summaryrefslogtreecommitdiff
path: root/ace/Synch.h
blob: 6a7d09d15482ccf8b180565349f2947d93ace472 (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
/* -*- C++ -*- */

//=============================================================================
/**
 *  @file    Synch.h
 *
 *  $Id$
 *
 *   Wrapper Facades for various synchronization mechanisms.
 *
 *  @author Douglas C. Schmidt <schmidt@cs.wustl.edu>
 */
//=============================================================================

#ifndef ACE_SYNCH_H
#define ACE_SYNCH_H
#include "ace/pre.h"

#include "ace/ACE.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

// Forward declarations.
/**
 * @class ACE_Time_Value;
 template <class ACE_COND_MUTEX> class ACE_Condition;
 */
class ACE_Time_Value;

/**
 * @class ACE_Lock
 *
 * @brief This is the abstract base class that contains the uniform
 * locking API that is supported by all the ACE synchronization
 * mechanisms.
 *
 * This class is typically used in conjunction with the
 * <ACE_Lock_Adapter> in order to provide a polymorphic
 * interface to the ACE synchronization mechanisms (e.g.,
 * <ACE_Mutex>, <ACE_Semaphore>, <ACE_RW_Mutex>, etc).  Note that
 * the reason that all of ACE doesn't use polymorphic locks is
 * that (1) they add ~20% extra overhead for virtual function
 * calls and (2) objects with virtual functions can't be placed
 * into shared memory.
 */
class ACE_Export ACE_Lock
{
public:
  /// CE needs a default ctor here.
  ACE_Lock (void);

  /// Noop virtual destructor
  virtual ~ACE_Lock (void);

  /**
   * Explicitly destroy the lock.  Note that only one thread should
   * call this method since it doesn't protect against race
   * conditions.
   */
  virtual int remove (void) = 0;

  /// Block the thread until the lock is acquired.  Returns -1 on
  /// failure.
  virtual int acquire (void) = 0;

  /**
   * Conditionally acquire the lock (i.e., won't block).  Returns -1
   * on failure.  If we "failed" because someone else already had the
   * lock, <errno> is set to <EBUSY>.
   */
  virtual int tryacquire (void) = 0;

  /// Release the lock.  Returns -1 on failure.
  virtual int release (void) = 0;

  /**
   * Block until the thread acquires a read lock.  If the locking
   * mechanism doesn't support read locks then this just calls
   * <acquire>.  Returns -1 on failure.
   */
  virtual int acquire_read (void) = 0;

  /**
   * Block until the thread acquires a write lock.  If the locking
   * mechanism doesn't support read locks then this just calls
   * <acquire>.  Returns -1 on failure.
   */
  virtual int acquire_write (void) = 0;

  /**
   * Conditionally acquire a read lock.  If the locking mechanism
   * doesn't support read locks then this just calls <acquire>.
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  virtual int tryacquire_read (void) = 0;

  /**
   * Conditionally acquire a write lock.  If the locking mechanism
   * doesn't support read locks then this just calls <acquire>.
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  virtual int tryacquire_write (void) = 0;

  /**
   * Conditionally try to upgrade a lock held for read to a write lock.
   * If the locking mechanism doesn't support read locks then this just
   * calls <acquire>. Returns 0 on success, -1 on failure.
   */
  virtual int tryacquire_write_upgrade (void) = 0;
};

/**
 * @class ACE_Adaptive_Lock
 *
 * @brief An adaptive general locking class that defers the decision of
 * lock type to run time.
 *
 * This class, as ACE_Lock, provide a set of general locking APIs.
 * However, it defers our decision of what kind of lock to use
 * to the run time and delegates all locking operations to the actual
 * lock.  Users must define a constructor in their subclass to
 * initialize <lock_>.
 */
class ACE_Export ACE_Adaptive_Lock : public ACE_Lock
{
public:
  /// You must also override the destructor function to match with how
  /// you construct the underneath <lock_>.
  virtual ~ACE_Adaptive_Lock (void);

  // = Lock/unlock operations.

  virtual int remove (void);
  virtual int acquire (void);
  virtual int tryacquire (void);
  virtual int release (void);
  virtual int acquire_read (void);
  virtual int acquire_write (void);
  virtual int tryacquire_read (void);
  virtual int tryacquire_write (void);
  virtual int tryacquire_write_upgrade (void);
  void dump (void) const;

protected:
  /**
   * Create and initialize create the actual lcok used in the class.
   * The default constructor simply set the <lock_> to 0 (null).  You
   * must overwrite this method for this class to work.
   */
  ACE_Adaptive_Lock (void);

  ACE_Lock *lock_;
};

/**
 * @class ACE_Semaphore
 *
 * @brief Wrapper for Dijkstra style general semaphores.
 */
class ACE_Export ACE_Semaphore
{
public:
  // = Initialization and termination.
  /// Initialize the semaphore, with initial value of "count".
  ACE_Semaphore (u_int count = 1, // By default make this unlocked.
                 int type = USYNC_THREAD,
                 const ACE_TCHAR *name = 0,
                 void * = 0,
                 int max = 0x7fffffff);

  /// Implicitly destroy the semaphore.
  ~ACE_Semaphore (void);

  /**
   * Explicitly destroy the semaphore.  Note that only one thread
   * should call this method since it doesn't protect against race
   * conditions.
   */
  int remove (void);

  /// Block the thread until the semaphore count becomes
  /// greater than 0, then decrement it.
  int acquire (void);

  /**
   * Block the thread until the semaphore count becomes greater than 0
   * (at which point it is decremented) or until <tv> times out (in
   * which case -1 is returned and <errno> == <ETIME>).  Note that <tv>
   * is assumed to be in "absolute" rather than "relative" time.  The
   * value of <tv> is updated upon return to show the actual
   * (absolute) acquisition time.
   *
   * NOTE: Solaris threads do not support timed semaphores.
   * Therefore, if you're running on Solaris you might want to
   * consider using the ACE POSIX pthreads implementation instead,
   * which can be enabled by compiling ACE with
   * -DACE_HAS_PTHREADS, rather than -DACE_HAS_STHREADS or
   * -DACE_HAS_POSIX_SEM. */  
  int acquire (ACE_Time_Value &tv);

