aboutsummaryrefslogblamecommitdiffstats
path: root/erts/emulator/test/distribution_SUITE.erl
blob: 79252d059300ef946fafad147573630bde34d9ae (plain) (tree)
1
2
3
4
5
6
7
8
9
10
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
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932

                   


                                                        




                                                                      
  



                                                                         
  



                            
              







                                                
                            






















                                                                          

                                           





































































                                                                                           
                                                       






                                               


                                                















                                                                              














































                                                                                                   









                            




































                                                                  





















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                   
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%

-module(distribution_SUITE).
-compile(r12).

%% Tests distribution and the tcp driver.

-include("test_server.hrl").

-export([all/1,
	 ping/1, bulk_send/1, bulk_send_small/1,
	 bulk_send_big/1,
	 bulk_send_bigbig/1,
	 local_send/1, local_send_small/1, local_send_big/1,
	 local_send_legal/1, link_to_busy/1, exit_to_busy/1,
	 lost_exit/1, link_to_dead/1, link_to_dead_new_node/1,
	 applied_monitor_node/1, ref_port_roundtrip/1, nil_roundtrip/1,
	 trap_bif/1, trap_bif_1/1, trap_bif_2/1, trap_bif_3/1,
	 stop_dist/1, dist_auto_connect/1, 
	 dist_auto_connect_never/1, dist_auto_connect_once/1,
	 dist_parallel_send/1,
	 atom_roundtrip/1,
	 atom_roundtrip_r12b/1,
	 contended_atom_cache_entry/1,
	 bad_dist_ext/1,
	 bad_dist_ext_receive/1,
	 bad_dist_ext_process_info/1,
	 bad_dist_ext_control/1,
	 bad_dist_ext_connection_id/1]).

-export([init_per_testcase/2, fin_per_testcase/2]).

%% Internal exports.
-export([sender/3, receiver2/2, dummy_waiter/0, dead_process/0,
	 roundtrip/1, bounce/1, do_dist_auto_connect/1, inet_rpc_server/1,
	 dist_parallel_sender/3, dist_parallel_receiver/0,
	 dist_evil_parallel_receiver/0,
         sendersender/4, sendersender2/4]).

all(suite) -> [
	       ping, bulk_send, local_send, link_to_busy, exit_to_busy,
	       lost_exit, link_to_dead, link_to_dead_new_node,
	       applied_monitor_node, ref_port_roundtrip, nil_roundtrip,
	       stop_dist, trap_bif, dist_auto_connect, dist_parallel_send,
	       atom_roundtrip, atom_roundtrip_r12b,
	       contended_atom_cache_entry,
	       bad_dist_ext
	      ].

-define(DEFAULT_TIMETRAP, 4*60*1000).

init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
    Dog=?t:timetrap(?DEFAULT_TIMETRAP),
    [{watchdog, Dog},{testcase, Func}|Config].

fin_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
    Dog=?config(watchdog, Config),
    ?t:timetrap_cancel(Dog).

%%% Don't be too hard on vxworks, the cross server gets nodedown
%%% cause the card is too busy if we don't sleep a little between pings.
sleep() ->
    case os:type() of
	vxworks ->
	    receive
	    after 10 ->
		    ok
	    end;
	_ ->
	    ok
    end.

ping(doc) ->
    ["Tests pinging a node in different ways."];
ping(Config) when is_list(Config) ->
    Times = 1024,

    %% Ping a non-existing node many times.  This used to crash the emulator
    %% on Windows.

    ?line Host = hostname(),
    ?line BadName = list_to_atom("__pucko__@" ++ Host),
    ?line io:format("Pinging ~s (assumed to not exist)", [BadName]),
    ?line test_server:do_times(Times, 
			       fun() -> pang = net_adm:ping(BadName),
					sleep() 
			       end),

    %% Pings another node.

    ?line {ok, OtherNode} = start_node(distribution_SUITE_other),
    ?line io:format("Pinging ~s (assumed to exist)", [OtherNode]),
    ?line test_server:do_times(Times, fun() -> pong = net_adm:ping(OtherNode),sleep() end),
    ?line stop_node(OtherNode),

    %% Pings our own node many times.

    ?line Node = node(),
    ?line io:format("Pinging ~s (the same node)", [Node]),
    ?line test_server:do_times(Times, fun() -> pong = net_adm:ping(Node),sleep() end),

    ok.

bulk_send(doc) ->
 ["Tests sending large amount of data to another node and measure",
  "the time. This tests that a process that is suspended on a ",
  "busy port will eventually be resumed."];
bulk_send(suite) ->
    [bulk_send_small, bulk_send_big, bulk_send_bigbig].

bulk_send_small(Config) when is_list(Config) ->
    ?line bulk_send(64, 32).

bulk_send_big(Config) when is_list(Config) ->
    ?line bulk_send(32, 64).

bulk_send_bigbig(Config) when is_list(Config) ->
    ?line bulk_sendsend(32*5, 4).

bulk_send(Terms, BinSize) ->
    ?line Dog = test_server:timetrap(test_server:seconds(30)),

    ?line io:format("Sending ~w binaries, each of size ~w K",
		    [Terms, BinSize]),
    ?line {ok, Node} = start_node(bulk_receiver),
    ?line Recv = spawn(Node, erlang, apply, [fun receiver/2, [0, 0]]),
    ?line Bin = list_to_binary(lists:duplicate(BinSize*1024, 253)),
    ?line Size = Terms*size(Bin),
    ?line {Elapsed, {Terms, Size}} = test_server:timecall(?MODULE, sender,
							  [Recv, Bin, Terms]),
    ?line stop_node(Node),

    ?line test_server:timetrap_cancel(Dog),
    {comment, integer_to_list(trunc(Size/1024/Elapsed+0.5)) ++ " K/s"}.

bulk_sendsend(Terms, BinSize) ->
    {Rate1, MonitorCount1} = bulk_sendsend2(Terms, BinSize,   5),
    {Rate2, MonitorCount2} = bulk_sendsend2(Terms, BinSize, 995),
    Ratio = if MonitorCount2 == 0 -> MonitorCount1 / 1.0;
               true               -> MonitorCount1 / MonitorCount2
            end,
    %% A somewhat arbitrary ratio, but hopefully one that will accomodate
    %% a wide range of CPU speeds.
    true = (Ratio > 8.0),
    {comment,
     integer_to_list(Rate1) ++ " K/s, " ++
     integer_to_list(Rate2) ++ " K/s, " ++
     integer_to_list(MonitorCount1) ++ " monitor msgs, " ++
     integer_to_list(MonitorCount2) ++ " monitor msgs, " ++
     float_to_list(Ratio) ++ " monitor ratio"}.    

bulk_sendsend2(Terms, BinSize, BusyBufSize) ->
    ?line Dog = test_server:timetrap(test_server:seconds(30)),

    ?line io:format("Sending ~w binaries, each of size ~w K",
		    [Terms, BinSize]),
    ?line {ok, NodeRecv} = start_node(bulk_receiver),
    ?line Recv = spawn(NodeRecv, erlang, apply, [fun receiver/2, [0, 0]]),
    ?line Bin = list_to_binary(lists:duplicate(BinSize*1024, 253)),
    ?line Size = Terms*size(Bin),

    %% SLF LEFT OFF HERE.
    %% When the caller uses small hunks, like 4k via
    %% bulk_sendsend(32*5, 4), then (on my laptop at least), we get
    %% zero monitor messages.  But if we use "+zdbbl 5", then we
    %% get a lot of monitor messages.  So, if we can count up the
    %% total number of monitor messages that we get when running both
    %% default busy size and "+zdbbl 5", and if the 5 case gets
    %% "many many more" monitor messages, then we know we're working.

    ?line {ok, NodeSend} = start_node(bulk_sender, "+zdbbl " ++ integer_to_list(BusyBufSize)),
    ?line _Send = spawn(NodeSend, erlang, apply, [fun sendersender/4, [self(), Recv, Bin, Terms]]),
    ?line {Elapsed, {TermsN, SizeN}, MonitorCount} =
        receive {sendersender, BigRes} ->
                BigRes
        end,
    ?line stop_node(NodeRecv),
    ?line stop_node(NodeSend),

    ?line test_server:timetrap_cancel(Dog),
    {trunc(SizeN/1024/Elapsed+0.5), MonitorCount}.

sender(To, _Bin, 0) ->
    To ! {done, self()},
    receive
	Any ->
	    Any
    end;
sender(To, Bin, Left) ->
    To ! {term, Bin},
    sender(To, Bin, Left-1).

