</command> to change this.
           </para>
 
           <para role="example-prefix">For example:</para>
diff --git a/scripts/rabbitmq-plugins b/scripts/rabbitmq-plugins
index bd7d0b6a..36910eff 100755
--- a/scripts/rabbitmq-plugins
+++ b/scripts/rabbitmq-plugins
@@ -21,6 +21,7 @@
 
 ##--- Set environment vars RABBITMQ_<var_name> to defaults if not set
 
+[ "x" = "x$RABBITMQ_NODENAME" ] && RABBITMQ_NODENAME=${NODENAME}
 [ "x" = "x$RABBITMQ_ENABLED_PLUGINS_FILE" ] && RABBITMQ_ENABLED_PLUGINS_FILE=${ENABLED_PLUGINS_FILE}
 [ "x" = "x$RABBITMQ_PLUGINS_DIR" ] && RABBITMQ_PLUGINS_DIR=${PLUGINS_DIR}
 
@@ -35,4 +36,5 @@ exec ${ERL_DIR}erl \
     -s rabbit_plugins_main \
     -enabled_plugins_file "$RABBITMQ_ENABLED_PLUGINS_FILE" \
     -plugins_dist_dir "$RABBITMQ_PLUGINS_DIR" \
+    -nodename $RABBITMQ_NODENAME \
     -extra "$@"
diff --git a/scripts/rabbitmq-plugins.bat b/scripts/rabbitmq-plugins.bat
index a535ebad..61e39e38 100755
--- a/scripts/rabbitmq-plugins.bat
+++ b/scripts/rabbitmq-plugins.bat
@@ -31,6 +31,10 @@ if "!RABBITMQ_BASE!"=="" (
     set RABBITMQ_BASE=!APPDATA!\!RABBITMQ_SERVICENAME!

 )

 

+if "!RABBITMQ_NODENAME!"=="" (

+    set RABBITMQ_NODENAME=rabbit@!COMPUTERNAME!

+)

+

 if not exist "!ERLANG_HOME!\bin\erl.exe" (

     echo.

     echo ******************************

@@ -51,7 +55,7 @@ if "!RABBITMQ_PLUGINS_DIR!"=="" (
     set RABBITMQ_PLUGINS_DIR=!TDP0!..\plugins

 )

 

-"!ERLANG_HOME!\bin\erl.exe" -pa "!TDP0!..\ebin" -noinput -hidden -sname rabbitmq-plugins!RANDOM!!TIME:~9! -s rabbit_plugins_main -enabled_plugins_file "!RABBITMQ_ENABLED_PLUGINS_FILE!" -plugins_dist_dir "!RABBITMQ_PLUGINS_DIR:\=/!" -extra !STAR!

+"!ERLANG_HOME!\bin\erl.exe" -pa "!TDP0!..\ebin" -noinput -hidden -sname rabbitmq-plugins!RANDOM!!TIME:~9! -s rabbit_plugins_main -enabled_plugins_file "!RABBITMQ_ENABLED_PLUGINS_FILE!" -plugins_dist_dir "!RABBITMQ_PLUGINS_DIR:\=/!" -nodename !RABBITMQ_NODENAME! -extra !STAR!

 

 endlocal

 endlocal

diff --git a/src/app_utils.erl b/src/app_utils.erl
index 0479ce66..e321888d 100644
--- a/src/app_utils.erl
+++ b/src/app_utils.erl
@@ -17,7 +17,7 @@
 
 -export([load_applications/1, start_applications/1, start_applications/2,
          stop_applications/1, stop_applications/2, app_dependency_order/2,
-         wait_for_applications/1]).
+         wait_for_applications/1, app_dependencies/1]).
 
 -ifdef(use_specs).
 
@@ -30,6 +30,7 @@
 -spec stop_applications([atom()], error_handler())  -> 'ok'.
 -spec wait_for_applications([atom()])               -> 'ok'.
 -spec app_dependency_order([atom()], boolean())     -> [digraph:vertex()].
+-spec app_dependencies(atom())                      -> [atom()].
 
 -endif.
 
@@ -74,8 +75,8 @@ wait_for_applications(Apps) ->
 
 app_dependency_order(RootApps, StripUnreachable) ->
     {ok, G} = rabbit_misc:build_acyclic_graph(
-                fun (App, _Deps) -> [{App, App}] end,
-                fun (App,  Deps) -> [{Dep, App} || Dep <- Deps] end,
+                fun ({App, _Deps}) -> [{App, App}] end,
+                fun ({App,  Deps}) -> [{Dep, App} || Dep <- Deps] end,
                 [{App, app_dependencies(App)} ||
                     {App, _Desc, _Vsn} <- application:loaded_applications()]),
     try
diff --git a/src/rabbit.erl b/src/rabbit.erl
index 29e38c1f..4901ea17 100644
--- a/src/rabbit.erl
+++ b/src/rabbit.erl
@@ -22,9 +22,8 @@
          stop_and_halt/0, await_startup/0, status/0, is_running/0,
          is_running/1, environment/0, rotate_logs/1, force_event_refresh/1,
          start_fhc/0]).
-
 -export([start/2, stop/1]).
-
+-export([start_apps/1, stop_apps/1]).
 -export([log_location/1]). %% for testing
 
 %%---------------------------------------------------------------------------
@@ -211,6 +210,7 @@
 %% this really should be an abstract type
 -type(log_location() :: 'tty' | 'undefined' | file:filename()).
 -type(param() :: atom()).
+-type(app_name() :: atom()).
 
 -spec(start/0 :: () -> 'ok').
 -spec(boot/0 :: () -> 'ok').
@@ -242,6 +242,8 @@
 -spec(maybe_insert_default_data/0 :: () -> 'ok').
 -spec(boot_delegate/0 :: () -> 'ok').
 -spec(recover/0 :: () -> 'ok').
+-spec(start_apps/1 :: ([app_name()]) -> 'ok').
+-spec(stop_apps/1 :: ([app_name()]) -> 'ok').
 
 -endif.
 
@@ -312,9 +314,7 @@ start() ->
                      ok = ensure_working_log_handlers(),
                      rabbit_node_monitor:prepare_cluster_status_files(),
                      rabbit_mnesia:check_cluster_consistency(),
-                     ok = app_utils:start_applications(
-                            app_startup_order(), fun handle_app_error/2),
-                     ok = log_broker_started(rabbit_plugins:active())
+                     broker_start()
              end).
 
 boot() ->
@@ -329,21 +329,14 @@ boot() ->
                      %% the upgrade, since if we are a secondary node the
                      %% primary node will have forgotten us
                      rabbit_mnesia:check_cluster_consistency(),
-                     Plugins = rabbit_plugins:setup(),
-                     ToBeLoaded = Plugins ++ ?APPS,
-                     ok = app_utils:load_applications(ToBeLoaded),
-                     StartupApps = app_utils:app_dependency_order(ToBeLoaded,
-                                                                  false),
-                     ok = app_utils:start_applications(
-                            StartupApps, fun handle_app_error/2),
-                     ok = log_broker_started(Plugins)
+                     broker_start()
              end).
 