  /**
   * If <tv> == 0 then call <acquire()> directly.  Otherwise, Block
   * the thread until the semaphore count becomes greater than 0 
   * (at which point it is decremented) or until <tv> times out (in
   * which case -1 is returned and <errno> == <ETIME>).  Note that
   * <*tv> is assumed to be in "absolute" rather than "relative" time.
   * The value of <*tv> is updated upon return to show the actual
   * (absolute) acquisition time. 
   *
   * NOTE: Solaris threads do not support timed semaphores.
   * Therefore, if you're running on Solaris you might want to
   * consider using the ACE POSIX pthreads implementation instead,
   * which can be enabled by compiling ACE with
   * -DACE_HAS_PTHREADS, rather than -DACE_HAS_STHREADS or 
   * -DACE_HAS_POSIX_SEM.  */
  int acquire (ACE_Time_Value *tv);

  /**
   * Conditionally decrement the semaphore if count is greater than 0
   * (i.e., won't block).  Returns -1 on failure.  If we "failed"
   * because someone else already had the lock, <errno> is set to
   * <EBUSY>.
   */
  int tryacquire (void);

  /// Increment the semaphore by 1, potentially unblocking a waiting
  /// thread.
  int release (void);

  /// Increment the semaphore by <release_count>, potentially
  /// unblocking waiting threads.
  int release (size_t release_count);

  /**
   * Acquire semaphore ownership.  This calls <acquire> and is only
   * here to make the <ACE_Semaphore> interface consistent with the
   * other synchronization APIs.
   */
  int acquire_read (void);

  /**
   * Acquire semaphore ownership.  This calls <acquire> and is only
   * here to make the <ACE_Semaphore> interface consistent with the
   * other synchronization APIs.
   */
  int acquire_write (void);

  /**
   * Conditionally acquire semaphore (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the <ACE_Semaphore>
   * interface consistent with the other synchronization APIs.
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_read (void);

  /**
   * Conditionally acquire semaphore (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the <ACE_Semaphore>
   * interface consistent with the other synchronization APIs.
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_write (void);

  /**
   * This is only here to make the <ACE_Semaphore>
   * interface consistent with the other synchronization APIs.
   * Assumes the caller has already acquired the semaphore using one of
   * the above calls, and returns 0 (success) always.
   */
  int tryacquire_write_upgrade (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

  /// Return the underlying lock.
  const ACE_sema_t &lock (void) const;

protected:
  ACE_sema_t semaphore_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Semaphore &);
  ACE_Semaphore (const ACE_Semaphore &);
};

/**
 * @class ACE_Null_Semaphore
 *
 * @brief Implement a do nothing <ACE_Semaphore>, i.e., all the methods are
 * no ops.
 *
 * Although the methods are no-ops, the return values are different for
 * the blocking as opposed to timed acquires.  The blocking version of
 * acquire() is often used to serialize access to a critical section,
 * whereas the timed version is often used to wait for another thread
 * to update some condition or change some shared state.  When using an
 * ACE_Null_Semaphore, however, there's no other thread involved to
 * change a state or condition (otherwise, a null semaphore would be
 * inappropriate).  Returning an error value signifies that the
 * state or condition has not been (and can't be) changed, which is
 * consistent with the behavior of the threaded case where a timeout
 * occurs before the state or condition is changed.
 */
class ACE_Export ACE_Null_Semaphore
{
public:
  ACE_Null_Semaphore (u_int count = 1, // By default make this unlocked.
                       int type = USYNC_THREAD,
                       const ACE_TCHAR *name = 0,
                       void * = 0,
                       int max = 0x7fffffff);
  ~ACE_Null_Semaphore (void);
  /// Return 0.
  int remove (void);

  /// Return 0.
  int acquire (void);

  /// Return -1 with <errno> == <ETIME>.
  int acquire (ACE_Time_Value &);

  /// Return -1 with <errno> == <ETIME>.
  int acquire (ACE_Time_Value *);

  /// Return 0.
  int tryacquire (void);

  /// Return 0.
  int release (void);

  /// Return 0.
  int release (size_t);

  /// Return 0.
  int acquire_write (void);

  /// Return 0.
  int tryacquire_write (void);

  /// Return 0.
  int tryacquire_write_upgrade (void);

  /// Return 0.
  int acquire_read (void);

  /// Return 0.
  int tryacquire_read (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};

/**
 * @class ACE_RW_Mutex
 *
 * @brief Wrapper for readers/writer locks.
 *
 * These are most useful for applications that have many more
 * parallel readers than writers...
 */
class ACE_Export ACE_RW_Mutex
{
public:
  /// Initialize a readers/writer lock.
  ACE_RW_Mutex (int type = USYNC_THREAD,
                const ACE_TCHAR *name = 0,
                void *arg = 0);

  /// Implicitly destroy a readers/writer lock
  ~ACE_RW_Mutex (void);

  /**
   * Explicitly destroy a readers/writer lock.  Note that only one
   * thread should call this method since it doesn't protect against
   * race conditions.
   */
  int remove (void);

  /// Acquire a read lock, but block if a writer hold the lock.
  int acquire_read (void);

  /// Acquire a write lock, but block if any readers or a
  /// writer hold the lock.
  int acquire_write (void);

  /**
   * Conditionally acquire a read lock (i.e., won't block).  Returns
   * -1 on failure.  If we "failed" because someone else already had
   * the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_read (void);

  /// Conditionally acquire a write lock (i.e., won't block).
  int tryacquire_write (void);

