Restart error_logger handler if it exits, cleanups

src/error_logger_lager_h.erl

@@ -21,6 +21,8 @@
 -export([init/1, handle_call/2, handle_event/2, handle_info/2, terminate/2,
         code_change/3]).
 
+-export([format_reason/1]).
+
 init(_) ->
     {ok, {}}.
 
@@ -57,10 +59,10 @@ handle_event(Event, State) ->
                     Offender = format_offender(Off),
                     lager:log(error, Pid, "Supervisor ~w had child ~s exit with reason ~w in context ~w", [element(2, Name), Offender, Reason, Ctx]);
                 _ ->
-                    lager:log(error, Pid, "SUPERVISOR REPORT" ++ print_silly_list(D))
+                    lager:log(error, Pid, "SUPERVISOR REPORT " ++ print_silly_list(D))
             end;
         {error_report, _GL, {Pid, crash_report, [Self, Neighbours]}} ->
-            lager:log(error, Pid, "CRASH REPORT " ++ format_crash_report(Self));
+            lager:log(error, Pid, "CRASH REPORT " ++ format_crash_report(Self, Neighbours));
         {info_msg, _GL, {Pid, Fmt, Args}} ->
             lager:log(info, Pid, Fmt, Args);
         {info_report, _GL, {Pid, std_info, D}} ->
@@ -82,7 +84,7 @@ handle_event(Event, State) ->
                     Pid = proplists:get_value(pid, Started),
                     lager:log(info, P, "Supervisor ~w started ~s at pid ~w", [element(2, Name), MFA, Pid]);
                 _ ->
-                    lager:log(info, P, "PROGRESS REPORT" ++ print_silly_list(D))
+                    lager:log(info, P, "PROGRESS REPORT " ++ print_silly_list(D))
             end;
         _ ->
             io:format("Event ~w~n", [Event])
@@ -100,10 +102,10 @@ code_change(_OldVsn, State, _Extra) ->
 
 %% internal functions
 
-format_crash_report(Report) ->
+format_crash_report(Report, Neighbours) ->
     Name = proplists:get_value(registered_name, Report, proplists:get_value(pid, Report)),
     {_Class, Reason, _Trace} = proplists:get_value(error_info, Report),
-    io_lib:format("Process ~w crashed with reason: ~s", [Name, format_reason(Reason)]).
+    io_lib:format("Process ~w with ~w neighbours crashed with reason: ~s", [Name, length(Neighbours), format_reason(Reason)]).
 
 format_offender(Off) ->
     case proplists:get_value(name, Off) of

src/lager.erl

@@ -96,7 +96,6 @@ get_loglevel(Handler) ->
 %% gen_server callbacks
 
 init([Handlers]) ->
-    %process_flag(trap_exit, true),
     %% start a gen_event linked to this process
     gen_event:start_link({local, lager_event}),
     %% spin up all the defined handlers
@@ -107,10 +106,9 @@ init([Handlers]) ->
         {ok, true} ->
             gen_event:add_sup_handler(error_logger, error_logger_lager_h, []),
             %% TODO allow user to whitelist handlers to not be removed
-            Removed = [begin gen_event:delete_handler(error_logger, X, {stop_please, ?MODULE}), X end ||
+            [gen_event:delete_handler(error_logger, X, {stop_please, ?MODULE}) ||
                 X <- gen_event:which_handlers(error_logger) -- [error_logger_lager_h]],
-            io:format("Removed handlers ~p~n", [Removed]),
-            {ok, #state{error_logger_handlers=Removed}};
+            {ok, #state{}};
         _ ->
             {ok, #state{}}
     end.
@@ -136,20 +134,16 @@ handle_call(_Request, _From, State) ->
 handle_cast(_Request, State) ->
     {noreply, State}.
 
+handle_info({gen_event_EXIT, error_logger_lager_h, {'EXIT', Reason}}, State) ->
+    lager:log(error, self(), ["Restarting lager error handler after it exited with ", error_logger_lager_h:format_reason(Reason)]),
+    gen_event:add_sup_handler(error_logger, error_logger_lager_h, []),
+    {noreply, State};
 handle_info(Info, State) ->
     io:format("got info ~p~n", [Info]),
     {noreply, State}.
 
-terminate(_Reason, #state{error_logger_handlers = Handlers}) ->
-    io:format("terminate ~p~n", Handlers),
+terminate(_Reason, _State) ->
     gen_event:stop(lager_event),
-    case Handlers of
-        undefined ->
-            ok;
-        _ ->
-            io:format("Reinstalling handlers ~p~n", [Handlers]),
-            [gen_event:add_handler(error_logger, X, []) || X <- Handlers]
-    end,
     ok.
 
 code_change(_OldVsn, State, _Extra) ->