aboutsummaryrefslogtreecommitdiffstats
path: root/erts/emulator/sys/win32/erl_poll.c
blob: 937a6787027649584d46117db07347d20ed4b4f7 (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
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
/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 2007-2011. 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%
 */
#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#define WANT_NONBLOCKING

#include "sys.h"
#include "erl_alloc.h"
#include "erl_poll.h"
#include "erl_time.h"

/*
 * Some debug macros 
 */

/*#define HARDDEBUG */
#ifdef HARDDEBUG
#ifdef HARDTRACE
#define HARDTRACEF(X) my_debug_printf##X
#else
#define HARDTRACEF(X)
#endif

#define HARDDEBUGF(X) my_debug_printf##X
static void my_debug_printf(char *fmt, ...)
{
    char buffer[1024];
    va_list args;

    va_start(args, fmt);
    erts_vsnprintf(buffer,1024,fmt,args);
    va_end(args);
    erts_fprintf(stderr,"%s\r\n",buffer);
}
#else
#define HARDTRACEF(X)
#define HARDDEBUGF(X)
#endif

#ifdef DEBUG
#define NoMansLandFill 0xFD	/* fill no-man's land with this */
#define DeadLandFill   0xDD	/* fill free objects with this */
#define CleanLandFill  0xCD	/* fill new objects with this */

static void consistency_check(struct _Waiter* w);
static void* debug_alloc(ErtsAlcType_t, Uint);
static void* debug_realloc(ErtsAlcType_t, void *, Uint, Uint);

#  define SEL_ALLOC	debug_alloc
#  define SEL_REALLOC	debug_realloc
#  define SEL_FREE	erts_free

static void *debug_alloc(ErtsAlcType_t type, Uint size)
{
    void* p = erts_alloc(type, size);
    memset(p, CleanLandFill, size);
    return p;
}

static void *debug_realloc(ErtsAlcType_t type, void *ptr, Uint prev_size,
			   Uint size)
{
    void *p;
    size_t fill_size;
    void *fill_ptr;

    if (prev_size > size) {
	size_t fill_size = (size_t) (prev_size - size);
	void *fill_ptr = (void *) (((char *) ptr) + size);
	memset(fill_ptr, NoMansLandFill, fill_size);
    }

    p = erts_realloc(type, ptr, size);

    if (size > prev_size) {
	size_t fill_size = (size_t) (size - prev_size);
	void *fill_ptr = (void *) (((char *) p) + prev_size);
	memset(fill_ptr, CleanLandFill, fill_size);
    }

    return p;
}
#else
#  define SEL_ALLOC	erts_alloc
#  define SEL_REALLOC	realloc_wrap
#  define SEL_FREE	erts_free

static ERTS_INLINE void *
realloc_wrap(ErtsAlcType_t t, void *p, Uint ps, Uint s)
{
    return erts_realloc(t, p, s);
}
#endif


#ifdef HARD_POLL_DEBUG
#define OP_SELECT 1
#define OP_DESELECT 2
#define OP_FIRED 3
#define OP_READ_BEGIN 4
#define OP_READ_DONE 5
#define OP_WRITE_BEGIN 6
#define OP_WRITE_DONE 7
#define OP_REPORTED 8
#define OP_DIED 9
#define OP_ASYNC_INIT 10
#define OP_ASYNC_IMMED 11
#define OP_FD_MOVED 12

static struct {
    int op;
    ErtsSysFdType active;
    int xdata;
} debug_save_ops[1024];

static int num_debug_save_ops = 0;

static ErtsSysFdType active_debug_fd;
static int active_debug_fd_set = 0;

static erts_mtx_t save_ops_mtx;

static void poll_debug_init(void)
{
    erts_mtx_init(&save_ops_mtx, "save_ops_lock");
}

void poll_debug_set_active_fd(ErtsSysFdType fd)
{
    erts_mtx_lock(&save_ops_mtx);
    active_debug_fd_set = 1;
    active_debug_fd = fd;
    erts_mtx_unlock(&save_ops_mtx);
}

static void do_save_op(ErtsSysFdType fd, int op, int xdata)
{
    erts_mtx_lock(&save_ops_mtx);
    if (fd == active_debug_fd && num_debug_save_ops < 1024) {
	int x = num_debug_save_ops++;
	debug_save_ops[x].op = op;
	debug_save_ops[x].active = fd;
	debug_save_ops[x].xdata = xdata;
    }
    erts_mtx_unlock(&save_ops_mtx);
}

void poll_debug_moved(ErtsSysFdType fd, int s1, int s2)
{
    do_save_op(fd,OP_FD_MOVED,s1 | (s2 << 16));
}

void poll_debug_select(ErtsSysFdType fd, int mode)
{
    do_save_op(fd,OP_SELECT,mode);
}

void poll_debug_deselect(ErtsSysFdType fd)
{
    do_save_op(fd,OP_DESELECT,0);
}

void poll_debug_fired(ErtsSysFdType fd)
{
    do_save_op(fd,OP_FIRED,0);
}

void poll_debug_read_begin(ErtsSysFdType fd)
{
    do_save_op(fd,OP_READ_BEGIN,0);
}

void poll_debug_read_done(ErtsSysFdType fd, int bytes)
{
    do_save_op(fd,OP_READ_DONE,bytes);
}

void poll_debug_async_initialized(ErtsSysFdType fd)
{
    do_save_op(fd,OP_ASYNC_INIT,0);
}

void poll_debug_async_immediate(ErtsSysFdType fd, int bytes)
{
    do_save_op(fd,OP_ASYNC_IMMED,bytes);
}

void poll_debug_write_begin(ErtsSysFdType fd)
{
    do_save_op(fd,OP_WRITE_BEGIN,0);
}

void poll_debug_write_done(ErtsSysFdType fd, int bytes)
{
    do_save_op(fd,OP_WRITE_DONE,bytes);
}

void poll_debug_reported(ErtsSysFdType fd, int mode)
{
    do_save_op(fd,OP_REPORTED,mode);
}

void poll_debug_died(ErtsSysFdType fd)
{
    do_save_op(fd,OP_DIED,0);
}

#endif /* DEBUG */

/*
 * End of debug macros
 */



/*
 * Handles that we poll, but that are actually signalled from outside 
 * this module
 */

extern HANDLE erts_service_event;
extern HANDLE erts_sys_break_event;