  /**
   * Conditionally upgrade a read lock to a write lock.  This only
   * works if there are no other readers present, in which case the
   * method returns 0.  Otherwise, the method returns -1 and sets
   * <errno> to <EBUSY>.  Note that the caller of this method *must*
   * already possess this lock as a read lock (but this condition is
   * not checked by the current implementation).
   */
  int tryacquire_write_upgrade (void);

  /**
   * Note, for interface uniformity with other synchronization
   * wrappers we include the <acquire> method.  This is implemented as
   * a write-lock to safe...
   */
  int acquire (void);

  /**
   * Note, for interface uniformity with other synchronization
   * wrappers we include the <tryacquire> method.  This is implemented
   * as a write-lock to be safe...  Returns -1 on failure.  If we
   * "failed" because someone else already had the lock, <errno> is
   * set to <EBUSY>.
   */
  int tryacquire (void);

  /// Unlock a readers/writer lock.
  int release (void);

  /// Return the underlying lock.
  const ACE_rwlock_t &lock (void) const;

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  /// Readers/writer lock.
  ACE_rwlock_t lock_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_RW_Mutex &);
  ACE_RW_Mutex (const ACE_RW_Mutex &);
};

/**
 * @class ACE_Mutex
 *
 * @brief <ACE_Mutex> wrapper (valid in same process or across
 * processes (depending on TYPE flag)).
 */
class ACE_Export ACE_Mutex
{
public:
  /// Initialize the mutex.
  ACE_Mutex (int type = USYNC_THREAD,
             const ACE_TCHAR *name = 0,
             ACE_mutexattr_t *arg = 0);

  /// Implicitly destroy the mutex.
  ~ACE_Mutex (void);

  /**
   * Explicitly destroy the mutex.  Note that only one thread should
   * call this method since it doesn't protect against race
   * conditions.
   */
  int remove (void);

  /// Acquire lock ownership (wait on queue if necessary).
  int acquire (void);

  /**
   * Block the thread until the mutex is acquired or <tv> times out,
   * in which case -1 is returned and <errno> == <ETIME>.  Note that
   * <tv> is assumed  to be in "absolute" rather than "relative" time.  
   * The value of <tv> is updated upon return to show the actual 
   * (absolute) acquisition time.
   */
  int acquire (ACE_Time_Value &tv);

  /**
   * If <tv> == 0 then call <acquire()> directly.  Otherwise, block
   * the thread until the mutex is acquired or <tv> times out, in
   * which case -1 is returned and <errno> == <ETIME>.  Note that
   * <*tv> is assumed to be in "absolute" rather than "relative" time.
   * The value of <*tv> is updated upon return to show the actual
   * (absolute) acquisition time.  */
  int acquire (ACE_Time_Value *tv);

  /**
   * Conditionally acquire lock (i.e., don't wait on queue).  Returns
   * -1 on failure.  If we "failed" because someone else already had
   * the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire (void);

  /// Release lock and unblock a thread at head of queue.
  int release (void);

  /**
   * Acquire mutex ownership.  This calls <acquire> and is only
   * here to make the <ACE_Mutex> interface consistent with the
   * other synchronization APIs.
   */
  int acquire_read (void);

  /**
   * Acquire mutex ownership.  This calls <acquire> and is only
   * here to make the <ACE_Mutex> interface consistent with the
   * other synchronization APIs.
   */
  int acquire_write (void);

  /**
   * Conditionally acquire mutex (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the <ACE_Mutex> interface
   * consistent with the other synchronization APIs.  Returns -1 on
   * failure.  If we "failed" because someone else already had the
   * lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_read (void);

  /**
   * Conditionally acquire mutex (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the <ACE_Mutex> interface
   * consistent with the other synchronization APIs.  Returns -1 on
   * failure.  If we "failed" because someone else already had the
   * lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_write (void);

  /**
   * This is only here for consistency with the other synchronization
   * APIs and usability with Lock adapters. Assumes the caller already has
   * acquired the mutex and returns 0 in all cases.
   */
  int tryacquire_write_upgrade (void);

  /// Return the underlying mutex.
  const ACE_mutex_t &lock (void) const;

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

  // = This should be protected but some C++ compilers complain...
public:
#if defined (CHORUS) || defined(ACE_HAS_PTHREADS) || defined(ACE_HAS_STHREADS)
  /// This lock resides in shared memory.
  ACE_mutex_t *process_lock_;

  /**
   * Remember the name of the mutex if we created it so we can unlink
   * it when we go away (only the actor that initialized the memory
   * can destroy it).
   */
  const ACE_TCHAR *lockname_;
#endif /* CHORUS || ACE_HAS_PTHREADS */

  /// Mutex type supported by the OS.
  ACE_mutex_t lock_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Mutex &);
  ACE_Mutex (const ACE_Mutex &);
};

/**
 * @class ACE_Null_Barrier
 *
 * @brief Implements "NULL barrier synchronization".
 */
class ACE_Export ACE_Null_Barrier
{
public:
  /// Initialize the barrier to synchronize <count> threads.
  ACE_Null_Barrier (u_int,
                    const char * = 0,
                    void * = 0);

  /// Default dtor.
  ~ACE_Null_Barrier (void);

  /// Block the caller until all <count> threads have called <wait> and
  /// then allow all the caller threads to continue in parallel.
  int wait (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Null_Barrier &);
  ACE_Null_Barrier (const ACE_Null_Barrier &);
};

/**
 * @class ACE_Null_Mutex
 *
 * @brief Implement a do nothing <ACE_Mutex>, i.e., all the methods are
 * no ops.
 */
class ACE_Export ACE_Null_Mutex
{
public:
  ACE_Null_Mutex (const ACE_TCHAR * = 0);
  ~ACE_Null_Mutex (void);
  /// Return 0.
  int remove (void);

  /// Return 0.
  int acquire (void);

  /// Return -1 with <errno> == <ETIME>.
  int acquire (ACE_Time_Value &timeout);

  /// Return -1 with <errno> == <ETIME>.
  int acquire (ACE_Time_Value *timeout);

  /// Return 0.
  int tryacquire (void);

  /// Return 0.
  int release (void);

