Use two supervisors (an overall one and the delegate underneath it) so that our behaviour is not affected by the users's choice of restart strategy.

2 files changed, 49 insertions, 42 deletions

diff --git a/src/mirrored_supervisor.erl b/src/mirrored_supervisor.erl
index 357c21d59e..add2c1208b 100644
--- a/src/mirrored_supervisor.erl
+++ b/src/mirrored_supervisor.erl
@@ -24,7 +24,6 @@
 
 -define(SUPERVISOR, supervisor2).
 -define(GEN_SERVER, gen_server2).
--define(ID, ?MODULE).
 
 -define(TABLE, mirrored_sup_childspec).
 -define(TABLE_DEF,
@@ -41,16 +40,17 @@
 -export([behaviour_info/1]).
 
 -behaviour(?GEN_SERVER).
+-behaviour(?SUPERVISOR).
 
 -export([init/1, handle_call/3, handle_info/2, terminate/2, code_change/3,
          handle_cast/2]).
 
--export([start_internal/3]).
+-export([start_internal/2]).
 -export([create_tables/0, table_definitions/0]).
 
--record(mirrored_sup_childspec, {id, sup_pid, childspec}).
+-record(mirrored_sup_childspec, {id, mirroring_pid, childspec}).
 
--record(state, {sup, group}).
+-record(state, {overall, group}).
 
 %%----------------------------------------------------------------------------
 
@@ -59,20 +59,16 @@ start_link(_Group, _Mod, _Args) ->
     exit(mirrored_supervisors_must_be_locally_named).
 
 start_link({local, SupName}, Group, Mod, Args) ->
-    {ok, SupPid} = ?SUPERVISOR:start_link({local, SupName}, Mod, Args),
-    {ok, _Me} = ?SUPERVISOR:start_child(
-                   SupPid, {?ID, {?MODULE, start_internal,
-                                  [SupName, Group, Args]},
-                            transient, 16#ffffffff, supervisor, [?MODULE]}),
-    {ok, SupPid};
+    ?SUPERVISOR:start_link({local, SupName}, ?MODULE,
+                           {overall, SupName, Group, Mod, Args});
 
 start_link({global, _SupName}, _Group, _Mod, _Args) ->
     exit(mirrored_supervisors_must_be_locally_named).
 
 start_child(Sup, ChildSpec)  -> call(Sup, {start_child,  ChildSpec}).
 delete_child(Sup, Name)      -> call(Sup, {delete_child, Name}).
-restart_child(Sup, Name)     -> call(Sup, {msg, restart_child,   [Sup, Name]}).
-terminate_child(Sup, Name)   -> call(Sup, {msg, terminate_child, [Sup, Name]}).
+restart_child(Sup, Name)     -> call(Sup, {msg, restart_child,   [Name]}).
+terminate_child(Sup, Name)   -> call(Sup, {msg, terminate_child, [Name]}).
 which_children(Sup)          -> ?SUPERVISOR:which_children(Sup).
 check_childspecs(ChildSpecs) -> ?SUPERVISOR:check_childspecs(ChildSpecs).
 
@@ -80,7 +76,7 @@ behaviour_info(callbacks) -> [{init,1}];
 behaviour_info(_Other)    -> undefined.
 
 call(Sup, Msg) ->
-    ?GEN_SERVER:call(child(Sup, ?ID), Msg, infinity).
+    ?GEN_SERVER:call(child(Sup, mirroring), Msg, infinity).
 
 child(Sup, Name) ->
     [Pid] = [Pid || {Name1, Pid, _, _} <- which_children(Sup), Name1 =:= Name],
@@ -88,12 +84,20 @@ child(Sup, Name) ->
 
 %%----------------------------------------------------------------------------
 
-start_internal(Sup, Group, Args) ->
-    ?GEN_SERVER:start_link(?MODULE, {Sup, Group, Args}, [{timeout, infinity}]).
+start_internal(Sup, Group) ->
+    ?GEN_SERVER:start_link(
+       ?MODULE, {mirroring, Sup, Group}, [{timeout, infinity}]).
 
 %%----------------------------------------------------------------------------
 
-init({Sup, Group, _Args}) ->
+init({overall, SupName, Group, Mod, Args}) ->
+    Delegate = {delegate, {?SUPERVISOR, start_link, [Mod, Args]},
+                transient, 16#ffffffff, supervisor, [?SUPERVISOR]},
+    Mirroring = {mirroring, {?MODULE, start_internal, [SupName, Group]},
+                 transient, 16#ffffffff, worker, [?MODULE]},
+    {ok, {{one_for_all, 0, 1}, [Delegate, Mirroring]}};
+
+init({mirroring, Sup, Group}) ->
     pg2_fixed:create(Group),
     [begin
          gen_server2:call(Pid, {hello, self()}, infinity),
@@ -101,26 +105,28 @@ init({Sup, Group, _Args}) ->
      end
      || Pid <- pg2_fixed:get_members(Group)],
     ok = pg2_fixed:join(Group, self()),
-    {ok, #state{sup = Sup, group = Group}}.
+    {ok, #state{overall = Sup, group = Group}}.
 
