aboutsummaryrefslogtreecommitdiffstats
path: root/lib/kernel/src/logger_simple.erl
blob: c8cdf258877c5f5d57d1d89971da5f1da8896f94 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2017. All Rights Reserved.
%%
%% Licensed 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.
%%
%% %CopyrightEnd%
%%
-module(logger_simple).

-export([adding_handler/2, removing_handler/2, log/2]).

%% This module implements a simple handler for logger. It is the
%% default used during system start.

%%%-----------------------------------------------------------------
%%% Logger callback

adding_handler(?MODULE,Config) ->
    Me = self(),
    case whereis(?MODULE) of
        undefined ->
            {Pid,Ref} = spawn_opt(fun() -> init(Me) end,
                                  [link,monitor,{message_queue_data,off_heap}]),
            receive
                {'DOWN',Ref,process,Pid,Reason} ->
                    {error,Reason};
                {Pid,started} ->
                    erlang:demonitor(Ref),
                    {ok,Config}
            end;
        _ ->
            {error,{handler_process_name_already_exists,?MODULE}}
    end.

removing_handler(?MODULE,_Config) ->
    case whereis(?MODULE) of
        undefined ->
            ok;
        Pid ->
            Ref = erlang:monitor(process,Pid),
            unlink(Pid),
            Pid ! stop,
            receive {'DOWN',Ref,process,Pid,_} ->
                    ok
            end
    end.

log(#{meta:=#{error_logger:=#{tag:=info_report,type:=Type}}},_Config)
  when Type=/=std_info ->
    %% Skip info reports that are not 'std_info' (ref simple logger in
    %% error_logger)
    ok;
log(#{msg:=_,meta:=#{time:=_}}=Log,_Config) ->
    _ = case whereis(?MODULE) of
            undefined ->
                %% Is the node on the way down? Real emergency?
                %% Log directly from client just to get it out
                do_log(
                  #{level=>error,
                    msg=>{report,{error,simple_handler_process_dead}},
                    meta=>#{time=>erlang:system_time(microsecond)}}),
                do_log(Log);
            _ ->
                ?MODULE ! {log,Log}
        end,
    ok;
log(_,_) ->
    %% Unexpected log.
    %% We don't want to crash the simple logger, so ignore this.
    ok.

%%%-----------------------------------------------------------------
%%% Process
init(Starter) ->
    register(?MODULE,self()),
    Starter ! {self(),started},
    loop(#{buffer_size=>10,dropped=>0,buffer=>[]}).

loop(Buffer) ->
    receive
        stop ->
            %% We replay the logger messages of there is
            %% a default handler when the simple handler
            %% is removed.
            case logger:get_handler_config(default) of
                {ok, _} ->
                    replay_buffer(Buffer);
                _ ->
                    ok
            end;
        {log,#{msg:=_,meta:=#{time:=_}}=Log} ->
            do_log(Log),
            loop(update_buffer(Buffer,Log));
        _ ->
            %% Unexpected message - flush it!
            loop(Buffer)
    end.

update_buffer(#{buffer_size:=0,dropped:=D}=Buffer,_Log) ->
    Buffer#{dropped=>D+1};
update_buffer(#{buffer_size:=S,buffer:=B}=Buffer,Log) ->
    Buffer#{buffer_size=>S-1,buffer=>[Log|B]}.

replay_buffer(#{ dropped := D, buffer := Buffer }) ->
    lists:foreach(
      fun F(#{msg := {Tag, Msg}} = L) when Tag =:= string; Tag =:= report ->
              F(L#{ msg := Msg });
          F(#{ level := Level, msg := Msg, meta := MD}) ->
              logger:log(Level, Msg, MD)
      end, lists:reverse(Buffer, drop_msg(D))).

drop_msg(0) ->
    [];
drop_msg(N) ->
    [#{level=>info,
       msg=>{"Simple handler buffer full, dropped ~w messages",[N]},
       meta=>#{time=>erlang:system_time(microsecond)}}].

%%%-----------------------------------------------------------------
%%% Internal

%% Can't do io_lib:format

do_log(#{msg:={report,Report},
         meta:=#{time:=T,error_logger:=#{type:=Type}}}) ->
    display_date(T),
    display_report(Type,Report);
do_log(#{msg:=Msg,meta:=#{time:=T}}) ->
    display_date(T),
    display(Msg).

display_date(Timestamp) when is_integer(Timestamp) ->
    Micro = Timestamp rem 1000000,
    Sec = Timestamp div 1000000,
    {{Y,Mo,D},{H,Mi,S}} = erlang:universaltime_to_localtime(
                            erlang:posixtime_to_universaltime(Sec)),
    erlang:display_string(
      integer_to_list(Y) ++ "-" ++
	  pad(Mo,2) ++ "-" ++
	  pad(D,2)  ++ " " ++
	  pad(H,2)  ++ ":" ++
	  pad(Mi,2) ++ ":" ++
	  pad(S,2)  ++ "." ++
          pad(Micro,6) ++ " ").

pad(Int,Size) when is_integer(Int) ->
    pad(integer_to_list(Int),Size);
pad(Str,Size) when length(Str)==Size ->
    Str;
pad(Str,Size) ->
    pad([$0|Str],Size).

display({string,Chardata}) ->
    try unicode:characters_to_list(Chardata) of
        String -> erlang:display_string(String), erlang:display_string("\n")
    catch _:_ -> erlang:display(Chardata)
    end;
display({report,Report}) when is_map(Report) ->
    display_report(maps:to_list(Report));
display({report,Report}) ->
    display_report(Report);
display({F, A}) when is_list(F), is_list(A) ->
    erlang:display_string(F ++ "\n"),
    [begin
	 erlang:display_string("\t"),
	 erlang:display(Arg)
     end || Arg <- A],
    ok.

display_report(Atom, A) when is_atom(Atom) ->
    %% The widest atom seems to be 'supervisor_report' at 17.
    ColumnWidth = 20,
    AtomString = atom_to_list(Atom),
    AtomLength = length(AtomString),
    Padding = lists:duplicate(ColumnWidth - AtomLength, $\s),
    erlang:display_string(AtomString ++ Padding),
    display_report(A);
display_report(F, A) ->
    erlang:display({F, A}).

display_report([A, []]) ->
    %% Special case for crash reports when process has no links
    display_report(A);
display_report(A = [_|_]) ->
    case lists:all(fun({Key,_Value}) -> is_atom(Key); (_) -> false end, A) of
	true ->
	    erlang:display_string("\n"),
	    lists:foreach(
	      fun({Key, Value}) ->
		      erlang:display_string(
			"    " ++
			    atom_to_list(Key) ++
			    ": "),
		      erlang:display(Value)
	      end, A);
	false ->
	    erlang:display(A)
    end;
display_report(A) ->
    erlang:display(A).