/*
 * The structure we hold for each event (i.e. fd)
 */
typedef struct _EventData {
    HANDLE event;		/* For convenience. */
    ErtsPollEvents mode;	/* The current select mode. */
    struct _EventData *next;	/* Next in free or delete lists. */
} EventData;

/*
 * The structure to represent a waiter thread
 */
typedef struct _Waiter {
    HANDLE events[MAXIMUM_WAIT_OBJECTS];     /* The events. */
    EventData* evdata[MAXIMUM_WAIT_OBJECTS]; /* Pointers to associated data. */
    int active_events;		/* Number of events to wait for */
    int total_events;		/* Total number of events in the arrays. */
    int highwater;              /* Events processed up to here */
    EventData evdata_heap[MAXIMUM_WAIT_OBJECTS]; /* Pre-allocated EventDatas */
    EventData* first_free_evdata; /* Index of first free EventData object. */
    HANDLE go_ahead;		/* The waiter may continue. (Auto-reset) */
    void *xdata;                /* used when thread parameter */
    erts_tid_t this;            /* Thread "handle" of this waiter */
    erts_mtx_t mtx;             /* Mutex for updating/reading pollset, but the
				   currently used set require thread stopping 
				   to be updated */
} Waiter;

/*
 * The structure for a pollset. There can currently be only one...
 */
struct ErtsPollSet_ {
    Waiter** waiter;
    int allocated_waiters;  /* Size ow waiter array */ 
    int num_waiters;	    /* Number of waiter threads. */
    int restore_events;        /* Tells us to restore waiters events 
				  next time around */
    HANDLE event_io_ready;     /* To be used when waiting for io */
    /* These are used to wait for workers to enter standby */
    volatile int standby_wait_counter; /* Number of threads to wait for */
    CRITICAL_SECTION standby_crit;     /* CS to guard the counter */
    HANDLE standby_wait_event;         /* Event signalled when counte == 0 */
    erts_atomic32_t wakeup_state;
#ifdef ERTS_SMP
    erts_smp_mtx_t mtx;
#endif
    erts_atomic64_t timeout_time;
};

#ifdef ERTS_SMP

#define ERTS_POLLSET_LOCK(PS) \
  erts_smp_mtx_lock(&(PS)->mtx)
#define ERTS_POLLSET_UNLOCK(PS) \
  erts_smp_mtx_unlock(&(PS)->mtx)

#else

#define ERTS_POLLSET_LOCK(PS)
#define ERTS_POLLSET_UNLOCK(PS)

#endif

/*
 * Communication with sys_interrupt
 */

#ifdef ERTS_SMP
extern erts_smp_atomic32_t erts_break_requested;
#define ERTS_SET_BREAK_REQUESTED \
  erts_smp_atomic32_set_nob(&erts_break_requested, (erts_aint32_t) 1)
#define ERTS_UNSET_BREAK_REQUESTED \
  erts_smp_atomic32_set_nob(&erts_break_requested, (erts_aint32_t) 0)
#else
extern volatile int erts_break_requested;
#define ERTS_SET_BREAK_REQUESTED (erts_break_requested = 1)
#define ERTS_UNSET_BREAK_REQUESTED (erts_break_requested = 0)
#endif

static erts_mtx_t break_waiter_lock;
static HANDLE break_happened_event;
static erts_atomic32_t break_waiter_state;
#define BREAK_WAITER_GOT_BREAK 1
#define BREAK_WAITER_GOT_HALT 2


/* 
 * Forward declarations
 */

static void *threaded_waiter(void *param);
static void *break_waiter(void *param);

/*
 * Sychronization macros and functions
 */
#define START_WAITER(PS, w) \
    SetEvent((w)->go_ahead)

#define STOP_WAITER(PS,w) \
do { \
    setup_standby_wait((PS),1); \
    SetEvent((w)->events[0]); \
    wait_standby(PS); \
} while(0)

#define START_WAITERS(PS) \
do { \
    int i; \
    for (i = 0; i < (PS)->num_waiters; i++) { \
	SetEvent((PS)->waiter[i]->go_ahead); \
    } \
 } while(0)

#define STOP_WAITERS(PS) \
do { \
    int i; \
    setup_standby_wait((PS),(PS)->num_waiters); \
    for (i = 0; i < (PS)->num_waiters; i++) { \
	SetEvent((PS)->waiter[i]->events[0]); \
    } \
    wait_standby(PS); \
 } while(0)

static ERTS_INLINE void
init_timeout_time(ErtsPollSet ps)
{
    erts_atomic64_init_nob(&ps->timeout_time,
			   (erts_aint64_t) ERTS_MONOTONIC_TIME_MAX);
}

static ERTS_INLINE void
set_timeout_time(ErtsPollSet ps, ErtsMonotonicTime time)
{
    erts_atomic64_set_relb(&ps->timeout_time,
			   (erts_aint64_t) time);
}

static ERTS_INLINE ErtsMonotonicTime
get_timeout_time(ErtsPollSet ps)
{
    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&ps->timeout_time);
}

