summaryrefslogtreecommitdiff
path: root/lib/tevent/tevent.h
blob: 6b4d371e4c5dae31307eaa2b6ea973cd7c148036 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
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
/* 
   Unix SMB/CIFS implementation.

   generalised event loop handling

   Copyright (C) Andrew Tridgell 2005
   Copyright (C) Stefan Metzmacher 2005-2009
   Copyright (C) Volker Lendecke 2008

     ** NOTE! The following LGPL license applies to the tevent
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

#ifndef __TEVENT_H__
#define __TEVENT_H__

#include <stdint.h>
#include <talloc.h>
#include <sys/time.h>
#include <stdbool.h>

struct tevent_context;
struct tevent_ops;
struct tevent_fd;
struct tevent_timer;
struct tevent_immediate;
struct tevent_signal;

/**
 * @defgroup tevent The tevent API
 *
 * The tevent low-level API
 *
 * This API provides the public interface to manage events in the tevent
 * mainloop. Functions are provided for managing low-level events such
 * as timer events, fd events and signal handling.
 *
 * @{
 */

/* event handler types */
/**
 * Called when a file descriptor monitored by tevent has
 * data to be read or written on it.
 */
typedef void (*tevent_fd_handler_t)(struct tevent_context *ev,
				    struct tevent_fd *fde,
				    uint16_t flags,
				    void *private_data);

/**
 * Called when tevent is ceasing the monitoring of a file descriptor.
 */
typedef void (*tevent_fd_close_fn_t)(struct tevent_context *ev,
				     struct tevent_fd *fde,
				     int fd,
				     void *private_data);

/**
 * Called when a tevent timer has fired.
 */
typedef void (*tevent_timer_handler_t)(struct tevent_context *ev,
				       struct tevent_timer *te,
				       struct timeval current_time,
				       void *private_data);

/**
 * Called when a tevent immediate event is invoked.
 */
typedef void (*tevent_immediate_handler_t)(struct tevent_context *ctx,
					   struct tevent_immediate *im,
					   void *private_data);

/**
 * Called after tevent detects the specified signal.
 */
typedef void (*tevent_signal_handler_t)(struct tevent_context *ev,
					struct tevent_signal *se,
					int signum,
					int count,
					void *siginfo,
					void *private_data);

/**
 * @brief Create a event_context structure.
 *
 * This must be the first events call, and all subsequent calls pass this
 * event_context as the first element. Event handlers also receive this as
 * their first argument.
 *
 * @param[in]  mem_ctx  The memory context to use.
 *
 * @return              An allocated tevent context, NULL on error.
 *
 * @see tevent_context_init()
 */
struct tevent_context *tevent_context_init(TALLOC_CTX *mem_ctx);

/**
 * @brief Create a event_context structure and select a specific backend.
 *
 * This must be the first events call, and all subsequent calls pass this
 * event_context as the first element. Event handlers also receive this as
 * their first argument.
 *
 * @param[in]  mem_ctx  The memory context to use.
 *
 * @param[in]  name     The name of the backend to use.
 *
 * @return              An allocated tevent context, NULL on error.
 */
struct tevent_context *tevent_context_init_byname(TALLOC_CTX *mem_ctx, const char *name);

/**
 * @brief Create a custom event context
 *
 * @param[in]  mem_ctx  The memory context to use.
 * @param[in]  ops      The function pointer table of the backend.
 * @param[in]  additional_data  The additional/private data to this instance
 *
 * @return              An allocated tevent context, NULL on error.
 *
 */
struct tevent_context *tevent_context_init_ops(TALLOC_CTX *mem_ctx,
					       const struct tevent_ops *ops,
					       void *additional_data);

/**
 * @brief List available backends.
 *
 * @param[in]  mem_ctx  The memory context to use.
 *
 * @return              A string vector with a terminating NULL element, NULL
 *                      on error.
 */
const char **tevent_backend_list(TALLOC_CTX *mem_ctx);

/**
 * @brief Set the default tevent backend.
 *
 * @param[in]  backend  The name of the backend to set.
 */
void tevent_set_default_backend(const char *backend);

#ifdef DOXYGEN
/**
 * @brief Add a file descriptor based event.
 *
 * @param[in]  ev       The event context to work on.
 *
 * @param[in]  mem_ctx  The talloc memory context to use.
 *
 * @param[in]  fd       The file descriptor to base the event on.
 *
 * @param[in]  flags    #TEVENT_FD_READ or #TEVENT_FD_WRITE
 *
 * @param[in]  handler  The callback handler for the event.
 *
 * @param[in]  private_data  The private data passed to the callback handler.
 *
 * @return              The file descriptor based event, NULL on error.
 *
 * @note To cancel the monitoring of a file descriptor, call talloc_free()
 * on the object returned by this function.
 */
struct tevent_fd *tevent_add_fd(struct tevent_context *ev,
				TALLOC_CTX *mem_ctx,
				int fd,
				uint16_t flags,
				tevent_fd_handler_t handler,
				void *private_data);
#else
struct tevent_fd *_tevent_add_fd(struct tevent_context *ev,
				 TALLOC_CTX *mem_ctx,
				 int fd,
				 uint16_t flags,
				 tevent_fd_handler_t handler,
				 void *private_data,
				 const char *handler_name,
				 const char *location);
#define tevent_add_fd(ev, mem_ctx, fd, flags, handler, private_data) \
	_tevent_add_fd(ev, mem_ctx, fd, flags, handler, private_data, \
		       #handler, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief Add a timed event
 *
 * @param[in]  ev       The event context to work on.
 *
 * @param[in]  mem_ctx  The talloc memory context to use.
 *
 * @param[in]  next_event  Timeval specifying the absolute time to fire this
 * event. This is not an offset.
 *
 * @param[in]  handler  The callback handler for the event.
 *
 * @param[in]  private_data  The private data passed to the callback handler.
 *
 * @return The newly-created timer event, or NULL on error.
 *
 * @note To cancel a timer event before it fires, call talloc_free() on the
 * event returned from this function. This event is automatically
 * talloc_free()-ed after its event handler files, if it hasn't been freed yet.
 *
 * @note Unlike some mainloops, tevent timers are one-time events. To set up
 * a recurring event, it is necessary to call tevent_add_timer() again during
 * the handler processing.
 *
 * @note Due to the internal mainloop processing, a timer set to run
 * immediately will do so after any other pending timers fire, but before
 * any further file descriptor or signal handling events fire. Callers should
 * not rely on this behavior!
 */
struct tevent_timer *tevent_add_timer(struct tevent_context *ev,
                                      TALLOC_CTX *mem_ctx,
                                      struct timeval next_event,
                                      tevent_timer_handler_t handler,
                                      void *private_data);
#else
struct tevent_timer *_tevent_add_timer(struct tevent_context *ev,
				       TALLOC_CTX *mem_ctx,
				       struct timeval next_event,
				       tevent_timer_handler_t handler,
				       void *private_data,
				       const char *handler_name,
				       const char *location);
#define tevent_add_timer(ev, mem_ctx, next_event, handler, private_data) \
	_tevent_add_timer(ev, mem_ctx, next_event, handler, private_data, \
			  #handler, __location__)
#endif

