Rework the 'old shell' warning, and some related work

Add ability for handlers to 'fatally' fail, so they won't attempt to
reinstall themselves later.

Also fix an issue with the INT_LOG macro not doing the right thing when
only the lager_throttle_backend was installed.

Author: Vagabond

include/lager.hrl

@@ -84,7 +84,7 @@
     %% from a gen_event handler
     spawn(fun() ->
             case catch(gen_event:which_handlers(lager_event)) of
-                X when X == []; X == {'EXIT', noproc} ->
+                X when X == []; X == {'EXIT', noproc}; X == [lager_backend_throttle] ->
                     %% there's no handlers yet or lager isn't running, try again
                     %% in half a second.
                     timer:sleep(500),

src/lager_console_backend.erl

@@ -40,31 +40,34 @@ init([Level, true]) -> % for backwards compatibility
 init([Level,false]) -> % for backwards compatibility
     init([Level,{lager_default_formatter,?TERSE_FORMAT ++ [eol()]}]);
 init([Level,{Formatter,FormatterConfig}]) when is_atom(Formatter) ->
-    IsSafe = case is_new_style_console_available() of
-                 false=Res ->
-                     spawn(fun warn_user/0),
-                     Res;
-                 Res ->
-                     Res
-             end,
     Colors = case application:get_env(lager, colored) of
         {ok, true} -> 
             {ok, LagerColors} = application:get_env(lager, colors),
             LagerColors;
         _ -> []
     end,
 
-    try {IsSafe, lager_util:config_to_mask(Level)} of
+    try {is_new_style_console_available(), lager_util:config_to_mask(Level)} of
         {false, _} ->
-            {error, "Old style console was detected"};
+            Msg = "Lager's console backend is incompatible with the 'old' shell, not enabling it",
+            %% be as noisy as possible, log to every possible place
+            try
+                alarm_handler:set_alarm({?MODULE, "WARNING: " ++ Msg})
+            catch
+                _:_ ->
+                    error_logger:warning_msg(Msg ++ "~n")
+            end,
+            io:format("WARNING: " ++ Msg ++ "~n"),
+            ?INT_LOG(warning, Msg, []),
+            {error, {fatal, old_shell}};
         {true, Levels} ->
             {ok, #state{level=Levels,
                     formatter=Formatter, 
                     format_config=FormatterConfig,
                     colors=Colors}}
     catch
         _:_ ->
-            {error, bad_log_level}
+            {error, {fatal, bad_log_level}}
     end;
 init(Level) ->
     init([Level,{lager_default_formatter,?TERSE_FORMAT ++ [eol()]}]).
@@ -134,19 +137,6 @@ is_new_style_console_available() ->
         is_pid(whereis(user_drv)).
 -endif.
 
-warn_user() ->
-    Msg = lists:flatten(
-            io_lib:format("WARNING: old-style console is in use, so ~s "
-                          "log output to the console is disabled.  "
-                          "Restart the VM on a pseudo-tty to ensure "
-                          "use of the new-style VM console.",
-                          [?MODULE])),
-    catch alarm_handler:set_alarm({?MODULE, Msg}),
-    [begin
-         error_logger:warning_msg(Msg),
-         timer:sleep(1000)
-     end || _ <- lists:seq(1, 10)].
-
 -ifdef(TEST).
 console_log_test_() ->
     %% tiny recursive fun that pretends to be a group leader

src/lager_file_backend.erl

@@ -99,7 +99,7 @@ init(LogFileConfig) when is_list(LogFileConfig) ->
     case validate_logfile_proplist(LogFileConfig) of
         false ->
             %% falied to validate config
-            {error, bad_config};
+            {error, {fatal, bad_config}};
         Config ->
             %% probabably a better way to do this, but whatever
             [Name, Level, Date, Size, Count, SyncInterval, SyncSize, SyncOn, CheckInterval, Formatter, FormatterConfig] =

src/lager_handler_watcher.erl

@@ -23,6 +23,8 @@
 
 -behaviour(gen_server).
 
+-include("lager.hrl").
+
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
 -endif.
@@ -73,6 +75,8 @@ handle_info({gen_event_EXIT, Module, Reason}, #state{module=Module,
 handle_info(reinstall_handler, #state{module=Module, config=Config, event=Event} = State) ->
     install_handler(Event, Module, Config),
     {noreply, State};
+handle_info(stop, State) ->
+    {stop, normal, State};
 handle_info(_Info, State) ->
     {noreply, State}.
 
@@ -87,12 +91,18 @@ code_change(_OldVsn, State, _Extra) ->
 install_handler(Event, Module, Config) ->
     case gen_event:add_sup_handler(Event, Module, Config) of
         ok ->
-            _ = lager:log(debug, self(), "Lager installed handler ~p into ~p", [Module, Event]),
+            ?INT_LOG(debug, "Lager installed handler ~p into ~p", [Module, Event]),
             lager:update_loglevel_config(),
             ok;
+        {error, {fatal, Reason}} ->
+            ?INT_LOG(error, "Lager fatally failed to install handler ~p into"
+                " ~p, NOT retrying: ~p", [Module, Event, Reason]),
+            %% tell ourselves to stop
+            self() ! stop,
+            ok;
         Error ->
             %% try to reinstall it later
-            _ = lager:log(error, self(), "Lager failed to install handler ~p into"
+            ?INT_LOG(error, "Lager failed to install handler ~p into"
                " ~p, retrying later : ~p", [Module, Event, Error]),
             erlang:send_after(5000, self(), reinstall_handler),
             ok
@@ -145,10 +155,10 @@ reinstall_on_runtime_failure_test_() ->
                         ?assert(lists:member(lager_crash_backend, gen_event:which_handlers(lager_event))),
                         timer:sleep(6000),
                         ?assertEqual(2, lager_test_backend:count()),
-                        {_Level, _Time, Message, _Metadata} = lager_test_backend:pop(),
-                        ?assertEqual("Lager event handler lager_crash_backend exited with reason crash", lists:flatten(Message)),
-                        {_Level2, _Time2, Message2, _Metadata} = lager_test_backend:pop(),
-                        ?assertMatch("Lager failed to install handler lager_crash_backend into lager_event, retrying later :"++_, lists:flatten(Message2)),
+                        {_Severity, _Date, Msg, _Metadata} = lager_test_backend:pop(),
+                        ?assertEqual("Lager event handler lager_crash_backend exited with reason crash", lists:flatten(Msg)),
+                        {_Severity2, _Date2, Msg2, _Metadata2} = lager_test_backend:pop(),
+                        ?assertMatch("Lager failed to install handler lager_crash_backend into lager_event, retrying later :"++_, lists:flatten(Msg2)),
                         ?assertEqual(false, lists:member(lager_crash_backend, gen_event:which_handlers(lager_event)))
                     after
                        application:stop(lager),

src/lager_handler_watcher_sup.erl

@@ -35,5 +35,5 @@ init([]) ->
     {ok, {{simple_one_for_one, 10, 60},
             [
                 {lager_handler_watcher, {lager_handler_watcher, start_link, []},
-                        transient, 5000, worker, [lager_handler_watcher]}
+                        temporary, 5000, worker, [lager_handler_watcher]}
                 ]}}.