-handle_app_error(App, {bad_return, {_MFA, {'EXIT', {Reason, _}}}}) ->
-    throw({could_not_start, App, Reason});
-
-handle_app_error(App, Reason) ->
-    throw({could_not_start, App, Reason}).
+broker_start() ->
+    Plugins = rabbit_plugins:setup(),
+    ToBeLoaded = Plugins ++ ?APPS,
+    start_apps(ToBeLoaded),
+    ok = log_broker_started(rabbit_plugins:active()).
 
 start_it(StartFun) ->
     Marker = spawn_link(fun() -> receive stop -> ok end end),
@@ -374,7 +367,7 @@ stop() ->
         _         -> await_startup()
     end,
     rabbit_log:info("Stopping RabbitMQ~n"),
-    ok = app_utils:stop_applications(app_shutdown_order()).
+    stop_apps(app_shutdown_order()).
 
 stop_and_halt() ->
     try
@@ -385,6 +378,36 @@ stop_and_halt() ->
     end,
     ok.
 
+start_apps(Apps) ->
+    app_utils:load_applications(Apps),
+    OrderedApps = app_utils:app_dependency_order(Apps, false),
+    case lists:member(rabbit, Apps) of
+        false -> run_boot_steps(Apps); %% plugin activation
+        true  -> ok                    %% will run during start of rabbit app
+    end,
+    ok = app_utils:start_applications(OrderedApps,
+                                      handle_app_error(could_not_start)).
+
+stop_apps(Apps) ->
+    ok = app_utils:stop_applications(
+           Apps, handle_app_error(error_during_shutdown)),
+    case lists:member(rabbit, Apps) of
+        false -> run_cleanup_steps(Apps); %% plugin deactivation
+        true  -> ok                       %% it's all going anyway
+    end,
+    ok.
+
+handle_app_error(Term) ->
+    fun(App, {bad_return, {_MFA, {'EXIT', {ExitReason, _}}}}) ->
+            throw({Term, App, ExitReason});
+       (App, Reason) ->
+            throw({Term, App, Reason})
+    end.
+
+run_cleanup_steps(Apps) ->
+    [run_step(Name, Attrs, cleanup) || {_, Name, Attrs} <- find_steps(Apps)],
+    ok.
+
 await_startup() ->
     app_utils:wait_for_applications(app_startup_order()).
 
@@ -468,7 +491,7 @@ start(normal, []) ->
             true = register(rabbit, self()),
             print_banner(),
             log_banner(),
-            [ok = run_boot_step(Step) || Step <- boot_steps()],
+            run_boot_steps(),
             {ok, SupPid};
         Error ->
             Error
@@ -496,29 +519,40 @@ app_shutdown_order() ->
 %%---------------------------------------------------------------------------
 %% boot step logic
 
-run_boot_step({_StepName, Attributes}) ->
-    case [MFA || {mfa, MFA} <- Attributes] of
+run_boot_steps() ->
+    run_boot_steps([App || {App, _, _} <- application:loaded_applications()]).
+
+run_boot_steps(Apps) ->
+    [ok = run_step(Step, Attrs, mfa) || {_, Step, Attrs} <- find_steps(Apps)],
+    ok.
+
+find_steps(Apps) ->
+    All = sort_boot_steps(rabbit_misc:all_module_attributes(rabbit_boot_step)),
+    [Step || {App, _, _} = Step <- All, lists:member(App, Apps)].
+
+run_step(StepName, Attributes, AttributeName) ->
+    case [MFA || {Key, MFA} <- Attributes,
+                 Key =:= AttributeName] of
         [] ->
             ok;
         MFAs ->
             [try
                  apply(M,F,A)
              of
-                 ok ->              ok;
-                 {error, Reason} -> boot_error(Reason, not_available)
+                 ok              -> ok;
+                 {error, Reason} -> boot_error({boot_step, StepName, Reason},
+                                               not_available)
              catch
-                 _:Reason -> boot_error(Reason, erlang:get_stacktrace())
+                 _:Reason -> boot_error({boot_step, StepName, Reason},
+                                        erlang:get_stacktrace())
              end || {M,F,A} <- MFAs],
             ok
     end.
 
-boot_steps() ->
-    sort_boot_steps(rabbit_misc:all_module_attributes(rabbit_boot_step)).
-
-vertices(_Module, Steps) ->
-    [{StepName, {StepName, Atts}} || {StepName, Atts} <- Steps].
+vertices({AppName, _Module, Steps}) ->
+    [{StepName, {AppName, StepName, Atts}} || {StepName, Atts} <- Steps].
 
-edges(_Module, Steps) ->
+edges({_AppName, _Module, Steps}) ->
     [case Key of
          requires -> {StepName, OtherStep};
          enables  -> {OtherStep, StepName}
@@ -527,7 +561,7 @@ edges(_Module, Steps) ->
             Key =:= requires orelse Key =:= enables].
 
 sort_boot_steps(UnsortedSteps) ->
-    case rabbit_misc:build_acyclic_graph(fun vertices/2, fun edges/2,
+    case rabbit_misc:build_acyclic_graph(fun vertices/1, fun edges/1,
                                          UnsortedSteps) of
         {ok, G} ->
             %% Use topological sort to find a consistent ordering (if
@@ -541,8 +575,8 @@ sort_boot_steps(UnsortedSteps) ->
             digraph:delete(G),
             %% Check that all mentioned {M,F,A} triples are exported.
             case [{StepName, {M,F,A}} ||
-                     {StepName, Attributes} <- SortedSteps,
-                     {mfa, {M,F,A}}         <- Attributes,
+                     {_App, StepName, Attributes} <- SortedSteps,
+                     {mfa, {M,F,A}}               <- Attributes,
                      not erlang:function_exported(M, F, length(A))] of
                 []               -> SortedSteps;
                 MissingFunctions -> basic_boot_error(
diff --git a/src/rabbit_amqqueue.erl b/src/rabbit_amqqueue.erl
index b0b78257..8a1d162a 100644
--- a/src/rabbit_amqqueue.erl
+++ b/src/rabbit_amqqueue.erl
@@ -18,7 +18,7 @@
 
 -export([recover/0, stop/0, start/1, declare/5, declare/6,
          delete_immediately/1, delete/3, purge/1, forget_all_durable/1]).
--export([pseudo_queue/2]).
+-export([pseudo_queue/2, immutable/1]).
 -export([lookup/1, not_found_or_absent/1, with/2, with/3, with_or_die/2,
          assert_equivalence/5,
          check_exclusive_access/2, with_exclusive_access_or_die/3,
@@ -30,7 +30,7 @@
 -export([notify_sent/2, notify_sent_queue_down/1, resume/2]).
 -export([notify_down_all/2, activate_limit_all/2, credit/5]).
 -export([on_node_down/1]).
--export([update/2, store_queue/1, policy_changed/2]).
+-export([update/2, store_queue/1, update_decorators/1, policy_changed/2]).
 -export([start_mirroring/1, stop_mirroring/1, sync_mirrors/1,
          cancel_sync_mirrors/1]).
 
