aboutsummaryrefslogtreecommitdiffstats
path: root/lib/stdlib/src/gen_server.erl
blob: 342cc2a8e32c6e14c4fe2c2d1c939e22ed667fdb (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
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
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2017. 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(gen_server).

%%% ---------------------------------------------------
%%%
%%% The idea behind THIS server is that the user module
%%% provides (different) functions to handle different
%%% kind of inputs. 
%%% If the Parent process terminates the Module:terminate/2
%%% function is called.
%%%
%%% The user module should export:
%%%
%%%   init(Args)  
%%%     ==> {ok, State}
%%%         {ok, State, Timeout}
%%%         ignore
%%%         {stop, Reason}
%%%
%%%   handle_call(Msg, {From, Tag}, State)
%%%
%%%    ==> {reply, Reply, State}
%%%        {reply, Reply, State, Timeout}
%%%        {noreply, State}
%%%        {noreply, State, Timeout}
%%%        {stop, Reason, Reply, State}  
%%%              Reason = normal | shutdown | Term terminate(State) is called
%%%
%%%   handle_cast(Msg, State)
%%%
%%%    ==> {noreply, State}
%%%        {noreply, State, Timeout}
%%%        {stop, Reason, State} 
%%%              Reason = normal | shutdown | Term terminate(State) is called
%%%
%%%   handle_info(Info, State) Info is e.g. {'EXIT', P, R}, {nodedown, N}, ...
%%%
%%%    ==> {noreply, State}
%%%        {noreply, State, Timeout}
%%%        {stop, Reason, State} 
%%%              Reason = normal | shutdown | Term, terminate(State) is called
%%%
%%%   terminate(Reason, State) Let the user module clean up
%%%        always called when server terminates
%%%
%%%    ==> ok
%%%
%%%
%%% The work flow (of the server) can be described as follows:
%%%
%%%   User module                          Generic
%%%   -----------                          -------
%%%     start            ----->             start
%%%     init             <-----              .
%%%
%%%                                         loop
%%%     handle_call      <-----              .
%%%                      ----->             reply
%%%
%%%     handle_cast      <-----              .
%%%
%%%     handle_info      <-----              .
%%%
%%%     terminate        <-----              .
%%%
%%%                      ----->             reply
%%%
%%%
%%% ---------------------------------------------------

%% API
-export([start/3, start/4,
	 start_link/3, start_link/4,
	 stop/1, stop/3,
	 call/2, call/3,
	 cast/2, reply/2,
	 abcast/2, abcast/3,
	 multi_call/2, multi_call/3, multi_call/4,
	 enter_loop/3, enter_loop/4, enter_loop/5, wake_hib/6]).

%% System exports
-export([system_continue/3,
	 system_terminate/4,
	 system_code_change/4,
	 system_get_state/1,
	 system_replace_state/2,
	 format_status/2]).

%% logger callback
-export([format_log/1]).

%% Internal exports
-export([init_it/6]).

-include("logger.hrl").

-define(
   STACKTRACE(),
   element(2, erlang:process_info(self(), current_stacktrace))).

%%%=========================================================================
%%%  API
%%%=========================================================================

-callback init(Args :: term()) ->
    {ok, State :: term()} | {ok, State :: term(), timeout() | hibernate | {continue, term()}} |
    {stop, Reason :: term()} | ignore.
-callback handle_call(Request :: term(), From :: {pid(), Tag :: term()},
                      State :: term()) ->
    {reply, Reply :: term(), NewState :: term()} |
    {reply, Reply :: term(), NewState :: term(), timeout() | hibernate | {continue, term()}} |
    {noreply, NewState :: term()} |
    {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
    {stop, Reason :: term(), Reply :: term(), NewState :: term()} |
    {stop, Reason :: term(), NewState :: term()}.
-callback handle_cast(Request :: term(), State :: term()) ->
    {noreply, NewState :: term()} |
    {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
    {stop, Reason :: term(), NewState :: term()}.
-callback handle_info(Info :: timeout | term(), State :: term()) ->
    {noreply, NewState :: term()} |
    {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
    {stop, Reason :: term(), NewState :: term()}.
-callback handle_continue(Info :: term(), State :: term()) ->
    {noreply, NewState :: term()} |
    {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
    {stop, Reason :: term(), NewState :: term()}.
-callback terminate(Reason :: (normal | shutdown | {shutdown, term()} |
                               term()),
                    State :: term()) ->
    term().
-callback code_change(OldVsn :: (term() | {down, term()}), State :: term(),
                      Extra :: term()) ->
    {ok, NewState :: term()} | {error, Reason :: term()}.
-callback format_status(Opt, StatusData) -> Status when
      Opt :: 'normal' | 'terminate',
      StatusData :: [PDict | State],
      PDict :: [{Key :: term(), Value :: term()}],
      State :: term(),
      Status :: term().

