merge bug25714 into default

4 files changed, 114 insertions, 41 deletions

diff --git a/src/delegate.erl b/src/delegate.erl
index f680d94a..0331ca01 100644
--- a/src/delegate.erl
+++ b/src/delegate.erl
@@ -18,22 +18,32 @@
 
 -behaviour(gen_server2).
 
--export([start_link/1, invoke_no_result/2, invoke/2, call/2, cast/2]).
+-export([start_link/1, invoke_no_result/2, invoke/2,
+         monitor/2, demonitor/1, call/2, cast/2]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2, code_change/3]).
 
+-record(state, {node, monitors, name}).
+
 %%----------------------------------------------------------------------------
 
 -ifdef(use_specs).
 
+-export_type([monitor_ref/0]).
+
+-type(monitor_ref() :: reference() | {atom(), pid()}).
 -type(fun_or_mfa(A) :: fun ((pid()) -> A) | {atom(), atom(), [any()]}).
+
 -spec(start_link/1 ::
         (non_neg_integer()) -> {'ok', pid()} | ignore | {'error', any()}).
 -spec(invoke/2 :: ( pid(),  fun_or_mfa(A)) -> A;
                   ([pid()], fun_or_mfa(A)) -> {[{pid(), A}],
                                                [{pid(), term()}]}).
 -spec(invoke_no_result/2 :: (pid() | [pid()], fun_or_mfa(any())) -> 'ok').
+-spec(monitor/2 :: ('process', pid()) -> monitor_ref()).
+-spec(demonitor/1 :: (monitor_ref()) -> 'true').
+
 -spec(call/2 ::
         ( pid(),  any()) -> any();
         ([pid()], any()) -> {[{pid(), any()}], [{pid(), term()}]}).
@@ -49,7 +59,8 @@
 %%----------------------------------------------------------------------------
 
 start_link(Num) ->
-    gen_server2:start_link({local, delegate_name(Num)}, ?MODULE, [], []).
+    Name = delegate_name(Num),
+    gen_server2:start_link({local, Name}, ?MODULE, [Name], []).
 
 invoke(Pid, FunOrMFA) when is_pid(Pid) andalso node(Pid) =:= node() ->
     apply1(FunOrMFA, Pid);
@@ -77,7 +88,7 @@ invoke(Pids, FunOrMFA) when is_list(Pids) ->
         case orddict:fetch_keys(Grouped) of
             []          -> {[], []};
             RemoteNodes -> gen_server2:multi_call(
-                             RemoteNodes, delegate(RemoteNodes),
+                             RemoteNodes, delegate(self(), RemoteNodes),
                              {invoke, FunOrMFA, Grouped}, infinity)
         end,
     BadPids = [{Pid, {exit, {nodedown, BadNode}, []}} ||
@@ -105,12 +116,25 @@ invoke_no_result(Pids, FunOrMFA) when is_list(Pids) ->
     {LocalPids, Grouped} = group_pids_by_node(Pids),
     case orddict:fetch_keys(Grouped) of
         []          -> ok;
-        RemoteNodes -> gen_server2:abcast(RemoteNodes, delegate(RemoteNodes),
-                                          {invoke, FunOrMFA, Grouped})
+        RemoteNodes -> gen_server2:abcast(
+                         RemoteNodes, delegate(self(), RemoteNodes),
+                         {invoke, FunOrMFA, Grouped})
     end,
     safe_invoke(LocalPids, FunOrMFA), %% must not die
     ok.
 
+monitor(process, Pid) when node(Pid) =:= node() ->
+    erlang:monitor(process, Pid);
+monitor(process, Pid) ->
+    Name = delegate(Pid, [node(Pid)]),
+    gen_server2:cast(Name, {monitor, self(), Pid}),
+    {Name, Pid}.
+
+demonitor(Ref) when is_reference(Ref) ->
+    erlang:demonitor(Ref);
+demonitor({Name, Pid}) ->
+    gen_server2:cast(Name, {demonitor, self(), Pid}).
+
 call(PidOrPids, Msg) ->
     invoke(PidOrPids, {gen_server2, call, [Msg, infinity]}).
 
@@ -133,10 +157,10 @@ group_pids_by_node(Pids) ->
 delegate_name(Hash) ->
     list_to_atom("delegate_" ++ integer_to_list(Hash)).
 
-delegate(RemoteNodes) ->
+delegate(Pid, RemoteNodes) ->
     case get(delegate) of
         undefined -> Name = delegate_name(
-                              erlang:phash2(self(),
+                              erlang:phash2(Pid,
                                             delegate_sup:count(RemoteNodes))),
                      put(delegate, Name),
                      Name;
@@ -157,23 +181,64 @@ apply1(Fun,       Arg) -> Fun(Arg).
 