#define ERTS_POLL_NOT_WOKEN		((erts_aint32_t) 0)
#define ERTS_POLL_WOKEN_IO_READY	((erts_aint32_t) 1)
#define ERTS_POLL_WOKEN_INTR		((erts_aint32_t) 2)
#define ERTS_POLL_WOKEN_TIMEDOUT	((erts_aint32_t) 3)

static ERTS_INLINE int
is_io_ready(ErtsPollSet ps)
{
    return erts_atomic32_read_nob(&ps->wakeup_state) == ERTS_POLL_WOKEN_IO_READY;
}

static ERTS_INLINE void
woke_up(ErtsPollSet ps)
{
    if (erts_atomic32_read_nob(&ps->wakeup_state) == ERTS_POLL_NOT_WOKEN)
	erts_atomic32_cmpxchg_nob(&ps->wakeup_state,
				  ERTS_POLL_WOKEN_TIMEDOUT,
				  ERTS_POLL_NOT_WOKEN);
#ifdef DEBUG
    {
	erts_aint32_t wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
	switch (wakeup_state) {
	case ERTS_POLL_WOKEN_IO_READY:
	case ERTS_POLL_WOKEN_INTR:
	case ERTS_POLL_WOKEN_TIMEDOUT:
	    break;
	default:
	    ASSERT(0);
	    break;
	}
    }
#endif
}

static ERTS_INLINE int
wakeup_cause(ErtsPollSet ps)
{
    int res;
    erts_aint32_t wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
    switch (wakeup_state) {
    case ERTS_POLL_WOKEN_IO_READY:
	res = 0;
	break;
    case ERTS_POLL_WOKEN_INTR:
	res = EINTR;
	break;
    case ERTS_POLL_WOKEN_TIMEDOUT:
	res = ETIMEDOUT;
	break;
    default:
	res = 0;
	erl_exit(ERTS_ABORT_EXIT,
		 "%s:%d: Internal error: Invalid wakeup_state=%d\n",
		 __FILE__, __LINE__, (int) wakeup_state);
    }
    return res;
}

static ERTS_INLINE DWORD
poll_wait_timeout(ErtsPollSet ps, ErtsMonotonicTime timeout_time)
{
    ErtsMonotonicTime current_time, diff_time, timeout;

    if (timeout_time == ERTS_POLL_NO_TIMEOUT) {
    no_timeout:
	set_timeout_time(ps, ERTS_MONOTONIC_TIME_MIN);
	woke_up(ps);
	return (DWORD) 0;
    }

    current_time = erts_get_monotonic_time();
    diff_time = timeout_time - current_time;
    if (diff_time <= 0)
	goto no_timeout;

    /* Round up to nearest milli second */
    timeout = (ERTS_MONOTONIC_TO_MSEC(diff_time - 1) + 1);
    if (timeout > INT_MAX)
	timeout = INT_MAX; /* Also prevents DWORD overflow */

    set_timeout_time(ps, current_time + ERTS_MSEC_TO_MONOTONIC(timeout));

    ResetEvent(ps->event_io_ready);
    /*
     * Since we don't know the internals of ResetEvent() we issue
     * a memory barrier as a safety precaution ensuring that
     * the load of wakeup_state wont be reordered with stores made
     * by ResetEvent().
     */
    ERTS_THR_MEMORY_BARRIER;
    if (erts_atomic32_read_nob(&ps->wakeup_state) != ERTS_POLL_NOT_WOKEN)
	return (DWORD) 0;

    return (DWORD) timeout;
}

static ERTS_INLINE void
wake_poller(ErtsPollSet ps, int io_ready)
{
    erts_aint32_t wakeup_state;
    if (io_ready) {
	/* We may set the event multiple times. This is, however, harmless. */
	wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
	erts_atomic32_set_relb(&ps->wakeup_state, ERTS_POLL_WOKEN_IO_READY);
    }
    else {
	ERTS_THR_MEMORY_BARRIER;
	wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
	while (wakeup_state != ERTS_POLL_WOKEN_IO_READY
	       && wakeup_state != ERTS_POLL_WOKEN_INTR) {
	    erts_aint32_t act = erts_atomic32_cmpxchg_nob(&ps->wakeup_state,
							  ERTS_POLL_WOKEN_INTR,
							  wakeup_state);
	    if (act == wakeup_state) {
		wakeup_state = act;
		break;
	    }
	    wakeup_state = act;
	}
    }
    if (wakeup_state == ERTS_POLL_NOT_WOKEN) {
	/*
	 * Since we don't know the internals of SetEvent() we issue
	 * a memory barrier as a safety precaution ensuring that
	 * the store we just made to wakeup_state wont be reordered
	 * with loads in SetEvent().
	 */
	ERTS_THR_MEMORY_BARRIER;
	SetEvent(ps->event_io_ready);
    }
}

static ERTS_INLINE void
reset_io_ready(ErtsPollSet ps)
{
    erts_atomic32_set_nob(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN);
}

static ERTS_INLINE void
restore_io_ready(ErtsPollSet ps)
{
    erts_atomic32_set_nob(&ps->wakeup_state, ERTS_POLL_WOKEN_IO_READY);
}

/*
 * notify_io_ready() is used by threads waiting for events, when
 * notifying a poller thread about I/O ready.
 */
static ERTS_INLINE void
notify_io_ready(ErtsPollSet ps)
{
    wake_poller(ps, 1);
}

static ERTS_INLINE void
reset_interrupt(ErtsPollSet ps)
{
    /* We need to keep io-ready if set */
    erts_aint32_t wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
    while (wakeup_state != ERTS_POLL_WOKEN_IO_READY
	   && wakeup_state != ERTS_POLL_NOT_WOKEN) {
	erts_aint32_t act = erts_atomic32_cmpxchg_nob(&ps->wakeup_state,
						      ERTS_POLL_NOT_WOKEN,
						      wakeup_state);
	if (wakeup_state == act)
	    break;
	wakeup_state = act;
    }
    ERTS_THR_MEMORY_BARRIER;
}

static ERTS_INLINE void
set_interrupt(ErtsPollSet ps)
{
    wake_poller(ps, 0);
}