%% Sender process to be run on a slave node

sendersender(Parent, To, Bin, Left) ->
    erlang:system_monitor(self(), [busy_dist_port]),
    [spawn(fun() -> sendersender2(To, Bin, Left, false) end) ||
        _ <- lists:seq(1,1)],
    {USec, {Res, MonitorCount}} =
        timer:tc(?MODULE, sendersender2, [To, Bin, Left, true]),
    Parent ! {sendersender, {USec/1000000, Res, MonitorCount}}.

sendersender2(To, Bin, Left, SendDone) ->
    sendersender3(To, Bin, Left, SendDone, 0).

sendersender3(To, _Bin, 0, SendDone, MonitorCount) ->
    if SendDone ->
            To ! {done, self()};
       true ->
            ok
    end,
    receive
        {monitor, _Pid, _Type, _Info} = M ->
            sendersender3(To, _Bin, 0, SendDone, MonitorCount + 1)
    after 0 ->
            if SendDone ->
                    receive
                        Any when is_tuple(Any), size(Any) == 2 ->
                            {Any, MonitorCount}
                    end;
               true ->
                    exit(normal)
            end
    end;
sendersender3(To, Bin, Left, SendDone, MonitorCount) ->
    To ! {term, Bin},
    %%timer:sleep(50),
    sendersender3(To, Bin, Left-1, SendDone, MonitorCount).

%% Receiver process to be run on a slave node.

receiver(Terms, Size) ->
    receive
	{term, Bin} ->
	    receiver(Terms+1, Size+size(Bin));
	{done, ReplyTo} ->
	    ReplyTo ! {Terms, Size}
    end.


local_send(suite) ->
    [local_send_small, local_send_big, local_send_legal];
local_send(doc) ->
    ["Tests sending small and big messages to a non-existing ",
     "local registered process."].

local_send_big(doc) ->
    ["Sends several big message to an non-registered process on ",
     "the local node."];
local_send_big(Config) when is_list(Config) ->
    Data0=local_send_big(doc)++local_send(doc),
    Data1=[Data0,[Data0, Data0, [Data0], Data0],Data0],
    Data2=Data0++lists:flatten(Data1)++
	list_to_binary(lists:flatten(Data1)),
    Func=fun() -> Data2= {arbitrary_name, node()} ! Data2 end,
    ?line test_server:do_times(4096, Func),
    ok.

local_send_small(doc) ->
    ["Sends a small message to an non-registered process on the ",
     "local node."];
local_send_small(Config) when is_list(Config) ->
    Data={some_stupid, "arbitrary", 'Data'},
    Func=fun() -> Data= {unregistered_name, node()} ! Data end,
    ?line test_server:do_times(4096, Func),
    ok.

local_send_legal(doc) ->
    ["Sends data to a registered process on the local node, ",
     "as if it was on another node."];
local_send_legal(Config) when is_list(Config) ->
    Times=16384,
    Data={local_send_legal(doc), local_send_legal(doc)},
    Pid=spawn(?MODULE,receiver2, [0, 0]) ,
    ?line true=register(registered_process, Pid),

    Func=fun() -> Data={registered_process, node()} ! Data end,
    TotalSize=size(Data)*Times,
    ?line test_server:do_times(Times, Func),

    % Check that all msgs really came through.
    Me=self(),
    ?line {done, Me}=
	{registered_process, node()} ! {done, Me},
    receive
	{Times, TotalSize} ->
	    ok;
	_ ->
	    test_server:fail("Wrong number of msgs received.")
    end,
    ok.

receiver2(Num, TotSize) ->
    receive
	{done, ReplyTo} ->
	    ReplyTo ! {Num, TotSize};
	Stuff ->
	    receiver2(Num+1, TotSize+size(Stuff))
    end.

link_to_busy(doc) -> "Test that link/1 to a busy distribution port works.";
link_to_busy(Config) when is_list(Config) ->
    ?line Dog = test_server:timetrap(test_server:seconds(30)),
    ?line {ok, Node} = start_node(link_to_busy),
    ?line Recv = spawn(Node, erlang, apply, [fun sink/1, [link_to_busy_sink]]),

    Tracer = case os:getenv("TRACE_BUSY_DIST_PORT") of
		 "true" -> start_busy_dist_port_tracer();
		 _ -> false
	     end,

    %% We will spawn off a process which will try to link to the other
    %% node.  The linker process will not actually run until this
    %% process is suspended due to the busy distribution port (because
    %% of the big send).  When the link/1 is run, the linker
    %% process will block, too, because of the because busy port,
    %% and will later be restarted.

    ?line do_busy_test(Node, fun () -> linker(Recv) end),

    %% Same thing, but we apply link/1 instead of calling it directly.

    ?line do_busy_test(Node, fun () -> applied_linker(Recv) end),

    %% Same thing again, but we apply link/1 in the tail of a function.

    ?line do_busy_test(Node, fun () -> tail_applied_linker(Recv) end),

    %% Done.
    ?line stop_node(Node),
    ?line stop_busy_dist_port_tracer(Tracer),
    ?line test_server:timetrap_cancel(Dog),
    ok.

linker(Pid) ->
    true = link(Pid),
    {links, Links} = process_info(self(), links),
    true = lists:member(Pid, Links).

applied_linker(Pid) ->
    true = apply(erlang, link, [Pid]),
    {links, Links} = process_info(self(), links),
    true = lists:member(Pid, Links).

tail_applied_linker(Pid) ->
    apply(erlang, link, [Pid]).
    
exit_to_busy(doc) -> "Test that exit/2 to a busy distribution port works.";
exit_to_busy(Config) when is_list(Config) ->
    ?line Dog = test_server:timetrap(test_server:seconds(30)),
    ?line {ok, Node} = start_node(exit_to_busy),

    Tracer = case os:getenv("TRACE_BUSY_DIST_PORT") of
		 "true" -> start_busy_dist_port_tracer();
		 _ -> false
	     end,

    %% We will spawn off a process which will try to exit a process on
    %% the other node.  That process will not actually run until this
    %% process is suspended due to the busy distribution port
    %% The process executing exit/2 will block,
    %% too, because of the busy distribution port, and will be allowed
    %% to continue when the port becomes non-busy.

    ?line Recv1 = spawn(Node, fun () -> sink(exit_to_busy_sink) end),
    ?line M1 = erlang:monitor(process, Recv1),
    ?line do_busy_test(Node, fun () -> joey_killer(Recv1) end),
    ?line receive
	      {'DOWN', M1, process, Recv1, R1} ->
		  ?line joey_said_die = R1
	  end,

    %% Same thing, but tail call to exit/2.
    ?line Recv2 = spawn(Node, fun () -> sink(exit_to_busy_sink) end),
    ?line M2 = erlang:monitor(process, Recv2),
    ?line do_busy_test(Node, fun () -> tail_joey_killer(Recv2) end),
    ?line receive
	      {'DOWN', M2, process, Recv2, R2} ->
		  ?line joey_said_die = R2
	  end,

    %% Same thing, but we apply exit/2 instead of calling it directly.
    ?line Recv3 = spawn(Node, fun () -> sink(exit_to_busy_sink) end),
    ?line M3 = erlang:monitor(process, Recv3),
    ?line do_busy_test(Node, fun () -> applied_joey_killer(Recv3) end),
    ?line receive
	      {'DOWN', M3, process, Recv3, R3} ->
		  ?line joey_said_die = R3
	  end,

    %% Same thing again, but we apply exit/2 in the tail of a function.
    ?line Recv4 = spawn(Node, fun () -> sink(exit_to_busy_sink) end),
    ?line M4 = erlang:monitor(process, Recv4),
    ?line do_busy_test(Node, fun () -> tail_applied_joey_killer(Recv4) end),
    ?line receive
	      {'DOWN', M4, process, Recv4, R4} ->
		  ?line joey_said_die = R4
	  end,
    
    %% Done.
    ?line stop_node(Node),
    ?line stop_busy_dist_port_tracer(Tracer),
    ?line test_server:timetrap_cancel(Dog),
    ok.

make_busy_data() ->
    Size = 1024*1024,
    Key = '__busy__port__data__',
    case get(Key) of
	undefined ->
	    Data = list_to_binary(lists:duplicate(Size, 253)),
	    put(Key, Data),
	    Data;
	Data ->
	    true = is_binary(Data),
	    true = size(Data) == Size,
	    Data
    end.