-optional_callbacks(
    [handle_info/2, handle_continue/2, terminate/2, code_change/3, format_status/2]).

%%%  -----------------------------------------------------------------
%%% Starts a generic server.
%%% start(Mod, Args, Options)
%%% start(Name, Mod, Args, Options)
%%% start_link(Mod, Args, Options)
%%% start_link(Name, Mod, Args, Options) where:
%%%    Name ::= {local, atom()} | {global, term()} | {via, atom(), term()}
%%%    Mod  ::= atom(), callback module implementing the 'real' server
%%%    Args ::= term(), init arguments (to Mod:init/1)
%%%    Options ::= [{timeout, Timeout} | {debug, [Flag]}]
%%%      Flag ::= trace | log | {logfile, File} | statistics | debug
%%%          (debug == log && statistics)
%%% Returns: {ok, Pid} |
%%%          {error, {already_started, Pid}} |
%%%          {error, Reason}
%%% -----------------------------------------------------------------
start(Mod, Args, Options) ->
    gen:start(?MODULE, nolink, Mod, Args, Options).

start(Name, Mod, Args, Options) ->
    gen:start(?MODULE, nolink, Name, Mod, Args, Options).

start_link(Mod, Args, Options) ->
    gen:start(?MODULE, link, Mod, Args, Options).

start_link(Name, Mod, Args, Options) ->
    gen:start(?MODULE, link, Name, Mod, Args, Options).


%% -----------------------------------------------------------------
%% Stop a generic server and wait for it to terminate.
%% If the server is located at another node, that node will
%% be monitored.
%% -----------------------------------------------------------------
stop(Name) ->
    gen:stop(Name).

stop(Name, Reason, Timeout) ->
    gen:stop(Name, Reason, Timeout).

%% -----------------------------------------------------------------
%% Make a call to a generic server.
%% If the server is located at another node, that node will
%% be monitored.
%% If the client is trapping exits and is linked server termination
%% is handled here (? Shall we do that here (or rely on timeouts) ?).
%% ----------------------------------------------------------------- 
call(Name, Request) ->
    case catch gen:call(Name, '$gen_call', Request) of
	{ok,Res} ->
	    Res;
	{'EXIT',Reason} ->
	    exit({Reason, {?MODULE, call, [Name, Request]}})
    end.

call(Name, Request, Timeout) ->
    case catch gen:call(Name, '$gen_call', Request, Timeout) of
	{ok,Res} ->
	    Res;
	{'EXIT',Reason} ->
	    exit({Reason, {?MODULE, call, [Name, Request, Timeout]}})
    end.

%% -----------------------------------------------------------------
%% Make a cast to a generic server.
%% -----------------------------------------------------------------
cast({global,Name}, Request) ->
    catch global:send(Name, cast_msg(Request)),
    ok;
cast({via, Mod, Name}, Request) ->
    catch Mod:send(Name, cast_msg(Request)),
    ok;
cast({Name,Node}=Dest, Request) when is_atom(Name), is_atom(Node) -> 
    do_cast(Dest, Request);
cast(Dest, Request) when is_atom(Dest) ->
    do_cast(Dest, Request);
cast(Dest, Request) when is_pid(Dest) ->
    do_cast(Dest, Request).

do_cast(Dest, Request) -> 
    do_send(Dest, cast_msg(Request)),
    ok.
    
cast_msg(Request) -> {'$gen_cast',Request}.

%% -----------------------------------------------------------------
%% Send a reply to the client.
%% -----------------------------------------------------------------
reply({To, Tag}, Reply) ->
    catch To ! {Tag, Reply}.

%% ----------------------------------------------------------------- 
%% Asynchronous broadcast, returns nothing, it's just send 'n' pray
%%-----------------------------------------------------------------  
abcast(Name, Request) when is_atom(Name) ->
    do_abcast([node() | nodes()], Name, cast_msg(Request)).

abcast(Nodes, Name, Request) when is_list(Nodes), is_atom(Name) ->
    do_abcast(Nodes, Name, cast_msg(Request)).

do_abcast([Node|Nodes], Name, Msg) when is_atom(Node) ->
    do_send({Name,Node},Msg),
    do_abcast(Nodes, Name, Msg);
do_abcast([], _,_) -> abcast.

%%% -----------------------------------------------------------------
%%% Make a call to servers at several nodes.
%%% Returns: {[Replies],[BadNodes]}
%%% A Timeout can be given
%%% 
%%% A middleman process is used in case late answers arrives after
%%% the timeout. If they would be allowed to glog the callers message
%%% queue, it would probably become confused. Late answers will 
%%% now arrive to the terminated middleman and so be discarded.
%%% -----------------------------------------------------------------
multi_call(Name, Req)
  when is_atom(Name) ->
    do_multi_call([node() | nodes()], Name, Req, infinity).

multi_call(Nodes, Name, Req) 
  when is_list(Nodes), is_atom(Name) ->
    do_multi_call(Nodes, Name, Req, infinity).

multi_call(Nodes, Name, Req, infinity) ->
    do_multi_call(Nodes, Name, Req, infinity);
multi_call(Nodes, Name, Req, Timeout) 
  when is_list(Nodes), is_atom(Name), is_integer(Timeout), Timeout >= 0 ->
    do_multi_call(Nodes, Name, Req, Timeout).