static void setup_standby_wait(ErtsPollSet ps, int num_threads)
{
    EnterCriticalSection(&(ps->standby_crit));
    ps->standby_wait_counter = num_threads;
    ResetEvent(ps->standby_wait_event);
    LeaveCriticalSection(&(ps->standby_crit));
}

static void signal_standby(ErtsPollSet ps) 
{
    EnterCriticalSection(&(ps->standby_crit));
    --(ps->standby_wait_counter);
    if (ps->standby_wait_counter < 0) {
	LeaveCriticalSection(&(ps->standby_crit));
	erl_exit(1,"Standby signalled by more threads than expected");
    }
    if (!(ps->standby_wait_counter)) {
	SetEvent(ps->standby_wait_event);
    }
    LeaveCriticalSection(&(ps->standby_crit));
}

static void wait_standby(ErtsPollSet ps)
{
    WaitForSingleObject(ps->standby_wait_event,INFINITE);
}

static void remove_event_from_set(Waiter *w, int j)
{
    w->evdata[j]->event = INVALID_HANDLE_VALUE;
    w->evdata[j]->mode = 0;
    w->evdata[j]->next = w->first_free_evdata;
    w->first_free_evdata = w->evdata[j];
    
    /*
     * If the event is active, we will overwrite it
     * with the last active event and make the hole
     * the first non-active event.
     */
    
    if (j < w->active_events) {
	w->active_events--;
	w->highwater--;
	w->total_events--;
	w->events[j] = w->events[w->active_events];
	w->evdata[j] = w->evdata[w->active_events];
	w->events[w->active_events] = w->events[w->highwater];
	w->evdata[w->active_events] = w->evdata[w->highwater];
	w->events[w->highwater] =  w->events[w->total_events];
	w->evdata[w->highwater] =  w->evdata[w->total_events];
    } else if (j < w->highwater) {
	w->highwater--;
	w->total_events--;
	w->events[j] = w->events[w->highwater];
	w->evdata[j] = w->evdata[w->highwater];
	w->events[w->highwater] =  w->events[w->total_events];
	w->evdata[w->highwater] =  w->evdata[w->total_events];
    } else {
	w->total_events--;
	w->events[j] = w->events[w->total_events];
	w->evdata[j] = w->evdata[w->total_events];
    }
    
#ifdef DEBUG
    w->events[w->total_events] = (HANDLE) CleanLandFill;
    w->evdata[w->total_events] = (EventData *) CleanLandFill;
    consistency_check(w);
#endif
}    

/* 
 * Thread handling
 */

#ifdef DEBUG
static void consistency_check(Waiter* w)
{
    int i;
    
    ASSERT(w->active_events <= w->total_events);
    ASSERT(w->evdata[0] == NULL);

    for (i = 1; i < w->total_events; i++) {
	ASSERT(w->events[i] == w->evdata[i]->event);
	ASSERT(w->evdata[i]->mode != 0);
    }
}

#endif

static void new_waiter(ErtsPollSet ps)
{
    register Waiter* w;
    DWORD tid;			/* Id for thread. */
    erts_tid_t thread;
    int i;
    int tres;

    if (ps->num_waiters == ps->allocated_waiters) {
	Uint old_size = sizeof(Waiter *)*ps->allocated_waiters;
	ps->allocated_waiters += 64;
	ps->waiter = SEL_REALLOC(ERTS_ALC_T_WAITER_OBJ,
				 (void *) ps->waiter,
				 old_size,
				 sizeof(Waiter *) * (ps->allocated_waiters));
    }
	
    w = (Waiter *) SEL_ALLOC(ERTS_ALC_T_WAITER_OBJ, sizeof(Waiter));
    ps->waiter[ps->num_waiters] = w;

    w->events[0] = CreateAutoEvent(FALSE);
    w->evdata[0] = NULL;	/* Should never be used. */
    w->active_events = 1;
    w->highwater = 1;
    w->total_events = 1;
    erts_mtx_init(&w->mtx, "pollwaiter");


    /*
     * Form the free list of EventData objects.
     */

    w->evdata_heap[0].next = 0;	/* Last in free list. */
    for (i = 1; i < MAXIMUM_WAIT_OBJECTS; i++) {
	w->evdata_heap[i].next = w->evdata_heap+i-1;
    }
    w->first_free_evdata = w->evdata_heap+MAXIMUM_WAIT_OBJECTS-1;

    /*
     * Create the other events.
     */

    w->go_ahead = CreateAutoEvent(FALSE);

    /*
     * Create the thread.
     */
    w->xdata = ps;
    erts_thr_create(&thread, &threaded_waiter, w, NULL);
    w->this = thread;

    /*
     * Finally, done.
     */

    (ps->num_waiters)++;
}

static void *break_waiter(void *param)
{
    HANDLE harr[2];
    int i = 0;
    harr[i++] = erts_sys_break_event;
    if (erts_service_event != NULL) {
	harr[i++] = erts_service_event;
    }

    for(;;) {
	switch (WaitForMultipleObjects(i,harr,FALSE,INFINITE)) {
	case WAIT_OBJECT_0:
	    ResetEvent(harr[0]);
	    erts_mtx_lock(&break_waiter_lock);
	    erts_atomic32_set_nob(&break_waiter_state,BREAK_WAITER_GOT_BREAK);
	    ERTS_THR_MEMORY_BARRIER;
	    SetEvent(break_happened_event);
	    erts_mtx_unlock(&break_waiter_lock);
	    break;
	case (WAIT_OBJECT_0+1):
	    ResetEvent(harr[1]);
	    erts_mtx_lock(&break_waiter_lock);
	    erts_atomic32_set_nob(&break_waiter_state,BREAK_WAITER_GOT_HALT);
	    ERTS_THR_MEMORY_BARRIER;
	    SetEvent(break_happened_event);
	    erts_mtx_unlock(&break_waiter_lock);
	    break;
	default:
	    erl_exit(1,"Unexpected event in break_waiter");
	}
    }
}
		    