#ifdef DOXYGEN
/**
 * Initialize an immediate event object
 *
 * This object can be used to trigger an event to occur immediately after
 * returning from the current event (before any other event occurs)
 *
 * @param[in] mem_ctx  The talloc memory context to use as the parent
 *
 * @return An empty tevent_immediate object. Use tevent_schedule_immediate
 * to populate and use it.
 *
 * @note Available as of tevent 0.9.8
 */
struct tevent_immediate *tevent_create_immediate(TALLOC_CTX *mem_ctx);
#else
struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx,
						  const char *location);
#define tevent_create_immediate(mem_ctx) \
	_tevent_create_immediate(mem_ctx, __location__)
#endif

#ifdef DOXYGEN

/**
 * Schedule an event for immediate execution. This event will occur
 * immediately after returning from the current event (before any other
 * event occurs)
 *
 * @param[in] im       The tevent_immediate object to populate and use
 * @param[in] ctx      The tevent_context to run this event
 * @param[in] handler  The event handler to run when this event fires
 * @param[in] private_data  Data to pass to the event handler
 */
void tevent_schedule_immediate(struct tevent_immediate *im,
                struct tevent_context *ctx,
                tevent_immediate_handler_t handler,
                void *private_data);
#else
void _tevent_schedule_immediate(struct tevent_immediate *im,
				struct tevent_context *ctx,
				tevent_immediate_handler_t handler,
				void *private_data,
				const char *handler_name,
				const char *location);
#define tevent_schedule_immediate(im, ctx, handler, private_data) \
	_tevent_schedule_immediate(im, ctx, handler, private_data, \
				   #handler, __location__);
#endif

#ifdef DOXYGEN
/**
 * @brief Add a tevent signal handler
 *
 * tevent_add_signal() creates a new event for handling a signal the next
 * time through the mainloop. It implements a very simple traditional signal
 * handler whose only purpose is to add the handler event into the mainloop.
 *
 * @param[in]  ev       The event context to work on.
 *
 * @param[in]  mem_ctx  The talloc memory context to use.
 *
 * @param[in]  signum   The signal to trap
 *
 * @param[in]  handler  The callback handler for the signal.
 *
 * @param[in]  sa_flags sigaction flags for this signal handler.
 *
 * @param[in]  private_data  The private data passed to the callback handler.
 *
 * @return The newly-created signal handler event, or NULL on error.
 *
 * @note To cancel a signal handler, call talloc_free() on the event returned
 * from this function.
 */
struct tevent_signal *tevent_add_signal(struct tevent_context *ev,
                     TALLOC_CTX *mem_ctx,
                     int signum,
                     int sa_flags,
                     tevent_signal_handler_t handler,
                     void *private_data);
#else
struct tevent_signal *_tevent_add_signal(struct tevent_context *ev,
					 TALLOC_CTX *mem_ctx,
					 int signum,
					 int sa_flags,
					 tevent_signal_handler_t handler,
					 void *private_data,
					 const char *handler_name,
					 const char *location);
#define tevent_add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data) \
	_tevent_add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data, \
			   #handler, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief Pass a single time through the mainloop
 *
 * This will process any appropriate signal, immediate, fd and timer events
 *
 * @param[in]  ev The event context to process
 *
 * @return Zero on success, nonzero if an internal error occurred
 */
int tevent_loop_once(struct tevent_context *ev);
#else
int _tevent_loop_once(struct tevent_context *ev, const char *location);
#define tevent_loop_once(ev) \
	_tevent_loop_once(ev, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief Run the mainloop
 *
 * The mainloop will run until there are no events remaining to be processed
 *
 * @param[in]  ev The event context to process
 *
 * @return Zero if all events have been processed. Nonzero if an internal
 * error occurred.
 */
int tevent_loop_wait(struct tevent_context *ev);
#else
int _tevent_loop_wait(struct tevent_context *ev, const char *location);
#define tevent_loop_wait(ev) \
	_tevent_loop_wait(ev, __location__)
#endif


/**
 * Assign a function to run when a tevent_fd is freed
 *
 * This function is a destructor for the tevent_fd. It does not automatically
 * close the file descriptor. If this is the desired behavior, then it must be
 * performed by the close_fn.
 *
 * @param[in] fde       File descriptor event on which to set the destructor
 * @param[in] close_fn  Destructor to execute when fde is freed
 */
void tevent_fd_set_close_fn(struct tevent_fd *fde,
			    tevent_fd_close_fn_t close_fn);

/**
 * Automatically close the file descriptor when the tevent_fd is freed
 *
 * This function calls close(fd) internally.
 *
 * @param[in] fde  File descriptor event to auto-close
 */
void tevent_fd_set_auto_close(struct tevent_fd *fde);

/**
 * Return the flags set on this file descriptor event
 *
 * @param[in] fde  File descriptor event to query
 *
 * @return The flags set on the event. See #TEVENT_FD_READ and
 * #TEVENT_FD_WRITE
 */
uint16_t tevent_fd_get_flags(struct tevent_fd *fde);

/**
 * Set flags on a file descriptor event
 *
 * @param[in] fde    File descriptor event to set
 * @param[in] flags  Flags to set on the event. See #TEVENT_FD_READ and
 * #TEVENT_FD_WRITE
 */
void tevent_fd_set_flags(struct tevent_fd *fde, uint16_t flags);

/**
 * Query whether tevent supports signal handling
 *
 * @param[in] ev  An initialized tevent context
 *
 * @return True if this platform and tevent context support signal handling
 */
bool tevent_signal_support(struct tevent_context *ev);

void tevent_set_abort_fn(void (*abort_fn)(const char *reason));

/* bits for file descriptor event flags */

/**
 * Monitor a file descriptor for write availability
 */
#define TEVENT_FD_READ 1
/**
 * Monitor a file descriptor for data to be read
 */
#define TEVENT_FD_WRITE 2

/**
 * Convenience function for declaring a tevent_fd writable
 */
#define TEVENT_FD_WRITEABLE(fde) \
	tevent_fd_set_flags(fde, tevent_fd_get_flags(fde) | TEVENT_FD_WRITE)

/**
 * Convenience function for declaring a tevent_fd readable
 */
#define TEVENT_FD_READABLE(fde) \
	tevent_fd_set_flags(fde, tevent_fd_get_flags(fde) | TEVENT_FD_READ)