%%-----------------------------------------------------------------
%% enter_loop(Mod, Options, State, <ServerName>, <TimeOut>) ->_ 
%%   
%% Description: Makes an existing process into a gen_server. 
%%              The calling process will enter the gen_server receive 
%%              loop and become a gen_server process.
%%              The process *must* have been started using one of the 
%%              start functions in proc_lib, see proc_lib(3). 
%%              The user is responsible for any initialization of the 
%%              process, including registering a name for it.
%%-----------------------------------------------------------------
enter_loop(Mod, Options, State) ->
    enter_loop(Mod, Options, State, self(), infinity).

enter_loop(Mod, Options, State, ServerName = {Scope, _})
  when Scope == local; Scope == global ->
    enter_loop(Mod, Options, State, ServerName, infinity);

enter_loop(Mod, Options, State, ServerName = {via, _, _}) ->
    enter_loop(Mod, Options, State, ServerName, infinity);

enter_loop(Mod, Options, State, Timeout) ->
    enter_loop(Mod, Options, State, self(), Timeout).

enter_loop(Mod, Options, State, ServerName, Timeout) ->
    Name = gen:get_proc_name(ServerName),
    Parent = gen:get_parent(),
    Debug = gen:debug_options(Name, Options),
    HibernateAfterTimeout = gen:hibernate_after(Options),
    loop(Parent, Name, State, Mod, Timeout, HibernateAfterTimeout, Debug).

%%%========================================================================
%%% Gen-callback functions
%%%========================================================================

%%% ---------------------------------------------------
%%% Initiate the new process.
%%% Register the name using the Rfunc function
%%% Calls the Mod:init/Args function.
%%% Finally an acknowledge is sent to Parent and the main
%%% loop is entered.
%%% ---------------------------------------------------
init_it(Starter, self, Name, Mod, Args, Options) ->
    init_it(Starter, self(), Name, Mod, Args, Options);
init_it(Starter, Parent, Name0, Mod, Args, Options) ->
    Name = gen:name(Name0),
    Debug = gen:debug_options(Name, Options),
    HibernateAfterTimeout = gen:hibernate_after(Options),

    case init_it(Mod, Args) of
	{ok, {ok, State}} ->
	    proc_lib:init_ack(Starter, {ok, self()}), 	    
	    loop(Parent, Name, State, Mod, infinity, HibernateAfterTimeout, Debug);
	{ok, {ok, State, Timeout}} ->
	    proc_lib:init_ack(Starter, {ok, self()}), 	    
	    loop(Parent, Name, State, Mod, Timeout, HibernateAfterTimeout, Debug);
	{ok, {stop, Reason}} ->
	    %% For consistency, we must make sure that the
	    %% registered name (if any) is unregistered before
	    %% the parent process is notified about the failure.
	    %% (Otherwise, the parent process could get
	    %% an 'already_started' error if it immediately
	    %% tried starting the process again.)
	    gen:unregister_name(Name0),
	    proc_lib:init_ack(Starter, {error, Reason}),
	    exit(Reason);
	{ok, ignore} ->
	    gen:unregister_name(Name0),
	    proc_lib:init_ack(Starter, ignore),
	    exit(normal);
	{ok, Else} ->
	    Error = {bad_return_value, Else},
	    proc_lib:init_ack(Starter, {error, Error}),
	    exit(Error);
	{'EXIT', Class, Reason, Stacktrace} ->
	    gen:unregister_name(Name0),
	    proc_lib:init_ack(Starter, {error, terminate_reason(Class, Reason, Stacktrace)}),
	    erlang:raise(Class, Reason, Stacktrace)
    end.
init_it(Mod, Args) ->
    try
	{ok, Mod:init(Args)}
    catch
	throw:R -> {ok, R};
	Class:R:S -> {'EXIT', Class, R, S}
    end.

