Force restart of system after a watcher kill.

This is, perhaps, not the most ideal setup. It still ignores other
sinks but does bring logging back online after the appropriate delay.

Signed-off-by: Brian L. Troutwine <brian.troutwine@adroll.com>

src/lager_app.erl

@@ -28,7 +28,8 @@
 -export([start/0,
          start/2,
          start_handler/3,
-         stop/1]).
+         stop/1,
+         boot/0]).
 
 -define(FILENAMES, '__lager_file_backend_filenames').
 -define(THROTTLE, lager_backend_throttle).
@@ -220,7 +221,10 @@ get_env_default({ok, Value}, _Default) ->
 
 start(_StartType, _StartArgs) ->
     {ok, Pid} = lager_sup:start_link(),
+    SavedHandlers = boot(),
+    {ok, Pid, SavedHandlers}.
 
+boot() ->
     %% Handle the default sink.
     determine_async_behavior(?DEFAULT_SINK,
                              application:get_env(lager, async_threshold),
@@ -246,8 +250,7 @@ start(_StartType, _StartArgs) ->
 
     clean_up_config_checks(),
 
-    {ok, Pid, SavedHandlers}.
-
+    SavedHandlers.
 
 stop(Handlers) ->
     lists:foreach(fun(Handler) ->

src/lager_handler_watcher.erl

@@ -63,11 +63,11 @@ handle_info({gen_event_EXIT, Module, shutdown}, #state{module=Module} = State) -
     {stop, normal, State};
 handle_info({gen_event_EXIT, Module, {'EXIT', {kill_me, [_KillerHWM, KillerReinstallAfter]}}},
         #state{module=Module, sink=Sink} = State) ->
-    % Brutally kill the manager but stay alive to restore settings.
+    %% Brutally kill the manager but stay alive to restore settings.
     Manager = whereis(Sink),
     unlink(Manager),
     exit(Manager, kill),
-    erlang:send_after(KillerReinstallAfter, self(), reinstall_handler),
+    erlang:send_after(KillerReinstallAfter, self(), reboot),
     {noreply, State};
 handle_info({gen_event_EXIT, Module, Reason}, #state{module=Module,
         config=Config, sink=Sink} = State) ->
@@ -80,8 +80,8 @@ handle_info({gen_event_EXIT, Module, Reason}, #state{module=Module,
         ok
     end,
     {noreply, State};
-handle_info(reinstall_handler, #state{module=Module, config=Config, sink=Sink} = State) ->
-    install_handler(Sink, Module, Config),
+handle_info(reboot, State) ->
+    lager_app:boot(),
     {noreply, State};
 handle_info(stop, State) ->
     {stop, normal, State};

src/lager_manager_killer.erl

@@ -4,6 +4,8 @@
 
 -export([init/1, handle_event/2, handle_call/2, handle_info/2, terminate/2, code_change/3]).
 
+-export([kill_me/0]).
+
 -include("lager.hrl").
 
 -record(state, {
@@ -11,6 +13,9 @@
           killer_reinstall_after :: non_neg_integer()
          }).
 
+kill_me() ->
+    gen_event:call(lager_event, ?MODULE, kill_self).
+
 init([KillerHWM, KillerReinstallAfter]) ->
     {ok, #state{killer_hwm=KillerHWM, killer_reinstall_after=KillerReinstallAfter}}.
 
@@ -20,6 +25,8 @@ handle_call({set_loglevel, _Level}, State) ->
     {ok, ok, State};
 handle_call(get_settings, State = #state{killer_hwm=KillerHWM, killer_reinstall_after=KillerReinstallAfter}) ->
     {ok, [KillerHWM, KillerReinstallAfter], State};
+handle_call(kill_self, #state{killer_hwm=KillerHWM, killer_reinstall_after=KillerReinstallAfter}) ->
+    exit({kill_me, [KillerHWM, KillerReinstallAfter]});
 handle_call(_Request, State) ->
     {ok, ok, State}.