make_busy(Node, Time) when is_integer(Time) ->
    Own = 500,
    freeze_node(Node, Time+Own),
    Data = make_busy_data(),
    %% first make port busy
    Pid = spawn_link(fun () ->
			     forever(fun () ->
					     dport_reg_send(Node,
							    '__noone__',
							    Data)
				     end)
		     end),
    receive after Own -> ok end,
    until(fun () ->
		  case process_info(Pid, status) of
		      {status, suspended} -> true;
		      _ -> false
		  end
	  end),
    %% then dist entry
    make_busy(Node, [nosuspend], Data),
    Pid.

make_busy(Node, Opts, Data) ->
    case erlang:send({'__noone__', Node}, Data, Opts) of
	nosuspend -> nosuspend;
	_ -> make_busy(Node, Opts, Data)
    end.

unmake_busy(Pid) ->
    unlink(Pid),
    exit(Pid, bang).

do_busy_test(Node, Fun) ->
    Busy = make_busy(Node, 1000),
    {P, M} = spawn_monitor(Fun),
    receive after 100 -> ok end,
    Pinfo = process_info(P, [status, current_function]),
    unmake_busy(Busy),
    ?t:format("~p : ~p~n", [P, Pinfo]),
    case Pinfo of
	undefined ->
	    receive
		{'DOWN', M, process, P, Reason} ->
		    ?t:format("~p died with exit reason ~p~n", [P, Reason])
	    end,
	    ?t:fail(premature_death);
	_ ->
	    %% Don't match arity; it is different in debug and
	    %% optimized emulator
	    [{status, suspended},
	     {current_function, {erlang, bif_return_trap, _}}] = Pinfo,
	    receive
		{'DOWN', M, process, P, Reason} ->
		    ?t:format("~p died with exit reason ~p~n", [P, Reason]),
		    normal = Reason
	    end
    end.

remote_is_process_alive(Pid) ->
    rpc:call(node(Pid), erlang, is_process_alive,
	     [Pid]).

joey_killer(Pid) ->
    exit(Pid, joey_said_die),
    until(fun () -> false == remote_is_process_alive(Pid) end).

tail_joey_killer(Pid) ->
    exit(Pid, joey_said_die).

applied_joey_killer(Pid) ->
    apply(erlang, exit, [Pid, joey_said_die]),
    until(fun () -> false == remote_is_process_alive(Pid) end).

tail_applied_joey_killer(Pid) ->
    apply(erlang, exit, [Pid, joey_said_die]).

sink(Name) ->
    register(Name, self()),
    sink1().

sink1() ->
    receive
	_Any -> sink1()
    end.

lost_exit(doc) ->
    "Test that EXIT and DOWN messages send to another node are not lost if "
	"if the distribution port is busy.";
lost_exit(Config) when is_list(Config) ->
    ?line {ok, Node} = start_node(lost_exit),

    Tracer = case os:getenv("TRACE_BUSY_DIST_PORT") of
		 "true" -> start_busy_dist_port_tracer();
		 _ -> false
	     end,

    Self = self(),
    Die = make_ref(),
    ?line R1 = spawn(fun () -> receive after infinity -> ok end end),
    ?line MR1 = erlang:monitor(process, R1),
    
    ?line {L1, ML1} = spawn_monitor(fun() ->
					    link(R1),
					    Self ! {self(), linked},
					    receive
						Die ->
						    exit(controlled_suicide)
					    end
				    end),

    ?line R2 = spawn(fun () ->
			     M = erlang:monitor(process, L1),
			     receive
				 {'DOWN', M, process, L1, R} ->
				     Self ! {self(), got_down_message, L1, R}
			     end
		     end),

    ?line receive {L1, linked} -> ok end,
    
    Busy = make_busy(Node, 2000),
    receive after 100 -> ok end,
    L1 ! Die,
    ?line receive
	      {'DOWN', ML1, process, L1, RL1} ->
		  ?line controlled_suicide = RL1
	  end,
    receive after 500 -> ok end,
    unmake_busy(Busy),

    ?line receive
	      {'DOWN', MR1, process, R1, RR1} ->
		  ?line controlled_suicide = RR1
	  end,
    
    ?line receive
	      {R2, got_down_message, L1, RR2} ->
		  ?line controlled_suicide = RR2
	  end,

    %% Done.
    ?line stop_busy_dist_port_tracer(Tracer),
    ?line stop_node(Node),
    ok.

dummy_waiter() ->
    receive
    after infinity ->
	    ok
    end.

link_to_dead(doc) ->
    ["Test that linking to a dead remote process gives an EXIT message ",
     "AND that the link is teared down."];
link_to_dead(Config) when is_list(Config) ->
    ?line process_flag(trap_exit, true),
    ?line {ok, Node} = start_node(link_to_dead),
%    ?line monitor_node(Node, true),
    ?line net_adm:ping(Node), %% Ts_cross_server workaround.
    ?line Pid = spawn(Node, ?MODULE, dead_process, []),
    receive
    after 5000 -> ok
    end,
    ?line link(Pid),
    ?line receive
	      {'EXIT', Pid, noproc} ->
		  ok;
	      Other ->
		  ?line test_server:fail({unexpected_message, Other})
	  after 5000 ->
		  ?line test_server:fail(nothing_received)
	  end,
    ?line {links, Links} = process_info(self(), links),
    ?line io:format("Pid=~p, links=~p", [Pid, Links]),
    ?line false = lists:member(Pid, Links),
    ?line stop_node(Node),
    ?line receive
	      Message ->
		  ?line test_server:fail({unexpected_message, Message})
	  after 3000 ->
		  ok
	  end,
    ok.
    
dead_process() ->
    erlang:error(die).

link_to_dead_new_node(doc) ->
    ["Test that linking to a pid on node that has gone and restarted gives ",
     "the correct EXIT message (OTP-2304)."];
link_to_dead_new_node(Config) when is_list(Config) ->
    ?line process_flag(trap_exit, true),

    %% Start the node, get a Pid and stop the node again.
    ?line {ok, Node} = start_node(link_to_dead_new_node),
    ?line Pid = spawn(Node, ?MODULE, dead_process, []),
    ?line stop_node(Node),

    %% Start a new node with the same name.
    ?line {ok, Node} = start_node(link_to_dead_new_node),
    ?line link(Pid),
    ?line receive
	      {'EXIT', Pid, noproc} ->
		  ok;
	      Other ->
		  ?line test_server:fail({unexpected_message, Other})
	  after 5000 ->
		  ?line test_server:fail(nothing_received)
	  end,

    %% Make sure that the link wasn't created.
    ?line {links, Links} = process_info(self(), links),
    ?line io:format("Pid=~p, links=~p", [Pid, Links]),
    ?line false = lists:member(Pid, Links),
    ?line stop_node(Node),
    ?line receive
	      Message ->
		  ?line test_server:fail({unexpected_message, Message})
	  after 3000 ->
		  ok
	  end,
    ok.

applied_monitor_node(doc) ->
    "Test that monitor_node/2 works when applied.";
applied_monitor_node(Config) when is_list(Config) ->
    ?line NonExisting = list_to_atom("__non_existing__@" ++ hostname()),

    %% Tail-recursive call to apply (since the node is non-existing,
    %% there will be a trap).

    ?line true = tail_apply(erlang, monitor_node, [NonExisting, true]),
    ?line [{nodedown, NonExisting}] = test_server:messages_get(),

    %% Ordinary call (with trap).