/**
 * Convenience function for declaring a tevent_fd non-writable
 */
#define TEVENT_FD_NOT_WRITEABLE(fde) \
	tevent_fd_set_flags(fde, tevent_fd_get_flags(fde) & ~TEVENT_FD_WRITE)

/**
 * Convenience function for declaring a tevent_fd non-readable
 */
#define TEVENT_FD_NOT_READABLE(fde) \
	tevent_fd_set_flags(fde, tevent_fd_get_flags(fde) & ~TEVENT_FD_READ)

/**
 * Debug level of tevent
 */
enum tevent_debug_level {
	TEVENT_DEBUG_FATAL,
	TEVENT_DEBUG_ERROR,
	TEVENT_DEBUG_WARNING,
	TEVENT_DEBUG_TRACE
};

/**
 * @brief The tevent debug callbac.
 *
 * @param[in]  context  The memory context to use.
 *
 * @param[in]  level    The debug level.
 *
 * @param[in]  fmt      The format string.
 *
 * @param[in]  ap       The arguments for the format string.
 */
typedef void (*tevent_debug_fn)(void *context,
				enum tevent_debug_level level,
				const char *fmt,
				va_list ap) PRINTF_ATTRIBUTE(3,0);

/**
 * Set destination for tevent debug messages
 *
 * @param[in] ev        Event context to debug
 * @param[in] debug     Function to handle output printing
 * @param[in] context   The context to pass to the debug function.
 *
 * @return Always returns 0 as of version 0.9.8
 *
 * @note Default is to emit no debug messages
 */
int tevent_set_debug(struct tevent_context *ev,
		     tevent_debug_fn debug,
		     void *context);

/**
 * Designate stderr for debug message output
 *
 * @param[in] ev     Event context to debug
 *
 * @note This function will only output TEVENT_DEBUG_FATAL, TEVENT_DEBUG_ERROR
 * and TEVENT_DEBUG_WARNING messages. For TEVENT_DEBUG_TRACE, please define a
 * function for tevent_set_debug()
 */
int tevent_set_debug_stderr(struct tevent_context *ev);

enum tevent_trace_point {
	/**
	 * Corresponds to a trace point just before waiting
	 */
	TEVENT_TRACE_BEFORE_WAIT,
	/**
	 * Corresponds to a trace point just after waiting
	 */
	TEVENT_TRACE_AFTER_WAIT,
#define TEVENT_HAS_LOOP_ONCE_TRACE_POINTS 1
	/**
	 * Corresponds to a trace point just before calling
	 * the loop_once() backend function.
	 */
	TEVENT_TRACE_BEFORE_LOOP_ONCE,
	/**
	 * Corresponds to a trace point right after the
	 * loop_once() backend function has returned.
	 */
	TEVENT_TRACE_AFTER_LOOP_ONCE,
};

typedef void (*tevent_trace_callback_t)(enum tevent_trace_point,
					void *private_data);

/**
 * Register a callback to be called at certain trace points
 *
 * @param[in] ev             Event context
 * @param[in] cb             Trace callback
 * @param[in] private_data   Data to be passed to callback
 *
 * @note The callback will be called at trace points defined by
 * tevent_trace_point.  Call with NULL to reset.
 */
void tevent_set_trace_callback(struct tevent_context *ev,
			       tevent_trace_callback_t cb,
			       void *private_data);

/**
 * Retrieve the current trace callback
 *
 * @param[in] ev             Event context
 * @param[out] cb            Registered trace callback
 * @param[out] private_data  Registered data to be passed to callback
 *
 * @note This can be used to allow one component that wants to
 * register a callback to respect the callback that another component
 * has already registered.
 */
void tevent_get_trace_callback(struct tevent_context *ev,
			       tevent_trace_callback_t *cb,
			       void *private_data);

/**
 * @}
 */

/**
 * @defgroup tevent_request The tevent request functions.
 * @ingroup tevent
 *
 * A tevent_req represents an asynchronous computation.
 *
 * The tevent_req group of API calls is the recommended way of
 * programming async computations within tevent. In particular the
 * file descriptor (tevent_add_fd) and timer (tevent_add_timed) events
 * are considered too low-level to be used in larger computations. To
 * read and write from and to sockets, Samba provides two calls on top
 * of tevent_add_fd: read_packet_send/recv and writev_send/recv. These
 * requests are much easier to compose than the low-level event
 * handlers called from tevent_add_fd.
 *
 * A lot of the simplicity tevent_req has brought to the notoriously
 * hairy async programming came via a set of conventions that every
 * async computation programmed should follow. One central piece of
 * these conventions is the naming of routines and variables.
 *
 * Every async computation needs a name (sensibly called "computation"
 * down from here). From this name quite a few naming conventions are
 * derived.
 *
 * Every computation that requires local state needs a
 * @code
 * struct computation_state {
 *     int local_var;
 * };
 * @endcode
 * Even if no local variables are required, such a state struct should
 * be created containing a dummy variable. Quite a few helper
 * functions and macros (for example tevent_req_create()) assume such
 * a state struct.
 *
 * An async computation is started by a computation_send
 * function. When it is finished, its result can be received by a
 * computation_recv function. For an example how to set up an async
 * computation, see the code example in the documentation for
 * tevent_req_create() and tevent_req_post(). The prototypes for _send
 * and _recv functions should follow some conventions:
 *
 * @code
 * struct tevent_req *computation_send(TALLOC_CTX *mem_ctx,
 *                                     struct tevent_req *ev,
 *                                     ... further args);
 * int computation_recv(struct tevent_req *req, ... further output args);
 * @endcode
 *
 * The "int" result of computation_recv() depends on the result the
 * sync version of the function would have, "int" is just an example
 * here.
 *
 * Another important piece of the conventions is that the program flow
 * is interrupted as little as possible. Because a blocking
 * sub-computation requires that the flow needs to continue in a
 * separate function that is the logical sequel of some computation,
 * it should lexically follow sending off the blocking
 * sub-computation. Setting the callback function via
 * tevent_req_set_callback() requires referencing a function lexically
 * below the call to tevent_req_set_callback(), forward declarations
 * are required. A lot of the async computations thus begin with a
 * sequence of declarations such as
 *
 * @code
 * static void computation_step1_done(struct tevent_req *subreq);
 * static void computation_step2_done(struct tevent_req *subreq);
 * static void computation_step3_done(struct tevent_req *subreq);
 * @endcode
 *
 * It really helps readability a lot to do these forward declarations,
 * because the lexically sequential program flow makes the async
 * computations almost as clear to read as a normal, sync program
 * flow.
 *
 * It is up to the user of the async computation to talloc_free it
 * after it has finished. If an async computation should be aborted,
 * the tevent_req structure can be talloc_free'ed. After it has
 * finished, it should talloc_free'ed by the API user.
 *
 * @{
 */

