Merge pull request #51 from basho/adt-better-special-process-errors

Better error handling for 'special processes'

src/error_logger_lager_h.erl

@@ -161,15 +161,14 @@ format_crash_report(Report, Neighbours) ->
             proplists:get_value(pid, Report);
         Atom -> Atom
     end,
-    {_Class, Reason, Trace} = proplists:get_value(error_info, Report),
-    ReasonStr = case is_atom(Reason) of
-        true ->
-            format_reason({Reason, Trace});
-        _ ->
-            format_reason(Reason)
+    {Class, Reason, Trace} = proplists:get_value(error_info, Report),
+    ReasonStr = format_reason({Reason, Trace}),
+    Type = case Class of
+        exit -> "exited";
+        _ -> "crashed"
     end,
-    io_lib:format("Process ~w with ~w neighbours crashed with reason: ~s",
-        [Name, length(Neighbours), ReasonStr]).
+    io_lib:format("Process ~w with ~w neighbours ~s with reason: ~s",
+        [Name, length(Neighbours), Type, ReasonStr]).
 
 format_offender(Off) ->
     case proplists:get_value(mfargs, Off) of
@@ -254,6 +253,11 @@ format_reason({noproc, MFA}) ->
     ["no such process or port in call to ", format_mfa(MFA)];
 format_reason({{badfun, Term}, [MFA|_]}) ->
     ["bad function ", print_val(Term), " in ", format_mfa(MFA)];
+format_reason({Reason, [{M, F, A}|_]}) when is_atom(M), is_atom(F), is_integer(A) ->
+    [format_reason(Reason), " in ", format_mfa({M, F, A})];
+format_reason({Reason, [{M, F, A, Props}|_]}) when is_atom(M), is_atom(F), is_integer(A), is_list(Props) ->
+    %% line numbers
+    [format_reason(Reason), " in ", format_mfa({M, F, A, Props})];
 format_reason(Reason) ->
     {Str, _} = lager_trunc_io:print(Reason, 500),
     Str.