  /// Return 0.
  int acquire_write (void);

  /// Return 0.
  int tryacquire_write (void);

  /// Return 0.
  int tryacquire_write_upgrade (void);

  /// Return 0.
  int acquire_read (void);

  /// Return 0.
  int tryacquire_read (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};

class ACE_Export ACE_Noop_Token : public ACE_Null_Mutex
{
public:
  int renew (int = 0, ACE_Time_Value * =0);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};

/**
 * @class ACE_Null_Condition
 *
 * @brief Implement a do nothing <ACE_Condition> variable wrapper,
 * i.e., all methods are no ops.  This class is necessary since
 * some C++ compilers are *very* lame...
 */
class ACE_Export ACE_Null_Condition
{
public:
  ACE_Null_Condition (const ACE_Null_Mutex &m,
                      const ACE_TCHAR * = 0,
                      void * = 0);
  ~ACE_Null_Condition (void);

  /// Returns 0.
  int remove (void);

  /// Returns -1 with <errno> == <ETIME>.
  int wait (ACE_Time_Value * = 0);

  /// Returns 0.
  int signal (void);

  /// Returns 0.
  int broadcast (void);
  ACE_Null_Mutex &mutex (void);

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.

protected:
  ACE_Null_Mutex &mutex_; // Reference to mutex lock.

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Null_Condition &);
  ACE_Null_Condition (const ACE_Null_Condition &);
};

#if defined (ACE_USES_OBSOLETE_GUARD_CLASSES)
/**
 * @class ACE_Null_Mutex_Guard
 *
 * @brief This data structure is meant to be used within a method or
 * function...  It performs automatic aquisition and release of
 * an ACE_Null_Mutex.
 *
 * This class is obsolete and should be replaced by
 * ACE_Guard<ACE_Null_Mutex>.
 */
class ACE_Export ACE_Null_Mutex_Guard
{
public:
  ACE_Null_Mutex_Guard (ACE_Null_Mutex &);
  ~ACE_Null_Mutex_Guard (void);
  int remove (void);
  int locked (void);
  int acquire (void);
  int tryacquire (void);
  int release (void);
  void dump (void) const;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Null_Mutex_Guard &);
  ACE_Null_Mutex_Guard (const ACE_Null_Mutex_Guard &);
};
#endif /* ACE_USES_OBSOLETE_GUARD_CLASSES */

/**
 * @class ACE_TSS_Adapter
 *
 * @brief This class encapsulates a TSS object and its associated
 * C++ destructor function.  It is used by the ACE_TSS...
 * methods (in Synch_T.cpp) in order to allow an extern
 * "C" cleanup routine to be used.  Needed by the "frigging"
 * MVS C++ compiler.
 *
 * Objects of this class are stored in thread specific
 * storage. ts_obj_ points to the "real" object and
 * func_ is a pointer to the C++ cleanup function for ts_obj_.
 */
class ACE_Export ACE_TSS_Adapter
{
public:
  /// Initialize the adapter.
  ACE_TSS_Adapter (void *object, ACE_THR_DEST f);

  /// Default dtor.
  ~ACE_TSS_Adapter (void);

  /// Perform the cleanup operation.
  void cleanup (void);

//private:

  /// The real TS object.
  void *ts_obj_;

  /// The real cleanup routine for ts_obj;
  ACE_THR_DEST func_;
};

/**
 * @class ACE_Event
 *
 * @brief A wrapper around the Win32 event locking mechanism.
 *
 * Portable implementation of an Event mechanism, which is
 * native to Win32, but must be emulated on UNIX.  Note that
 * this only provides global naming and system-scope locking support
 * on Win32 platforms.
 */
class ACE_Export ACE_Event
{
public:
  /// Constructor that creates event.
  ACE_Event (int manual_reset = 0,
             int initial_state = 0,
             int type = USYNC_THREAD,
             const ACE_TCHAR *name = 0,
             void *arg = 0);

  /// Implicitly destroy the event variable.
  ~ACE_Event (void);

  /**
   * Explicitly destroy the event variable.  Note that only one thread
   * should call this method since it doesn't protect against race
   * conditions.
   */
  int remove (void);

  /// Underlying handle to event.
  ACE_event_t handle (void) const;

  /**
   * Set the underlying handle to event. Note that this method assumes
   * ownership of the <handle> and will close it down in <remove>.  If
   * you want the <handle> to stay open when <remove> is called make
   * sure to call <dup> on the <handle> before closing it.  You are
   * responsible for the closing the existing <handle> before
   * overwriting it.
   */
  void handle (ACE_event_t new_handle);

  /**
   * if MANUAL reset
   *    sleep till the event becomes signaled
   *    event remains signaled after wait() completes.
   * else AUTO reset
   *    sleep till the event becomes signaled
   *    event resets wait() completes.
   */
  int wait (void);

  /// Same as wait() above, but this one can be timed
  /// <abstime> is absolute time-of-day.
  int wait (const ACE_Time_Value *abstime);

  /**
   * if MANUAL reset
   *    wake up all waiting threads
   *    set to signaled state
   * else AUTO reset
   *    if no thread is waiting, set to signaled state
   *    if thread(s) are waiting, wake up one waiting thread and
   *    reset event
   */
  int signal (void);

  /**
   * if MANUAL reset
   *    wakeup all waiting threads and
   *    reset event
   * else AUTO reset
   *    wakeup one waiting thread (if present) and
   *    reset event
   */
  int pulse (void);

  /// Set to nonsignaled state.
  int reset (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks
  ACE_ALLOC_HOOK_DECLARE;

protected:
  /// The underlying handle.
  ACE_event_t handle_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent copying.
  ACE_Event (const ACE_Event& event);
  const ACE_Event &operator= (const ACE_Event &rhs);
};