%%%========================================================================
%%% Internal functions
%%%========================================================================
%%% ---------------------------------------------------
%%% The MAIN loop.
%%% ---------------------------------------------------

loop(Parent, Name, State, Mod, {continue, Continue} = Msg, HibernateAfterTimeout, Debug) ->
    Reply = try_dispatch(Mod, handle_continue, Continue, State),
    case Debug of
	[] ->
	    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod,
				HibernateAfterTimeout, State);
	_ ->
	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name, Msg),
	    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod,
				HibernateAfterTimeout, State, Debug1)
    end;

loop(Parent, Name, State, Mod, hibernate, HibernateAfterTimeout, Debug) ->
    proc_lib:hibernate(?MODULE,wake_hib,[Parent, Name, State, Mod, HibernateAfterTimeout, Debug]);

loop(Parent, Name, State, Mod, infinity, HibernateAfterTimeout, Debug) ->
	receive
		Msg ->
			decode_msg(Msg, Parent, Name, State, Mod, infinity, HibernateAfterTimeout, Debug, false)
	after HibernateAfterTimeout ->
		loop(Parent, Name, State, Mod, hibernate, HibernateAfterTimeout, Debug)
	end;

loop(Parent, Name, State, Mod, Time, HibernateAfterTimeout, Debug) ->
    Msg = receive
	      Input ->
		    Input
	  after Time ->
		  timeout
	  end,
    decode_msg(Msg, Parent, Name, State, Mod, Time, HibernateAfterTimeout, Debug, false).

wake_hib(Parent, Name, State, Mod, HibernateAfterTimeout, Debug) ->
    Msg = receive
	      Input ->
		  Input
	  end,
    decode_msg(Msg, Parent, Name, State, Mod, hibernate, HibernateAfterTimeout, Debug, true).

decode_msg(Msg, Parent, Name, State, Mod, Time, HibernateAfterTimeout, Debug, Hib) ->
    case Msg of
	{system, From, Req} ->
	    sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug,
				  [Name, State, Mod, Time, HibernateAfterTimeout], Hib);
	{'EXIT', Parent, Reason} ->
	    terminate(Reason, ?STACKTRACE(), Name, undefined, Msg, Mod, State, Debug);
	_Msg when Debug =:= [] ->
	    handle_msg(Msg, Parent, Name, State, Mod, HibernateAfterTimeout);
	_Msg ->
	    Debug1 = sys:handle_debug(Debug, fun print_event/3,
				      Name, {in, Msg}),
	    handle_msg(Msg, Parent, Name, State, Mod, HibernateAfterTimeout, Debug1)
    end.

%%% ---------------------------------------------------
%%% Send/receive functions
%%% ---------------------------------------------------
do_send(Dest, Msg) ->
    try erlang:send(Dest, Msg)
    catch
        error:_ -> ok
    end,
    ok.

do_multi_call(Nodes, Name, Req, infinity) ->
    Tag = make_ref(),
    Monitors = send_nodes(Nodes, Name, Tag, Req),
    rec_nodes(Tag, Monitors, Name, undefined);
do_multi_call(Nodes, Name, Req, Timeout) ->
    Tag = make_ref(),
    Caller = self(),
    Receiver =
	spawn(
	  fun() ->
		  %% Middleman process. Should be unsensitive to regular
		  %% exit signals. The sychronization is needed in case
		  %% the receiver would exit before the caller started
		  %% the monitor.
		  process_flag(trap_exit, true),
		  Mref = erlang:monitor(process, Caller),
		  receive
		      {Caller,Tag} ->
			  Monitors = send_nodes(Nodes, Name, Tag, Req),
			  TimerId = erlang:start_timer(Timeout, self(), ok),
			  Result = rec_nodes(Tag, Monitors, Name, TimerId),
			  exit({self(),Tag,Result});
		      {'DOWN',Mref,_,_,_} ->
			  %% Caller died before sending us the go-ahead.
			  %% Give up silently.
			  exit(normal)
		  end
	  end),
    Mref = erlang:monitor(process, Receiver),
    Receiver ! {self(),Tag},
    receive
	{'DOWN',Mref,_,_,{Receiver,Tag,Result}} ->
	    Result;
	{'DOWN',Mref,_,_,Reason} ->
	    %% The middleman code failed. Or someone did 
	    %% exit(_, kill) on the middleman process => Reason==killed
	    exit(Reason)
    end.

send_nodes(Nodes, Name, Tag, Req) ->
    send_nodes(Nodes, Name, Tag, Req, []).

send_nodes([Node|Tail], Name, Tag, Req, Monitors)
  when is_atom(Node) ->
    Monitor = start_monitor(Node, Name),
    %% Handle non-existing names in rec_nodes.
    catch {Name, Node} ! {'$gen_call', {self(), {Tag, Node}}, Req},
    send_nodes(Tail, Name, Tag, Req, [Monitor | Monitors]);
send_nodes([_Node|Tail], Name, Tag, Req, Monitors) ->
    %% Skip non-atom Node
    send_nodes(Tail, Name, Tag, Req, Monitors);
send_nodes([], _Name, _Tag, _Req, Monitors) -> 
    Monitors.

