summaryrefslogtreecommitdiff
path: root/lib/kernel/src/kernel.erl
blob: 8877ceea8e26659c8e40d50954b7a22f6fd4cd1d (plain)
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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
%%
%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 1996-2018. 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(kernel).

-behaviour(supervisor).

%% External exports
-export([start/2, init/1, stop/1]).
-export([config_change/3]).

%%%-----------------------------------------------------------------
%%% The kernel is the first application started.
%%% Callback functions for the kernel application.
%%%-----------------------------------------------------------------
start(_, []) ->
    %% Setup the logger and configure the kernel logger environment
    ok = logger:internal_init_logger(),
    case supervisor:start_link({local, kernel_sup}, kernel, []) of
	{ok, Pid} ->
            ok = erl_signal_handler:start(),
            ok = logger:add_handlers(kernel),
            {ok, Pid, []};
	Error -> Error
    end.

stop(_State) ->
    ok.

%%-------------------------------------------------------------------
%% Some configuration parameters for kernel are changed
%%-------------------------------------------------------------------
config_change(Changed, New, Removed) ->
    do_distribution_change(Changed, New, Removed),
    do_global_groups_change(Changed, New, Removed),
    ok.

%%%-----------------------------------------------------------------
%%% The process structure in kernel is as shown in the figure.
%%%
%%%               ---------------
%%%              | kernel_sup (A)|
%%%	          ---------------
%%%                      |
%%%        -------------------------------
%%%       |              |                |
%%%  <std services> -------------   -------------
%%%   (file,code,  | erl_dist (A)| | safe_sup (1)|
%%%    rpc, ...)    -------------   -------------
%%%		          |               |
%%%                  (net_kernel,  (disk_log, pg2,
%%%          	      auth, ...)     ...)
%%%
%%% The rectangular boxes are supervisors.  All supervisors except
%%% for kernel_safe_sup terminates the entire erlang node if any of
%%% their children dies.  Any child that can't be restarted in case
%%% of failure must be placed under one of these supervisors.  Any
%%% other child must be placed under safe_sup.  These children may
%%% be restarted. Be aware that if a child is restarted the old state
%%% and all data will be lost.
%%%-----------------------------------------------------------------
%%% Callback functions for the kernel_sup supervisor.
%%%-----------------------------------------------------------------

init([]) ->
    SupFlags = #{strategy => one_for_all,
                 intensity => 0,
                 period => 1},

    Config = #{id => kernel_config,
               start => {kernel_config, start_link, []},
               restart => permanent,
               shutdown => 2000,
               type => worker,
               modules => [kernel_config]},

    RefC = #{id => kernel_refc,
             start => {kernel_refc, start_link, []},
             restart => permanent,
             shutdown => 2000,
             type => worker,
             modules => [kernel_refc]},

    Code = #{id => code_server,
             start => {code, start_link, []},
             restart => permanent,
             shutdown => 2000,
             type => worker,
             modules => [code]},

    File = #{id => file_server_2,
             start => {file_server, start_link, []},
             restart => permanent,
             shutdown => 2000,
             type => worker,
             modules => [file, file_server, file_io_server, prim_file]},

    StdError = #{id => standard_error,
                 start => {standard_error, start_link, []},
                 restart => temporary,
                 shutdown => 2000,
                 type => supervisor,
                 modules => [standard_error]},

    User = #{id => user,
             start => {user_sup, start, []},
             restart => temporary,
             shutdown => 2000,
             type => supervisor,
             modules => [user_sup]},

    SafeSup = #{id => kernel_safe_sup,
                start =>{supervisor, start_link, [{local, kernel_safe_sup}, ?MODULE, safe]},
                restart => permanent,
                shutdown => infinity,
                type => supervisor,
                modules => [?MODULE]},