/**
 * An async request moves from TEVENT_REQ_INIT to
 * TEVENT_REQ_IN_PROGRESS. All other states are valid after a request
 * has finished.
 */
enum tevent_req_state {
	/**
	 * We are creating the request
	 */
	TEVENT_REQ_INIT,
	/**
	 * We are waiting the request to complete
	 */
	TEVENT_REQ_IN_PROGRESS,
	/**
	 * The request is finished successfully
	 */
	TEVENT_REQ_DONE,
	/**
	 * A user error has occurred. The user error has been
	 * indicated by tevent_req_error(), it can be retrieved via
	 * tevent_req_is_error().
	 */
	TEVENT_REQ_USER_ERROR,
	/**
	 * Request timed out after the timeout set by tevent_req_set_endtime.
	 */
	TEVENT_REQ_TIMED_OUT,
	/**
	 * An internal allocation has failed, or tevent_req_nomem has
	 * been given a NULL pointer as the first argument.
	 */
	TEVENT_REQ_NO_MEMORY,
	/**
	 * The request has been received by the caller. No further
	 * action is valid.
	 */
	TEVENT_REQ_RECEIVED
};

/**
 * @brief An async request
 */
struct tevent_req;

/**
 * @brief A tevent request callback function.
 *
 * @param[in]  req      The tevent async request which executed this callback.
 */
typedef void (*tevent_req_fn)(struct tevent_req *req);

/**
 * @brief Set an async request callback.
 *
 * See the documentation of tevent_req_post() for an example how this
 * is supposed to be used.
 *
 * @param[in]  req      The async request to set the callback.
 *
 * @param[in]  fn       The callback function to set.
 *
 * @param[in]  pvt      A pointer to private data to pass to the async request
 *                      callback.
 */
void tevent_req_set_callback(struct tevent_req *req, tevent_req_fn fn, void *pvt);

#ifdef DOXYGEN
/**
 * @brief Get the private data cast to the given type for a callback from
 *        a tevent request structure.
 *
 * @code
 * static void computation_done(struct tevent_req *subreq) {
 *     struct tevent_req *req = tevent_req_callback_data(subreq, struct tevent_req);
 *     struct computation_state *state = tevent_req_data(req, struct computation_state);
 *     .... more things, eventually maybe call tevent_req_done(req);
 * }
 * @endcode
 *
 * @param[in]  req      The structure to get the callback data from.
 *
 * @param[in]  type     The type of the private callback data to get.
 *
 * @return              The type casted private data set NULL if not set.
 */
void *tevent_req_callback_data(struct tevent_req *req, #type);
#else
void *_tevent_req_callback_data(struct tevent_req *req);
#define tevent_req_callback_data(_req, _type) \
	talloc_get_type_abort(_tevent_req_callback_data(_req), _type)
#endif

#ifdef DOXYGEN
/**
 * @brief Get the private data for a callback from a tevent request structure.
 *
 * @param[in]  req      The structure to get the callback data from.
 *
 * @param[in]  req      The structure to get the data from.
 *
 * @return              The private data or NULL if not set.
 */
void *tevent_req_callback_data_void(struct tevent_req *req);
#else
#define tevent_req_callback_data_void(_req) \
	_tevent_req_callback_data(_req)
#endif

#ifdef DOXYGEN
/**
 * @brief Get the private data from a tevent request structure.
 *
 * When the tevent_req has been created by tevent_req_create, the
 * result of tevent_req_data() is the state variable created by
 * tevent_req_create() as a child of the req.
 *
 * @param[in]  req      The structure to get the private data from.
 *
 * @param[in]  type	The type of the private data
 *
 * @return              The private data or NULL if not set.
 */
void *tevent_req_data(struct tevent_req *req, #type);
#else
void *_tevent_req_data(struct tevent_req *req);
#define tevent_req_data(_req, _type) \
	talloc_get_type_abort(_tevent_req_data(_req), _type)
#endif

/**
 * @brief The print function which can be set for a tevent async request.
 *
 * @param[in]  req      The tevent async request.
 *
 * @param[in]  ctx      A talloc memory context which can be uses to allocate
 *                      memory.
 *
 * @return              An allocated string buffer to print.
 *
 * Example:
 * @code
 *   static char *my_print(struct tevent_req *req, TALLOC_CTX *mem_ctx)
 *   {
 *     struct my_data *data = tevent_req_data(req, struct my_data);
 *     char *result;
 *
 *     result = tevent_req_default_print(mem_ctx, req);
 *     if (result == NULL) {
 *       return NULL;
 *     }
 *
 *     return talloc_asprintf_append_buffer(result, "foo=%d, bar=%d",
 *       data->foo, data->bar);
 *   }
 * @endcode
 */
typedef char *(*tevent_req_print_fn)(struct tevent_req *req, TALLOC_CTX *ctx);

/**
 * @brief This function sets a print function for the given request.
 *
 * This function can be used to setup a print function for the given request.
 * This will be triggered if the tevent_req_print() function was
 * called on the given request.
 *
 * @param[in]  req      The request to use.
 *
 * @param[in]  fn       A pointer to the print function
 *
 * @note This function should only be used for debugging.
 */
void tevent_req_set_print_fn(struct tevent_req *req, tevent_req_print_fn fn);

/**
 * @brief The default print function for creating debug messages.
 *
 * The function should not be used by users of the async API,
 * but custom print function can use it and append custom text
 * to the string.
 *
 * @param[in]  req      The request to be printed.
 *
 * @param[in]  mem_ctx  The memory context for the result.
 *
 * @return              Text representation of request.
 *
 */
char *tevent_req_default_print(struct tevent_req *req, TALLOC_CTX *mem_ctx);

/**
 * @brief Print an tevent_req structure in debug messages.
 *
 * This function should be used by callers of the async API.
 *
 * @param[in]  mem_ctx  The memory context for the result.
 *
 * @param[in] req       The request to be printed.
 *
 * @return              Text representation of request.
 */
char *tevent_req_print(TALLOC_CTX *mem_ctx, struct tevent_req *req);

/**
 * @brief A typedef for a cancel function for a tevent request.
 *
 * @param[in]  req      The tevent request calling this function.
 *
 * @return              True if the request could be canceled, false if not.
 */
typedef bool (*tevent_req_cancel_fn)(struct tevent_req *req);

/**
 * @brief This function sets a cancel function for the given tevent request.
 *
 * This function can be used to setup a cancel function for the given request.
 * This will be triggered if the tevent_req_cancel() function was
 * called on the given request.
 *
 * @param[in]  req      The request to use.
 *
 * @param[in]  fn       A pointer to the cancel function.
 */
void tevent_req_set_cancel_fn(struct tevent_req *req, tevent_req_cancel_fn fn);