test/lager_test_backend.erl

@@ -655,7 +655,7 @@ error_logger_redirect_test_() ->
             },
             {"crash report for emfile",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, {emfile, [{stack, trace, 1}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, emfile, [{stack, trace, 1}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         Expected = lists:flatten(io_lib:format("[error] ~w CRASH REPORT Process ~w with 0 neighbours crashed with reason: maximum number of file descriptors exhausted, check ulimit -n", [self(), self()])),
@@ -664,7 +664,7 @@ error_logger_redirect_test_() ->
             },
             {"crash report for system process limit",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, {system_limit, [{erlang, spawn, 1}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, system_limit, [{erlang, spawn, 1}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         Expected = lists:flatten(io_lib:format("[error] ~w CRASH REPORT Process ~w with 0 neighbours crashed with reason: system limit: maximum number of processes exceeded", [self(), self()])),
@@ -673,7 +673,7 @@ error_logger_redirect_test_() ->
             },
             {"crash report for system process limit2",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, {system_limit, [{erlang, spawn_opt, 1}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, system_limit, [{erlang, spawn_opt, 1}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         Expected = lists:flatten(io_lib:format("[error] ~w CRASH REPORT Process ~w with 0 neighbours crashed with reason: system limit: maximum number of processes exceeded", [self(), self()])),
@@ -682,7 +682,7 @@ error_logger_redirect_test_() ->
             },
             {"crash report for system port limit",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, {system_limit, [{erlang, open_port, 1}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, system_limit, [{erlang, open_port, 1}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         Expected = lists:flatten(io_lib:format("[error] ~w CRASH REPORT Process ~w with 0 neighbours crashed with reason: system limit: maximum number of ports exceeded", [self(), self()])),
@@ -691,7 +691,7 @@ error_logger_redirect_test_() ->
             },
             {"crash report for system port limit",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, {system_limit, [{erlang, list_to_atom, 1}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, []}, {error_info, {error, system_limit, [{erlang, list_to_atom, 1}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         Expected = lists:flatten(io_lib:format("[error] ~w CRASH REPORT Process ~w with 0 neighbours crashed with reason: system limit: tried to create an atom larger than 255, or maximum atom count exceeded", [self(), self()])),
@@ -700,7 +700,7 @@ error_logger_redirect_test_() ->
             },
             {"crash report for system ets table limit",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, test}, {error_info, {error, {system_limit,[{ets,new,[segment_offsets,[ordered_set,public]]},{mi_segment,open_write,1},{mi_buffer_converter,handle_cast,2},{gen_server,handle_msg,5},{proc_lib,init_p_do_apply,3}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {registered_name, test}, {error_info, {error, system_limit, [{ets,new,[segment_offsets,[ordered_set,public]]},{mi_segment,open_write,1},{mi_buffer_converter,handle_cast,2},{gen_server,handle_msg,5},{proc_lib,init_p_do_apply,3}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         Expected = lists:flatten(io_lib:format("[error] ~w CRASH REPORT Process ~w with 0 neighbours crashed with reason: system limit: maximum number of ETS tables exceeded", [self(), test])),
@@ -709,14 +709,14 @@ error_logger_redirect_test_() ->
             },
             {"crash report for unknown system limit should be truncated at 500 characters",
                 fun() ->
-                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {error_info, {error, {system_limit,[{wtf,boom,[string:copies("aaaa", 4096)]}]}, []}}], []]),
+                        sync_error_logger:error_report(crash_report, [[{pid, self()}, {error_info, {error, system_limit, [{wtf,boom,[string:copies("aaaa", 4096)]}]}}], []]),
                         _ = gen_event:which_handlers(error_logger),
                         {_, _, Msg} = pop(),
                         ?assert(length(lists:flatten(Msg)) > 600),
                         ?assert(length(lists:flatten(Msg)) < 650)
                 end
             },
-            {"crash reports for 'special processes' should be handled right", 
+            {"crash reports for 'special processes' should be handled right - function_clause", 
                 fun() ->
                         {ok, Pid} = special_process:start(),
                         unlink(Pid),
@@ -729,6 +729,45 @@ error_logger_redirect_test_() ->
                         test_body(Expected, lists:flatten(Msg))
                 end
             },
+            {"crash reports for 'special processes' should be handled right - case_clause", 
+                fun() ->
+                        {ok, Pid} = special_process:start(),
+                        unlink(Pid),
+                        Pid ! {case_clause, wtf},
+                        timer:sleep(500),
+                        _ = gen_event:which_handlers(error_logger),
+                        {_, _, Msg} = pop(),
+                        Expected = lists:flatten(io_lib:format("[error] ~p CRASH REPORT Process ~p with 0 neighbours crashed with reason: no case clause matching wtf in special_process:loop/0",
+                                [Pid, Pid])),
+                        test_body(Expected, lists:flatten(Msg))
+                end
+            },
+            {"crash reports for 'special processes' should be handled right - exit", 
+                fun() ->
+                        {ok, Pid} = special_process:start(),
+                        unlink(Pid),
+                        Pid ! exit,
+                        timer:sleep(500),
+                        _ = gen_event:which_handlers(error_logger),
+                        {_, _, Msg} = pop(),
+                        Expected = lists:flatten(io_lib:format("[error] ~p CRASH REPORT Process ~p with 0 neighbours exited with reason: byebye in special_process:loop/0",
+                                [Pid, Pid])),
+                        test_body(Expected, lists:flatten(Msg))
+                end
+            },
+            {"crash reports for 'special processes' should be handled right - error", 
+                fun() ->
+                        {ok, Pid} = special_process:start(),
+                        unlink(Pid),
+                        Pid ! error,
+                        timer:sleep(500),
+                        _ = gen_event:which_handlers(error_logger),
+                        {_, _, Msg} = pop(),
+                        Expected = lists:flatten(io_lib:format("[error] ~p CRASH REPORT Process ~p with 0 neighbours crashed with reason: mybad in special_process:loop/0",
+                                [Pid, Pid])),
+                        test_body(Expected, lists:flatten(Msg))
+                end
+            },
             {"messages should not be generated if they don't satisfy the threshold",
                 fun() ->
                         lager:set_loglevel(?MODULE, error),

test/special_process.erl

@@ -19,6 +19,14 @@ loop() ->
         error ->
             erlang:error(mybad),
             loop();
+        {case_clause, X} ->
+            case X of
+                notgonnamatch ->
+                    ok;
+                notthiseither ->
+                    error
+            end,
+            loop();
         _ ->
             loop()
     end.