/**
 * @class ACE_Manual_Event
 *
 * @brief Manual Events.
 *
 * Specialization of Event mechanism which wakes up all waiting
 * threads on <signal>.  Note that this only provides
 * global naming and system-scope locking support on Win32 platforms.
 */
class ACE_Export ACE_Manual_Event : public ACE_Event
{
public:
  /// constructor which will create manual event
  ACE_Manual_Event (int initial_state = 0,
                    int type = USYNC_THREAD,
                    const char *name = 0,
                    void *arg = 0);

#if defined (ACE_HAS_WCHAR)
  /// constructor which will create manual event (wchar_t version)
  ACE_Manual_Event (int initial_state,
                    int type,
                    const wchar_t *name,
                    void *arg = 0);
#endif /* ACE_HAS_WCHAR */

  /// Default dtor.
  ~ACE_Manual_Event (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks
  ACE_ALLOC_HOOK_DECLARE;
};

/**
 * @class ACE_Auto_Event
 *
 * @brief Auto Events.
 *
 * Specialization of Event mechanism which wakes up one waiting
 * thread on <signal>.  Note that this only provides
 * global naming and system-scope locking support on Win32 platforms.
 */
class ACE_Export ACE_Auto_Event : public ACE_Event
{
public:
  /// constructor which will create auto event
  ACE_Auto_Event (int initial_state = 0,
                  int type = USYNC_THREAD,
                  const char *name = 0,
                  void *arg = 0);

#if defined (ACE_HAS_WCHAR)
  /// constructor which will create auto event (wchar_t version)
  ACE_Auto_Event (int initial_state,
                  int type,
                  const wchar_t *name,
                  void *arg = 0);
#endif /* ACE_HAS_WCHAR */

  /// Default dtor.
  ~ACE_Auto_Event (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks
  ACE_ALLOC_HOOK_DECLARE;
};

// ACE platform supports some form of threading.
#if !defined (ACE_HAS_THREADS)
/**
 * @class ACE_Barrier
 *
 * @brief This is a no-op to make ACE "syntactically consistent."
 */
class ACE_Barrier
{
public:
  ACE_Barrier (u_int, const ACE_TCHAR * = 0, void * = 0) {}
  ~ACE_Barrier (void) {}
  int wait (void) { ACE_NOTSUP_RETURN (-1); }
  void dump (void) const {}
};
#else
  /**
   * @class ACE_Thread_Mutex
   *
   * @brief ACE_Thread_Mutex wrapper (only valid for threads in the same
   * process).
   *
   * This implementation is optimized for locking threads that are
   * in the same process.  It maps to <CRITICAL_SECTION>s on NT
   * and <ACE_mutex_t> with <type> set to <USYNC_THREAD> on UNIX.
   * ACE_Thread_Mutex is recursive on some platforms (like
   * Win32). However, on most platforms (like Solaris) it is not
   * recursive.  To be totally safe and portable, developers
   * should use <ACE_Recursive_Thread_Mutex> when they need a
   * recursive mutex.
   */
class ACE_Export ACE_Thread_Mutex
{
  friend class ACE_Condition_Thread_Mutex;
public:
  /// Constructor.
  ACE_Thread_Mutex (const ACE_TCHAR *name = 0,
                    ACE_mutexattr_t *attributes = 0);

  /// Implicitly destroy the mutex.
  ~ACE_Thread_Mutex (void);

  /**
   * Explicitly destroy the mutex.  Note that only one thread should
   * call this method since it doesn't protect against race
   * conditions.
   */
  int remove (void);

  /// Acquire lock ownership (wait on queue if necessary).
  int acquire (void);

  /**
   * Block the thread until we acquire the mutex or until <tv> times
   * out, in which case -1 is returned with <errno> == <ETIME>.  Note
   * that <tv> is assumed to be in "absolute" rather than "relative"
   * time.  The value of <tv> is updated upon return to show the
   * actual (absolute) acquisition time.
   */
  int acquire (ACE_Time_Value &tv);

  /**
   * If <tv> == 0 the call <acquire()> directly.  Otherwise, Block the
   * thread until we acquire the mutex or until <tv> times out, in
   * which case -1 is returned with <errno> == <ETIME>.  Note that
   * <*tv> is assumed to be in "absolute" rather than "relative" time.
   * The value of <*tv> is updated upon return to show the actual
   * (absolute) acquisition time.  
   */
  int acquire (ACE_Time_Value *tv);

  /**
   * Conditionally acquire lock (i.e., don't wait on queue).  Returns
   * -1 on failure.  If we "failed" because someone else already had
   * the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire (void);

  /// Release lock and unblock a thread at head of queue.
  int release (void);

  /**
   * Acquire mutex ownership.  This calls <acquire> and is only here
   * to make the <ACE_Thread_Mutex> interface consistent with the
   * other synchronization APIs.
   */
  int acquire_read (void);

  /**
   * Acquire mutex ownership.  This calls <acquire> and is only here
   * to make the <ACE_Thread_Mutex> interface consistent with the
   * other synchronization APIs.
   */
  int acquire_write (void);

  /**
   * Conditionally acquire mutex (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the <ACE_Thread_Mutex>
   * interface consistent with the other synchronization APIs.
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_read (void);

  /**
   * Conditionally acquire mutex (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the <ACE_Thread_Mutex>
   * interface consistent with the other synchronization APIs.
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire_write (void);

  /**
   * This is only here to make the <ACE_Thread_Mutex>
   * interface consistent with the other synchronization APIs.
   * Assumes the caller has already acquired the mutex using one of
   * the above calls, and returns 0 (success) always.
   */
  int tryacquire_write_upgrade (void);

  /// Return the underlying mutex.
  const ACE_thread_mutex_t &lock (void) const;

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

  // protected:
  /// Mutex type that supports single-process locking efficiently.
  ACE_thread_mutex_t lock_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Thread_Mutex &);
  ACE_Thread_Mutex (const ACE_Thread_Mutex &);
};