    ?line true = apply(erlang, monitor_node, [NonExisting, true]),
    ?line [{nodedown, NonExisting}] = test_server:messages_get(),
    
    ok.

tail_apply(M, F, A) ->
    apply(M, F, A).

ref_port_roundtrip(doc) ->
    "Test that sending a port or reference to another node and back again "
	"doesn't correct them in any way.";
ref_port_roundtrip(Config) when is_list(Config) ->
    ?line process_flag(trap_exit, true),
    ?line Port = open_port({spawn, efile}, []),
    ?line Ref = make_ref(),
    ?line {ok, Node} = start_node(ref_port_roundtrip),
    ?line net_adm:ping(Node),
    ?line Term = {Port, Ref},
    ?line io:format("Term before: ~p", [show_term(Term)]),
    ?line Pid = spawn_link(Node, ?MODULE, roundtrip, [Term]),
    ?line receive after 5000 -> ok end,
    ?line stop_node(Node),
    ?line receive
	      {'EXIT', Pid, {Port, Ref}} ->
		  ?line io:format("Term after: ~p", [show_term(Term)]),
		  ok;
	      Other ->
		  ?line io:format("Term after: ~p", [show_term(Term)]),
		  ?line test_server:fail({unexpected, Other})
	  after 10000 ->
		  ?line test_server:fail(timeout)
	  end,
    ok.

roundtrip(Term) ->
    exit(Term).

nil_roundtrip(doc) ->
    "Test that the smallest external term [] aka NIL can be sent to "
	"another node node and back again.";
nil_roundtrip(Config) when is_list(Config) ->
    ?line process_flag(trap_exit, true),
    ?line {ok, Node} = start_node(nil_roundtrip),
    ?line net_adm:ping(Node),
    ?line Pid = spawn_link(Node, ?MODULE, bounce, [self()]),
    ?line Pid ! [],
    ?line receive
	      [] ->
		  ?line receive
			    {'EXIT', Pid, []} ->
				?line stop_node(Node),
				ok
			end
	  end.

bounce(Dest) ->
    receive Msg ->
	    Dest ! Msg,
	    exit(Msg)
    end.

show_term(Term) ->
    binary_to_list(term_to_binary(Term)).

stop_dist(doc) ->
    ["Tests behaviour after net_kernel:stop (OTP-2586)."];
stop_dist(Config) when is_list(Config) ->
    ?line Str = os:cmd(atom_to_list(lib:progname())
		       ++ " -noshell -pa "
		       ++ ?config(data_dir, Config)
		       ++ " -s run"),
    %% The "true" may be followed by an error report, so ignore anything that
    %% follows it.
    ?line "true\n"++_ = Str,

    %% "May fail on FreeBSD due to differently configured name lookup - ask Arndt",
    %% if you can find him.

    ok.

trap_bif(doc) ->
    ["Verifies that BIFs which are traps to Erlang work (OTP-2680)."];
trap_bif(suite) -> [trap_bif_1, trap_bif_2, trap_bif_3].

trap_bif_1(doc) ->
    [""];
trap_bif_1(Config) when is_list(Config) ->
    ?line {true} = tr1(),
    ok.

trap_bif_2(doc) ->
    [""];
trap_bif_2(Config) when is_list(Config) ->
    ?line {true} = tr2(),
    ok.

trap_bif_3(doc) ->
    [""];
trap_bif_3(Config) when is_list(Config) ->
    ?line {hoo} = tr3(),
    ok.

tr1() ->
    ?line NonExisting = 'abc@boromir',
    ?line X = erlang:monitor_node(NonExisting, true),
    {X}.

tr2() ->
    ?line NonExisting = 'abc@boromir',
    ?line X = apply(erlang, monitor_node, [NonExisting, true]),
    {X}.

tr3() ->
    ?line NonExisting = 'abc@boromir',
    ?line X = {NonExisting, glirp} ! hoo,
    {X}.



dist_auto_connect(doc) ->
    ["Tests the kernel parameter 'dist_auto_connect'."];
dist_auto_connect(suite) ->
    [dist_auto_connect_never, dist_auto_connect_once].

% This has to be done by nodes with differrent cookies, otherwise global
% will connect nodes, which is correct, but makes it hard to test.
% * Start two nodes, n1 and n2. n2 with the dist_auto_connect once parameter
% * n2 pings n1 -> connection
% * check that they now know each other
% * Kill n1
% * Make sure n2 gets pang when pinging n1
% * restart n1
% * Make sure n2 *still gets pang*!
% * Ping n2 from n1 -> pong
% * n2 now also gets pong when pinging n1
% * disconnect n2 from n1
% * n2 gets pang when pinging n1
% * n2 forces connection by using net_kernel:connect_node (ovverrides)
% * n2 gets pong when pinging n1.
dist_auto_connect_once(doc) -> "Test the dist_auto_connect once kernel parameter";
dist_auto_connect_once(Config) when is_list(Config) ->
    ?line Sock = start_relay_node(dist_auto_connect_relay_node,[]),
    ?line NN = inet_rpc_nodename(Sock),
    ?line Sock2 = start_relay_node(dist_auto_connect_once_node,
				   "-kernel dist_auto_connect once"),
    ?line NN2 = inet_rpc_nodename(Sock2),
    ?line {ok,[]} = do_inet_rpc(Sock,erlang,nodes,[]),
    ?line {ok, pong} = do_inet_rpc(Sock2,net_adm,ping,[NN]),
    ?line {ok,[NN2]} = do_inet_rpc(Sock,erlang,nodes,[]),
    ?line {ok,[NN]} = do_inet_rpc(Sock2,erlang,nodes,[]),
    ?line [_,HostPartPeer] = string:tokens(atom_to_list(NN),"@"),
    ?line [_,MyHostPart] = string:tokens(atom_to_list(node()),"@"),
    % Give net_kernel a chance to change the state of the node to up to.
    ?line receive after 1000 -> ok end,
    case HostPartPeer of
	MyHostPart ->
	    ?line ok = stop_relay_node(Sock),
	    ?line {ok,pang} = do_inet_rpc(Sock2,net_adm,ping,[NN]);
	_ ->
	    ?line {ok, true} = do_inet_rpc(Sock,net_kernel,disconnect,[NN2]),
	    receive
	    after 500 -> ok
	    end
    end,
    ?line {ok, []} = do_inet_rpc(Sock2,erlang,nodes,[]),
    Sock3 = case HostPartPeer of
		MyHostPart ->
		    ?line start_relay_node(dist_auto_connect_relay_node,[]);
		_ ->
		    Sock
	    end,
    ?line TS1 = timestamp(),
    ?line {ok, pang} = do_inet_rpc(Sock2,net_adm,ping,[NN]),
    ?line TS2 = timestamp(),
    RefT = net_kernel:connecttime() - 1000,
    ?line true = ((TS2 - TS1) < RefT),
    ?line TS3 = timestamp(),
    ?line {ok, true} = do_inet_rpc(Sock2,erlang,monitor_node,
				   [NN,true,[allow_passive_connect]]),
    ?line TS4 = timestamp(),
    ?line true = ((TS4 - TS3) > RefT),
    ?line {ok, pong} = do_inet_rpc(Sock3,net_adm,ping,[NN2]),
    ?line {ok, pong} = do_inet_rpc(Sock2,net_adm,ping,[NN]),
    ?line {ok, true} = do_inet_rpc(Sock3,net_kernel,disconnect,[NN2]),
    receive
    after 500 -> ok
    end,
    ?line {ok, pang} = do_inet_rpc(Sock2,net_adm,ping,[NN]),
    ?line {ok, true} = do_inet_rpc(Sock2,net_kernel,connect_node,[NN]),
    ?line {ok, pong} = do_inet_rpc(Sock2,net_adm,ping,[NN]),
    ?line stop_relay_node(Sock3),
    ?line stop_relay_node(Sock2).
    


%% Start a relay node and a lonely (dist_auto_connect never) node.
%% Lonely node pings relay node. That should fail. 
%% Lonely node connects to relay node with net_kernel:connect_node/1.
%% Result is sent here through relay node.
dist_auto_connect_never(Config) when is_list(Config) ->
    Self = self(),
    ?line {ok, RelayNode} = 
	start_node(dist_auto_connect_relay),
    ?line spawn(RelayNode, 
	      fun() ->
		      register(dist_auto_connect_relay, self()),
		      dist_auto_connect_relay(Self) 
	      end),
    ?line {ok, Handle} = dist_auto_connect_start(dist_auto_connect, never),
    ?line Result = 
	receive
	    {do_dist_auto_connect, ok} ->
		ok;
	    {do_dist_auto_connect, Error} ->
		{error, Error};
	    Other ->
		{error, Other}
	after 32000 ->
		timeout
	end,
    ?line stop_node(RelayNode),
    ?line Stopped =  dist_auto_connect_stop(Handle),
    ?line Junk = 
	receive 
	    {do_dist_auto_connect, _} = J -> 
		J 
	after 0 -> 
		ok 
	end,
    ?line {ok, ok, ok} = {Result, Stopped, Junk},
    ok.


do_dist_auto_connect([never]) ->
    Node = list_to_atom("dist_auto_connect_relay@" ++ hostname()),
    io:format("~p:do_dist_auto_connect([false]) Node=~p~n", 
	      [?MODULE, Node]),
    Ping = net_adm:ping(Node),
    io:format("~p:do_dist_auto_connect([false]) Ping=~p~n", 
	      [?MODULE, Ping]),
    Result = case Ping of
		 pang -> ok;
		 _ -> {error, Ping}
	     end,
    io:format("~p:do_dist_auto_connect([false]) Result=~p~n", 
	      [?MODULE, Result]),
    net_kernel:connect_node(Node),
    catch {dist_auto_connect_relay, Node} ! {do_dist_auto_connect, Result};
%    receive after 1000 -> ok end,
%    halt();

do_dist_auto_connect(Arg) ->
    io:format("~p:do_dist_auto_connect(~p)~n", 
	      [?MODULE, Arg]),
    receive after 10000 -> ok end,
    halt().
	    