@@ -176,7 +176,9 @@
 -spec(set_maximum_since_use/2 :: (pid(), non_neg_integer()) -> 'ok').
 -spec(on_node_down/1 :: (node()) -> 'ok').
 -spec(pseudo_queue/2 :: (name(), pid()) -> rabbit_types:amqqueue()).
+-spec(immutable/1 :: (rabbit_types:amqqueue()) -> rabbit_types:amqqueue()).
 -spec(store_queue/1 :: (rabbit_types:amqqueue()) -> 'ok').
+-spec(update_decorators/1 :: (name()) -> 'ok').
 -spec(policy_changed/2 ::
         (rabbit_types:amqqueue(), rabbit_types:amqqueue()) -> 'ok').
 -spec(start_mirroring/1 :: (pid()) -> 'ok').
@@ -311,13 +313,23 @@ store_queue(Q = #amqqueue{durable = true}) ->
                                  sync_slave_pids = [],
                                  gm_pids         = [],
                                  decorators      = undefined}, write),
-    store_queue0(Q);
+    store_queue_ram(Q);
 store_queue(Q = #amqqueue{durable = false}) ->
-    store_queue0(Q).
+    store_queue_ram(Q).
 
-store_queue0(Q) ->
+store_queue_ram(Q) ->
     ok = mnesia:write(rabbit_queue, rabbit_queue_decorator:set(Q), write).
 
+update_decorators(Name) ->
+    rabbit_misc:execute_mnesia_transaction(
+      fun() ->
+              case mnesia:wread({rabbit_queue, Name}) of
+                  [Q] -> store_queue_ram(Q),
+                         ok;
+                  []  -> ok
+              end
+      end).
+
 policy_changed(Q1 = #amqqueue{decorators = Decorators1},
                Q2 = #amqqueue{decorators = Decorators2}) ->
     rabbit_mirror_queue_misc:update_mirrors(Q1, Q2),
@@ -712,6 +724,13 @@ pseudo_queue(QueueName, Pid) ->
               pid          = Pid,
               slave_pids   = []}.
 
+immutable(Q) -> Q#amqqueue{pid             = none,
+                           slave_pids      = none,
+                           sync_slave_pids = none,
+                           gm_pids         = none,
+                           policy          = none,
+                           decorators      = none}.
+
 deliver([], _Delivery, _Flow) ->
     %% /dev/null optimisation
     [];
diff --git a/src/rabbit_amqqueue_process.erl b/src/rabbit_amqqueue_process.erl
index 753d8e15..97206df3 100644
--- a/src/rabbit_amqqueue_process.erl
+++ b/src/rabbit_amqqueue_process.erl
@@ -1165,7 +1165,7 @@ handle_cast({force_event_refresh, Ref},
                       emit_consumer_created(
                         Ch, CTag, true, AckRequired, QName, Prefetch, Args, Ref)
     end,
-    noreply(State);
+    noreply(rabbit_event:init_stats_timer(State, #q.stats_timer));
 
 handle_cast(notify_decorators, State) ->
     notify_decorators(State),
diff --git a/src/rabbit_channel.erl b/src/rabbit_channel.erl
index 74f9cacf..15944270 100644
--- a/src/rabbit_channel.erl
+++ b/src/rabbit_channel.erl
@@ -341,7 +341,7 @@ handle_cast({send_drained, CTagCredit}, State = #ch{writer_pid = WriterPid}) ->
 handle_cast({force_event_refresh, Ref}, State) ->
     rabbit_event:notify(channel_created, infos(?CREATION_EVENT_KEYS, State),
                         Ref),
-    noreply(State);
+    noreply(rabbit_event:init_stats_timer(State, #ch.stats_timer));
 
 handle_cast({mandatory_received, MsgSeqNo}, State = #ch{mandatory = Mand}) ->
     %% NB: don't call noreply/1 since we don't want to send confirms.
diff --git a/src/rabbit_event.erl b/src/rabbit_event.erl
index b867223b..a33103fd 100644
--- a/src/rabbit_event.erl
+++ b/src/rabbit_event.erl
@@ -23,6 +23,7 @@
          ensure_stats_timer/3, stop_stats_timer/2, reset_stats_timer/2]).
 -export([stats_level/2, if_enabled/3]).
 -export([notify/2, notify/3, notify_if/3]).
+-export([sync_notify/2, sync_notify/3]).
 
 %%----------------------------------------------------------------------------
 
@@ -61,6 +62,9 @@
 -spec(notify/2 :: (event_type(), event_props()) -> 'ok').
 -spec(notify/3 :: (event_type(), event_props(), reference() | 'none') -> 'ok').
 -spec(notify_if/3 :: (boolean(), event_type(), event_props()) -> 'ok').
+-spec(sync_notify/2 :: (event_type(), event_props()) -> 'ok').
+-spec(sync_notify/3 :: (event_type(), event_props(),
+                        reference() | 'none') -> 'ok').
 
 -endif.
 
@@ -145,7 +149,16 @@ notify_if(false, _Type, _Props) -> ok.
 notify(Type, Props) -> notify(Type, Props, none).
 
 notify(Type, Props, Ref) ->
-    gen_event:notify(?MODULE, #event{type      = Type,
-                                     props     = Props,
-                                     reference = Ref,
-                                     timestamp = os:timestamp()}).
+    gen_event:notify(?MODULE, event_cons(Type, Props, Ref)).
+
+sync_notify(Type, Props) -> sync_notify(Type, Props, none).
+
+sync_notify(Type, Props, Ref) ->
+    gen_event:sync_notify(?MODULE, event_cons(Type, Props, Ref)).
+
+event_cons(Type, Props, Ref) ->
+    #event{type      = Type,
+           props     = Props,
+           reference = Ref,
+           timestamp = os:timestamp()}.
+
diff --git a/src/rabbit_exchange.erl b/src/rabbit_exchange.erl
index 350de2a8..a1772f0a 100644
--- a/src/rabbit_exchange.erl
+++ b/src/rabbit_exchange.erl
@@ -20,7 +20,8 @@
 
 -export([recover/0, policy_changed/2, callback/4, declare/6,
          assert_equivalence/6, assert_args_equivalence/2, check_type/1,
-         lookup/1, lookup_or_die/1, list/1, lookup_scratch/2, update_scratch/3,
+         lookup/1, lookup_or_die/1, list/0, list/1, lookup_scratch/2,
+         update_scratch/3, update_decorators/1, immutable/1,
          info_keys/0, info/1, info/2, info_all/1, info_all/2,
          route/2, delete/2, validate_binding/2]).
 %% these must be run inside a mnesia tx
@@ -61,6 +62,7 @@
 -spec(lookup_or_die/1 ::
         (name()) -> rabbit_types:exchange() |
                     rabbit_types:channel_exit()).
+-spec(list/0 :: () -> [rabbit_types:exchange()]).
 -spec(list/1 :: (rabbit_types:vhost()) -> [rabbit_types:exchange()]).
 -spec(lookup_scratch/2 :: (name(), atom()) ->
                                rabbit_types:ok(term()) |
@@ -70,6 +72,8 @@
         (name(),
          fun((rabbit_types:exchange()) -> rabbit_types:exchange()))
          -> not_found | rabbit_types:exchange()).
+-spec(update_decorators/1 :: (name()) -> 'ok').
+-spec(immutable/1 :: (rabbit_types:exchange()) -> rabbit_types:exchange()).
 -spec(info_keys/0 :: () -> rabbit_types:info_keys()).
 -spec(info/1 :: (rabbit_types:exchange()) -> rabbit_types:infos()).
 -spec(info/2 ::
@@ -107,7 +111,7 @@ recover() ->
            end,
            fun (X, Tx) ->
                    X1 = case Tx of
-                            true  -> store0(X);
+                            true  -> store_ram(X);
                             false -> rabbit_exchange_decorator:set(X)
                         end,
                    callback(X1, create, map_create_tx(Tx), [X1])
@@ -185,11 +189,11 @@ map_create_tx(false) -> none.
 store(X = #exchange{durable = true}) ->
     mnesia:write(rabbit_durable_exchange, X#exchange{decorators = undefined},
                  write),
-    store0(X);
+    store_ram(X);
 store(X = #exchange{durable = false}) ->
-    store0(X).
+    store_ram(X).
 
