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
|
/*****************************************************************************
Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2008, Google Inc.
Portions of this file contain modifications contributed and copyrighted by
Google, Inc. Those modifications are gratefully acknowledged and are described
briefly in the InnoDB documentation. The contributions by Google are
incorporated with their permission, and subject to the conditions contained in
the file COPYING.Google.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file sync/sync0sync.cc
Mutex, the basic synchronization primitive
Created 9/5/1995 Heikki Tuuri
*******************************************************/
#include "sync0sync.h"
#ifdef UNIV_NONINL
#include "sync0sync.ic"
#include "sync0arr.ic"
#endif
#include "sync0rw.h"
#include "buf0buf.h"
#include "srv0srv.h"
#include "btr0types.h"
#include "buf0types.h"
#include "os0sync.h" /* for HAVE_ATOMIC_BUILTINS */
#ifdef UNIV_SYNC_DEBUG
# include "srv0start.h" /* srv_is_being_started */
#endif /* UNIV_SYNC_DEBUG */
#include "ha_prototypes.h"
#include "my_cpu.h"
#include <vector>
/*
REASONS FOR IMPLEMENTING THE SPIN LOCK MUTEX
============================================
Semaphore operations in operating systems are slow: Solaris on a 1993 Sparc
takes 3 microseconds (us) for a lock-unlock pair and Windows NT on a 1995
Pentium takes 20 microseconds for a lock-unlock pair. Therefore, we have to
implement our own efficient spin lock mutex. Future operating systems may
provide efficient spin locks, but we cannot count on that.
Another reason for implementing a spin lock is that on multiprocessor systems
it can be more efficient for a processor to run a loop waiting for the
semaphore to be released than to switch to a different thread. A thread switch
takes 25 us on both platforms mentioned above. See Gray and Reuter's book
Transaction processing for background.
How long should the spin loop last before suspending the thread? On a
uniprocessor, spinning does not help at all, because if the thread owning the
mutex is not executing, it cannot be released. Spinning actually wastes
resources.
On a multiprocessor, we do not know if the thread owning the mutex is
executing or not. Thus it would make sense to spin as long as the operation
guarded by the mutex would typically last assuming that the thread is
executing. If the mutex is not released by that time, we may assume that the
thread owning the mutex is not executing and suspend the waiting thread.
A typical operation (where no i/o involved) guarded by a mutex or a read-write
lock may last 1 - 20 us on the current Pentium platform. The longest
operations are the binary searches on an index node.
We conclude that the best choice is to set the spin time at 20 us. Then the
system should work well on a multiprocessor. On a uniprocessor we have to
make sure that thread swithches due to mutex collisions are not frequent,
i.e., they do not happen every 100 us or so, because that wastes too much
resources. If the thread switches are not frequent, the 20 us wasted in spin
loop is not too much.
Empirical studies on the effect of spin time should be done for different
platforms.
IMPLEMENTATION OF THE MUTEX
===========================
For background, see Curt Schimmel's book on Unix implementation on modern
architectures. The key points in the implementation are atomicity and
serialization of memory accesses. The test-and-set instruction (XCHG in
Pentium) must be atomic. As new processors may have weak memory models, also
serialization of memory references may be necessary. The successor of Pentium,
P6, has at least one mode where the memory model is weak. As far as we know,
in Pentium all memory accesses are serialized in the program order and we do
not have to worry about the memory model. On other processors there are
special machine instructions called a fence, memory barrier, or storage
barrier (STBAR in Sparc), which can be used to serialize the memory accesses
to happen in program order relative to the fence instruction.
Leslie Lamport has devised a "bakery algorithm" to implement a mutex without
the atomic test-and-set, but his algorithm should be modified for weak memory
models. We do not use Lamport's algorithm, because we guess it is slower than
the atomic test-and-set.
Our mutex implementation works as follows: After that we perform the atomic
test-and-set instruction on the memory word. If the test returns zero, we
know we got the lock first. If the test returns not zero, some other thread
was quicker and got the lock: then we spin in a loop reading the memory word,
waiting it to become zero. It is wise to just read the word in the loop, not
perform numerous test-and-set instructions, because they generate memory
traffic between the cache and the main memory. The read loop can just access
the cache, saving bus bandwidth.
If we cannot acquire the mutex lock in the specified time, we reserve a cell
in the wait array, set the waiters byte in the mutex to 1. To avoid a race
condition, after setting the waiters byte and before suspending the waiting
thread, we still have to check that the mutex is reserved, because it may
have happened that the thread which was holding the mutex has just released
it and did not see the waiters byte set to 1, a case which would lead the
other thread to an infinite wait.
LEMMA 1: After a thread resets the event of a mutex (or rw_lock), some
======
thread will eventually call os_event_set() on that particular event.
Thus no infinite wait is possible in this case.
Proof: After making the reservation the thread sets the waiters field in the
mutex to 1. Then it checks that the mutex is still reserved by some thread,
or it reserves the mutex for itself. In any case, some thread (which may be
also some earlier thread, not necessarily the one currently holding the mutex)
will set the waiters field to 0 in mutex_exit, and then call
os_event_set() with the mutex as an argument.