dist_auto_connect_start(Name, Value) when is_atom(Name) ->
    dist_auto_connect_start(atom_to_list(Name), Value);
dist_auto_connect_start(Name, Value) when is_list(Name), is_atom(Value) ->
    Node = list_to_atom(lists:append([Name, "@", hostname()])),
    ModuleDir = filename:dirname(code:which(?MODULE)),
    ValueStr = atom_to_list(Value),
    Cookie = atom_to_list(erlang:get_cookie()),
    Cmd = lists:concat(
	    [%"xterm -e ",
	     atom_to_list(lib:progname()),
%	     " -noinput ",
	     " -detached ", 
	     long_or_short(), " ", Name,
	     " -setcookie ", Cookie,
	     " -pa ", ModuleDir,
	     " -s ", atom_to_list(?MODULE), 
	     " do_dist_auto_connect ", ValueStr,
	     " -kernel dist_auto_connect ", ValueStr]),
    io:format("~p:dist_auto_connect_start() cmd: ~p~n", [?MODULE, Cmd]),
    Port = open_port({spawn, Cmd}, [stream]),
    {ok, {Port, Node}}.


dist_auto_connect_stop({Port, Node}) ->
    Pid = spawn_link(fun() -> rpc:call(Node, erlang, halt, []) end),
    dist_auto_connect_stop(Port, Node, Pid, 5000).

dist_auto_connect_stop(Port, _Node, Pid, N) when is_integer(N), N =< 0 ->
    exit(Pid, normal),
    catch erlang:port_close(Port),
    Result = {error, node_not_down},
    io:format("~p:dist_auto_connect_stop() ~p~n", [?MODULE, Result]),
    Result;
dist_auto_connect_stop(Port, Node, Pid, N) when is_integer(N) ->
    case net_adm:ping(Node) of
	pong ->
	    receive after 100 -> ok end,
	    dist_auto_connect_stop(Port, Node, Pid, N-100);
	pang ->
	    exit(Pid, normal),
	    catch erlang:port_close(Port),
	    io:format("~p:dist_auto_connect_stop() ok~n", [?MODULE]),
	    ok
    end.


dist_auto_connect_relay(Parent) ->	    
    receive X ->
	    catch Parent ! X
    end,
    dist_auto_connect_relay(Parent).


dist_parallel_send(doc) ->
    [];
dist_parallel_send(suite) ->
    [];
dist_parallel_send(Config) when is_list(Config) ->
    ?line {ok, RNode} = start_node(dist_parallel_receiver),
    ?line {ok, SNode} = start_node(dist_parallel_sender),
    ?line WatchDog = spawn_link(
		       fun () ->
			       TRef = erlang:start_timer((?DEFAULT_TIMETRAP
							  div 2),
							 self(),
							 oops),
			       receive
				   {timeout, TRef, _ } ->
				       spawn(SNode,
					     fun () ->
						     abort(timeout)
					     end),
				       spawn(RNode,
					     fun () ->
						     abort(timeout)
					     end)
%%				       rpc:cast(SNode, erlang, halt,
%%						["Timetrap (sender)"]),
%%				       rpc:cast(RNode, erlang, halt,
%%						["Timetrap (receiver)"])
			       end
		       end),
    ?line MkSndrs = fun (Receiver) ->
			    lists:map(fun (_) ->
					      spawn_link(SNode,
							 ?MODULE,
							 dist_parallel_sender,
							 [self(),
							  Receiver,
							  1000])
				      end,
				      lists:seq(1, 64))
		    end,
    ?line SndrsStart = fun (Sndrs) ->
			       Parent = self(),
			       spawn_link(
				 SNode,
				 fun () ->
					 lists:foreach(fun (P) ->
							       P ! {go, Parent}
						       end,
						       Sndrs)
				 end)
		       end,
    ?line SndrsWait = fun (Sndrs) ->
			      lists:foreach(fun (P) ->
						    receive {P, done} -> ok end
					    end,
					    Sndrs)
		      end,
    ?line DPR = spawn_link(RNode, ?MODULE, dist_parallel_receiver, []),
    ?line Sndrs1 = MkSndrs(DPR),
    ?line SndrsStart(Sndrs1),
    ?line SndrsWait(Sndrs1),
    ?line unlink(DPR),
    ?line exit(DPR, bang),

    ?line DEPR = spawn_link(RNode, ?MODULE, dist_evil_parallel_receiver, []),
    ?line Sndrs2 = MkSndrs(DEPR),
    ?line SndrsStart(Sndrs2),
    ?line SndrsWait(Sndrs2),
    ?line unlink(DEPR),
    ?line exit(DEPR, bang),

    ?line unlink(WatchDog),
    ?line exit(WatchDog, bang),

    ?line stop_node(RNode),
    ?line stop_node(SNode),

    ?line ok.

do_dist_parallel_sender(Parent, _Receiver, 0) ->
    Parent ! {self(), done};
do_dist_parallel_sender(Parent, Receiver, N) ->
    Receiver ! {self(), "Some data"},
    do_dist_parallel_sender(Parent, Receiver, N-1).

dist_parallel_sender(Parent, Receiver, N) ->
    receive {go, Parent} -> ok end,
    do_dist_parallel_sender(Parent, Receiver, N).

dist_parallel_receiver() ->
    receive {_Sender, _Data} -> ok end,
    dist_parallel_receiver().

dist_evil_parallel_receiver() ->
    receive {Sender, _Data} -> ok end,
    net_kernel:disconnect(node(Sender)),
    dist_evil_parallel_receiver().

atom_roundtrip(Config) when is_list(Config) ->
    ?line AtomData = atom_data(),
    ?line verify_atom_data(AtomData),
    ?line {ok, Node} = start_node(Config),
    ?line do_atom_roundtrip(Node, AtomData),
    ?line stop_node(Node),
    ?line ok.

atom_roundtrip_r12b(Config) when is_list(Config) ->
    case ?t:is_release_available("r12b") of
	true ->
	    ?line AtomData = atom_data(),
	    ?line verify_atom_data(AtomData),
	    ?line {ok, Node} = start_node(Config, [], "r12b"),
	    ?line do_atom_roundtrip(Node, AtomData),
	    ?line stop_node(Node),
	    ?line ok;
	false ->
	    ?line {skip,"No OTP R12B available"}
    end.

do_atom_roundtrip(Node, AtomData) ->
    ?line Parent = self(),
    ?line Proc = spawn_link(Node, fun () -> verify_atom_data_loop(Parent) end),
    ?line Proc ! {self(), AtomData},
    ?line receive {Proc, AD1} -> AtomData = AD1 end,
    ?line Proc ! {self(), AtomData},
    ?line receive {Proc, AD2} -> AtomData = AD2 end,
    ?line RevAtomData = lists:reverse(AtomData),
    ?line Proc ! {self(), RevAtomData},
    ?line receive {Proc, RAD1} -> RevAtomData = RAD1 end,
    ?line unlink(Proc),
    ?line exit(Proc, bang),
    ?line ok.

verify_atom_data_loop(From) ->
    receive
	{From, AtomData} ->
	    verify_atom_data(AtomData),
	    From ! {self(), AtomData},
	    verify_atom_data_loop(From)
    end.

atom_data() ->
    lists:map(fun (N) ->
		      ATxt = "a"++integer_to_list(N),
		      {list_to_atom(ATxt), ATxt}
	      end,
	      lists:seq(1, 2000)).

verify_atom_data(AtomData) ->
    lists:foreach(fun ({Atom, AtomTxt}) ->
			  AtomTxt = atom_to_list(Atom)
		  end,
		  AtomData).