%% Against old nodes:
%% If no reply has been delivered within 2 secs. (per node) check that
%% the server really exists and wait for ever for the answer.
%%
%% Against contemporary nodes:
%% Wait for reply, server 'DOWN', or timeout from TimerId.

rec_nodes(Tag, Nodes, Name, TimerId) -> 
    rec_nodes(Tag, Nodes, Name, [], [], 2000, TimerId).

rec_nodes(Tag, [{N,R}|Tail], Name, Badnodes, Replies, Time, TimerId ) ->
    receive
	{'DOWN', R, _, _, _} ->
	    rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, Time, TimerId);
	{{Tag, N}, Reply} ->  %% Tag is bound !!!
	    erlang:demonitor(R, [flush]),
	    rec_nodes(Tag, Tail, Name, Badnodes, 
		      [{N,Reply}|Replies], Time, TimerId);
	{timeout, TimerId, _} ->	
	    erlang:demonitor(R, [flush]),
	    %% Collect all replies that already have arrived
	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
    end;
rec_nodes(Tag, [N|Tail], Name, Badnodes, Replies, Time, TimerId) ->
    %% R6 node
    receive
	{nodedown, N} ->
	    monitor_node(N, false),
	    rec_nodes(Tag, Tail, Name, [N|Badnodes], Replies, 2000, TimerId);
	{{Tag, N}, Reply} ->  %% Tag is bound !!!
	    receive {nodedown, N} -> ok after 0 -> ok end,
	    monitor_node(N, false),
	    rec_nodes(Tag, Tail, Name, Badnodes,
		      [{N,Reply}|Replies], 2000, TimerId);
	{timeout, TimerId, _} ->	
	    receive {nodedown, N} -> ok after 0 -> ok end,
	    monitor_node(N, false),
	    %% Collect all replies that already have arrived
	    rec_nodes_rest(Tag, Tail, Name, [N | Badnodes], Replies)
    after Time ->
	    case rpc:call(N, erlang, whereis, [Name]) of
		Pid when is_pid(Pid) -> % It exists try again.
		    rec_nodes(Tag, [N|Tail], Name, Badnodes,
			      Replies, infinity, TimerId);
		_ -> % badnode
		    receive {nodedown, N} -> ok after 0 -> ok end,
		    monitor_node(N, false),
		    rec_nodes(Tag, Tail, Name, [N|Badnodes],
			      Replies, 2000, TimerId)
	    end
    end;
rec_nodes(_, [], _, Badnodes, Replies, _, TimerId) ->
    case catch erlang:cancel_timer(TimerId) of
	false ->  % It has already sent it's message
	    receive
		{timeout, TimerId, _} -> ok
	    after 0 ->
		    ok
	    end;
	_ -> % Timer was cancelled, or TimerId was 'undefined'
	    ok
    end,
    {Replies, Badnodes}.

%% Collect all replies that already have arrived
rec_nodes_rest(Tag, [{N,R}|Tail], Name, Badnodes, Replies) ->
    receive
	{'DOWN', R, _, _, _} ->
	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies);
	{{Tag, N}, Reply} -> %% Tag is bound !!!
	    erlang:demonitor(R, [flush]),
	    rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies])
    after 0 ->
	    erlang:demonitor(R, [flush]),
	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
    end;
rec_nodes_rest(Tag, [N|Tail], Name, Badnodes, Replies) ->
    %% R6 node
    receive
	{nodedown, N} ->
	    monitor_node(N, false),
	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies);
	{{Tag, N}, Reply} ->  %% Tag is bound !!!
	    receive {nodedown, N} -> ok after 0 -> ok end,
	    monitor_node(N, false),
	    rec_nodes_rest(Tag, Tail, Name, Badnodes, [{N,Reply}|Replies])
    after 0 ->
	    receive {nodedown, N} -> ok after 0 -> ok end,
	    monitor_node(N, false),
	    rec_nodes_rest(Tag, Tail, Name, [N|Badnodes], Replies)
    end;
rec_nodes_rest(_Tag, [], _Name, Badnodes, Replies) ->
    {Replies, Badnodes}.


%%% ---------------------------------------------------
%%% Monitor functions
%%% ---------------------------------------------------

start_monitor(Node, Name) when is_atom(Node), is_atom(Name) ->
    if node() =:= nonode@nohost, Node =/= nonode@nohost ->
	    Ref = make_ref(),
	    self() ! {'DOWN', Ref, process, {Name, Node}, noconnection},
	    {Node, Ref};
       true ->
	    case catch erlang:monitor(process, {Name, Node}) of
		{'EXIT', _} ->
		    %% Remote node is R6
		    monitor_node(Node, true),
		    Node;
		Ref when is_reference(Ref) ->
		    {Node, Ref}
	    end
    end.