static void *threaded_waiter(void *param)
{
    register Waiter* w = (Waiter *) param;
    ErtsPollSet ps = (ErtsPollSet) w->xdata;
#ifdef HARD_POLL_DEBUG2
    HANDLE oold_fired[64];
    int num_oold_fired;
    HANDLE old_fired[64];
    int num_old_fired = 0;
    HANDLE fired[64];
    int num_fired = 0;
    HANDLE errors[1024];
    int num_errors = 0;
    HANDLE save_events[64];
    int save_active_events;
    int save_total_events;
    int save_highwater;
#endif

 again:
    WaitForSingleObject(w->go_ahead, INFINITE);
    /* Atomic enough when just checking, skip lock */
    if (w->total_events == 0) {
	return NULL;
    }
    if (w->active_events == 0) {
	goto again;
    }
    ASSERT(w->evdata[0] == NULL);
#ifdef HARD_POLL_DEBUG2
    num_oold_fired = num_old_fired;
    memcpy(oold_fired,old_fired,num_old_fired*sizeof(HANDLE));
    num_old_fired = num_fired;
    memcpy(old_fired,fired,num_fired*sizeof(HANDLE));
    num_fired = 0;
#endif
    for (;;) {
	int i;
	int j;
#ifdef HARD_POLL_DEBUG2
	erts_mtx_lock(&w->mtx);
	memcpy(save_events,w->events,w->active_events*sizeof(HANDLE));
	save_active_events = w->active_events;
	save_total_events = w->total_events;
	save_highwater = w->highwater;
	erts_mtx_unlock(&w->mtx);	
#endif
	i = WaitForMultipleObjects(w->active_events, w->events, FALSE, INFINITE);
	switch (i) {
	case WAIT_FAILED:
	    DEBUGF(("Wait failed: %s\n", last_error()));
	    erts_mtx_lock(&w->mtx);
	    /* Dont wait for our signal event */
	    for (j = 1; j < w->active_events; j++) {
		int tmp;
		if ((tmp = WaitForSingleObject(w->events[j], 0)) 
		    == WAIT_FAILED) {
		    DEBUGF(("Invalid handle: i = %d, handle = 0x%0x\n",
			    j, w->events[j]));
#ifdef HARD_POLL_DEBUG2
		    if (num_errors < 1024)
			errors[num_errors++] = w->events[j];
#endif
#ifdef HARD_POLL_DEBUG
		    poll_debug_died(w->events[j]);
#endif
		    remove_event_from_set(w,j);
#ifdef DEBUG
		    consistency_check(w);
#endif
		} else if (tmp == WAIT_OBJECT_0) {
		    i = WAIT_OBJECT_0 + j;
		    goto event_happened;
		}
	    }
	    erts_mtx_unlock(&w->mtx);
	    break;
	case WAIT_OBJECT_0:
	    signal_standby(ps);
	    goto again;
#ifdef DEBUG
	case WAIT_TIMEOUT:
	    ASSERT(0);
#endif
	default:
	    erts_mtx_lock(&w->mtx);
#ifdef HARD_POLL_DEBUG2
	    {
		int x = memcmp(save_events,w->events,w->active_events*sizeof(HANDLE));
		ASSERT(x == 0 && save_active_events == w->active_events);
	    }
#endif
event_happened:
#ifdef DEBUG
	    consistency_check(w);
#endif
	    ASSERT(WAIT_OBJECT_0 < i && i < WAIT_OBJECT_0+w->active_events);
	    notify_io_ready(ps);

	    /* 
	     * The main thread wont start working on our arrays untill we're
	     * stopped, so we can work in peace although the main thread runs 
	     */
	    ASSERT(i >= WAIT_OBJECT_0+1);
	    i -= WAIT_OBJECT_0;
	    ASSERT(i >= 1);
	    w->active_events--;
	    HARDDEBUGF(("i = %d, a,h,t = %d,%d,%d",i,
			w->active_events, w->highwater, w->total_events));
#ifdef HARD_POLL_DEBUG2
	    fired[num_fired++] = w->events[i];
#endif
#ifdef HARD_POLL_DEBUG
	    poll_debug_fired(w->events[i]);
#endif
	    if (i < w->active_events) {
		HANDLE te = w->events[i];
		EventData* tp = w->evdata[i];
		w->events[i] = w->events[w->active_events];
		w->evdata[i] = w->evdata[w->active_events];
		w->events[w->active_events] = te;
		w->evdata[w->active_events] = tp;
	    }
	    HARDDEBUGF(("i = %d, a,h,t = %d,%d,%d",i,
			w->active_events, w->highwater, w->total_events));
#ifdef DEBUG
	    consistency_check(w);
#endif
	    erts_mtx_unlock(&w->mtx);	    
	    break;
	}
    }
}

/*
 * The actual adding and removing from pollset utilities 
 */

static int set_driver_select(ErtsPollSet ps, HANDLE event, ErtsPollEvents mode)
{
    int i;
    int best_waiter = -1;	/* The waiter with lowest number of events. */
    int lowest = MAXIMUM_WAIT_OBJECTS; /* Lowest number of events
					* in any waiter.
					*/
    EventData* ev;
    Waiter* w;

    /*
     * Find the waiter which is least busy.
     */

#ifdef HARD_POLL_DEBUG
    poll_debug_select(event, mode);
#endif

    /* total_events can no longer be read without the lock, it's changed in the waiter */
    for (i = 0; i < ps->num_waiters; i++) {
	erts_mtx_lock(&(ps->waiter[i]->mtx));
	if (ps->waiter[i]->total_events < lowest) {
	    lowest = ps->waiter[i]->total_events;
	    best_waiter = i;
	}
	erts_mtx_unlock(&(ps->waiter[i]->mtx));
    }