contended_atom_cache_entry(Config) when is_list(Config) ->
    ?line TestServer = self(),
    ?line ProcessPairs = 10,
    ?line Msgs = 100000,
    ?line {ok, SNode} = start_node(Config),
    ?line {ok, RNode} = start_node(Config),
    ?line Success = make_ref(),
    ?line Mstr
	= spawn_link(
	    SNode,
	    fun () ->
		    erts_debug:set_internal_state(available_internal_state,
						  true),
		    Master = self(),
		    CIX = get_cix(),
		    TestAtoms = get_conflicting_atoms(CIX, ProcessPairs),
		    io:format("Testing with the following atoms all using "
			      "cache index ~p:~n ~p~n",
			      [CIX, TestAtoms]),
		    Ps = lists:map(
			   fun (A) ->
				   Ref = make_ref(),
				   R = spawn_link(
					 RNode,
					 fun () ->
						 Atom = receive
							    {Ref, txt, ATxt} ->
								list_to_atom(
								  ATxt)
							end,
						 receive_ref_atom(Ref,
								  Atom,
								  Msgs),
						 Master ! {self(), success}
					 end),
				   S = spawn_link(
					 SNode,
					 fun () ->
						 receive go -> ok end,
						 R ! {Ref,
						      txt,
						      atom_to_list(A)},
						 send_ref_atom(R, Ref, A, Msgs)
					 end),
				   {S, R}
			   end,
			   TestAtoms),
		    lists:foreach(fun ({S, _}) ->
					  S ! go
				  end,
				  Ps),
		    lists:foreach(fun ({_, R}) ->
					  receive {R, success} -> ok end
				  end,
				  Ps),
		    TestServer ! Success
	    end),
    ?line receive
	      Success ->
		  ok
	  end,
    ?line stop_node(SNode),
    ?line stop_node(RNode),
    ?line ok.

send_ref_atom(To, Ref, Atom, 0) ->
    ok;
send_ref_atom(To, Ref, Atom, N) ->
    To ! {Ref, Atom},
    send_ref_atom(To, Ref, Atom, N-1).

receive_ref_atom(Ref, Atom, 0) ->
    ok;
receive_ref_atom(Ref, Atom, N) ->
    receive
	{Ref, Value} ->
	    Atom = Value
    end,
    receive_ref_atom(Ref, Atom, N-1).
      
get_cix() ->
    get_cix(1000).

get_cix(CIX) when is_integer(CIX), CIX < 0 ->
    get_cix(0);
get_cix(CIX) when is_integer(CIX) ->
    get_cix(CIX,
	    unwanted_cixs(),
	    erts_debug:get_internal_state(max_atom_out_cache_index)).

get_cix(CIX, Unwanted, MaxCIX) when CIX > MaxCIX ->
    get_cix(0, Unwanted, MaxCIX);
get_cix(CIX, Unwanted, MaxCIX) ->
    case lists:member(CIX, Unwanted) of
	true -> get_cix(CIX+1, Unwanted, MaxCIX);
	false -> CIX
    end.

unwanted_cixs() ->
    lists:map(fun (Node) ->
		      erts_debug:get_internal_state({atom_out_cache_index,
						     Node})
	      end,
	      nodes()).
    
    
get_conflicting_atoms(CIX, 0) ->
    [];
get_conflicting_atoms(CIX, N) ->
    {A, B, C} = now(),
    Atom = list_to_atom("atom" ++ integer_to_list(A*1000000000000
						  + B*1000000
						  + C)),
    case erts_debug:get_internal_state({atom_out_cache_index, Atom}) of
	CIX ->
	    [Atom|get_conflicting_atoms(CIX, N-1)];
	_ ->
	    get_conflicting_atoms(CIX, N)
    end.


bad_dist_ext(doc) -> [];
bad_dist_ext(suite) ->
    [bad_dist_ext_receive,
     bad_dist_ext_process_info,
     bad_dist_ext_control,
     bad_dist_ext_connection_id].


bad_dist_ext_receive(Config) when is_list(Config) ->
    ?line {ok, Offender} = start_node(bad_dist_ext_receive_offender),
    ?line {ok, Victim} = start_node(bad_dist_ext_receive_victim),
    ?line start_node_monitors([Offender,Victim]),

    ?line Parent = self(),

    ?line P = spawn_link(Victim,
			 fun () ->
				 Parent ! {self(), started},
				 receive check_msgs -> ok end,
				 bad_dist_ext_check_msgs([one,
							  two,
							  three]),
				 Parent ! {self(), messages_checked},
				 receive done -> ok end
			 end),

    ?line receive {P, started} -> ok end,
    ?line pong = rpc:call(Victim, net_adm, ping, [Offender]),
    ?line verify_up(Offender, Victim),
    ?line true = lists:member(Offender, rpc:call(Victim, erlang, nodes, [])),
    ?line P ! one,
    ?line send_bad_msg(Offender, P),
    ?line P ! two,
    ?line verify_down(Offender, connection_closed, Victim, killed),
    ?line {message_queue_len, 2}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),

    ?line Suspended = make_ref(),
    ?line S = spawn(Victim,
		     fun () ->
			     erlang:suspend_process(P),
			     Parent ! Suspended,
			     receive after infinity -> ok end
		     end),
    ?line MS = erlang:monitor(process, S),
    ?line receive Suspended -> ok end,
    ?line pong = rpc:call(Victim, net_adm, ping, [Offender]),
    ?line verify_up(Offender, Victim),
    ?line true = lists:member(Offender, rpc:call(Victim, erlang, nodes, [])),
    ?line send_bad_msgs(Offender, P, 5),
    ?line true = lists:member(Offender, rpc:call(Victim, erlang, nodes, [])),
    ?line P ! three,
    ?line send_bad_msgs(Offender, P, 5),

    %% Make sure bad msgs has reached Victim
    ?line rpc:call(Offender, rpc, call, [Victim, erlang, node, []]),

    ?line verify_still_up(Offender, Victim),
    ?line {message_queue_len, 13}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),
    
    ?line exit(S, bang),
    ?line receive {'DOWN', MS, process, S, bang} -> ok end,
    ?line verify_down(Offender, connection_closed, Victim, killed),
    ?line {message_queue_len, 3}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),

    ?line P ! check_msgs,
    ?line receive {P, messages_checked} -> ok end,

    ?line {message_queue_len, 0}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),
    
    ?line P ! done,
    ?line unlink(P),
    ?line verify_no_down(Offender, Victim),
    ?line stop_node(Offender),
    ?line stop_node(Victim).


bad_dist_ext_process_info(Config) when is_list(Config) ->
    ?line {ok, Offender} = start_node(bad_dist_ext_process_info_offender),
    ?line {ok, Victim} = start_node(bad_dist_ext_process_info_victim),
    ?line start_node_monitors([Offender,Victim]),

    ?line Parent = self(),
    ?line P = spawn_link(Victim,
			 fun () ->
				 Parent ! {self(), started},
				 receive check_msgs -> ok end,
				 bad_dist_ext_check_msgs([one, two]),
				 Parent ! {self(), messages_checked},
				 receive done -> ok end
			 end),

    ?line receive {P, started} -> ok end,
    ?line P ! one,
    
    ?line Suspended = make_ref(),
    ?line S = spawn(Victim,
		     fun () ->
			     erlang:suspend_process(P),
			     Parent ! Suspended,
			     receive after infinity -> ok end
		     end),

    ?line receive Suspended -> ok end,
    ?line pong = rpc:call(Victim, net_adm, ping, [Offender]),
    ?line verify_up(Offender, Victim),
    ?line send_bad_msgs(Offender, P, 5),

    ?line P ! two,
    ?line send_bad_msgs(Offender, P, 5),

    %% Make sure bad msgs has reached Victim
    ?line rpc:call(Offender, rpc, call, [Victim, erlang, node, []]),

    ?line verify_still_up(Offender, Victim),
    ?line {message_queue_len, 12}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),
    ?line verify_still_up(Offender, Victim),
    ?line [{message_queue_len, 2},
	   {messages, [one, two]}]
	= rpc:call(Victim, erlang, process_info, [P, [message_queue_len,
						      messages]]),
    ?line verify_down(Offender, connection_closed, Victim, killed),

    ?line P ! check_msgs,
    ?line exit(S, bang),
    ?line receive {P, messages_checked} -> ok end,

    ?line {message_queue_len, 0}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),

    ?line P ! done,
    ?line unlink(P),
    ?line verify_no_down(Offender, Victim),
    ?line stop_node(Offender),
    ?line stop_node(Victim).

bad_dist_ext_control(Config) when is_list(Config) ->
    ?line {ok, Offender} = start_node(bad_dist_ext_control_offender),
    ?line {ok, Victim} = start_node(bad_dist_ext_control_victim),
    ?line start_node_monitors([Offender,Victim]),

    ?line pong = rpc:call(Victim, net_adm, ping, [Offender]),
    ?line verify_up(Offender, Victim),
    ?line send_bad_dhdr(Offender, Victim),
    ?line verify_down(Offender, connection_closed, Victim, killed),