-store0(X) ->
+store_ram(X) ->
     X1 = rabbit_exchange_decorator:set(X),
     ok = mnesia:write(rabbit_exchange, rabbit_exchange_decorator:set(X1),
                       write),
@@ -241,6 +245,8 @@ lookup_or_die(Name) ->
         {error, not_found} -> rabbit_misc:not_found(Name)
     end.
 
+list() -> mnesia:dirty_match_object(rabbit_exchange, #exchange{_ = '_'}).
+
 %% Not dirty_match_object since that would not be transactional when used in a
 %% tx context
 list(VHostPath) ->
@@ -285,6 +291,16 @@ update_scratch(Name, App, Fun) ->
               ok
       end).
 
+update_decorators(Name) ->
+    rabbit_misc:execute_mnesia_transaction(
+      fun() ->
+              case mnesia:wread({rabbit_exchange, Name}) of
+                  [X] -> store_ram(X),
+                         ok;
+                  []  -> ok
+              end
+      end).
+
 update(Name, Fun) ->
     case mnesia:wread({rabbit_exchange, Name}) of
         [X] -> X1 = Fun(X),
@@ -292,6 +308,10 @@ update(Name, Fun) ->
         []  -> not_found
     end.
 
+immutable(X) -> X#exchange{scratches  = none,
+                           policy     = none,
+                           decorators = none}.
+
 info_keys() -> ?INFO_KEYS.
 
 map(VHostPath, F) ->
diff --git a/src/rabbit_exchange_decorator.erl b/src/rabbit_exchange_decorator.erl
index 2f056b1b..900f9c32 100644
--- a/src/rabbit_exchange_decorator.erl
+++ b/src/rabbit_exchange_decorator.erl
@@ -18,7 +18,7 @@
 
 -include("rabbit.hrl").
 
--export([select/2, set/1]).
+-export([select/2, set/1, register/2, unregister/1]).
 
 %% This is like an exchange type except that:
 %%
@@ -104,3 +104,25 @@ list() -> [M || {_, M} <- rabbit_registry:lookup_all(exchange_decorator)].
 
 cons_if_eq(Select,  Select, Item,  List) -> [Item | List];
 cons_if_eq(_Select, _Other, _Item, List) -> List.
+
+register(TypeName, ModuleName) ->
+    rabbit_registry:register(exchange_decorator, TypeName, ModuleName),
+    [maybe_recover(X) || X <- rabbit_exchange:list()],
+    ok.
+
+unregister(TypeName) ->
+    rabbit_registry:unregister(exchange_decorator, TypeName),
+    [maybe_recover(X) || X <- rabbit_exchange:list()],
+    ok.
+
+maybe_recover(X = #exchange{name       = Name,
+                            decorators = Decs}) ->
+    #exchange{decorators = Decs1} = set(X),
+    Old = lists:sort(select(all, Decs)),
+    New = lists:sort(select(all, Decs1)),
+    case New of
+        Old -> ok;
+        _   -> %% TODO create a tx here for non-federation decorators
+               [M:create(none, X) || M <- New -- Old],
+               rabbit_exchange:update_decorators(Name)
+    end.
diff --git a/src/rabbit_misc.erl b/src/rabbit_misc.erl
index cff16040..6f353da5 100644
--- a/src/rabbit_misc.erl
+++ b/src/rabbit_misc.erl
@@ -210,7 +210,8 @@
          [string()])
         -> {'ok', {atom(), [{string(), string()}], [string()]}} |
            'no_command').
--spec(all_module_attributes/1 :: (atom()) -> [{atom(), [term()]}]).
+-spec(all_module_attributes/1 ::
+        (atom()) -> [{atom(), atom(), [term()]}]).
 -spec(build_acyclic_graph/3 ::
         (graph_vertex_fun(), graph_edge_fun(), [{atom(), [term()]}])
         -> rabbit_types:ok_or_error2(digraph(),
@@ -852,20 +853,20 @@ module_attributes(Module) ->
     end.
 
 all_module_attributes(Name) ->
-    Modules =
+    Targets =
         lists:usort(
           lists:append(
-            [Modules || {App, _, _}   <- application:loaded_applications(),
-                        {ok, Modules} <- [application:get_key(App, modules)]])),
+            [[{App, Module} || Module <- Modules] ||
+                {App, _, _}   <- application:loaded_applications(),
+                {ok, Modules} <- [application:get_key(App, modules)]])),
     lists:foldl(
-      fun (Module, Acc) ->
+      fun ({App, Module}, Acc) ->
               case lists:append([Atts || {N, Atts} <- module_attributes(Module),
                                          N =:= Name]) of
                   []   -> Acc;
-                  Atts -> [{Module, Atts} | Acc]
+                  Atts -> [{App, Module, Atts} | Acc]
               end
-      end, [], Modules).
-
+      end, [], Targets).
 
 build_acyclic_graph(VertexFun, EdgeFun, Graph) ->
     G = digraph:new([acyclic]),
@@ -873,13 +874,13 @@ build_acyclic_graph(VertexFun, EdgeFun, Graph) ->
         [case digraph:vertex(G, Vertex) of
              false -> digraph:add_vertex(G, Vertex, Label);
              _     -> ok = throw({graph_error, {vertex, duplicate, Vertex}})
-         end || {Module, Atts}  <- Graph,
-                {Vertex, Label} <- VertexFun(Module, Atts)],
+         end || GraphElem       <- Graph,
+                {Vertex, Label} <- VertexFun(GraphElem)],
         [case digraph:add_edge(G, From, To) of
              {error, E} -> throw({graph_error, {edge, E, From, To}});
              _          -> ok
-         end || {Module, Atts} <- Graph,
-                {From, To}     <- EdgeFun(Module, Atts)],
+         end || GraphElem  <- Graph,
+                {From, To} <- EdgeFun(GraphElem)],
         {ok, G}
     catch {graph_error, Reason} ->
             true = digraph:delete(G),
diff --git a/src/rabbit_plugins.erl b/src/rabbit_plugins.erl
index c0fb05e2..7817626c 100644
--- a/src/rabbit_plugins.erl
+++ b/src/rabbit_plugins.erl
@@ -18,6 +18,7 @@
 -include("rabbit.hrl").
 
 -export([setup/0, active/0, read_enabled/1, list/1, dependencies/3]).
+-export([ensure/1]).
 
 %%----------------------------------------------------------------------------
 
@@ -31,22 +32,54 @@
 -spec(read_enabled/1 :: (file:filename()) -> [plugin_name()]).
 -spec(dependencies/3 :: (boolean(), [plugin_name()], [#plugin{}]) ->
                              [plugin_name()]).
-
+-spec(ensure/1  :: (string()) -> {'ok', [atom()], [atom()]} | {error, any()}).
 -endif.
 