    /*
     * Stop the selected waiter, or start a new waiter if all were busy.
     */

    if (best_waiter >= 0) {
	w = ps->waiter[best_waiter];
	STOP_WAITER(ps,w);
	erts_mtx_lock(&w->mtx);
    } else {
	new_waiter(ps);
	w = ps->waiter[(ps->num_waiters)-1];
	erts_mtx_lock(&w->mtx);
    }

#ifdef DEBUG
    consistency_check(w);
#endif

    /*
     * Allocate and initialize an EventData structure.
     */

    ev = w->first_free_evdata;
    w->first_free_evdata = ev->next;
    ev->event = event;
    ev->mode = mode;
    ev->next = NULL;

    /*
     * At this point, the selected waiter (newly-created or not) is
     * standing by.  Put the new event into the active part of the array.
     */

    if (w->active_events < w->total_events) {
	/*
	 * Move the first event beyond the active part of the array to
	 * the very end to make place for the new event.
	 */

#ifdef HARD_POLL_DEBUG
	poll_debug_moved(w->events[w->highwater],w->highwater,w->total_events);
#endif
	w->events[w->total_events] = w->events[w->highwater];
	w->evdata[w->total_events] = w->evdata[w->highwater];
#ifdef HARD_POLL_DEBUG
	poll_debug_moved(w->events[w->active_events],w->active_events,w->highwater);
#endif
	w->events[w->highwater] = w->events[w->active_events];
	w->evdata[w->highwater] = w->evdata[w->active_events];

    }
    w->events[w->active_events] = event;
    w->evdata[w->active_events] = ev;
    w->active_events++;
    w->highwater++;
    w->total_events++;

#ifdef DEBUG
    consistency_check(w);
#endif
    erts_mtx_unlock(&w->mtx);
    START_WAITER(ps,w);
    HARDDEBUGF(("add select %d %d %d %d",best_waiter,
		w->active_events,w->highwater,w->total_events));
    return mode;
}


static int cancel_driver_select(ErtsPollSet ps, HANDLE event)
{
    int i;

    ASSERT(event != INVALID_HANDLE_VALUE);
 restart:
    for (i = 0; i < ps->num_waiters; i++) {
	Waiter* w = ps->waiter[i];
	int j;

	erts_mtx_lock(&w->mtx);
#ifdef DEBUG
	consistency_check(w);
#endif
	for (j = 0; j < w->total_events; j++) {
	    if (w->events[j] == event) {
		int stopped = 0;
		/*
		 * Free the event's EventData structure.
		 */

		if (j < w->active_events) {
		    HARDDEBUGF(("Stopped in remove select"));
		    stopped = 1;
		    erts_mtx_unlock(&w->mtx);
		    STOP_WAITER(ps,w);
		    erts_mtx_lock(&w->mtx);
		    if ( j >= w->active_events || w->events[j] != event) {
			/* things happened while unlocked */
			START_WAITER(ps,w);
			erts_mtx_unlock(&w->mtx);
			goto restart;
		    }
		}
#ifdef HARD_POLL_DEBUG
		poll_debug_deselect(w->events[j]);
#endif
		remove_event_from_set(w, j);
		if (stopped) {
		    START_WAITER(ps,w);
		}
		HARDDEBUGF(("removed select %d,%d %d %d %d",i,j,
			    w->active_events,w->highwater,w->total_events));
		break;
	    }
	}
	erts_mtx_unlock(&w->mtx);
    }
    return 0;
}

/*
 * Interface functions
 */

void  erts_poll_interrupt(ErtsPollSet ps, int set /* bool */)
{
    HARDTRACEF(("In erts_poll_interrupt(%d)",set));
    if (!set)
	reset_interrupt(ps);
    else
	set_interrupt(ps);
    HARDTRACEF(("Out erts_poll_interrupt(%d)",set));
}

void erts_poll_interrupt_timed(ErtsPollSet ps,
			       int set /* bool */,
			       ErtsMonotonicTime timeout_time)
{
    HARDTRACEF(("In erts_poll_interrupt_timed(%d,%ld)",set,timeout_time));
    if (!set)
	reset_interrupt(ps);
    else if (get_timeout_time(ps) > timeout_time)
	set_interrupt(ps);
    HARDTRACEF(("Out erts_poll_interrupt_timed"));
}


/*
 * Windows is special, there is actually only one event type, and
 * the only difference between ERTS_POLL_EV_IN and ERTS_POLL_EV_OUT
 * is which driver callback will eventually be called.
 */
static ErtsPollEvents do_poll_control(ErtsPollSet ps,
				      ErtsSysFdType fd,
				      ErtsPollEvents pe,
				      int on /* bool */)
{
    HANDLE event = (HANDLE) fd;
    ErtsPollEvents mode;
    ErtsPollEvents result;
    ASSERT(event != INVALID_HANDLE_VALUE);

    if (on) {
	if (pe & ERTS_POLL_EV_IN || !(pe & ERTS_POLL_EV_OUT )) {
	    mode = ERTS_POLL_EV_IN;
	} else {
	    mode = ERTS_POLL_EV_OUT; /* ready output only in this case */
	}
	result = set_driver_select(ps, event, mode);
    } else {
	result = cancel_driver_select(ps, event);
    }
    return result;
}

ErtsPollEvents erts_poll_control(ErtsPollSet ps,
				 ErtsSysFdType fd,
				 ErtsPollEvents pe,
				 int on,
				 int* do_wake) /* In: Wake up polling thread */
				               /* Out: Poller is woken */
{
    ErtsPollEvents result;
    HARDTRACEF(("In erts_poll_control(0x%08X, %u, %d)",(unsigned long) fd, (unsigned) pe, on));
    ERTS_POLLSET_LOCK(ps);
    result=do_poll_control(ps,fd,pe,on);
    ERTS_POLLSET_UNLOCK(ps);
    *do_wake = 0; /* Never any need to wake polling threads on windows */
    HARDTRACEF(("Out erts_poll_control -> %u",(unsigned) result));
    return result;
}

void erts_poll_controlv(ErtsPollSet ps,
			ErtsPollControlEntry pcev[],
			int len)
{
    int i;
    int hshur = 0;
    int do_wake = 0;