    ?line pong = rpc:call(Victim, net_adm, ping, [Offender]),
    ?line verify_up(Offender, Victim),
    ?line send_bad_ctl(Offender, Victim),
    ?line verify_down(Offender, connection_closed, Victim, killed),

    ?line verify_no_down(Offender, Victim),
    ?line stop_node(Offender),
    ?line stop_node(Victim).

bad_dist_ext_connection_id(Config) when is_list(Config) ->
    ?line {ok, Offender} = start_node(bad_dist_ext_receive_offender),
    ?line {ok, Victim} = start_node(bad_dist_ext_receive_victim),
    ?line start_node_monitors([Offender,Victim]),

    ?line Parent = self(),
    ?line P = spawn_link(Victim,
			 fun () ->
				 Parent ! {self(), started},
				 receive check_msgs -> ok end,
				 bad_dist_ext_check_msgs([]),
				 Parent ! {self(), messages_checked},
				 receive done -> ok end
			 end),

    ?line receive {P, started} -> ok end,
    ?line Suspended = make_ref(),
    ?line S = spawn(Victim,
		    fun () ->
			    erlang:suspend_process(P),
			    Parent ! Suspended,
			    receive after infinity -> ok end
		    end),
    ?line MS = erlang:monitor(process, S),
    ?line receive Suspended -> ok end,
    ?line pong = rpc:call(Victim, net_adm, ping, [Offender]),
    ?line verify_up(Offender, Victim),
    ?line send_bad_msg(Offender, P),

    %% Make sure bad msg has reached Victim
    ?line rpc:call(Offender, rpc, call, [Victim, erlang, node, []]),

    ?line {message_queue_len, 1}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),

    ?line true = rpc:call(Offender, net_kernel, disconnect, [Victim]),
    ?line verify_down(Offender, disconnect, Victim, connection_closed),
    ?line pong = rpc:call(Offender, net_adm, ping, [Victim]),

    ?line verify_up(Offender, Victim),
    %% We have a new connection between Offender and Victim, bad message
    %% should not bring it down.

    ?line {message_queue_len, 1}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),

    ?line exit(S, bang),
    ?line receive {'DOWN', MS, process, S, bang} -> ok end,
    %% Wait for a while (if the connection is taken down it might take a
    %% while).
    ?line receive after 2000 -> ok end,
    ?line verify_still_up(Offender, Victim),

    ?line P ! check_msgs,
    ?line receive {P, messages_checked} -> ok end,

    ?line {message_queue_len, 0}
	= rpc:call(Victim, erlang, process_info, [P, message_queue_len]),
    
    ?line verify_still_up(Offender, Victim),
    ?line P ! done,
    ?line unlink(P),
    ?line verify_no_down(Offender, Victim),
    ?line stop_node(Offender),
    ?line stop_node(Victim).


bad_dist_ext_check_msgs([]) ->
    receive
	Msg ->
	    exit({unexpected_message, Msg})
    after 0 ->
	    ok
    end;
bad_dist_ext_check_msgs([M|Ms]) ->
    receive
	Msg ->
	    M = Msg,
	    bad_dist_ext_check_msgs(Ms)
    end.
    
-define(COOKIE, '').
-define(DOP_LINK,		1).
-define(DOP_SEND,		2).
-define(DOP_EXIT,		3).
-define(DOP_UNLINK,		4).
-define(DOP_NODE_LINK,		5).
-define(DOP_REG_SEND,		6).
-define(DOP_GROUP_LEADER,	7).
-define(DOP_EXIT2,		8).

-define(DOP_SEND_TT,		12).
-define(DOP_EXIT_TT,		13).
-define(DOP_REG_SEND_TT,	16).
-define(DOP_EXIT2_TT,		18).

-define(DOP_MONITOR_P,		19).
-define(DOP_DEMONITOR_P,	20).
-define(DOP_MONITOR_P_EXIT,	21).

dport_reg_send(Node, Name, Msg) ->
    DPrt = case dport(Node) of
	       undefined ->
		   pong = net_adm:ping(Node),
		   dport(Node);
	       Prt ->
		   Prt
	   end,
    port_command(DPrt, [dmsg_hdr(),
			dmsg_ext({?DOP_REG_SEND,
				  self(),
				  ?COOKIE,
				  Name}),
			dmsg_ext(Msg)]).


dport_send(To, Msg) ->
    Node = node(To),
    DPrt = case dport(Node) of
	       undefined ->
		   pong = net_adm:ping(Node),
		   dport(Node);
	       Prt ->
		   Prt
	   end,
    port_command(DPrt, [dmsg_hdr(),
			dmsg_ext({?DOP_SEND,
				  ?COOKIE,
				  To}),
			dmsg_ext(Msg)]).

%% send_bad_msgs():
%% Send a valid distribution header and control message
%% but an invalid message. This invalid message will be
%% enqueued in the receivers message queue.
send_bad_msg(BadNode, To) ->
    send_bad_msgs(BadNode, To, 1).

send_bad_msgs(BadNode, To, Repeat) when is_atom(BadNode),
					is_pid(To),
					is_integer(Repeat) ->
    Parent = self(),
    Done = make_ref(),
    spawn_link(BadNode,
	       fun () ->
		       Node = node(To),
		       pong = net_adm:ping(Node),
		       DPrt = dport(Node),
		       DData = [dmsg_hdr(),
				dmsg_ext({?DOP_SEND, ?COOKIE, To}),
				dmsg_bad_atom_cache_ref()],
		       repeat(fun () -> port_command(DPrt, DData) end, Repeat),
		       Parent ! Done
	       end),
    receive Done -> ok end.

%% send_bad_ctl():
%% Send a valid distribution header but an invalid control message.
send_bad_ctl(BadNode, ToNode) when is_atom(BadNode), is_atom(ToNode) ->
    Parent = self(),
    Done = make_ref(),
    spawn_link(BadNode,
	       fun () ->
		       pong = net_adm:ping(ToNode),
		       %% We creat a valid ctl msg and replace an
		       %% atom with an invalid atom cache reference
		       <<131,Replace/binary>> = term_to_binary(replace),
		       Ctl = dmsg_ext({?DOP_REG_SEND,
				       self(),
				       ?COOKIE,
				       replace}),
		       CtlBeginSize = size(Ctl) - size(Replace),
		       <<CtlBegin:CtlBeginSize/binary, Replace/binary>> = Ctl,
		       port_command(dport(ToNode),
				    [dmsg_fake_hdr2(),
				     CtlBegin,
				     dmsg_bad_atom_cache_ref(),
				     dmsg_ext({a, message})]),
		       Parent ! Done
	       end),
    receive Done -> ok end.

%% send_bad_dhr():
%% Send an invalid distribution header
send_bad_dhdr(BadNode, ToNode) when is_atom(BadNode), is_atom(ToNode) ->
    Parent = self(),
    Done = make_ref(),
    spawn_link(BadNode,
	       fun () ->
		       pong = net_adm:ping(ToNode),
		       port_command(dport(ToNode), dmsg_bad_hdr()),
		       Parent ! Done
	       end),
    receive Done -> ok end.

dport(Node) when is_atom(Node) ->
    case catch erts_debug:get_internal_state(available_internal_state) of
	true -> true;
	_ -> erts_debug:set_internal_state(available_internal_state, true)
    end,
    erts_debug:get_internal_state({dist_port, Node}).

dmsg_hdr() ->
    [131, % Version Magic
     $D,  % Dist header
     0].  % No atom cache referenses

dmsg_bad_hdr() ->
    [131, % Version Magic
     $D,  % Dist header
     255].  % 255 atom references
    

dmsg_fake_hdr1() ->
    A = <<"fake header atom 1">>,
    [131, % Version Magic
     $D, 1, 16#8, 0, size(A), A]. % Fake header

dmsg_fake_hdr2() ->
    A1 = <<"fake header atom 1">>,
    A2 = <<"atom 2">>,
    A3 = <<"atom 3">>,
    [131, % Version Magic
     $D,
     3,
     16#88, 16#08, % Flags
     0, size(A1), A1,
     1, size(A2), A2,
     2, size(A3), A3].

dmsg_ext(Term) ->	
    <<131, Res/binary>> = term_to_binary(Term),
    Res.

dmsg_bad_atom_cache_ref() ->
    [$R, 137].