-handle_call({start_child, ChildSpec}, _From, State = #state{sup = Sup}) ->
+handle_call({start_child, ChildSpec}, _From,
+            State = #state{overall = Overall}) ->
     {reply, case mnesia:transaction(fun() -> check_start(ChildSpec) end) of
-                {atomic, start} -> start(Sup, ChildSpec);
+                {atomic, start} -> start(Overall, ChildSpec);
                 {atomic, Pid}   -> {ok, Pid}
             end, State};
 
-handle_call({delete_child, Id}, _From, State = #state{sup = Sup}) ->
+handle_call({delete_child, Id}, _From,
+            State = #state{overall = Overall}) ->
     {atomic, ok} = mnesia:transaction(fun() -> delete(Id) end),
-    {reply, stop(Sup, Id), State};
+    {reply, stop(Overall, Id), State};
 
-handle_call({msg, F, A}, _From, State) ->
-    {reply, apply(?SUPERVISOR, F, A), State};
+handle_call({msg, F, A}, _From, State = #state{overall = Overall}) ->
+    {reply, apply(?SUPERVISOR, F, [child(Overall, delegate) | A]), State};
 
 handle_call({hello, Pid}, _From, State) ->
     erlang:monitor(process, Pid),
     {reply, ok, State};
 
-handle_call(supervisor, _From, State = #state{sup = Sup}) ->
+handle_call(overall_supervisor, _From, State = #state{overall = Sup}) ->
     {reply, Sup, State};
 
 handle_call(Msg, _From, State) ->
@@ -130,7 +136,7 @@ handle_cast(Msg, State) ->
     {stop, {unexpected_cast, Msg}, State}.
 
 handle_info({'DOWN', _Ref, process, Pid, _Reason},
-            State = #state{sup = Sup, group = Group}) ->
+            State = #state{overall = Overall, group = Group}) ->
     %% TODO load balance this
     %% We remove the dead pid here because pg2_fixed is slightly racy,
     %% most of the time it will be gone before we get here but not
@@ -139,7 +145,7 @@ handle_info({'DOWN', _Ref, process, Pid, _Reason},
     case lists:sort(pg2_fixed:get_members(Group)) -- [Pid] of
         [Self | _] -> {atomic, ChildSpecs} =
                           mnesia:transaction(fun() -> update_all(Pid) end),
-                      [start(Sup, ChildSpec) || ChildSpec <- ChildSpecs];
+                      [start(Overall, ChildSpec) || ChildSpec <- ChildSpecs];
         _          -> ok
     end,
     {noreply, State};
@@ -159,36 +165,36 @@ check_start(ChildSpec) ->
     case mnesia:wread({?TABLE, id(ChildSpec)}) of
         []  -> write(ChildSpec),
                start;
-        [S] -> #mirrored_sup_childspec{id      = Id,
-                                       sup_pid = Pid} = S,
+        [S] -> #mirrored_sup_childspec{id            = Id,
+                                       mirroring_pid = Pid} = S,
                case supervisor(Pid) of
                    dead -> delete(ChildSpec),
                            write(ChildSpec),
                            start;
-                   Sup  -> child(Sup, Id)
+                   Sup  -> child(child(Sup, delegate), Id)
                end
     end.
 
 supervisor(Pid) ->
     try
-        gen_server:call(Pid, supervisor, infinity)
+        gen_server:call(Pid, overall_supervisor, infinity)
     catch
         exit:{noproc, _} -> dead
     end.
 
 write(ChildSpec) ->
-    ok = mnesia:write(#mirrored_sup_childspec{id        = id(ChildSpec),
-                                              sup_pid   = self(),
-                                              childspec = ChildSpec}).
+    ok = mnesia:write(#mirrored_sup_childspec{id              = id(ChildSpec),
+                                              mirroring_pid   = self(),
+                                              childspec       = ChildSpec}).
 
 delete(Id) ->
     ok = mnesia:delete({?TABLE, Id}).
 
-start(Sup, ChildSpec) ->
-    apply(?SUPERVISOR, start_child, [Sup, ChildSpec]).
+start(Overall, ChildSpec) ->
+    apply(?SUPERVISOR, start_child, [child(Overall, delegate), ChildSpec]).
 
-stop(Sup, Id) ->
-    apply(?SUPERVISOR, delete_child, [Sup, Id]).
+stop(Overall, Id) ->
+    apply(?SUPERVISOR, delete_child, [child(Overall, delegate), Id]).
 
 id({Id, _, _, _, _, _}) -> Id.
 
@@ -198,9 +204,9 @@ update(ChildSpec) ->
     ChildSpec.
 
 update_all(OldPid) ->
-    MatchHead = #mirrored_sup_childspec{sup_pid   = OldPid,
-                                        childspec = '$1',
-                                        _         = '_'},
+    MatchHead = #mirrored_sup_childspec{mirroring_pid   = OldPid,
+                                        childspec       = '$1',
+                                        _               = '_'},
     [update(C) || C <- mnesia:select(?TABLE, [{MatchHead, [], ['$1']}])].
 
 %%----------------------------------------------------------------------------
diff --git a/src/rabbit_upgrade_functions.erl b/src/rabbit_upgrade_functions.erl
index 15887af1d7..797e9fb971 100644
--- a/src/rabbit_upgrade_functions.erl
+++ b/src/rabbit_upgrade_functions.erl
@@ -157,8 +157,9 @@ gm() ->
                       {attributes, [name, version, members]}]).
 
 mirrored_supervisor() ->
-    create(mirrored_sup_childspec, [{record_name, mirrored_sup_childspec},
-                                    {attributes, [id, sup_pid, childspec]}]).
+    create(mirrored_sup_childspec,
+           [{record_name, mirrored_sup_childspec},
+            {attributes, [id, mirroring_pid, childspec]}]).
 
 %%--------------------------------------------------------------------