    HARDTRACEF(("In erts_poll_controlv(%d)",len));
    ERTS_POLLSET_LOCK(ps);

    for (i = 0; i < len; i++) {
	pcev[i].events = do_poll_control(ps,
					 pcev[i].fd,
					 pcev[i].events,
					 pcev[i].on);
    }
    ERTS_POLLSET_UNLOCK(ps);
    HARDTRACEF(("Out erts_poll_controlv"));
}

int erts_poll_wait(ErtsPollSet ps,
		   ErtsPollResFd pr[],
		   int *len,
		   ErtsMonotonicTime timeout_time)
{
    int no_fds;
    DWORD timeout;
    EventData* ev;
    int res = 0;
    int num = 0;
    int n; 
    int i;
    int break_state;

    HARDTRACEF(("In erts_poll_wait"));
    ERTS_POLLSET_LOCK(ps);

    if (!is_io_ready(ps) && ps->restore_events) {
	HARDDEBUGF(("Restore events: %d",ps->num_waiters));
	ps->restore_events = 0;
	for (i = 0; i < ps->num_waiters; ++i) {
	   Waiter* w = ps->waiter[i];
	   erts_mtx_lock(&w->mtx);
	   HARDDEBUGF(("Maybe reset %d %d %d %d",i,
		       w->active_events,w->highwater,w->total_events));
	   if (w->active_events < w->total_events) {
	       erts_mtx_unlock(&w->mtx);
	       STOP_WAITER(ps,w);
	       HARDDEBUGF(("Need reset %d %d %d %d",i,
			   w->active_events,w->highwater,w->total_events));
	       erts_mtx_lock(&w->mtx);	       
	       /* Need reset, just check that it doesn't have got more to tell */
	       if (w->highwater != w->active_events) {
		   HARDDEBUGF(("Oups!"));
		   /* Oups, got signalled before we took the lock, can't reset */
		   if(!is_io_ready(ps)) {
		       erl_exit(1,"Internal error: "
				"Inconsistent io structures in erl_poll.\n");
		   }
		   START_WAITER(ps,w);
		   erts_mtx_unlock(&w->mtx);
		   ps->restore_events = 1; 
		   continue;
	       }
	       w->active_events = w->highwater =  w->total_events;
	       START_WAITER(ps,w);
	       erts_mtx_unlock(&w->mtx);
	   } else {
	       erts_mtx_unlock(&w->mtx);
	   }
	}
    }

    no_fds = *len;

#ifdef ERTS_POLL_MAX_RES
    if (no_fds >= ERTS_POLL_MAX_RES)
	no_fds = ERTS_POLL_MAX_RES;
#endif

    timeout = poll_wait_timeout(ps, timeout_time);

    /*HARDDEBUGF(("timeout = %ld",(long) timeout));*/

    if (timeout > 0 && !erts_atomic32_read_nob(&break_waiter_state)) {
	HANDLE harr[2] = {ps->event_io_ready, break_happened_event};
	int num_h = 2;

	HARDDEBUGF(("Start waiting %d [%d]",num_h, (int) timeout));
	ERTS_POLLSET_UNLOCK(ps);
#ifdef ERTS_SMP
	erts_thr_progress_prepare_wait(NULL);
#endif
	WaitForMultipleObjects(num_h, harr, FALSE, timeout);
#ifdef ERTS_SMP
	erts_thr_progress_finalize_wait(NULL);
#endif
	ERTS_POLLSET_LOCK(ps);
	HARDDEBUGF(("Stop waiting %d [%d]",num_h, (int) timeout));
	woke_up(ps);
    }

    ERTS_UNSET_BREAK_REQUESTED;
    if(erts_atomic32_read_nob(&break_waiter_state)) {
	erts_mtx_lock(&break_waiter_lock);
	break_state = erts_atomic32_read_nob(&break_waiter_state);
	erts_atomic32_set_nob(&break_waiter_state,0);
	ResetEvent(break_happened_event);
	erts_mtx_unlock(&break_waiter_lock);
	switch (break_state) {
	case  BREAK_WAITER_GOT_BREAK:
	    ERTS_SET_BREAK_REQUESTED;
	    break;
	case  BREAK_WAITER_GOT_HALT:
	    erl_exit(0,"");
	    break;
	default:
	    break;
	}
    }

    res = wakeup_cause(ps);
    if (res != 0) {
	HARDDEBUGF(("%s!", res == EINTR ? "EINTR" : "ETIMEDOUT"));
	goto done;
    }

    reset_io_ready(ps);

    n = ps->num_waiters;	

    for (i = 0; i < n; i++) {
	Waiter* w = ps->waiter[i];
	int j;
	int first;
	int last;
	erts_mtx_lock(&w->mtx);
#ifdef DEBUG
	consistency_check(w);
#endif

	first = w->active_events;
	last = w->highwater;
	w->highwater = w->active_events;

	for (j = last-1; j >= first; --j) {
	    if (num >= no_fds) {
		w->highwater=j+1;
		erts_mtx_unlock(&w->mtx);
		/* This might mean we still have data to report,
		   restore flag indicating I/O ready! */
		restore_io_ready(ps);
		HARDDEBUGF(("To many FD's to report!"));
		goto done;
	    }
	    HARDDEBUGF(("SET! Restore events"));
	    ps->restore_events = 1;
	    HARDDEBUGF(("Report %d,%d",i,j));
	    pr[num].fd = (ErtsSysFdType) w->events[j];
	    pr[num].events = w->evdata[j]->mode;
#ifdef HARD_POLL_DEBUG
	    poll_debug_reported(w->events[j],w->highwater | (j << 16));
	    poll_debug_reported(w->events[j],first | (last << 16));
#endif
	    ++num;
	}