#ifdef DOXYGEN
/**
 * @brief Try to cancel the given tevent request.
 *
 * This function can be used to cancel the given request.
 *
 * It is only possible to cancel a request when the implementation
 * has registered a cancel function via the tevent_req_set_cancel_fn().
 *
 * @param[in]  req      The request to use.
 *
 * @return              This function returns true is the request is cancelable,
 *                      othererwise false is returned.
 *
 * @note Even if the function returns true, the caller need to wait
 *       for the function to complete normally.
 *       Only the _recv() function of the given request indicates
 *       if the request was really canceled.
 */
bool tevent_req_cancel(struct tevent_req *req);
#else
bool _tevent_req_cancel(struct tevent_req *req, const char *location);
#define tevent_req_cancel(req) \
	_tevent_req_cancel(req, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief Create an async tevent request.
 *
 * The new async request will be initialized in state TEVENT_REQ_IN_PROGRESS.
 *
 * @code
 * struct tevent_req *req;
 * struct computation_state *state;
 * req = tevent_req_create(mem_ctx, &state, struct computation_state);
 * @endcode
 *
 * Tevent_req_create() creates the state variable as a talloc child of
 * its result. The state variable should be used as the talloc parent
 * for all temporary variables that are allocated during the async
 * computation. This way, when the user of the async computation frees
 * the request, the state as a talloc child will be free'd along with
 * all the temporary variables hanging off the state.
 *
 * @param[in] mem_ctx   The memory context for the result.
 * @param[in] pstate    Pointer to the private request state.
 * @param[in] type      The name of the request.
 *
 * @return              A new async request. NULL on error.
 */
struct tevent_req *tevent_req_create(TALLOC_CTX *mem_ctx,
				     void **pstate, #type);
#else
struct tevent_req *_tevent_req_create(TALLOC_CTX *mem_ctx,
				      void *pstate,
				      size_t state_size,
				      const char *type,
				      const char *location);

#define tevent_req_create(_mem_ctx, _pstate, _type) \
	_tevent_req_create((_mem_ctx), (_pstate), sizeof(_type), \
			   #_type, __location__)
#endif

/**
 * @brief Set a timeout for an async request.
 *
 * @param[in]  req      The request to set the timeout for.
 *
 * @param[in]  ev       The event context to use for the timer.
 *
 * @param[in]  endtime  The endtime of the request.
 *
 * @return              True if succeeded, false if not.
 */
bool tevent_req_set_endtime(struct tevent_req *req,
			    struct tevent_context *ev,
			    struct timeval endtime);

#ifdef DOXYGEN
/**
 * @brief Call the notify callback of the given tevent request manually.
 *
 * @param[in]  req      The tevent request to call the notify function from.
 *
 * @see tevent_req_set_callback()
 */
void tevent_req_notify_callback(struct tevent_req *req);
#else
void _tevent_req_notify_callback(struct tevent_req *req, const char *location);
#define tevent_req_notify_callback(req)		\
	_tevent_req_notify_callback(req, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief An async request has successfully finished.
 *
 * This function is to be used by implementors of async requests. When a
 * request is successfully finished, this function calls the user's completion
 * function.
 *
 * @param[in]  req       The finished request.
 */
void tevent_req_done(struct tevent_req *req);
#else
void _tevent_req_done(struct tevent_req *req,
		      const char *location);
#define tevent_req_done(req) \
	_tevent_req_done(req, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief An async request has seen an error.
 *
 * This function is to be used by implementors of async requests. When a
 * request can not successfully completed, the implementation should call this
 * function with the appropriate status code.
 *
 * If error is 0 the function returns false and does nothing more.
 *
 * @param[in]  req      The request with an error.
 *
 * @param[in]  error    The error code.
 *
 * @return              On success true is returned, false if error is 0.
 *
 * @code
 * int error = first_function();
 * if (tevent_req_error(req, error)) {
 *      return;
 * }
 *
 * error = second_function();
 * if (tevent_req_error(req, error)) {
 *      return;
 * }
 *
 * tevent_req_done(req);
 * return;
 * @endcode
 */
bool tevent_req_error(struct tevent_req *req,
		      uint64_t error);
#else
bool _tevent_req_error(struct tevent_req *req,
		       uint64_t error,
		       const char *location);
#define tevent_req_error(req, error) \
	_tevent_req_error(req, error, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief Helper function for nomem check.
 *
 * Convenience helper to easily check alloc failure within a callback
 * implementing the next step of an async request.
 *
 * @param[in]  p        The pointer to be checked.
 *
 * @param[in]  req      The request being processed.
 *
 * @code
 * p = talloc(mem_ctx, bla);
 * if (tevent_req_nomem(p, req)) {
 *      return;
 * }
 * @endcode
 */
bool tevent_req_nomem(const void *p,
		      struct tevent_req *req);
#else
bool _tevent_req_nomem(const void *p,
		       struct tevent_req *req,
		       const char *location);
#define tevent_req_nomem(p, req) \
	_tevent_req_nomem(p, req, __location__)
#endif

#ifdef DOXYGEN
/**
 * @brief Indicate out of memory to a request
 *
 * @param[in]  req      The request being processed.
 */
void tevent_req_oom(struct tevent_req *req);
#else
void _tevent_req_oom(struct tevent_req *req,
		     const char *location);
#define tevent_req_oom(req) \
	_tevent_req_oom(req, __location__)
#endif

/**
 * @brief Finish a request before the caller had the change to set the callback.
 *
 * An implementation of an async request might find that it can either finish
 * the request without waiting for an external event, or it can not even start
 * the engine. To present the illusion of a callback to the user of the API,
 * the implementation can call this helper function which triggers an
 * immediate event. This way the caller can use the same calling
 * conventions, independent of whether the request was actually deferred.
 *
 * @code
 * struct tevent_req *computation_send(TALLOC_CTX *mem_ctx,
 *                                     struct tevent_context *ev)
 * {
 *     struct tevent_req *req, *subreq;
 *     struct computation_state *state;
 *     req = tevent_req_create(mem_ctx, &state, struct computation_state);
 *     if (req == NULL) {
 *         return NULL;
 *     }
 *     subreq = subcomputation_send(state, ev);
 *     if (tevent_req_nomem(subreq, req)) {
 *         return tevent_req_post(req, ev);
 *     }
 *     tevent_req_set_callback(subreq, computation_done, req);
 *     return req;
 * }
 * @endcode
 *
 * @param[in]  req      The finished request.
 *
 * @param[in]  ev       The tevent_context for the immediate event.
 *
 * @return              The given request will be returned.
 */
struct tevent_req *tevent_req_post(struct tevent_req *req,
				   struct tevent_context *ev);