#if defined (ACE_USES_OBSOLETE_GUARD_CLASSES)
/**
 * @class ACE_Thread_Mutex_Guard
 *
 * @brief This data structure is meant to be used within a method or
 * function...  It performs automatic aquisition and release of
 * an <ACE_Thread_Mutex>.
 *
 * This class is obsolete and should be replaced by
 * ACE_Guard<ACE_Thread_Mutex>.
 */
class ACE_Export ACE_Thread_Mutex_Guard
{
public:
  /// Implicitly and automatically acquire the lock.
  ACE_Thread_Mutex_Guard (ACE_Thread_Mutex &m, int block = 1);

  /// Implicitly release the lock.
  ~ACE_Thread_Mutex_Guard (void);

  /// 1 if locked, 0 if couldn't acquire the lock (errno will contain
  /// the reason for this).
  int locked (void);

  /**
   * Explicitly release the lock.  Note that only one thread should
   * call this method since it doesn't protect against race
   * conditions.
   */
  int remove (void);

  /// Explicitly acquire the lock.
  int acquire (void);

  /**
   * Conditionally acquire the lock (i.e., won't block).  Returns -1
   * on failure.  If we "failed" because someone else already had the
   * lock, <errno> is set to <EBUSY>.
   */
  int tryacquire (void);

  /// Explicitly release the lock.
  int release (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  /// Reference to the mutex.
  ACE_Thread_Mutex &lock_;

  /// Keeps track of whether we acquired the lock or failed.
  int owner_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Thread_Mutex_Guard &);
  ACE_Thread_Mutex_Guard (const ACE_Thread_Mutex_Guard &);
};
#endif /* ACE_USES_OBSOLETE_GUARD_CLASSES */

class ACE_Export ACE_Condition_Attributes
{
public:
  /// Constructor
  ACE_Condition_Attributes (int type = ACE_DEFAULT_SYNCH_TYPE);

  /// Destructor
  ~ACE_Condition_Attributes (void);

private:
  friend class ACE_Condition_Thread_Mutex;

  /// The attributes
  ACE_condattr_t attributes_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Condition_Attributes &);
  ACE_Condition_Attributes (const ACE_Condition_Attributes &);
};

/**
 * @class ACE_Condition_Thread_Mutex
 *
 * @brief ACE_Condition variable wrapper written using ACE_Mutexes This
 * allows threads to block until shared data changes state.
 * A condition variable enables threads to atomically block and
 * test the condition under the protection of a mutual exclu-
 * sion lock (mutex) until the condition is satisfied.  That is,
 * the mutex must have been held by the thread before calling
 * wait or signal on the condition.  If the condition is false,
 * a thread blocks on a condition variable and atomically
 * releases the mutex that is waiting for the condition to
 * change.  If another thread changes the condition, it may wake
 * up waiting threads by signaling the associated condition
 * variable.  The waiting threads, upon awakening, reacquire the
 * mutex and re-evaluate the condition.
 *
 * This should be an instantiation of ACE_Condition but problems
 * with compilers precludes this...
 */
class ACE_Export ACE_Condition_Thread_Mutex
{
public:
  /// Initialize the condition variable.
  ACE_Condition_Thread_Mutex (const ACE_Thread_Mutex &m,
                              const ACE_TCHAR *name = 0,
                              void *arg = 0);

  /// Initialize the condition variable.
  ACE_Condition_Thread_Mutex (const ACE_Thread_Mutex &m,
                              ACE_Condition_Attributes &attributes,
                              const ACE_TCHAR *name = 0,
                              void *arg = 0);

  /// Implicitly destroy the condition variable.
  ~ACE_Condition_Thread_Mutex (void);

  /**
   * Explicitly destroy the condition variable.  Note that only one
   * thread should call this method since it doesn't protect against
   * race conditions.
   */
  int remove (void);

  /**
   * Block on condition, or until absolute time-of-day has passed.  If
   * abstime == 0 use "blocking" <wait> semantics.  Else, if <abstime>
   * != 0 and the call times out before the condition is signaled
   * <wait> returns -1 and sets errno to ETIME.
   */
  int wait (const ACE_Time_Value *abstime);

  /// Block on condition.
  int wait (void);

  /**
   * Block on condition or until absolute time-of-day has passed.  If
   * abstime == 0 use "blocking" wait() semantics on the <mutex>
   * passed as a parameter (this is useful if you need to store the
   * <Condition> in shared memory).  Else, if <abstime> != 0 and the
   * call times out before the condition is signaled <wait> returns -1
   * and sets errno to ETIME.
   */
  int wait (ACE_Thread_Mutex &mutex, const ACE_Time_Value *abstime = 0);

  /// Signal one waiting thread.
  int signal (void);

  /// Signal *all* waiting threads.
  int broadcast (void);

  /// Returns a reference to the underlying mutex_;
  ACE_Thread_Mutex &mutex (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  /// Condition variable.
  ACE_cond_t cond_;

  /// Reference to mutex lock.
  ACE_Thread_Mutex &mutex_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Condition_Thread_Mutex &);
  ACE_Condition_Thread_Mutex (const ACE_Condition_Thread_Mutex &);
};

/**
 * @class ACE_Recursive_Thread_Mutex
 *
 * @brief Implement a C++ wrapper that allows nested acquisition and
 * release of a mutex that occurs in the same thread.
 */
class ACE_Export ACE_Recursive_Thread_Mutex
{
public:
  /// Initialize a recursive mutex.
  ACE_Recursive_Thread_Mutex (const ACE_TCHAR *name = 0,
                              ACE_mutexattr_t *arg = 0);

  /// Implicitly release a recursive mutex.
  ~ACE_Recursive_Thread_Mutex (void);

  /**
   * Implicitly release a recursive mutex.  Note that only one thread
   * should call this method since it doesn't protect against race
   * conditions.
   */
  int remove (void);

  /**
   * Acquire a recursive mutex (will increment the nesting level and
   * not deadmutex if the owner of the mutex calls this method more
   * than once).
   */
  int acquire (void);