 %%----------------------------------------------------------------------------
 
-init([]) ->
-    {ok, node(), hibernate,
+init([Name]) ->
+    {ok, #state{node = node(), monitors = dict:new(), name = Name}, hibernate,
      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
 
-handle_call({invoke, FunOrMFA, Grouped}, _From, Node) ->
-    {reply, safe_invoke(orddict:fetch(Node, Grouped), FunOrMFA), Node,
+handle_call({invoke, FunOrMFA, Grouped}, _From, State = #state{node = Node}) ->
+    {reply, safe_invoke(orddict:fetch(Node, Grouped), FunOrMFA), State,
      hibernate}.
 
-handle_cast({invoke, FunOrMFA, Grouped}, Node) ->
+handle_cast({monitor, MonitoringPid, Pid},
+            State = #state{monitors = Monitors}) ->
+    Monitors1 = case dict:find(Pid, Monitors) of
+                    {ok, {Ref, Pids}} ->
+                        Pids1 = gb_sets:add_element(MonitoringPid, Pids),
+                        dict:store(Pid, {Ref, Pids1}, Monitors);
+                    error ->
+                        Ref = erlang:monitor(process, Pid),
+                        Pids = gb_sets:singleton(MonitoringPid),
+                        dict:store(Pid, {Ref, Pids}, Monitors)
+                end,
+    {noreply, State#state{monitors = Monitors1}, hibernate};
+
+handle_cast({demonitor, MonitoringPid, Pid},
+            State = #state{monitors = Monitors}) ->
+    Monitors1 = case dict:find(Pid, Monitors) of
+                    {ok, {Ref, Pids}} ->
+                        Pids1 = gb_sets:del_element(MonitoringPid, Pids),
+                        case gb_sets:is_empty(Pids1) of
+                            true  -> erlang:demonitor(Ref),
+                                     dict:erase(Pid, Monitors);
+                            false -> dict:store(Pid, {Ref, Pids1}, Monitors)
+                        end;
+                    error ->
+                        Monitors
+                end,
+    {noreply, State#state{monitors = Monitors1}, hibernate};
+
+handle_cast({invoke, FunOrMFA, Grouped}, State = #state{node = Node}) ->
     safe_invoke(orddict:fetch(Node, Grouped), FunOrMFA),
-    {noreply, Node, hibernate}.
-
-handle_info(_Info, Node) ->
-    {noreply, Node, hibernate}.
+    {noreply, State, hibernate}.
+
+handle_info({'DOWN', Ref, process, Pid, Info},
+            State = #state{monitors = Monitors, name = Name}) ->
+    {noreply,
+     case dict:find(Pid, Monitors) of
+         {ok, {Ref, Pids}} ->
+             Msg = {'DOWN', {Name, Pid}, process, Pid, Info},
+             gb_sets:fold(fun (MonitoringPid, _) -> MonitoringPid ! Msg end,
+                          none, Pids),
+             State#state{monitors = dict:erase(Pid, Monitors)};
+         error ->
+             State
+     end, hibernate};
+
+handle_info(_Info, State) ->
+    {noreply, State, hibernate}.
 
 terminate(_Reason, _State) ->
     ok.
 
-code_change(_OldVsn, Node, _Extra) ->
-    {ok, Node}.
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
diff --git a/src/pmon.erl b/src/pmon.erl
index b9db66fb..86308167 100644
--- a/src/pmon.erl
+++ b/src/pmon.erl
@@ -16,22 +16,26 @@
 
 -module(pmon).
 
--export([new/0, monitor/2, monitor_all/2, demonitor/2, is_monitored/2, erase/2,
-         monitored/1, is_empty/1]).
+-export([new/0, new/1, monitor/2, monitor_all/2, demonitor/2,
+         is_monitored/2, erase/2, monitored/1, is_empty/1]).
 
 -compile({no_auto_import, [monitor/2]}).
 
+-record(state, {dict, module}).
+
 -ifdef(use_specs).
 
 %%----------------------------------------------------------------------------
 
 -export_type([?MODULE/0]).
 
--opaque(?MODULE()    :: dict()).
+-opaque(?MODULE() :: #state{dict   :: dict(),
+                            module :: atom()}).
 
 -type(item()         :: pid() | {atom(), node()}).
 
 -spec(new/0          :: () -> ?MODULE()).
+-spec(new/1          :: ('erlang' | 'delegate') -> ?MODULE()).
 -spec(monitor/2      :: (item(), ?MODULE()) -> ?MODULE()).
 -spec(monitor_all/2  :: ([item()], ?MODULE()) -> ?MODULE()).
 -spec(demonitor/2    :: (item(), ?MODULE()) -> ?MODULE()).
@@ -42,29 +46,33 @@
 
 -endif.
 