/**
 * @brief Finish multiple requests within one function
 *
 * Normally tevent_req_notify_callback() and all wrappers
 * (e.g. tevent_req_done() and tevent_req_error())
 * need to be the last thing an event handler should call.
 * This is because the callback is likely to destroy the
 * context of the current function.
 *
 * If a function wants to notify more than one caller,
 * it is dangerous if it just triggers multiple callbacks
 * in a row. With tevent_req_defer_callback() it is possible
 * to set an event context that will be used to defer the callback
 * via an immediate event (similar to tevent_req_post()).
 *
 * @code
 * struct complete_state {
 *       struct tevent_context *ev;
 *
 *       struct tevent_req **reqs;
 * };
 *
 * void complete(struct complete_state *state)
 * {
 *       size_t i, c = talloc_array_length(state->reqs);
 *
 *       for (i=0; i < c; i++) {
 *            tevent_req_defer_callback(state->reqs[i], state->ev);
 *            tevent_req_done(state->reqs[i]);
 *       }
 * }
 * @endcode
 *
 * @param[in]  req      The finished request.
 *
 * @param[in]  ev       The tevent_context for the immediate event.
 *
 * @return              The given request will be returned.
 */
void tevent_req_defer_callback(struct tevent_req *req,
			       struct tevent_context *ev);

/**
 * @brief Check if the given request is still in progress.
 *
 * It is typically used by sync wrapper functions.
 *
 * @param[in]  req      The request to poll.
 *
 * @return              The boolean form of "is in progress".
 */
bool tevent_req_is_in_progress(struct tevent_req *req);

/**
 * @brief Actively poll for the given request to finish.
 *
 * This function is typically used by sync wrapper functions.
 *
 * @param[in]  req      The request to poll.
 *
 * @param[in]  ev       The tevent_context to be used.
 *
 * @return              On success true is returned. If a critical error has
 *                      happened in the tevent loop layer false is returned.
 *                      This is not the return value of the given request!
 *
 * @note This should only be used if the given tevent context was created by the
 * caller, to avoid event loop nesting.
 *
 * @code
 * req = tstream_writev_queue_send(mem_ctx,
 *                                 ev_ctx,
 *                                 tstream,
 *                                 send_queue,
 *                                 iov, 2);
 * ok = tevent_req_poll(req, tctx->ev);
 * rc = tstream_writev_queue_recv(req, &sys_errno);
 * TALLOC_FREE(req);
 * @endcode
 */
bool tevent_req_poll(struct tevent_req *req,
		     struct tevent_context *ev);

/**
 * @brief Get the tevent request state and the actual error set by
 * tevent_req_error.
 *
 * @code
 * int computation_recv(struct tevent_req *req, uint64_t *perr)
 * {
 *     enum tevent_req_state state;
 *     uint64_t err;
 *     if (tevent_req_is_error(req, &state, &err)) {
 *         *perr = err;
 *         return -1;
 *     }
 *     return 0;
 * }
 * @endcode
 *
 * @param[in]  req      The tevent request to get the error from.
 *
 * @param[out] state    A pointer to store the tevent request error state.
 *
 * @param[out] error    A pointer to store the error set by tevent_req_error().
 *
 * @return              True if the function could set error and state, false
 *                      otherwise.
 *
 * @see tevent_req_error()
 */
bool tevent_req_is_error(struct tevent_req *req,
			 enum tevent_req_state *state,
			 uint64_t *error);

/**
 * @brief Use as the last action of a _recv() function.
 *
 * This function destroys the attached private data.
 *
 * @param[in]  req      The finished request.
 */
void tevent_req_received(struct tevent_req *req);

/**
 * @brief Create a tevent subrequest at a given time.
 *
 * The idea is that always the same syntax for tevent requests.
 *
 * @param[in]  mem_ctx  The talloc memory context to use.
 *
 * @param[in]  ev       The event handle to setup the request.
 *
 * @param[in]  wakeup_time The time to wakeup and execute the request.
 *
 * @return              The new subrequest, NULL on error.
 *
 * Example:
 * @code
 *   static void my_callback_wakeup_done(tevent_req *subreq)
 *   {
 *     struct tevent_req *req = tevent_req_callback_data(subreq,
 *                              struct tevent_req);
 *     bool ok;
 *
 *     ok = tevent_wakeup_recv(subreq);
 *     TALLOC_FREE(subreq);
 *     if (!ok) {
 *         tevent_req_error(req, -1);
 *         return;
 *     }
 *     ...
 *   }
 * @endcode
 *
 * @code
 *   subreq = tevent_wakeup_send(mem_ctx, ev, wakeup_time);
 *   if (tevent_req_nomem(subreq, req)) {
 *     return false;
 *   }
 *   tevent_set_callback(subreq, my_callback_wakeup_done, req);
 * @endcode
 *
 * @see tevent_wakeup_recv()
 */
struct tevent_req *tevent_wakeup_send(TALLOC_CTX *mem_ctx,
				      struct tevent_context *ev,
				      struct timeval wakeup_time);

/**
 * @brief Check if the wakeup has been correctly executed.
 *
 * This function needs to be called in the callback function set after calling
 * tevent_wakeup_send().
 *
 * @param[in]  req      The tevent request to check.
 *
 * @return              True on success, false otherwise.
 *
 * @see tevent_wakeup_recv()
 */
bool tevent_wakeup_recv(struct tevent_req *req);

/* @} */

/**
 * @defgroup tevent_helpers The tevent helper functiions
 * @ingroup tevent
 *
 * @todo description
 *
 * @{
 */

/**
 * @brief Compare two timeval values.
 *
 * @param[in]  tv1      The first timeval value to compare.
 *
 * @param[in]  tv2      The second timeval value to compare.
 *
 * @return              0 if they are equal.
 *                      1 if the first time is greater than the second.
 *                      -1 if the first time is smaller than the second.
 */
int tevent_timeval_compare(const struct timeval *tv1,
			   const struct timeval *tv2);

/**
 * @brief Get a zero timval value.
 *
 * @return              A zero timval value.
 */
struct timeval tevent_timeval_zero(void);

/**
 * @brief Get a timeval value for the current time.
 *
 * @return              A timval value with the current time.
 */
struct timeval tevent_timeval_current(void);

/**
 * @brief Get a timeval structure with the given values.
 *
 * @param[in]  secs     The seconds to set.
 *
 * @param[in]  usecs    The microseconds to set.
 *
 * @return              A timeval structure with the given values.
 */
struct timeval tevent_timeval_set(uint32_t secs, uint32_t usecs);