  /**
   * Conditionally acquire a recursive mutex (i.e., won't block).
   * Returns -1 on failure.  If we "failed" because someone else
   * already had the lock, <errno> is set to <EBUSY>.
   */
  int tryacquire (void);

  /**
   * Acquire mutex ownership.  This calls <acquire> and is only
   * here to make the <ACE_Recusive_Thread_Mutex> interface consistent
   * with the other synchronization APIs.
   */
  int acquire_read (void);

  /**
   * Acquire mutex ownership.  This calls <acquire> and is only
   * here to make the <ACE_Recusive_Thread_Mutex> interface consistent
   * with the other synchronization APIs.
   */
  int acquire_write (void);

  /**
   * Conditionally acquire mutex (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the
   * <ACE_Recusive_Thread_Mutex> interface consistent with the other
   * synchronization APIs.  Returns -1 on failure.  If we "failed"
   * because someone else already had the lock, <errno> is set to
   * <EBUSY>.
   */
  int tryacquire_read (void);

  /**
   * Conditionally acquire mutex (i.e., won't block).  This calls
   * <tryacquire> and is only here to make the
   * <ACE_Recusive_Thread_Mutex> interface consistent with the other
   * synchronization APIs.  Returns -1 on failure.  If we "failed"
   * because someone else already had the lock, <errno> is set to
   * <EBUSY>.
   */
  int tryacquire_write (void);

  /**
   * This is only here to make the <ACE_Recursive_Thread_Mutex>
   * interface consistent with the other synchronization APIs.
   * Assumes the caller has already acquired the mutex using one of
   * the above calls, and returns 0 (success) always.
   */
  int tryacquire_write_upgrade (void);

  /**
   * Releases a recursive mutex (will not release mutex until all the
   * nesting level drops to 0, which means the mutex is no longer
   * held).
   */
  int release (void);

  /// Return the id of the thread that currently owns the mutex.
  ACE_thread_t get_thread_id (void);

  /**
   * Return the nesting level of the recursion.  When a thread has
   * acquired the mutex for the first time, the nesting level == 1.
   * The nesting level is incremented every time the thread acquires
   * the mutex recursively.
   */
  int get_nesting_level (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  // = This method should *not* be public (they hold no locks...)
  void set_thread_id (ACE_thread_t t);

  /// Recursive mutex.
  ACE_recursive_thread_mutex_t recursive_mutex_;

  /// Keeps track of whether <remove> has been called yet to avoid
  /// multiple <remove> calls, e.g., explicitly and implicitly in the
  /// destructor.  This flag isn't protected by a lock, so make sure
  /// that you don't have multiple threads simultaneously calling
  /// <remove> on the same object, which is a bad idea anyway...
  int removed_;

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Recursive_Thread_Mutex &);
  ACE_Recursive_Thread_Mutex (const ACE_Recursive_Thread_Mutex &);
};

/**
 * @class ACE_RW_Thread_Mutex
 *
 * @brief Wrapper for readers/writer locks that exist within a process.
 */
class ACE_Export ACE_RW_Thread_Mutex : public ACE_RW_Mutex
{
public:
  ACE_RW_Thread_Mutex (const ACE_TCHAR *name = 0,
                       void *arg = 0);

  /// Default dtor.
  ~ACE_RW_Thread_Mutex (void);

  /**
   * Conditionally upgrade a read lock to a write lock.  This only
   * works if there are no other readers present, in which case the
   * method returns 0.  Otherwise, the method returns -1 and sets
   * <errno> to <EBUSY>.  Note that the caller of this method *must*
   * already possess this lock as a read lock (but this condition is
   * not checked by the current implementation).
   */
  int tryacquire_write_upgrade (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};

/**
 * @class ACE_Thread_Semaphore
 *
 * @brief Wrapper for Dijkstra style general semaphores that work
 * only within one process.
 */
class ACE_Export ACE_Thread_Semaphore : public ACE_Semaphore
{
public:
  /// Initialize the semaphore, with an initial value of <count>,
  /// maximum value of <max>, and unlocked by default.
  ACE_Thread_Semaphore (u_int count = 1, // By default make this unlocked.
                        const ACE_TCHAR *name = 0,
                        void * = 0,
                        int max = 0x7FFFFFFF);

  /// Default dtor.
  ~ACE_Thread_Semaphore (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};

struct ACE_Export ACE_Sub_Barrier
{
  // = Initialization.
  ACE_Sub_Barrier (u_int count,
                   ACE_Thread_Mutex &lock,
                   const ACE_TCHAR *name = 0,
                   void *arg = 0);

  ~ACE_Sub_Barrier (void);

  ACE_Condition_Thread_Mutex barrier_finished_;
  // True if this generation of the barrier is done.

  int running_threads_;
  // Number of threads that are still running.

  void dump (void) const;
  // Dump the state of an object.

  ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.
};

/**
 * @class ACE_Barrier
 *
 * @brief Implements "barrier synchronization".
 *
 * This class allows <count> number of threads to synchronize
 * their completion of (one round of) a task, which is known as
 * "barrier synchronization".  The implementation uses a
 * "sub-barrier generation numbering" scheme to avoid overhead
 * and to ensure that all threads wait to leave the barrier
 * correct.  This code is based on an article from SunOpsis
 * Vol. 4, No. 1 by Richard Marejka
 * (Richard.Marejka@canada.sun.com).
 */
class ACE_Export ACE_Barrier
{
public:
  /// Initialize the barrier to synchronize <count> threads.
  ACE_Barrier (u_int count,
               const ACE_TCHAR *name = 0,
               void *arg = 0);

  /// Default dtor.
  ~ACE_Barrier (void);

  /// Block the caller until all <count> threads have called <wait> and
  /// then allow all the caller threads to continue in parallel.
  int wait (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  /// Serialize access to the barrier state.
  ACE_Thread_Mutex lock_;

  /// Either 0 or 1, depending on whether we are the first generation
  /// of waiters or the next generation of waiters.
  int current_generation_;

  /// Total number of threads that can be waiting at any one time.
  int count_;

  /**
   * We keep two <sub_barriers>, one for the first "generation" of
   * waiters, and one for the next "generation" of waiters.  This
   * efficiently solves the problem of what to do if all the first
   * generation waiters don't leave the barrier before one of the
   * threads calls wait() again (i.e., starts up the next generation
   * barrier).
   */
  ACE_Sub_Barrier sub_barrier_1_;
  ACE_Sub_Barrier sub_barrier_2_;
  ACE_Sub_Barrier *sub_barrier_[2];

private:
  // = Prevent assignment and initialization.
  void operator= (const ACE_Barrier &);
  ACE_Barrier (const ACE_Barrier &);
};

#if 0
// The following two classes are commented out since there doesn't
// appear to be a portable and robust means of implementing this
// functionality across platforms.  If you know of a portable and
// robust way to implement this functionality please let us know.