 %%----------------------------------------------------------------------------
 
+ensure(FileJustChanged) ->
+    {ok, OurFile} = application:get_env(rabbit, enabled_plugins_file),
+    case OurFile of
+        FileJustChanged ->
+            {ok, Dir} = application:get_env(rabbit, plugins_dir),
+            Enabled = read_enabled(OurFile),
+            Wanted = dependencies(false, Enabled, list(Dir)),
+            prepare_plugins(Enabled),
+            Current = active(),
+            Start = Wanted -- Current,
+            Stop = Current -- Wanted,
+            rabbit:start_apps(Start),
+            %% We need sync_notify here since mgmt will attempt to look at all
+            %% the modules for the disabled plugins - if they are unloaded
+            %% that won't work.
+            ok = rabbit_event:sync_notify(plugins_changed, [{enabled,  Start},
+                                                            {disabled, Stop}]),
+            rabbit:stop_apps(Stop),
+            clean_plugins(Stop),
+            {ok, Start, Stop};
+        _ ->
+            {error, {enabled_plugins_mismatch, FileJustChanged, OurFile}}
+    end.
+
 %% @doc Prepares the file system and installs all enabled plugins.
 setup() ->
-    {ok, PluginDir}   = application:get_env(rabbit, plugins_dir),
     {ok, ExpandDir}   = application:get_env(rabbit, plugins_expand_dir),
+
+    %% Eliminate the contents of the destination directory
+    case delete_recursively(ExpandDir) of
+        ok          -> ok;
+        {error, E1} -> throw({error, {cannot_delete_plugins_expand_dir,
+                                      [ExpandDir, E1]}})
+    end,
+
     {ok, EnabledFile} = application:get_env(rabbit, enabled_plugins_file),
-    prepare_plugins(EnabledFile, PluginDir, ExpandDir).
+    Enabled = read_enabled(EnabledFile),
+    prepare_plugins(Enabled).
 
 %% @doc Lists the plugins which are currently running.
 active() ->
     {ok, ExpandDir} = application:get_env(rabbit, plugins_expand_dir),
-    InstalledPlugins = [ P#plugin.name || P <- list(ExpandDir) ],
+    InstalledPlugins = plugin_names(list(ExpandDir)),
     [App || {App, _, _} <- rabbit_misc:which_applications(),
             lists:member(App, InstalledPlugins)].
 
@@ -67,7 +100,7 @@ list(PluginsDir) ->
         _  -> error_logger:warning_msg(
                 "Problem reading some plugins: ~p~n", [Problems])
     end,
-    Plugins.
+    ensure_dependencies(Plugins).
 
 %% @doc Read the list of enabled plugins from the supplied term file.
 read_enabled(PluginsFile) ->
@@ -86,15 +119,10 @@ read_enabled(PluginsFile) ->
 %% the resulting list, otherwise they're skipped.
 dependencies(Reverse, Sources, AllPlugins) ->
     {ok, G} = rabbit_misc:build_acyclic_graph(
-                fun (App, _Deps) -> [{App, App}] end,
-                fun (App,  Deps) -> [{App, Dep} || Dep <- Deps] end,
-                lists:ukeysort(
-                  1, [{Name, Deps} ||
-                         #plugin{name         = Name,
-                                 dependencies = Deps} <- AllPlugins] ++
-                      [{Dep,   []} ||
-                          #plugin{dependencies = Deps} <- AllPlugins,
-                          Dep                          <- Deps])),
+                fun ({App, _Deps}) -> [{App, App}] end,
+                fun ({App,  Deps}) -> [{App, Dep} || Dep <- Deps] end,
+                [{Name, Deps} || #plugin{name         = Name,
+                                         dependencies = Deps} <- AllPlugins]),
     Dests = case Reverse of
                 false -> digraph_utils:reachable(Sources, G);
                 true  -> digraph_utils:reaching(Sources, G)
@@ -102,11 +130,35 @@ dependencies(Reverse, Sources, AllPlugins) ->
     true = digraph:delete(G),
     Dests.
 
+%% Make sure we don't list OTP apps in here, and also that we create
+%% fake plugins for missing dependencies.
+ensure_dependencies(Plugins) ->
+    Names = plugin_names(Plugins),
+    NotThere = [Dep || #plugin{dependencies = Deps} <- Plugins,
+                       Dep                          <- Deps,
+                       not lists:member(Dep, Names)],
+    {OTP, Missing} = lists:partition(fun is_loadable/1, NotThere),
+    Plugins1 = [P#plugin{dependencies = Deps -- OTP}
+                || P = #plugin{dependencies = Deps} <- Plugins],
+    Fake = [#plugin{name         = Name,
+                    dependencies = []}|| Name <- Missing],
+    Plugins1 ++ Fake.
+
+is_loadable(App) ->
+    case application:load(App) of
+        {error, {already_loaded, _}} -> true;
+        ok                           -> application:unload(App),
+                                        true;
+        _                            -> false
+   end.
+
 %%----------------------------------------------------------------------------
 
-prepare_plugins(EnabledFile, PluginsDistDir, ExpandDir) ->
+prepare_plugins(Enabled) ->
+    {ok, PluginsDistDir} = application:get_env(rabbit, plugins_dir),
+    {ok, ExpandDir} = application:get_env(rabbit, plugins_expand_dir),
+
     AllPlugins = list(PluginsDistDir),
-    Enabled = read_enabled(EnabledFile),
     ToUnpack = dependencies(false, Enabled, AllPlugins),
     ToUnpackPlugins = lookup_plugins(ToUnpack, AllPlugins),
 
@@ -117,12 +169,6 @@ prepare_plugins(EnabledFile, PluginsDistDir, ExpandDir) ->
                      [Missing])
     end,
 
-    %% Eliminate the contents of the destination directory
-    case delete_recursively(ExpandDir) of
-        ok          -> ok;
-        {error, E1} -> throw({error, {cannot_delete_plugins_expand_dir,
-                                      [ExpandDir, E1]}})
-    end,
     case filelib:ensure_dir(ExpandDir ++ "/") of
         ok          -> ok;
         {error, E2} -> throw({error, {cannot_create_plugins_expand_dir,
@@ -134,6 +180,20 @@ prepare_plugins(EnabledFile, PluginsDistDir, ExpandDir) ->
     [prepare_dir_plugin(PluginAppDescPath) ||
         PluginAppDescPath <- filelib:wildcard(ExpandDir ++ "/*/ebin/*.app")].
 
+clean_plugins(Plugins) ->
+    {ok, ExpandDir} = application:get_env(rabbit, plugins_expand_dir),
+    [clean_plugin(Plugin, ExpandDir) || Plugin <- Plugins].
+
+clean_plugin(Plugin, ExpandDir) ->
+    {ok, Mods} = application:get_key(Plugin, modules),
+    application:unload(Plugin),
+    [begin
+         code:soft_purge(Mod),
+         code:delete(Mod),
+         false = code:is_loaded(Mod)
+     end || Mod <- Mods],
+    delete_recursively(rabbit_misc:format("~s/~s", [ExpandDir, Plugin])).
+
 prepare_dir_plugin(PluginAppDescPath) ->
     code:add_path(filename:dirname(PluginAppDescPath)),
     list_to_atom(filename:basename(PluginAppDescPath, ".app")).
@@ -172,8 +232,7 @@ plugin_info(Base, {app, App0}) ->
 mkplugin(Name, Props, Type, Location) ->
     Version = proplists:get_value(vsn, Props, "0"),
     Description = proplists:get_value(description, Props, ""),
-    Dependencies =
-        filter_applications(proplists:get_value(applications, Props, [])),
+    Dependencies = proplists:get_value(applications, Props, []),
     #plugin{name = Name, version = Version, description = Description,
             dependencies = Dependencies, location = Location, type = Type}.
 