Q.E.D.
LEMMA 2: If an os_event_set() call is made after some thread has called
======
the os_event_reset() and before it starts wait on that event, the call
will not be lost to the second thread. This is true even if there is an
intervening call to os_event_reset() by another thread.
Thus no infinite wait is possible in this case.
Proof (non-windows platforms): os_event_reset() returns a monotonically
increasing value of signal_count. This value is increased at every
call of os_event_set() If thread A has called os_event_reset() followed
by thread B calling os_event_set() and then some other thread C calling
os_event_reset(), the is_set flag of the event will be set to FALSE;
but now if thread A calls os_event_wait_low() with the signal_count
value returned from the earlier call of os_event_reset(), it will
return immediately without waiting.
Q.E.D.
Proof (windows): If there is a writer thread which is forced to wait for
the lock, it may be able to set the state of rw_lock to RW_LOCK_WAIT_EX
The design of rw_lock ensures that there is one and only one thread
that is able to change the state to RW_LOCK_WAIT_EX and this thread is
guaranteed to acquire the lock after it is released by the current
holders and before any other waiter gets the lock.
On windows this thread waits on a separate event i.e.: wait_ex_event.
Since only one thread can wait on this event there is no chance
of this event getting reset before the writer starts wait on it.
Therefore, this thread is guaranteed to catch the os_set_event()
signalled unconditionally at the release of the lock.
Q.E.D. */
/* Number of spin waits on mutexes: for performance monitoring */
/** The number of iterations in the mutex_spin_wait() spin loop.
Intended for performance monitoring. */
UNIV_INTERN ib_counter_t<ib_int64_t, IB_N_SLOTS> mutex_spin_round_count;
/** The number of mutex_spin_wait() calls. Intended for
performance monitoring. */
UNIV_INTERN ib_counter_t<ib_int64_t, IB_N_SLOTS> mutex_spin_wait_count;
/** The number of OS waits in mutex_spin_wait(). Intended for
performance monitoring. */
UNIV_INTERN ib_counter_t<ib_int64_t, IB_N_SLOTS> mutex_os_wait_count;
/** The number of mutex_exit() calls. Intended for performance
monitoring. */
UNIV_INTERN ib_int64_t mutex_exit_count;
/** This variable is set to TRUE when sync_init is called */
UNIV_INTERN ibool sync_initialized = FALSE;
#ifdef UNIV_SYNC_DEBUG
/** An acquired mutex or rw-lock and its level in the latching order */
struct sync_level_t;
/** Mutexes or rw-locks held by a thread */
struct sync_thread_t;
/** The latch levels currently owned by threads are stored in this data
structure; the size of this array is OS_THREAD_MAX_N */
UNIV_INTERN sync_thread_t* sync_thread_level_arrays;
/** Mutex protecting sync_thread_level_arrays */
UNIV_INTERN ib_mutex_t sync_thread_mutex;
# ifdef UNIV_PFS_MUTEX
UNIV_INTERN mysql_pfs_key_t sync_thread_mutex_key;
# endif /* UNIV_PFS_MUTEX */
#endif /* UNIV_SYNC_DEBUG */
/** Global list of database mutexes (not OS mutexes) created. */
UNIV_INTERN ut_list_base_node_t mutex_list;
/** Mutex protecting the mutex_list variable */
UNIV_INTERN ib_mutex_t mutex_list_mutex;
#ifdef UNIV_PFS_MUTEX
UNIV_INTERN mysql_pfs_key_t mutex_list_mutex_key;
#endif /* UNIV_PFS_MUTEX */
#ifdef UNIV_SYNC_DEBUG
/** Latching order checks start when this is set TRUE */
UNIV_INTERN ibool sync_order_checks_on = FALSE;
/** Number of slots reserved for each OS thread in the sync level array */
static const ulint SYNC_THREAD_N_LEVELS = 10000;
/** Array for tracking sync levels per thread. */
typedef std::vector<sync_level_t> sync_arr_t;
/** Mutexes or rw-locks held by a thread */
struct sync_thread_t{
os_thread_id_t id; /*!< OS thread id */
sync_arr_t* levels; /*!< level array for this thread; if
this is NULL this slot is unused */
};
/** An acquired mutex or rw-lock and its level in the latching order */
struct sync_level_t{
void* latch; /*!< pointer to a mutex or an
rw-lock; NULL means that
the slot is empty */
ulint level; /*!< level of the latch in the
latching order. This field is
overloaded to serve as a node in a
linked list of free nodes too. When
latch == NULL then this will contain