/**
 * @class ACE_Process_Condition
 *
 * @brief ACE_Condition variable wrapper that works across processes.
 */
class ACE_Export ACE_Process_Condition
{
public:
  ACE_Process_Condition (MUTEX &m, const ACE_TCHAR *name = 0, void *arg = 0);

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.
};
#endif /* 0 */

#if 0
/**
 * @class ACE_Process_Barrier
 *
 * @brief Implements "barrier synchronization" using ACE_Process_Mutexes!
 *
 * This class is just a simple wrapper for ACE_Barrier that
 * selects the USYNC_PROCESS variant for the locks.
 */
class ACE_Export ACE_Process_Barrier : public ACE_Barrier
{
public:
  /// Create a Process_Barrier, passing in the optional <name>.
  ACE_Process_Barrier (u_int count, const ACE_TCHAR *name = 0);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};
#endif /* 0 */

/**
 * @class ACE_Thread_Barrier
 *
 * @brief Implements "barrier synchronization" using ACE_Thread_Mutexes!
 *
 * This class is just a simple wrapper for ACE_Barrier that
 * selects the USYNC_THREAD variant for the locks.
 */
class ACE_Export ACE_Thread_Barrier : public ACE_Barrier
{
public:
  /// Create a Thread_Barrier, passing in the optional <name>.
  ACE_Thread_Barrier (u_int count, const ACE_TCHAR *name = 0);

  /// Default dtor.
  ~ACE_Thread_Barrier (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;
};
#endif /* ACE_HAS_THREADS */

#if defined (__ACE_INLINE__)
#include "ace/Synch.i"
#endif /* __ACE_INLINE__ */

// Include the templates here.
#include "ace/Synch_T.h"

template <class ACE_LOCK>
class ACE_Guard;

ACE_TEMPLATE_SPECIALIZATION
/**
 * @class ACE_Guard<ACE_Null_Mutex>
 *
 * @brief Template specialization of <ACE_Guard> for the
 * <ACE_Null_Mutex>.
 *
 * This specialization is useful since it helps to speedup
 * performance of the "Null_Mutex" considerably.
 */
class ACE_Export ACE_Guard<ACE_Null_Mutex>
{
public:
  // = Initialization and termination methods.
  ACE_Guard (ACE_Null_Mutex &) {}
  ACE_Guard (ACE_Null_Mutex &, int) {}
#if defined (ACE_WIN32)
  ~ACE_Guard (void) {}
#endif /* ACE_WIN32 */

  int acquire (void) { return 0; }
  int tryacquire (void) { return 0; }
  int release (void) { return 0; }
  int locked (void) { return 1; }
  int remove (void) { return 0; }
  void dump (void) const {}

private:
  // = Prevent assignment and initialization.
  ACE_UNIMPLEMENTED_FUNC (void operator= (const ACE_Guard<ACE_Null_Mutex> &))
  ACE_UNIMPLEMENTED_FUNC (ACE_Guard (const ACE_Guard<ACE_Null_Mutex> &))
};

template <class ACE_LOCK>
class ACE_Write_Guard;

ACE_TEMPLATE_SPECIALIZATION
/**
 * @class ACE_Write_Guard<ACE_Null_Mutex>
 *
 */
class ACE_Export ACE_Write_Guard<ACE_Null_Mutex> : public ACE_Guard<ACE_Null_Mutex>
{
public:
  ACE_Write_Guard (ACE_Null_Mutex &m)
    : ACE_Guard<ACE_Null_Mutex> (m) {}
  ACE_Write_Guard (ACE_Null_Mutex &m, int blocked)
    : ACE_Guard<ACE_Null_Mutex> (m, blocked) {}

  int acquire_write (void) { return 0; }
  int acquire (void) { return 0; }
  int tryacquire_write (void) { return 0; }
  int tryacquire (void) { return 0; }
  void dump (void) const {}
};

template <class ACE_LOCK>
class ACE_Read_Guard;

ACE_TEMPLATE_SPECIALIZATION
/**
 * @class ACE_Read_Guard<ACE_Null_Mutex>
 *
 */
class ACE_Export ACE_Read_Guard<ACE_Null_Mutex> : public ACE_Guard<ACE_Null_Mutex>
{
public:
  ACE_Read_Guard (ACE_Null_Mutex &m)
    : ACE_Guard<ACE_Null_Mutex> (m) {}
  ACE_Read_Guard (ACE_Null_Mutex &m, int blocked)
    : ACE_Guard<ACE_Null_Mutex> (m, blocked) {}

  int acquire_read (void) { return 0; }
  int acquire (void) { return 0; }
  int tryacquire_read (void) { return 0; }
  int tryacquire (void) { return 0; }
  void dump (void) const {}
};

#if defined (ACE_LEGACY_MODE)
# include "ace/File_Lock.h"
# include "ace/Process_Semaphore.h"
# include "ace/Process_Mutex.h"
# include "ace/RW_Process_Mutex.h"
# include "ace/Test_and_Set.h"
#endif  /* ACE_LEGACY_MODE */

#include "ace/post.h"
#endif /* ACE_SYNCH_H */