@@ -206,18 +265,6 @@ parse_binary(Bin) ->
         Err -> {error, {invalid_app, Err}}
     end.
 
-filter_applications(Applications) ->
-    [Application || Application <- Applications,
-                    not is_available_app(Application)].
-
-is_available_app(Application) ->
-    case application:load(Application) of
-        {error, {already_loaded, _}} -> true;
-        ok                           -> application:unload(Application),
-                                        true;
-        _                            -> false
-    end.
-
 plugin_names(Plugins) ->
     [Name || #plugin{name = Name} <- Plugins].
 
diff --git a/src/rabbit_plugins_main.erl b/src/rabbit_plugins_main.erl
index 89e16f14..98418d8c 100644
--- a/src/rabbit_plugins_main.erl
+++ b/src/rabbit_plugins_main.erl
@@ -18,23 +18,33 @@
 -include("rabbit.hrl").
 
 -export([start/0, stop/0]).
+-export([action/6]).
 
+-define(NODE_OPT, "-n").
 -define(VERBOSE_OPT, "-v").
 -define(MINIMAL_OPT, "-m").
 -define(ENABLED_OPT, "-E").
 -define(ENABLED_ALL_OPT, "-e").
+-define(OFFLINE_OPT, "--offline").
+-define(ONLINE_OPT, "--online").
 
+-define(NODE_DEF(Node), {?NODE_OPT, {option, Node}}).
 -define(VERBOSE_DEF, {?VERBOSE_OPT, flag}).
 -define(MINIMAL_DEF, {?MINIMAL_OPT, flag}).
 -define(ENABLED_DEF, {?ENABLED_OPT, flag}).
 -define(ENABLED_ALL_DEF, {?ENABLED_ALL_OPT, flag}).
+-define(OFFLINE_DEF, {?OFFLINE_OPT, flag}).
+-define(ONLINE_DEF, {?ONLINE_OPT, flag}).
 
--define(GLOBAL_DEFS, []).
+-define(RPC_TIMEOUT, infinity).
+
+-define(GLOBAL_DEFS(Node), [?NODE_DEF(Node)]).
 
 -define(COMMANDS,
         [{list, [?VERBOSE_DEF, ?MINIMAL_DEF, ?ENABLED_DEF, ?ENABLED_ALL_DEF]},
-         enable,
-         disable]).
+         {enable, [?OFFLINE_DEF, ?ONLINE_DEF]},
+         {disable, [?OFFLINE_DEF, ?ONLINE_DEF]},
+         {sync, []}]).
 
 %%----------------------------------------------------------------------------
 
@@ -51,11 +61,10 @@
 start() ->
     {ok, [[PluginsFile|_]|_]} =
         init:get_argument(enabled_plugins_file),
+    {ok, [[NodeStr|_]|_]} = init:get_argument(nodename),
     {ok, [[PluginsDir|_]|_]} = init:get_argument(plugins_dist_dir),
     {Command, Opts, Args} =
-        case rabbit_misc:parse_arguments(?COMMANDS, ?GLOBAL_DEFS,
-                                         init:get_plain_arguments())
-        of
+        case parse_arguments(init:get_plain_arguments(), NodeStr) of
             {ok, Res}  -> Res;
             no_command -> print_error("could not recognise command", []),
                           usage()
@@ -67,7 +76,8 @@ start() ->
                             [string:join([atom_to_list(Command) | Args], " ")])
         end,
 
-    case catch action(Command, Args, Opts, PluginsFile, PluginsDir) of
+    Node = proplists:get_value(?NODE_OPT, Opts),
+    case catch action(Command, Node, Args, Opts, PluginsFile, PluginsDir) of
         ok ->
             rabbit_misc:quit(0);
         {'EXIT', {function_clause, [{?MODULE, action, _} | _]}} ->
@@ -82,6 +92,13 @@ start() ->
         {error_string, Reason} ->
             print_error("~s", [Reason]),
             rabbit_misc:quit(2);
+        {badrpc, {'EXIT', Reason}} ->
+            print_error("~p", [Reason]),
+            rabbit_misc:quit(2);
+        {badrpc, Reason} ->
+            print_error("unable to connect to node ~w: ~w", [Node, Reason]),
+            print_badrpc_diagnostics([Node]),
+            rabbit_misc:quit(2);
         Other ->
             print_error("~p", [Other]),
             rabbit_misc:quit(2)
@@ -92,20 +109,32 @@ stop() ->
 
 %%----------------------------------------------------------------------------
 
-action(list, [], Opts, PluginsFile, PluginsDir) ->
-    action(list, [".*"], Opts, PluginsFile, PluginsDir);
-action(list, [Pat], Opts, PluginsFile, PluginsDir) ->
-    format_plugins(Pat, Opts, PluginsFile, PluginsDir);
+parse_arguments(CmdLine, NodeStr) ->
+    case rabbit_misc:parse_arguments(
+           ?COMMANDS, ?GLOBAL_DEFS(NodeStr), CmdLine) of
+        {ok, {Cmd, Opts0, Args}} ->
+            Opts = [case K of
+                        ?NODE_OPT -> {?NODE_OPT, rabbit_nodes:make(V)};
+                        _         -> {K, V}
+                    end || {K, V} <- Opts0],
+            {ok, {Cmd, Opts, Args}};
+        E ->
+            E
+    end.
+
+action(list, Node, [], Opts, PluginsFile, PluginsDir) ->
+    action(list, Node, [".*"], Opts, PluginsFile, PluginsDir);
+action(list, Node, [Pat], Opts, PluginsFile, PluginsDir) ->
+    format_plugins(Node, Pat, Opts, PluginsFile, PluginsDir);
 
-action(enable, ToEnable0, _Opts, PluginsFile, PluginsDir) ->
+action(enable, Node, ToEnable0, Opts, PluginsFile, PluginsDir) ->
     case ToEnable0 of
         [] -> throw({error_string, "Not enough arguments for 'enable'"});
         _  -> ok
     end,
     AllPlugins = rabbit_plugins:list(PluginsDir),
     Enabled = rabbit_plugins:read_enabled(PluginsFile),
-    ImplicitlyEnabled = rabbit_plugins:dependencies(false,
-                                                    Enabled, AllPlugins),
+    ImplicitlyEnabled = rabbit_plugins:dependencies(false, Enabled, AllPlugins),
     ToEnable = [list_to_atom(Name) || Name <- ToEnable0],
     Missing = ToEnable -- plugin_names(AllPlugins),
     NewEnabled = lists:usort(Enabled ++ ToEnable),
@@ -124,18 +153,20 @@ action(enable, ToEnable0, _Opts, PluginsFile, PluginsDir) ->
     case NewEnabled -- ImplicitlyEnabled of
         [] -> io:format("Plugin configuration unchanged.~n");
         _  -> print_list("The following plugins have been enabled:",
-                         NewImplicitlyEnabled -- ImplicitlyEnabled),
-              report_change()
-    end;
+                         NewImplicitlyEnabled -- ImplicitlyEnabled)
+    end,
+    action_change(
+      Opts, Node, ImplicitlyEnabled, NewImplicitlyEnabled, PluginsFile);
 