#ifdef DEBUG
	consistency_check(w);
#endif
	erts_mtx_unlock(&w->mtx);
    }
 done:
    set_timeout_time(ps, ERTS_MONOTONIC_TIME_MAX);
    *len = num;
    ERTS_POLLSET_UNLOCK(ps);
    HARDTRACEF(("Out erts_poll_wait"));
    return res;

}

int erts_poll_max_fds(void)
{
    int res = sys_max_files();
    HARDTRACEF(("In/Out erts_poll_max_fds -> %d",res));
    return res;
}

void erts_poll_info(ErtsPollSet ps,
		    ErtsPollInfo *pip)
{
    Uint size = 0;
    Uint num_events = 0;
    int i;

    HARDTRACEF(("In erts_poll_info"));
    ERTS_POLLSET_LOCK(ps);

    size += sizeof(struct ErtsPollSet_);
    size += sizeof(Waiter *) * ps->allocated_waiters;
    for (i = 0; i < ps->num_waiters; ++i) {
	Waiter *w = ps->waiter[i];
	if (w != NULL) {
	    size += sizeof(Waiter);
	    erts_mtx_lock(&w->mtx);
	    size += sizeof(EventData) * w->total_events;
	    num_events += (w->total_events - 1); /* First event is internal */
	    erts_mtx_unlock(&w->mtx);
	}
    }

    pip->primary = "WaitForMultipleObjects"; 

    pip->fallback = NULL;

    pip->kernel_poll = NULL;

    pip->memory_size = size;

    pip->poll_set_size = num_events;

    pip->fallback_poll_set_size = 0;

    pip->lazy_updates = 0;

    pip->pending_updates = 0;

    pip->batch_updates = 0;

    pip->concurrent_updates = 0;
    ERTS_POLLSET_UNLOCK(ps);

    pip->max_fds = erts_poll_max_fds();
    HARDTRACEF(("Out erts_poll_info"));

}

ErtsPollSet erts_poll_create_pollset(void)
{
    ErtsPollSet ps = SEL_ALLOC(ERTS_ALC_T_POLLSET,
			       sizeof(struct ErtsPollSet_));
    HARDTRACEF(("In erts_poll_create_pollset"));

    ps->num_waiters = 0;
    ps->allocated_waiters = 64;
    ps->waiter = SEL_ALLOC(ERTS_ALC_T_WAITER_OBJ,
			   sizeof(Waiter *)*ps->allocated_waiters);
    InitializeCriticalSection(&(ps->standby_crit));
    ps->standby_wait_counter = 0;
    ps->event_io_ready = CreateManualEvent(FALSE);
    ps->standby_wait_event = CreateManualEvent(FALSE); 
    ps->restore_events = 0;

    erts_atomic32_init_nob(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN);
#ifdef ERTS_SMP
    erts_smp_mtx_init(&ps->mtx, "pollset");
#endif
    init_timeout_time(ps);

    HARDTRACEF(("Out erts_poll_create_pollset"));
    return ps;
}

void erts_poll_destroy_pollset(ErtsPollSet ps)
{
    int i;
    HARDTRACEF(("In erts_poll_destroy_pollset"));
    ERTS_POLLSET_LOCK(ps);
    STOP_WAITERS(ps);
    for (i=0;i<ps->num_waiters;++i) {
	Waiter *w = ps->waiter[i];
	void *dummy;
	erts_tid_t t = w->this;
	/* Assume we're alone, no locking here... */
	w->active_events = w->total_events = w->highwater = 0;
	START_WAITER(ps,w);
	erts_thr_join(t,&dummy);
	CloseHandle(w->go_ahead);
	CloseHandle(w->events[0]);
	erts_mtx_destroy(&w->mtx);
	SEL_FREE(ERTS_ALC_T_WAITER_OBJ, (void *) w);
    }
    SEL_FREE(ERTS_ALC_T_WAITER_OBJ,ps->waiter);
    CloseHandle(ps->event_io_ready);
    CloseHandle(ps->standby_wait_event);
    ERTS_POLLSET_UNLOCK(ps);
#ifdef ERTS_SMP
    erts_smp_mtx_destroy(&ps->mtx);
#endif
    SEL_FREE(ERTS_ALC_T_POLLSET, (void *) ps);
    HARDTRACEF(("Out erts_poll_destroy_pollset"));
}

/*
 * Actually mostly initializes the friend module sys_interrupt...
 */
void  erts_poll_init(void)
{
    erts_tid_t thread;

#ifdef HARD_POLL_DEBUG
    poll_debug_init();
#endif

    HARDTRACEF(("In erts_poll_init"));
    erts_sys_break_event = CreateManualEvent(FALSE);

    erts_mtx_init(&break_waiter_lock,"break_waiter_lock");
    break_happened_event = CreateManualEvent(FALSE);
    erts_atomic32_init_nob(&break_waiter_state, 0); 

    erts_thr_create(&thread, &break_waiter, NULL, NULL);
    ERTS_UNSET_BREAK_REQUESTED;
    HARDTRACEF(("Out erts_poll_init"));
}

/*
 * Non windows friendly interface, not used when fd's are not continous
 */
void  erts_poll_get_selected_events(ErtsPollSet ps,
				    ErtsPollEvents ev[],
				    int len)
{
    int i;
    HARDTRACEF(("In erts_poll_get_selected_events"));
    for (i = 0; i < len; ++i)
	ev[i] = 0;
    HARDTRACEF(("Out erts_poll_get_selected_events"));
}