    LoggerSup = #{id => logger_sup,
                  start => {logger_sup, start_link, []},
                  restart => permanent,
                  shutdown => infinity,
                  type => supervisor,
                  modules => [logger_sup]},

    case init:get_argument(mode) of
        {ok, [["minimal"]|_]} ->
            {ok, {SupFlags,
                  [Code, File, StdError, User, LoggerSup, Config, RefC, SafeSup]}};
        _ ->
            DistChildren =
		case application:get_env(kernel, start_distribution) of
		    {ok, false} -> [];
		    _ -> start_distribution()
		end,

            InetDb = #{id => inet_db,
                       start => {inet_db, start_link, []},
                       restart => permanent,
                       shutdown => 2000,
                       type => worker,
                       modules => [inet_db]},

            SigSrv = #{id => erl_signal_server,
                       start => {gen_event, start_link, [{local, erl_signal_server}]},
                       restart => permanent,
                       shutdown => 2000,
                       type => worker,
                       modules => dynamic},

            Timer = start_timer(),
            CompileServer = start_compile_server(),

            {ok, {SupFlags,
                  [Code, InetDb | DistChildren] ++
                      [File, SigSrv, StdError, User, Config, RefC, SafeSup, LoggerSup] ++
                      Timer ++ CompileServer}}
    end;
init(safe) ->
    SupFlags = #{strategy => one_for_one,
                 intensity => 4,
                 period => 3600},

    Boot = start_boot_server(),
    DiskLog = start_disk_log(),
    Pg2 = start_pg2(),

    %% Run the on_load handlers for all modules that have been
    %% loaded so far. Running them at this point means that
    %% on_load handlers can safely call kernel processes
    %% (and in particular call code:priv_dir/1 or code:lib_dir/1).
    init:run_on_load_handlers(),

    {ok, {SupFlags, Boot ++ DiskLog ++ Pg2}}.

start_distribution() ->
    Rpc = #{id => rex,
            start => {rpc, start_link, []},
            restart => permanent,
            shutdown => 2000,
            type => worker,
            modules => [rpc]},

    Global = #{id => global_name_server,
               start => {global, start_link, []},
               restart => permanent,
               shutdown => 2000,
               type => worker,
               modules => [global]},

    DistAC = start_dist_ac(),

    NetSup = #{id => net_sup,
               start => {erl_distribution, start_link, []},
               restart => permanent,
               shutdown => infinity,
               type => supervisor,
               modules => [erl_distribution]},

    GlGroup = #{id => global_group,
                start => {global_group,start_link,[]},
                restart => permanent,
                shutdown => 2000,
                type => worker,
                modules => [global_group]},

    [Rpc, Global | DistAC] ++ [NetSup, GlGroup].

start_dist_ac() ->
    Spec = [#{id => dist_ac,
              start => {dist_ac,start_link,[]},
              restart => permanent,
              shutdown => 2000,
              type => worker,
              modules => [dist_ac]}],
    case application:get_env(kernel, start_dist_ac) of
        {ok, true} -> Spec;
        {ok, false} -> [];
        undefined ->
            case application:get_env(kernel, distributed) of
                {ok, _} -> Spec;
                _ -> []
            end
    end.

start_boot_server() ->
    case application:get_env(kernel, start_boot_server) of
        {ok, true} ->
            Args = get_boot_args(),
            [#{id => boot_server,
               start => {erl_boot_server, start_link, [Args]},
               restart => permanent,
               shutdown => 1000,
               type => worker,
               modules => [erl_boot_server]}];
        _ ->
            []
    end.

get_boot_args() ->
    case application:get_env(kernel, boot_server_slaves) of
        {ok, Slaves} -> Slaves;
        _            -> []
    end.

start_disk_log() ->
    case application:get_env(kernel, start_disk_log) of
        {ok, true} ->
            [#{id => disk_log_server,
               start => {disk_log_server, start_link, []},
               restart => permanent,
               shutdown => 2000,
               type => worker,
               modules => [disk_log_server]},
             #{id => disk_log_sup,
               start => {disk_log_sup, start_link, []},
               restart => permanent,
               shutdown => 1000,
               type => supervisor,
               modules => [disk_log_sup]}];
        _ ->
            []
    end.