/**
 * @brief Get the difference between two timeval values.
 *
 * @param[in]  tv1      The first timeval.
 *
 * @param[in]  tv2      The second timeval.
 *
 * @return              A timeval structure with the difference between the
 *                      first and the second value.
 */
struct timeval tevent_timeval_until(const struct timeval *tv1,
				    const struct timeval *tv2);

/**
 * @brief Check if a given timeval structure is zero.
 *
 * @param[in]  tv       The timeval to check if it is zero.
 *
 * @return              True if it is zero, false otherwise.
 */
bool tevent_timeval_is_zero(const struct timeval *tv);

/**
 * @brief Add the given amount of time to a timeval structure.
 *
 * @param[in]  tv        The timeval structure to add the time.
 *
 * @param[in]  secs      The seconds to add to the timeval.
 *
 * @param[in]  usecs     The microseconds to add to the timeval.
 *
 * @return               The timeval structure with the new time.
 */
struct timeval tevent_timeval_add(const struct timeval *tv, uint32_t secs,
				  uint32_t usecs);

/**
 * @brief Get a timeval in the future with a specified offset from now.
 *
 * @param[in]  secs     The seconds of the offset from now.
 *
 * @param[in]  usecs    The microseconds of the offset from now.
 *
 * @return              A timval with the given offset in the future.
 */
struct timeval tevent_timeval_current_ofs(uint32_t secs, uint32_t usecs);

/* @} */


/**
 * @defgroup tevent_queue The tevent queue functions
 * @ingroup tevent
 *
 * A tevent_queue is used to queue up async requests that must be
 * serialized. For example writing buffers into a socket must be
 * serialized. Writing a large lump of data into a socket can require
 * multiple write(2) or send(2) system calls. If more than one async
 * request is outstanding to write large buffers into a socket, every
 * request must individually be completed before the next one begins,
 * even if multiple syscalls are required.
 *
 * Take a look at @ref tevent_queue_tutorial for more details.
 * @{
 */

struct tevent_queue;
struct tevent_queue_entry;

#ifdef DOXYGEN
/**
 * @brief Create and start a tevent queue.
 *
 * @param[in]  mem_ctx  The talloc memory context to allocate the queue.
 *
 * @param[in]  name     The name to use to identify the queue.
 *
 * @return              An allocated tevent queue on success, NULL on error.
 *
 * @see tevent_queue_start()
 * @see tevent_queue_stop()
 */
struct tevent_queue *tevent_queue_create(TALLOC_CTX *mem_ctx,
					 const char *name);
#else
struct tevent_queue *_tevent_queue_create(TALLOC_CTX *mem_ctx,
					  const char *name,
					  const char *location);

#define tevent_queue_create(_mem_ctx, _name) \
	_tevent_queue_create((_mem_ctx), (_name), __location__)
#endif

/**
 * @brief A callback trigger function run by the queue.
 *
 * @param[in]  req      The tevent request the trigger function is executed on.
 *
 * @param[in]  private_data The private data pointer specified by
 *                          tevent_queue_add().
 *
 * @see tevent_queue_add()
 * @see tevent_queue_add_entry()
 * @see tevent_queue_add_optimize_empty()
 */
typedef void (*tevent_queue_trigger_fn_t)(struct tevent_req *req,
					  void *private_data);

/**
 * @brief Add a tevent request to the queue.
 *
 * @param[in]  queue    The queue to add the request.
 *
 * @param[in]  ev       The event handle to use for the request.
 *
 * @param[in]  req      The tevent request to add to the queue.
 *
 * @param[in]  trigger  The function triggered by the queue when the request
 *                      is called. Since tevent 0.9.14 it's possible to
 *                      pass NULL, in order to just add a "blocker" to the
 *                      queue.
 *
 * @param[in]  private_data The private data passed to the trigger function.
 *
 * @return              True if the request has been successfully added, false
 *                      otherwise.
 */
bool tevent_queue_add(struct tevent_queue *queue,
		      struct tevent_context *ev,
		      struct tevent_req *req,
		      tevent_queue_trigger_fn_t trigger,
		      void *private_data);

/**
 * @brief Add a tevent request to the queue.
 *
 * The request can be removed from the queue by calling talloc_free()
 * (or a similar function) on the returned queue entry. This
 * is the only difference to tevent_queue_add().
 *
 * @param[in]  queue    The queue to add the request.
 *
 * @param[in]  ev       The event handle to use for the request.
 *
 * @param[in]  req      The tevent request to add to the queue.
 *
 * @param[in]  trigger  The function triggered by the queue when the request
 *                      is called. Since tevent 0.9.14 it's possible to
 *                      pass NULL, in order to just add a "blocker" to the
 *                      queue.
 *
 * @param[in]  private_data The private data passed to the trigger function.
 *
 * @return              a pointer to the tevent_queue_entry if the request
 *                      has been successfully added, NULL otherwise.
 *
 * @see tevent_queue_add()
 * @see tevent_queue_add_optimize_empty()
 */
struct tevent_queue_entry *tevent_queue_add_entry(
					struct tevent_queue *queue,
					struct tevent_context *ev,
					struct tevent_req *req,
					tevent_queue_trigger_fn_t trigger,
					void *private_data);

/**
 * @brief Add a tevent request to the queue using a possible optimization.
 *
 * This tries to optimize for the empty queue case and may calls
 * the trigger function directly. This is the only difference compared
 * to tevent_queue_add_entry().
 *
 * The caller needs to be prepared that the trigger function has
 * already called tevent_req_notify_callback(), tevent_req_error(),
 * tevent_req_done() or a similar function.
 *
 * The request can be removed from the queue by calling talloc_free()
 * (or a similar function) on the returned queue entry.
 *
 * @param[in]  queue    The queue to add the request.
 *
 * @param[in]  ev       The event handle to use for the request.
 *
 * @param[in]  req      The tevent request to add to the queue.
 *
 * @param[in]  trigger  The function triggered by the queue when the request
 *                      is called. Since tevent 0.9.14 it's possible to
 *                      pass NULL, in order to just add a "blocker" to the
 *                      queue.
 *
 * @param[in]  private_data The private data passed to the trigger function.
 *
 * @return              a pointer to the tevent_queue_entry if the request
 *                      has been successfully added, NULL otherwise.
 *
 * @see tevent_queue_add()
 * @see tevent_queue_add_entry()
 */
struct tevent_queue_entry *tevent_queue_add_optimize_empty(
					struct tevent_queue *queue,
					struct tevent_context *ev,
					struct tevent_req *req,
					tevent_queue_trigger_fn_t trigger,
					void *private_data);

/**
 * @brief Start a tevent queue.
 *
 * The queue is started by default.
 *
 * @param[in]  queue    The queue to start.
 */
void tevent_queue_start(struct tevent_queue *queue);

/**
 * @brief Stop a tevent queue.
 *
 * The queue is started by default.
 *
 * @param[in]  queue    The queue to stop.
 */
void tevent_queue_stop(struct tevent_queue *queue);