%% ---------------------------------------------------
%% Helper functions for try-catch of callbacks.
%% Returns the return value of the callback, or
%% {'EXIT', Class, Reason, Stack} (if an exception occurs)
%%
%% The Class, Reason and Stack are given to erlang:raise/3
%% to make sure proc_lib receives the proper reasons and
%% stacktraces.
%% ---------------------------------------------------

try_dispatch({'$gen_cast', Msg}, Mod, State) ->
    try_dispatch(Mod, handle_cast, Msg, State);
try_dispatch(Info, Mod, State) ->
    try_dispatch(Mod, handle_info, Info, State).

try_dispatch(Mod, Func, Msg, State) ->
    try
	{ok, Mod:Func(Msg, State)}
    catch
	throw:R ->
	    {ok, R};
        error:undef = R:Stacktrace when Func == handle_info ->
            case erlang:function_exported(Mod, handle_info, 2) of
                false ->
                    ?LOG_WARNING(
                       #{label=>{gen_server,no_handle_info},
                         module=>Mod,
                         message=>Msg},
                       #{domain=>[otp],
                         report_cb=>fun gen_server:format_log/1,
                         error_logger=>#{tag=>warning_msg}}),
                    {ok, {noreply, State}};
                true ->
                    {'EXIT', error, R, Stacktrace}
            end;
	Class:R:Stacktrace ->
	    {'EXIT', Class, R, Stacktrace}
    end.

try_handle_call(Mod, Msg, From, State) ->
    try
	{ok, Mod:handle_call(Msg, From, State)}
    catch
	throw:R ->
	    {ok, R};
	Class:R:Stacktrace ->
	    {'EXIT', Class, R, Stacktrace}
    end.

try_terminate(Mod, Reason, State) ->
    case erlang:function_exported(Mod, terminate, 2) of
	true ->
	    try
		{ok, Mod:terminate(Reason, State)}
	    catch
		throw:R ->
		    {ok, R};
		Class:R:Stacktrace ->
		    {'EXIT', Class, R, Stacktrace}
	   end;
	false ->
	    {ok, ok}
    end.


%%% ---------------------------------------------------
%%% Message handling functions
%%% ---------------------------------------------------

handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, HibernateAfterTimeout) ->
    Result = try_handle_call(Mod, Msg, From, State),
    case Result of
	{ok, {reply, Reply, NState}} ->
	    reply(From, Reply),
	    loop(Parent, Name, NState, Mod, infinity, HibernateAfterTimeout, []);
	{ok, {reply, Reply, NState, Time1}} ->
	    reply(From, Reply),
	    loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, []);
	{ok, {noreply, NState}} ->
	    loop(Parent, Name, NState, Mod, infinity, HibernateAfterTimeout, []);
	{ok, {noreply, NState, Time1}} ->
	    loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, []);
	{ok, {stop, Reason, Reply, NState}} ->
	    try
		terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, [])
	    after
		reply(From, Reply)
	    end;
	Other -> handle_common_reply(Other, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State)
    end;
handle_msg(Msg, Parent, Name, State, Mod, HibernateAfterTimeout) ->
    Reply = try_dispatch(Msg, Mod, State),
    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod, HibernateAfterTimeout, State).

handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, HibernateAfterTimeout, Debug) ->
    Result = try_handle_call(Mod, Msg, From, State),
    case Result of
	{ok, {reply, Reply, NState}} ->
	    Debug1 = reply(Name, From, Reply, NState, Debug),
	    loop(Parent, Name, NState, Mod, infinity, HibernateAfterTimeout, Debug1);
	{ok, {reply, Reply, NState, Time1}} ->
	    Debug1 = reply(Name, From, Reply, NState, Debug),
	    loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, Debug1);
	{ok, {noreply, NState}} ->
	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
				      {noreply, NState}),
	    loop(Parent, Name, NState, Mod, infinity, HibernateAfterTimeout, Debug1);
	{ok, {noreply, NState, Time1}} ->
	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
				      {noreply, NState}),
	    loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, Debug1);
	{ok, {stop, Reason, Reply, NState}} ->
	    try
		terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, Debug)
	    after
		_ = reply(Name, From, Reply, NState, Debug)
	    end;
	Other ->
	    handle_common_reply(Other, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State, Debug)
    end;
handle_msg(Msg, Parent, Name, State, Mod, HibernateAfterTimeout, Debug) ->
    Reply = try_dispatch(Msg, Mod, State),
    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod, HibernateAfterTimeout, State, Debug).

handle_common_reply(Reply, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State) ->
    case Reply of
	{ok, {noreply, NState}} ->
	    loop(Parent, Name, NState, Mod, infinity, HibernateAfterTimeout, []);
	{ok, {noreply, NState, Time1}} ->
	    loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, []);
	{ok, {stop, Reason, NState}} ->
	    terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, []);
	{'EXIT', Class, Reason, Stacktrace} ->
	    terminate(Class, Reason, Stacktrace, Name, From, Msg, Mod, State, []);
	{ok, BadReply} ->
	    terminate({bad_return_value, BadReply}, ?STACKTRACE(), Name, From, Msg, Mod, State, [])
    end.