%%% Utilities

timestamp() ->
    {A,B,C} = erlang:now(),
    (C div 1000) + (B * 1000) + (A * 1000000000).

start_node(X) ->
    start_node(X, [], []).

start_node(X, Y) ->
    start_node(X, Y, []).

start_node(Name, Args, Rel) when is_atom(Name), is_list(Rel) ->
    Pa = filename:dirname(code:which(?MODULE)),
    Cookie = atom_to_list(erlang:get_cookie()),
    RelArg = case Rel of
		 [] -> [];
		 _ -> [{erl,[{release,Rel}]}]
	     end,
    test_server:start_node(Name, slave, 
			   [{args,
			     Args++" -setcookie "++Cookie++" -pa "++Pa}
			    | RelArg]);
start_node(Config, Args, Rel) when is_list(Config), is_list(Rel) ->
    Name = list_to_atom((atom_to_list(?MODULE)
			 ++ "-"
			 ++ atom_to_list(?config(testcase, Config))
			 ++ "-"
			 ++ integer_to_list(timestamp()))),
    start_node(Name, Args, Rel).

stop_node(Node) ->
    test_server:stop_node(Node).

freeze_node(Node, MS) ->
    Own = 300,
    DoingIt = make_ref(),
    Freezer = self(),
    spawn_link(Node,
	       fun () ->
		       erts_debug:set_internal_state(available_internal_state,
						     true),
		       dport_send(Freezer, DoingIt),
		       receive after Own -> ok end,
		       erts_debug:set_internal_state(block, MS+Own)
	       end),
    receive DoingIt -> ok end,
    receive after Own -> ok end.

inet_rpc_nodename({N,H,_Sock}) ->
    list_to_atom(N++"@"++H).

do_inet_rpc({_,_,Sock},M,F,A) ->
    Bin = term_to_binary({M,F,A}),
    gen_tcp:send(Sock,Bin),
    case gen_tcp:recv(Sock,0) of
	{ok, Bin2} ->
	    T = binary_to_term(Bin2),
	    {ok,T};
	Else ->
	    {error, Else}
    end.

inet_rpc_server([Host, PortList]) ->
    Port = list_to_integer(PortList),
    {ok, Sock} = gen_tcp:connect(Host, Port,[binary, {packet, 4}, 
                                        {active, false}]),
    inet_rpc_server_loop(Sock).

inet_rpc_server_loop(Sock) ->
    case gen_tcp:recv(Sock,0) of
	{ok, Bin} ->
	    {M,F,A} = binary_to_term(Bin),
	    Res = (catch apply(M,F,A)),
	    RB = term_to_binary(Res),
	    gen_tcp:send(Sock,RB),
	    inet_rpc_server_loop(Sock);
	_ ->
	    erlang:halt()
    end.
				 

start_relay_node(Node, Args) ->
    Pa = filename:dirname(code:which(?MODULE)),
    Cookie = "NOT"++atom_to_list(erlang:get_cookie()),
    {ok, LSock} = gen_tcp:listen(0, [binary, {packet, 4}, 
                                        {active, false}]),
    {ok, Port} = inet:port(LSock),
    {ok, Host} = inet:gethostname(),
    RunArg = "-run " ++ atom_to_list(?MODULE) ++ " inet_rpc_server " ++
	Host ++ " " ++ integer_to_list(Port),
    {ok, NN} = 
	test_server:start_node(Node, peer, 
			       [{args, Args ++
				 " -setcookie "++Cookie++" -pa "++Pa++" "++
				 RunArg}]),
    [N,H] = string:tokens(atom_to_list(NN),"@"),
    {ok, Sock} = gen_tcp:accept(LSock),
    pang = net_adm:ping(NN),
    {N,H,Sock}.

stop_relay_node({N,H,Sock}) ->
    catch do_inet_rpc(Sock,erlang,halt,[]),
    catch gen_tcp:close(Sock),
    wait_dead(N,H,10).

wait_dead(N,H,0) ->
    {error,{not_dead,N,H}};
wait_dead(N,H,X) ->
    case erl_epmd:port_please(N,H) of
	{port,_,_} ->
	    receive 
	    after 1000 ->
		    ok
	    end,
	    wait_dead(N,H,X-1);
	noport ->
	    ok;
	Else ->
	    {error, {unexpected, Else}}
    end.
    

start_node_monitors(Nodes) ->
    Master = self(),
    lists:foreach(fun (Node) ->
			  spawn(Node,
				fun () ->
					node_monitor(Master)
				end)
		  end,
		  Nodes),
    ok.

node_monitor(Master) ->
    Opts = [nodedown_reason,{node_type,all}],
    Nodes0 = nodes(connected),
    net_kernel:monitor_nodes(true, Opts),
    Nodes1 = nodes(connected),
    case lists:sort(Nodes0) == lists:sort(Nodes1) of
	true ->
	    lists:foreach(fun (Node) ->
				  Master ! {nodeup, node(), Node}
			  end,
			  Nodes0),
	    ?t:format("~p ~p: ~p~n", [node(), erlang:now(), Nodes0]),
	    node_monitor_loop(Master);
	false ->
	    net_kernel:monitor_nodes(false, Opts),
	    flush_node_changes(),
	    node_monitor(Master)
    end.

flush_node_changes() ->
    receive
	{NodeChange, _Node, _InfoList} when NodeChange == nodeup;
					    NodeChange == nodedown ->
	    flush_node_changes()
    after 0 ->
	    ok
    end.

node_monitor_loop(Master) ->
    receive
	{nodeup, Node, InfoList} = Msg ->
	    Master ! {nodeup, node(), Node},
	    ?t:format("~p ~p: ~p~n", [node(), erlang:now(), Msg]),
	    node_monitor_loop(Master);
	{nodedown, Node, InfoList} = Msg ->
	    Reason = case lists:keysearch(nodedown_reason, 1, InfoList) of
			 {value, {nodedown_reason, R}} -> R;
			 _ -> undefined
		     end,
	    Master ! {nodedown, node(), Node, Reason},
	    ?t:format("~p ~p: ~p~n", [node(), erlang:now(), Msg]),
	    node_monitor_loop(Master)
    end.

verify_up(A, B) ->
    receive {nodeup, A, B} -> ok end,
    receive {nodeup, B, A} -> ok end.

verify_still_up(A, B) ->
    true = lists:member(B, rpc:call(A, erlang, nodes, [connected])),
    true = lists:member(A, rpc:call(B, erlang, nodes, [connected])),
    verify_no_down(A, B).

verify_no_down(A, B) ->
    receive
	{nodedown, A, B, _} = Msg0 ->
	    ?t:fail(Msg0)
    after 0 ->
	    ok
    end,
    receive
	{nodedown, B, A, _} = Msg1 ->
	    ?t:fail(Msg1)
    after 0 ->
	    ok
    end.

verify_down(A, B) ->
    receive {nodedown, A, B, _} -> ok end,
    receive {nodedown, B, A, _} -> ok end.

verify_down(A, ReasonA, B, ReasonB) ->
    receive
	{nodedown, A, B, _} = Msg0 ->
	    {nodedown, A, B, ReasonA} = Msg0
    end,
    receive
	{nodedown, B, A, _} = Msg1 ->
	    {nodedown, B, A, ReasonB} = Msg1
    end,
    ok.

hostname() ->
    from($@, atom_to_list(node())).

from(H, [H | T]) -> T;
from(H, [_ | T]) -> from(H, T);
from(_, []) -> [].

fun_spawn(Fun) ->
    fun_spawn(Fun, []).

fun_spawn(Fun, Args) ->
    spawn_link(erlang, apply, [Fun, Args]).


long_or_short() -> 
    case net_kernel:longnames() of
	true -> " -name ";
	false -> " -sname "
    end.

until(Fun) ->
    case Fun() of
	true ->
	    ok;
	false ->
	    receive after 10 -> ok end,
	    until(Fun)
    end.

forever(Fun) ->
    Fun(),
    forever(Fun).

abort(Why) ->
    erts_debug:set_internal_state(available_internal_state, true),
    erts_debug:set_internal_state(abort, Why).


start_busy_dist_port_tracer() ->
    Tracer = spawn_link(fun () -> busy_dist_port_tracer() end),
    erlang:system_monitor(Tracer, [busy_dist_port]),
    Tracer.

stop_busy_dist_port_tracer(Tracer) when is_pid(Tracer) ->
    unlink(Tracer),
    exit(Tracer, bye);
stop_busy_dist_port_tracer(_) ->
    true.

busy_dist_port_tracer() ->
    receive
	{monitor, _SuspendedProcess, busy_dist_port, _Port} = M ->
	    erlang:display(M),
	    busy_dist_port_tracer()
    end.

repeat(_Fun, 0) ->
    ok;
repeat(Fun, N) ->
    Fun(),
    repeat(Fun, N-1).