/**
 * @brief Get the length of the queue.
 *
 * @param[in]  queue    The queue to get the length from.
 *
 * @return              The number of elements.
 */
size_t tevent_queue_length(struct tevent_queue *queue);

/**
 * @brief Is the tevent queue running.
 *
 * The queue is started by default.
 *
 * @param[in]  queue    The queue.
 *
 * @return              Wether the queue is running or not..
 */
bool tevent_queue_running(struct tevent_queue *queue);

typedef int (*tevent_nesting_hook)(struct tevent_context *ev,
				   void *private_data,
				   uint32_t level,
				   bool begin,
				   void *stack_ptr,
				   const char *location);
#ifdef TEVENT_DEPRECATED
#ifndef _DEPRECATED_
#if (__GNUC__ >= 3) && (__GNUC_MINOR__ >= 1 )
#define _DEPRECATED_ __attribute__ ((deprecated))
#else
#define _DEPRECATED_
#endif
#endif
void tevent_loop_allow_nesting(struct tevent_context *ev) _DEPRECATED_;
void tevent_loop_set_nesting_hook(struct tevent_context *ev,
				  tevent_nesting_hook hook,
				  void *private_data) _DEPRECATED_;
int _tevent_loop_until(struct tevent_context *ev,
		       bool (*finished)(void *private_data),
		       void *private_data,
		       const char *location) _DEPRECATED_;
#define tevent_loop_until(ev, finished, private_data) \
	_tevent_loop_until(ev, finished, private_data, __location__)
#endif

int tevent_re_initialise(struct tevent_context *ev);

/* @} */

/**
 * @defgroup tevent_ops The tevent operation functions
 * @ingroup tevent
 *
 * The following structure and registration functions are exclusively
 * needed for people writing and pluggin a different event engine.
 * There is nothing useful for normal tevent user in here.
 * @{
 */

struct tevent_ops {
	/* context init */
	int (*context_init)(struct tevent_context *ev);

	/* fd_event functions */
	struct tevent_fd *(*add_fd)(struct tevent_context *ev,
				    TALLOC_CTX *mem_ctx,
				    int fd, uint16_t flags,
				    tevent_fd_handler_t handler,
				    void *private_data,
				    const char *handler_name,
				    const char *location);
	void (*set_fd_close_fn)(struct tevent_fd *fde,
				tevent_fd_close_fn_t close_fn);
	uint16_t (*get_fd_flags)(struct tevent_fd *fde);
	void (*set_fd_flags)(struct tevent_fd *fde, uint16_t flags);

	/* timed_event functions */
	struct tevent_timer *(*add_timer)(struct tevent_context *ev,
					  TALLOC_CTX *mem_ctx,
					  struct timeval next_event,
					  tevent_timer_handler_t handler,
					  void *private_data,
					  const char *handler_name,
					  const char *location);

	/* immediate event functions */
	void (*schedule_immediate)(struct tevent_immediate *im,
				   struct tevent_context *ev,
				   tevent_immediate_handler_t handler,
				   void *private_data,
				   const char *handler_name,
				   const char *location);

	/* signal functions */
	struct tevent_signal *(*add_signal)(struct tevent_context *ev,
					    TALLOC_CTX *mem_ctx,
					    int signum, int sa_flags,
					    tevent_signal_handler_t handler,
					    void *private_data,
					    const char *handler_name,
					    const char *location);

	/* loop functions */
	int (*loop_once)(struct tevent_context *ev, const char *location);
	int (*loop_wait)(struct tevent_context *ev, const char *location);
};

bool tevent_register_backend(const char *name, const struct tevent_ops *ops);

/* @} */

/**
 * @defgroup tevent_compat The tevent compatibility functions
 * @ingroup tevent
 *
 * The following definitions are usueful only for compatibility with the
 * implementation originally developed within the samba4 code and will be
 * soon removed. Please NEVER use in new code.
 *
 * @todo Ignore it?
 *
 * @{
 */

#ifdef TEVENT_COMPAT_DEFINES

#define event_context	tevent_context
#define event_ops	tevent_ops
#define fd_event	tevent_fd
#define timed_event	tevent_timer
#define signal_event	tevent_signal

#define event_fd_handler_t	tevent_fd_handler_t
#define event_timed_handler_t	tevent_timer_handler_t
#define event_signal_handler_t	tevent_signal_handler_t

#define event_context_init(mem_ctx) \
	tevent_context_init(mem_ctx)

#define event_context_init_byname(mem_ctx, name) \
	tevent_context_init_byname(mem_ctx, name)

#define event_backend_list(mem_ctx) \
	tevent_backend_list(mem_ctx)

#define event_set_default_backend(backend) \
	tevent_set_default_backend(backend)

#define event_add_fd(ev, mem_ctx, fd, flags, handler, private_data) \
	tevent_add_fd(ev, mem_ctx, fd, flags, handler, private_data)

#define event_add_timed(ev, mem_ctx, next_event, handler, private_data) \
	tevent_add_timer(ev, mem_ctx, next_event, handler, private_data)

#define event_add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data) \
	tevent_add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data)

#define event_loop_once(ev) \
	tevent_loop_once(ev)

#define event_loop_wait(ev) \
	tevent_loop_wait(ev)

#define event_get_fd_flags(fde) \
	tevent_fd_get_flags(fde)

#define event_set_fd_flags(fde, flags) \
	tevent_fd_set_flags(fde, flags)

#define EVENT_FD_READ		TEVENT_FD_READ
#define EVENT_FD_WRITE		TEVENT_FD_WRITE

#define EVENT_FD_WRITEABLE(fde) \
	TEVENT_FD_WRITEABLE(fde)

#define EVENT_FD_READABLE(fde) \
	TEVENT_FD_READABLE(fde)

#define EVENT_FD_NOT_WRITEABLE(fde) \
	TEVENT_FD_NOT_WRITEABLE(fde)

#define EVENT_FD_NOT_READABLE(fde) \
	TEVENT_FD_NOT_READABLE(fde)

#define ev_debug_level		tevent_debug_level

#define EV_DEBUG_FATAL		TEVENT_DEBUG_FATAL
#define EV_DEBUG_ERROR		TEVENT_DEBUG_ERROR
#define EV_DEBUG_WARNING	TEVENT_DEBUG_WARNING
#define EV_DEBUG_TRACE		TEVENT_DEBUG_TRACE

#define ev_set_debug(ev, debug, context) \
	tevent_set_debug(ev, debug, context)

#define ev_set_debug_stderr(_ev) tevent_set_debug_stderr(ev)

#endif /* TEVENT_COMPAT_DEFINES */

/* @} */

#endif /* __TEVENT_H__ */