handle_common_reply(Reply, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State, Debug) ->
    case Reply of
	{ok, {noreply, NState}} ->
	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
				      {noreply, NState}),
	    loop(Parent, Name, NState, Mod, infinity, HibernateAfterTimeout, Debug1);
	{ok, {noreply, NState, Time1}} ->
	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
				      {noreply, NState}),
	    loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, Debug1);
	{ok, {stop, Reason, NState}} ->
	    terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, Debug);
	{'EXIT', Class, Reason, Stacktrace} ->
	    terminate(Class, Reason, Stacktrace, Name, From, Msg, Mod, State, Debug);
	{ok, BadReply} ->
	    terminate({bad_return_value, BadReply}, ?STACKTRACE(), Name, From, Msg, Mod, State, Debug)
    end.

reply(Name, {To, Tag}, Reply, State, Debug) ->
    reply({To, Tag}, Reply),
    sys:handle_debug(Debug, fun print_event/3, Name,
		     {out, Reply, To, State} ).


%%-----------------------------------------------------------------
%% Callback functions for system messages handling.
%%-----------------------------------------------------------------
system_continue(Parent, Debug, [Name, State, Mod, Time, HibernateAfterTimeout]) ->
    loop(Parent, Name, State, Mod, Time, HibernateAfterTimeout, Debug).

-spec system_terminate(_, _, _, [_]) -> no_return().

system_terminate(Reason, _Parent, Debug, [Name, State, Mod, _Time, _HibernateAfterTimeout]) ->
    terminate(Reason, ?STACKTRACE(), Name, undefined, [], Mod, State, Debug).

system_code_change([Name, State, Mod, Time, HibernateAfterTimeout], _Module, OldVsn, Extra) ->
    case catch Mod:code_change(OldVsn, State, Extra) of
	{ok, NewState} -> {ok, [Name, NewState, Mod, Time, HibernateAfterTimeout]};
	Else -> Else
    end.

system_get_state([_Name, State, _Mod, _Time, _HibernateAfterTimeout]) ->
    {ok, State}.

system_replace_state(StateFun, [Name, State, Mod, Time, HibernateAfterTimeout]) ->
    NState = StateFun(State),
    {ok, NState, [Name, NState, Mod, Time, HibernateAfterTimeout]}.

%%-----------------------------------------------------------------
%% Format debug messages.  Print them as the call-back module sees
%% them, not as the real erlang messages.  Use trace for that.
%%-----------------------------------------------------------------
print_event(Dev, {in, Msg}, Name) ->
    case Msg of
	{'$gen_call', {From, _Tag}, Call} ->
	    io:format(Dev, "*DBG* ~tp got call ~tp from ~w~n",
		      [Name, Call, From]);
	{'$gen_cast', Cast} ->
	    io:format(Dev, "*DBG* ~tp got cast ~tp~n",
		      [Name, Cast]);
	_ ->
	    io:format(Dev, "*DBG* ~tp got ~tp~n", [Name, Msg])
    end;
print_event(Dev, {out, Msg, To, State}, Name) ->
    io:format(Dev, "*DBG* ~tp sent ~tp to ~w, new state ~tp~n",
	      [Name, Msg, To, State]);
print_event(Dev, {noreply, State}, Name) ->
    io:format(Dev, "*DBG* ~tp new state ~tp~n", [Name, State]);
print_event(Dev, Event, Name) ->
    io:format(Dev, "*DBG* ~tp dbg  ~tp~n", [Name, Event]).


%%% ---------------------------------------------------
%%% Terminate the server.
%%%
%%% terminate/8 is triggered by {stop, Reason} or bad
%%% return values. The stacktrace is generated via the
%%% ?STACKTRACE() macro and the ReportReason must not
%%% be wrapped in tuples.
%%%
%%% terminate/9 is triggered in case of error/exit in
%%% the user callback. In this case the report reason
%%% always includes the user stacktrace.
%%%
%%% The reason received in the terminate/2 callbacks
%%% always includes the stacktrace for errors and never
%%% for exits.
%%% ---------------------------------------------------

-spec terminate(_, _, _, _, _, _, _, _) -> no_return().
terminate(Reason, Stacktrace, Name, From, Msg, Mod, State, Debug) ->
  terminate(exit, Reason, Stacktrace, Reason, Name, From, Msg, Mod, State, Debug).

-spec terminate(_, _, _, _, _, _, _, _, _) -> no_return().
terminate(Class, Reason, Stacktrace, Name, From, Msg, Mod, State, Debug) ->
  ReportReason = {Reason, Stacktrace},
  terminate(Class, Reason, Stacktrace, ReportReason, Name, From, Msg, Mod, State, Debug).