-action(disable, ToDisable0, _Opts, PluginsFile, PluginsDir) ->
+action(disable, Node, ToDisable0, Opts, PluginsFile, PluginsDir) ->
     case ToDisable0 of
         [] -> throw({error_string, "Not enough arguments for 'disable'"});
         _  -> ok
     end,
-    ToDisable = [list_to_atom(Name) || Name <- ToDisable0],
-    Enabled = rabbit_plugins:read_enabled(PluginsFile),
     AllPlugins = rabbit_plugins:list(PluginsDir),
+    Enabled = rabbit_plugins:read_enabled(PluginsFile),
+    ImplicitlyEnabled = rabbit_plugins:dependencies(false, Enabled, AllPlugins),
+    ToDisable = [list_to_atom(Name) || Name <- ToDisable0],
     Missing = ToDisable -- plugin_names(AllPlugins),
     case Missing of
         [] -> ok;
@@ -144,30 +175,35 @@ action(disable, ToDisable0, _Opts, PluginsFile, PluginsDir) ->
     end,
     ToDisableDeps = rabbit_plugins:dependencies(true, ToDisable, AllPlugins),
     NewEnabled = Enabled -- ToDisableDeps,
+    NewImplicitlyEnabled = rabbit_plugins:dependencies(false,
+                                                       NewEnabled, AllPlugins),
     case length(Enabled) =:= length(NewEnabled) of
         true  -> io:format("Plugin configuration unchanged.~n");
-        false -> ImplicitlyEnabled =
-                     rabbit_plugins:dependencies(false, Enabled, AllPlugins),
-                 NewImplicitlyEnabled =
-                     rabbit_plugins:dependencies(false,
-                                                 NewEnabled, AllPlugins),
-                 print_list("The following plugins have been disabled:",
+        false -> print_list("The following plugins have been disabled:",
                             ImplicitlyEnabled -- NewImplicitlyEnabled),
-                 write_enabled_plugins(PluginsFile, NewEnabled),
-                 report_change()
-    end.
+                 write_enabled_plugins(PluginsFile, NewEnabled)
+    end,
+    action_change(
+      Opts, Node, ImplicitlyEnabled, NewImplicitlyEnabled, PluginsFile);
+
+action(sync, Node, [], _Opts, PluginsFile, _PluginsDir) ->
+    sync(Node, true, PluginsFile).
 
 %%----------------------------------------------------------------------------
 
-print_error(Format, Args) ->
-    rabbit_misc:format_stderr("Error: " ++ Format ++ "~n", Args).
+fmt_stderr(Format, Args) -> rabbit_misc:format_stderr(Format ++ "~n", Args).
+
+print_error(Format, Args) -> fmt_stderr("Error: " ++ Format, Args).
+
+print_badrpc_diagnostics(Nodes) ->
+    fmt_stderr(rabbit_nodes:diagnostics(Nodes), []).
 
 usage() ->
     io:format("~s", [rabbit_plugins_usage:usage()]),
     rabbit_misc:quit(1).
 
 %% Pretty print a list of plugins.
-format_plugins(Pattern, Opts, PluginsFile, PluginsDir) ->
+format_plugins(Node, Pattern, Opts, PluginsFile, PluginsDir) ->
     Verbose = proplists:get_bool(?VERBOSE_OPT, Opts),
     Minimal = proplists:get_bool(?MINIMAL_OPT, Opts),
     Format = case {Verbose, Minimal} of
@@ -182,9 +218,14 @@ format_plugins(Pattern, Opts, PluginsFile, PluginsDir) ->
 
     AvailablePlugins = rabbit_plugins:list(PluginsDir),
     EnabledExplicitly = rabbit_plugins:read_enabled(PluginsFile),
-    EnabledImplicitly =
-        rabbit_plugins:dependencies(false, EnabledExplicitly,
-                                    AvailablePlugins) -- EnabledExplicitly,
+    AllEnabled = rabbit_plugins:dependencies(false, EnabledExplicitly,
+                                             AvailablePlugins),
+    EnabledImplicitly = AllEnabled -- EnabledExplicitly,
+    {StatusMsg, Running} =
+        case rpc:call(Node, rabbit_plugins, active, [], ?RPC_TIMEOUT) of
+            {badrpc, _} -> {"[failed to contact ~s - status not shown]", []};
+            Active      -> {"* = running on ~s", Active}
+        end,
     Missing = [#plugin{name = Name, dependencies = []} ||
                   Name <- ((EnabledExplicitly ++ EnabledImplicitly) --
                                plugin_names(AvailablePlugins))],
@@ -192,31 +233,42 @@ format_plugins(Pattern, Opts, PluginsFile, PluginsDir) ->
     Plugins = [ Plugin ||
                   Plugin = #plugin{name = Name} <- AvailablePlugins ++ Missing,
                   re:run(atom_to_list(Name), RE, [{capture, none}]) =:= match,
-                  if OnlyEnabled    ->  lists:member(Name, EnabledExplicitly);
-                     OnlyEnabledAll -> (lists:member(Name,
-                                                     EnabledExplicitly) or
-                                        lists:member(Name, EnabledImplicitly));
+                  if OnlyEnabled    -> lists:member(Name, EnabledExplicitly);
+                     OnlyEnabledAll -> lists:member(Name, EnabledExplicitly) or
+                                           lists:member(Name,EnabledImplicitly);
                      true           -> true
                   end],
     Plugins1 = usort_plugins(Plugins),
     MaxWidth = lists:max([length(atom_to_list(Name)) ||
                              #plugin{name = Name} <- Plugins1] ++ [0]),
-    [format_plugin(P, EnabledExplicitly, EnabledImplicitly,
+    case Format of
+        minimal -> ok;
+        _       -> io:format(" Configured: E = explicitly enabled; "
+                             "e = implicitly enabled; ! = missing~n"
+                             " | Status:   ~s~n"
+                             " |/~n", [rabbit_misc:format(StatusMsg, [Node])])
+    end,
+    [format_plugin(P, EnabledExplicitly, EnabledImplicitly, Running,
                    plugin_names(Missing), Format, MaxWidth) || P <- Plugins1],
     ok.
 
