first stab at handler supervision with dedicated supervisor and guard…

… processes

ebin/riak_core.app

@@ -23,6 +23,8 @@
              riak_core_claim,
              riak_core_config,
              riak_core_gossip,
+             riak_core_handler_guard,
+             riak_core_handler_sup,
              riak_core_handoff_listener,
              riak_core_handoff_manager,
              riak_core_handoff_receiver,

src/riak_core_app.erl

@@ -68,7 +68,7 @@ start(_StartType, _StartArgs) ->
     %% Spin up the supervisor; prune ring files as necessary
     case riak_core_sup:start_link() of
         {ok, Pid} ->
-            ok = riak_core_ring_events:add_handler(riak_core_ring_handler, []),
+            ok = riak_core_ring_events:add_sup_handler(riak_core_ring_handler, []),
             %% App is running; search for latest ring file and initialize with it
             riak_core_ring_manager:prune_ringfiles(),
             case riak_core_ring_manager:find_latest_ringfile() of

src/riak_core_handler_guard.erl

@@ -0,0 +1,48 @@
+%% -------------------------------------------------------------------
+%%
+%% riak_core_handler_guard: Guard process for persistent event handlers.
+%%
+%% Copyright (c) 2007-2011 Basho Technologies, Inc.  All Rights Reserved.
+%%
+%% This file is provided to you under the Apache License,
+%% Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing,
+%% software distributed under the License is distributed on an
+%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%% KIND, either express or implied.  See the License for the
+%% specific language governing permissions and limitations
+%% under the License.
+%%
+%% -------------------------------------------------------------------
+-module(riak_core_handler_guard).
+-behaviour(gen_server).
+-export([start_link/3]).
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+         terminate/2, code_change/3]).
+-record(state, {}).
+
+start_link(HandlerMod, Handler, Args) ->
+    gen_server:start_link(?MODULE, [HandlerMod, Handler, Args], []).
+
+init([HandlerMod, Handler, Args]) ->
+    ok = gen_event:add_sup_handler(HandlerMod, Handler, Args),
+    {ok, #state{}}.
+
+handle_call(_Request, _From, State) -> {reply, ok, State}.
+
+handle_cast(_Msg, State) -> {noreply, State}.
+
+handle_info({gen_event_EXIT, Handler, Reason}, State) ->
+    error_logger:error_msg("~w: ~s: handler ~w exited for reason ~s",
+                           [self(), ?MODULE, Handler, Reason]),
+    {stop, gen_event_EXIT, State}.
+
+terminate(_Reason, _State) -> ok.
+
+code_change(_OldVsn, State, _Extra) -> {ok, State}.
+

src/riak_core_handler_sup.erl

@@ -0,0 +1,47 @@
+%% -------------------------------------------------------------------
+%%
+%% riak_core_handler_sup: supervise minder processes for gen_event handlers
+%%
+%% Copyright (c) 2007-2011 Basho Technologies, Inc.  All Rights Reserved.
+%%
+%% This file is provided to you under the Apache License,
+%% Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing,
+%% software distributed under the License is distributed on an
+%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%% KIND, either express or implied.  See the License for the
+%% specific language governing permissions and limitations
+%% under the License.
+%%
+%% -------------------------------------------------------------------
+
+%% @doc supervise riak_core_handler_guard processes
+
+-module(riak_core_handler_sup).
+-behaviour(supervisor).
+-export([start_link/0, init/1]).
+-export([start_handler_guard/3]).
+
+start_handler_guard(HandlerMod, Handler, Args) ->
+    case supervisor:start_child(?MODULE, handler_spec(HandlerMod, Handler, Args)) of
+        {ok, _Pid} -> ok;
+        Other -> Other
+    end.
+
+handler_spec(HandlerMod, Handler, Args) ->
+    {{HandlerMod, Handler},
+     {riak_core_handler_guard, start_link, [HandlerMod, Handler, Args]},
+     permanent, 5000, worker, [riak_core_handler_guard]}.
+
+start_link() ->
+    supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+%% @private
+init([]) ->
+    {ok, {{one_for_one, 10, 10}, []}}.
+

src/riak_core_node_watcher_events.erl

@@ -48,13 +48,13 @@ add_handler(Handler, Args) ->
     gen_event:add_handler(?MODULE, Handler, Args).
 
 add_sup_handler(Handler, Args) ->
-    gen_event:add_sup_handler(?MODULE, Handler, Args).
+    riak_core_handler_sup:start_handler_guard(?MODULE, Handler, Args).
 
 add_callback(Fn) when is_function(Fn) ->
     gen_event:add_handler(?MODULE, {?MODULE, make_ref()}, [Fn]).
 
 add_sup_callback(Fn) when is_function(Fn) ->
-    gen_event:add_sup_handler(?MODULE, {?MODULE, make_ref()}, [Fn]).
+    riak_core_handler_sup:start_handler_guard(?MODULE, {?MODULE, make_ref()}, [Fn]).
 
 service_update(Services) ->
     gen_event:notify(?MODULE, {service_update, Services}).

src/riak_core_ring_events.erl

@@ -51,13 +51,13 @@ add_handler(Handler, Args) ->
     gen_event:add_handler(?MODULE, Handler, Args).
 
 add_sup_handler(Handler, Args) ->
-    gen_event:add_sup_handler(?MODULE, Handler, Args).
+    riak_core_handler_sup:start_handler_guard(?MODULE, Handler, Args).
 
 add_callback(Fn) when is_function(Fn) ->
     gen_event:add_handler(?MODULE, {?MODULE, make_ref()}, [Fn]).
 
 add_sup_callback(Fn) when is_function(Fn) ->
-    gen_event:add_sup_handler(?MODULE, {?MODULE, make_ref()}, [Fn]).
+    riak_core_handler_sup:start_handler_guard(?MODULE, {?MODULE, make_ref()}, [Fn]).
 
 force_update() ->
     {ok, Ring} = riak_core_ring_manager:get_my_ring(),

src/riak_core_sup.erl

@@ -59,6 +59,7 @@ init([]) ->
     Children = lists:flatten(
                  [?CHILD(riak_core_sysmon_minder, worker),
                   ?CHILD(riak_core_vnode_sup, supervisor),
+                  ?CHILD(riak_core_handler_sup, supervisor),
                   ?CHILD(riak_core_handoff_manager, worker),
                   ?CHILD(riak_core_handoff_listener, worker),
                   ?CHILD(riak_core_ring_events, worker),