-spec terminate(_, _, _, _, _, _, _, _, _, _) -> no_return().
terminate(Class, Reason, Stacktrace, ReportReason, Name, From, Msg, Mod, State, Debug) ->
    Reply = try_terminate(Mod, terminate_reason(Class, Reason, Stacktrace), State),
    case Reply of
	{'EXIT', C, R, S} ->
	    error_info({R, S}, Name, From, Msg, Mod, State, Debug),
	    erlang:raise(C, R, S);
	_ ->
	    case {Class, Reason} of
		{exit, normal} -> ok;
		{exit, shutdown} -> ok;
		{exit, {shutdown,_}} -> ok;
		_ ->
		    error_info(ReportReason, Name, From, Msg, Mod, State, Debug)
	    end
    end,
    case Stacktrace of
	[] ->
	    erlang:Class(Reason);
	_ ->
	    erlang:raise(Class, Reason, Stacktrace)
    end.

terminate_reason(error, Reason, Stacktrace) -> {Reason, Stacktrace};
terminate_reason(exit, Reason, _Stacktrace) -> Reason.

error_info(_Reason, application_controller, _From, _Msg, _Mod, _State, _Debug) ->
    %% OTP-5811 Don't send an error report if it's the system process
    %% application_controller which is terminating - let init take care
    %% of it instead
    ok;
error_info(Reason, Name, From, Msg, Mod, State, Debug) ->
    ?LOG_ERROR(#{label=>{gen_server,terminate},
                 name=>Name,
                 last_message=>Msg,
                 state=>format_status(terminate, Mod, get(), State),
                 reason=>Reason,
                 client_info=>client_stacktrace(From)},
               #{domain=>[otp],
                 report_cb=>fun gen_server:format_log/1,
                 error_logger=>#{tag=>error}}),
    sys:print_log(Debug),
    ok.

client_stacktrace(undefined) ->
    undefined;
client_stacktrace({From,_Tag}) ->
    client_stacktrace(From);
client_stacktrace(From) when is_pid(From), node(From) =:= node() ->
    case process_info(From, [current_stacktrace, registered_name]) of
        undefined ->
            {From,dead};
        [{current_stacktrace, Stacktrace}, {registered_name, []}]  ->
            {From,{From,Stacktrace}};
        [{current_stacktrace, Stacktrace}, {registered_name, Name}]  ->
            {From,{Name,Stacktrace}}
    end;
client_stacktrace(From) when is_pid(From) ->
    {From,remote}.

format_log(#{label:={gen_server,terminate},
             name:=Name,
             last_message:=Msg,
             state:=State,
             reason:=Reason,
             client_info:=Client}) ->
    Reason1 = 
	case Reason of
	    {undef,[{M,F,A,L}|MFAs]} ->
		case code:is_loaded(M) of
		    false ->
			{'module could not be loaded',[{M,F,A,L}|MFAs]};
		    _ ->
			case erlang:function_exported(M, F, length(A)) of
			    true ->
				Reason;
			    false ->
				{'function not exported',[{M,F,A,L}|MFAs]}
			end
		end;
	    _ ->
		error_logger:limit_term(Reason)
	end,    
    {ClientFmt,ClientArgs} = format_client_log(Client),
    {"** Generic server ~tp terminating \n"
     "** Last message in was ~tp~n"
     "** When Server state == ~tp~n"
     "** Reason for termination == ~n** ~tp~n" ++ ClientFmt,
     [Name, Msg, error_logger:limit_term(State), Reason1] ++ ClientArgs};
format_log(#{label:={gen_server,no_handle_info},
             module:=Mod,
             message:=Msg}) ->
    {"** Undefined handle_info in ~p~n"
     "** Unhandled message: ~tp~n",
     [Mod, Msg]}.

format_client_log(undefined) ->
    {"", []};
format_client_log({From,dead}) ->
    {"** Client ~p is dead~n", [From]};
format_client_log({From,remote}) ->
    {"** Client ~p is remote on node ~p~n", [From, node(From)]};
format_client_log({_From,{Name,Stacktrace}}) ->
    {"** Client ~tp stacktrace~n"
     "** ~tp~n",
     [Name, Stacktrace]}.

%%-----------------------------------------------------------------
%% Status information
%%-----------------------------------------------------------------
format_status(Opt, StatusData) ->
    [PDict, SysState, Parent, Debug, [Name, State, Mod, _Time, _HibernateAfterTimeout]] = StatusData,
    Header = gen:format_status_header("Status for generic server", Name),
    Log = sys:get_debug(log, Debug, []),
    Specfic = case format_status(Opt, Mod, PDict, State) of
		  S when is_list(S) -> S;
		  S -> [S]
	      end,
    [{header, Header},
     {data, [{"Status", SysState},
	     {"Parent", Parent},
	     {"Logged events", Log}]} |
     Specfic].

format_status(Opt, Mod, PDict, State) ->
    DefStatus = case Opt of
		    terminate -> State;
		    _ -> [{data, [{"State", State}]}]
		end,
    case erlang:function_exported(Mod, format_status, 2) of
	true ->
	    case catch Mod:format_status(Opt, [PDict, State]) of
		{'EXIT', _} -> DefStatus;
		Else -> Else
	    end;
	_ ->
	    DefStatus
    end.