start_pg2() ->
    case application:get_env(kernel, start_pg2) of
        {ok, true} ->
            [#{id => pg2,
               start => {pg2, start_link, []},
               restart => permanent,
               shutdown => 1000,
               type => worker,
               modules => [pg2]}];
        _ ->
            []
    end.

start_timer() ->
    case application:get_env(kernel, start_timer) of
        {ok, true} ->
            [#{id => timer_server,
               start => {timer, start_link, []},
               restart => permanent,
               shutdown => 1000,
               type => worker,
               modules => [timer]}];
        _ ->
            []
    end.

start_compile_server() ->
    case application:get_env(kernel, start_compile_server) of
        {ok, true} ->
            [#{id => erl_compile_server,
               start => {erl_compile_server, start_link, []},
               restart => permanent,
               shutdown => 2000,
               type => worker,
               modules => [erl_compile_server]}];
        _ ->
            []
    end.

%%-----------------------------------------------------------------
%% The change of the distributed parameter is taken care of here
%%-----------------------------------------------------------------
do_distribution_change(Changed, New, Removed) ->
    %% check if the distributed parameter is changed. It is not allowed
    %% to make a local application to a distributed one, or vice versa.
    case is_dist_changed(Changed, New, Removed) of
	%%{changed, new, removed}
	{false, false, false} ->
	    ok;
	{C, false, false} ->
	    %% At last, update the parameter.
	    gen_server:call(dist_ac, {distribution_changed, C}, infinity);
	{false, _, false} ->
	    error_logger:error_report("Distribution not changed: "
				      "Not allowed to add the 'distributed' "
				      "parameter."),
	    {error, {distribution_not_changed, "Not allowed to add the "
		     "'distributed' parameter"}};
	{false, false, _} ->
	    error_logger:error_report("Distribution not changed: "
				      "Not allowed to remove the "
				      "distribution parameter."),
	    {error, {distribution_not_changed, "Not allowed to remove the "
		     "'distributed' parameter"}}
    end.

%%-----------------------------------------------------------------
%% Check if distribution is changed in someway.
%%-----------------------------------------------------------------
is_dist_changed(Changed, New, Removed) ->
    C = case lists:keyfind(distributed, 1, Changed) of
	    false ->
		false;
	    {distributed, NewDistC} ->
		NewDistC
	end,
    N = case lists:keyfind(distributed, 1, New) of
	    false ->
		false;
	    {distributed, NewDistN} ->
		NewDistN
	end,
    R = lists:member(distributed, Removed),
    {C, N, R}.

%%-----------------------------------------------------------------
%% The change of the global_groups parameter is taken care of here
%%-----------------------------------------------------------------
do_global_groups_change(Changed, New, Removed) ->
    %% check if the global_groups parameter is changed.
    case is_gg_changed(Changed, New, Removed) of
	%%{changed, new, removed}
	{false, false, false} ->
	    ok;
	{C, false, false} ->
	    %% At last, update the parameter.
	    global_group:global_groups_changed(C);
	{false, N, false} ->
	    global_group:global_groups_added(N);
	{false, false, R} ->
	    global_group:global_groups_removed(R)
    end.

%%-----------------------------------------------------------------
%% Check if global_groups is changed in someway.
%%-----------------------------------------------------------------
is_gg_changed(Changed, New, Removed) ->
    C = case lists:keyfind(global_groups, 1, Changed) of
	    false ->
		false;
	    {global_groups, NewDistC} ->
		NewDistC
	end,
    N = case lists:keyfind(global_groups, 1, New) of
	    false ->
		false;
	    {global_groups, NewDistN} ->
		NewDistN
	end,
    R = lists:member(global_groups, Removed),
    {C, N, R}.