-new() -> dict:new().
+new() -> new(erlang).
+
+new(Module) -> #state{dict   = dict:new(),
+                      module = Module}.
 
-monitor(Item, M) ->
+monitor(Item, S = #state{dict = M, module = Module}) ->
     case dict:is_key(Item, M) of
-        true  -> M;
-        false -> dict:store(Item, erlang:monitor(process, Item), M)
+        true  -> S;
+        false -> S#state{dict = dict:store(
+                                  Item, Module:monitor(process, Item), M)}
     end.
 
-monitor_all([],     M) -> M;                %% optimisation
-monitor_all([Item], M) -> monitor(Item, M); %% optimisation
-monitor_all(Items,  M) -> lists:foldl(fun monitor/2, M, Items).
+monitor_all([],     S) -> S;                %% optimisation
+monitor_all([Item], S) -> monitor(Item, S); %% optimisation
+monitor_all(Items,  S) -> lists:foldl(fun monitor/2, S, Items).
 
-demonitor(Item, M) ->
+demonitor(Item, S = #state{dict = M, module = Module}) ->
     case dict:find(Item, M) of
-        {ok, MRef} -> erlang:demonitor(MRef),
-                      dict:erase(Item, M);
+        {ok, MRef} -> Module:demonitor(MRef),
+                      S#state{dict = dict:erase(Item, M)};
         error      -> M
     end.
 
-is_monitored(Item, M) -> dict:is_key(Item, M).
+is_monitored(Item, #state{dict = M}) -> dict:is_key(Item, M).
 
-erase(Item, M) -> dict:erase(Item, M).
+erase(Item, S = #state{dict = M}) -> S#state{dict = dict:erase(Item, M)}.
 
-monitored(M) -> dict:fetch_keys(M).
+monitored(#state{dict = M}) -> dict:fetch_keys(M).
 
-is_empty(M) -> dict:size(M) == 0.
+is_empty(#state{dict = M}) -> dict:size(M) == 0.
diff --git a/src/rabbit_amqqueue_process.erl b/src/rabbit_amqqueue_process.erl
index e61cba02..6e0eb9bf 100644
--- a/src/rabbit_amqqueue_process.erl
+++ b/src/rabbit_amqqueue_process.erl
@@ -146,7 +146,7 @@ init_state(Q) ->
                exclusive_consumer  = none,
                has_had_consumers   = false,
                active_consumers    = queue:new(),
-               senders             = pmon:new(),
+               senders             = pmon:new(delegate),
                msg_id_to_channel   = gb_trees:empty(),
                status              = running},
     rabbit_event:init_stats_timer(State, #q.stats_timer).
diff --git a/src/rabbit_mirror_queue_slave.erl b/src/rabbit_mirror_queue_slave.erl
index b74ae3a5..82819cbe 100644
--- a/src/rabbit_mirror_queue_slave.erl
+++ b/src/rabbit_mirror_queue_slave.erl
@@ -118,7 +118,7 @@ init(Q = #amqqueue { name = QName }) ->
                              msg_id_ack          = dict:new(),
 
                              msg_id_status       = dict:new(),
-                             known_senders       = pmon:new(),
+                             known_senders       = pmon:new(delegate),
 
                              depth_delta         = undefined
                    },
@@ -270,7 +270,8 @@ handle_info({'DOWN', _MonitorRef, process, MPid, _Reason},
     noreply(State);
 
 handle_info({'DOWN', _MonitorRef, process, ChPid, _Reason}, State) ->
-    noreply(local_sender_death(ChPid, State));
+    local_sender_death(ChPid, State),
+    noreply(State);
 
 handle_info({'EXIT', _Pid, Reason}, State) ->
     {stop, Reason, State};
@@ -601,7 +602,7 @@ stop_rate_timer(State) -> rabbit_misc:stop_timer(State, #state.rate_timer_ref).
 ensure_monitoring(ChPid, State = #state { known_senders = KS }) ->
     State #state { known_senders = pmon:monitor(ChPid, KS) }.
 
-local_sender_death(ChPid, State = #state { known_senders = KS }) ->
+local_sender_death(ChPid, #state { known_senders = KS }) ->
     %% The channel will be monitored iff we have received a delivery
     %% from it but not heard about its death from the master. So if it
     %% is monitored we need to point the death out to the master (see
@@ -609,8 +610,7 @@ local_sender_death(ChPid, State = #state { known_senders = KS }) ->
     ok = case pmon:is_monitored(ChPid, KS) of
              false -> ok;
              true  -> confirm_sender_death(ChPid)
-         end,
-    State.
+         end.
 
 confirm_sender_death(Pid) ->
     %% We have to deal with the possibility that we'll be promoted to