 format_plugin(#plugin{name = Name, version = Version,
                       description = Description, dependencies = Deps},
-              EnabledExplicitly, EnabledImplicitly, Missing,
-              Format, MaxWidth) ->
-    Glyph = case {lists:member(Name, EnabledExplicitly),
-                  lists:member(Name, EnabledImplicitly),
-                  lists:member(Name, Missing)} of
-                {true, false, false} -> "[E]";
-                {false, true, false} -> "[e]";
-                {_,        _,  true} -> "[!]";
-                _                    -> "[ ]"
-            end,
+              EnabledExplicitly, EnabledImplicitly, Running,
+              Missing, Format, MaxWidth) ->
+    EnabledGlyph = case {lists:member(Name, EnabledExplicitly),
+                         lists:member(Name, EnabledImplicitly),
+                         lists:member(Name, Missing)} of
+                       {true, false, false} -> "E";
+                       {false, true, false} -> "e";
+                       {_,        _,  true} -> "!";
+                       _                    -> " "
+                   end,
+    RunningGlyph = case lists:member(Name, Running) of
+                       true  -> "*";
+                       false -> " "
+                   end,
+    Glyph = rabbit_misc:format("[~s~s]", [EnabledGlyph, RunningGlyph]),
     Opt = fun (_F, A, A) -> ok;
               ( F, A, _) -> io:format(F, [A])
           end,
@@ -227,9 +279,9 @@ format_plugin(#plugin{name = Name, version = Version,
                    Opt("~s", Version, undefined),
                    io:format("~n");
         verbose -> io:format("~s ~w~n", [Glyph, Name]),
-                   Opt("    Version:     \t~s~n", Version,     undefined),
-                   Opt("    Dependencies:\t~p~n", Deps,        []),
-                   Opt("    Description: \t~s~n", Description, undefined),
+                   Opt("     Version:     \t~s~n", Version,     undefined),
+                   Opt("     Dependencies:\t~p~n", Deps,        []),
+                   Opt("     Description: \t~s~n", Description, undefined),
                    io:format("~n")
     end.
 
@@ -262,6 +314,51 @@ write_enabled_plugins(PluginsFile, Plugins) ->
                                           PluginsFile, Reason}})
     end.
 
-report_change() ->
-    io:format("Plugin configuration has changed. "
-              "Restart RabbitMQ for changes to take effect.~n").
+action_change(Opts, Node, Old, New, PluginsFile) ->
+    action_change0(proplists:get_bool(?OFFLINE_OPT, Opts),
+                   proplists:get_bool(?ONLINE_OPT, Opts),
+                   Node, Old, New, PluginsFile).
+
+action_change0(true, _Online, _Node, Same, Same, _PluginsFile) ->
+    %% Definitely nothing to do
+    ok;
+action_change0(true, _Online, _Node, _Old, _New, _PluginsFile) ->
+    io:format("Offline change; changes will take effect at broker restart.~n");
+action_change0(false, Online, Node, _Old, _New, PluginsFile) ->
+    sync(Node, Online, PluginsFile).
+
+sync(Node, ForceOnline, PluginsFile) ->
+    rpc_call(Node, ForceOnline, rabbit_plugins, ensure, [PluginsFile]).
+
+rpc_call(Node, Online, Mod, Fun, Args) ->
+    io:format("Applying plugin configuration to ~s...", [Node]),
+    case rpc:call(Node, Mod, Fun, Args) of
+        {ok, [], []} ->
+            io:format(" nothing to do.~n", []);
+        {ok, Start, []} ->
+            io:format(" started ~b plugin~s.~n", [length(Start), plur(Start)]);
+        {ok, [], Stop} ->
+            io:format(" stopped ~b plugin~s.~n", [length(Stop), plur(Stop)]);
+        {ok, Start, Stop} ->
+            io:format(" stopped ~b plugin~s and started ~b plugin~s.~n",
+                      [length(Stop), plur(Stop), length(Start), plur(Start)]);
+        {badrpc, nodedown} = Error ->
+            io:format(" failed.~n", []),
+            case Online of
+                true  -> Error;
+                false -> io:format(
+                           " * Could not contact node ~s.~n"
+                           " * Changes will take effect at broker restart.~n"
+                           " * Specify --online for diagnostics and to treat "
+                           "this as a failure.~n"
+                           " * Specify --offline to disable changes to running "
+                           "broker.~n",
+                           [Node])
+            end;
+        Error ->
+            io:format(" failed.~n", []),
+            Error
+    end.
+
+plur([_]) -> "";
+plur(_)   -> "s".
diff --git a/src/rabbit_queue_decorator.erl b/src/rabbit_queue_decorator.erl
index 6205e2dc..adfe0c7f 100644
--- a/src/rabbit_queue_decorator.erl
+++ b/src/rabbit_queue_decorator.erl
@@ -2,7 +2,7 @@
 
 -include("rabbit.hrl").
 
--export([select/1, set/1]).
+-export([select/1, set/1, register/2, unregister/1]).
 
 %%----------------------------------------------------------------------------
 
@@ -41,3 +41,24 @@ select(Modules) ->
 set(Q) -> Q#amqqueue{decorators = [D || D <- list(), D:active_for(Q)]}.
 
 list() -> [M || {_, M} <- rabbit_registry:lookup_all(queue_decorator)].
+
+register(TypeName, ModuleName) ->
+    rabbit_registry:register(queue_decorator, TypeName, ModuleName),
+    [maybe_recover(Q) || Q <- rabbit_amqqueue:list()],
+    ok.
+
+unregister(TypeName) ->
+    rabbit_registry:unregister(queue_decorator, TypeName),
+    [maybe_recover(Q) || Q <- rabbit_amqqueue:list()],
+    ok.
+
+maybe_recover(Q = #amqqueue{name       = Name,
+                            decorators = Decs}) ->
+    #amqqueue{decorators = Decs1} = set(Q),
+    Old = lists:sort(select(Decs)),
+    New = lists:sort(select(Decs1)),
+    case New of
+        Old -> ok;
+        _   -> [M:startup(Q) || M <- New -- Old],
+               rabbit_amqqueue:update_decorators(Name)
+    end.
diff --git a/src/rabbit_reader.erl b/src/rabbit_reader.erl
index ddaf205e..906c4b6e 100644
--- a/src/rabbit_reader.erl
+++ b/src/rabbit_reader.erl
@@ -410,7 +410,7 @@ handle_other({'$gen_cast', {force_event_refresh, Ref}}, State)
     rabbit_event:notify(
       connection_created,
       [{type, network} | infos(?CREATION_EVENT_KEYS, State)], Ref),
-    State;
+    rabbit_event:init_stats_timer(State, #v1.stats_timer);
 handle_other({'$gen_cast', force_event_refresh}, State) ->
     %% Ignore, we will emit a created event once we start running.
     State;
diff --git a/src/rabbit_version.erl b/src/rabbit_version.erl
index d943b599..3a041508 100644
--- a/src/rabbit_version.erl
+++ b/src/rabbit_version.erl
@@ -114,8 +114,8 @@ upgrades_required(Scope) ->
 
 with_upgrade_graph(Fun, Scope) ->
     case rabbit_misc:build_acyclic_graph(
-           fun (Module, Steps) -> vertices(Module, Steps, Scope) end,
-           fun (Module, Steps) -> edges(Module, Steps, Scope) end,
+           fun ({_App, Module, Steps}) -> vertices(Module, Steps, Scope) end,
+           fun ({_App, Module, Steps}) -> edges(Module, Steps, Scope) end,
            rabbit_misc:all_module_attributes(rabbit_upgrade)) of
         {ok, G} -> try
                        Fun(G)
@@ -161,7 +161,7 @@ heads(G) ->
 
 categorise_by_scope(Version) when is_list(Version) ->
     Categorised =
-        [{Scope, Name} || {_Module, Attributes} <-
+        [{Scope, Name} || {_App, _Module, Attributes} <-
                               rabbit_misc:all_module_attributes(rabbit_upgrade),
                           {Name, Scope, _Requires} <- Attributes,
                           lists:member(Name, Version)],