the ordinal value of the next free
element */
};
#endif /* UNIV_SYNC_DEBUG */
/******************************************************************//**
Creates, or rather, initializes a mutex object in a specified memory
location (which must be appropriately aligned). The mutex is initialized
in the reset state. Explicit freeing of the mutex with mutex_free is
necessary only if the memory block containing it is freed. */
UNIV_INTERN
void
mutex_create_func(
/*==============*/
ib_mutex_t* mutex, /*!< in: pointer to memory */
#ifdef UNIV_DEBUG
# ifdef UNIV_SYNC_DEBUG
ulint level, /*!< in: level */
# endif /* UNIV_SYNC_DEBUG */
#endif /* UNIV_DEBUG */
const char* cfile_name, /*!< in: file name where created */
ulint cline, /*!< in: file line where created */
const char* cmutex_name) /*!< in: mutex name */
{
#if defined(HAVE_ATOMIC_BUILTINS)
mutex_reset_lock_word(mutex);
#else
os_fast_mutex_init(PFS_NOT_INSTRUMENTED, &mutex->os_fast_mutex);
mutex->lock_word = 0;
#endif
os_event_create(&mutex->event);
mutex_set_waiters(mutex, 0);
#ifdef UNIV_DEBUG
mutex->magic_n = MUTEX_MAGIC_N;
mutex->level = level;
#endif /* UNIV_DEBUG */
mutex->line = 0;
mutex->file_name = "not yet reserved";
mutex->cfile_name = cfile_name;
mutex->cline = cline;
mutex->count_os_wait = 0;
mutex->cmutex_name= cmutex_name;
/* Check that lock_word is aligned; this is important on Intel */
ut_ad(((ulint)(&(mutex->lock_word))) % 4 == 0);
/* NOTE! The very first mutexes are not put to the mutex list */
if (mutex == &mutex_list_mutex
#ifdef UNIV_SYNC_DEBUG
|| mutex == &sync_thread_mutex
#endif /* UNIV_SYNC_DEBUG */
) {
return;
}
mutex_enter(&mutex_list_mutex);
ut_ad(UT_LIST_GET_LEN(mutex_list) == 0
|| UT_LIST_GET_FIRST(mutex_list)->magic_n == MUTEX_MAGIC_N);
UT_LIST_ADD_FIRST(list, mutex_list, mutex);
mutex_exit(&mutex_list_mutex);
}
/******************************************************************//**
Creates, or rather, initializes a priority mutex object in a specified memory
location (which must be appropriately aligned). The mutex is initialized
in the reset state. Explicit freeing of the mutex with mutex_free is
necessary only if the memory block containing it is freed. */
UNIV_INTERN
void
mutex_create_func(
/*==============*/
ib_prio_mutex_t* mutex, /*!< in: pointer to memory */
#ifdef UNIV_DEBUG
# ifdef UNIV_SYNC_DEBUG
ulint level, /*!< in: level */
# endif /* UNIV_SYNC_DEBUG */
#endif /* UNIV_DEBUG */
const char* cfile_name, /*!< in: file name where
created */
ulint cline, /*!< in: file line where
created */
const char* cmutex_name) /*!< in: mutex name */
{
mutex_create_func(&mutex->base_mutex,
#ifdef UNIV_DEBUG
# ifdef UNIV_SYNC_DEBUG
level,
#endif /* UNIV_SYNC_DEBUG */
#endif /* UNIV_DEBUG */
cfile_name,
cline,
cmutex_name);
mutex->high_priority_waiters = 0;
os_event_create(&mutex->high_priority_event);
}
/******************************************************************//**
NOTE! Use the corresponding macro mutex_free(), not directly this function!
Calling this function is obligatory only if the memory buffer containing
the mutex is freed. Removes a mutex object from the mutex list. The mutex
is checked to be in the reset state. */
UNIV_INTERN
void
mutex_free_func(
/*============*/
ib_mutex_t* mutex) /*!< in: mutex */
{
ut_ad(mutex_validate(mutex));
ut_a(mutex_get_lock_word(mutex) == 0);
ut_a(mutex_get_waiters(mutex) == 0);
#ifdef UNIV_MEM_DEBUG
if (mutex == &mem_hash_mutex) {
ut_ad(UT_LIST_GET_LEN(mutex_list) == 1);
ut_ad(UT_LIST_GET_FIRST(mutex_list) == &mem_hash_mutex);
UT_LIST_REMOVE(list, mutex_list, mutex);
goto func_exit;
}
#endif /* UNIV_MEM_DEBUG */
if (mutex != &mutex_list_mutex
#ifdef UNIV_SYNC_DEBUG
&& mutex != &sync_thread_mutex
#endif /* UNIV_SYNC_DEBUG */
) {
mutex_enter(&mutex_list_mutex);
ut_ad(!UT_LIST_GET_PREV(list, mutex)
|| UT_LIST_GET_PREV(list, mutex)->magic_n
== MUTEX_MAGIC_N);
ut_ad(!UT_LIST_GET_NEXT(list, mutex)
|| UT_LIST_GET_NEXT(list, mutex)->magic_n
== MUTEX_MAGIC_N);
UT_LIST_REMOVE(list, mutex_list, mutex);
mutex_exit(&mutex_list_mutex);
}
os_event_free(&mutex->event, false);
#ifdef UNIV_MEM_DEBUG
func_exit:
#endif /* UNIV_MEM_DEBUG */
#if !defined(HAVE_ATOMIC_BUILTINS)
os_fast_mutex_free(&(mutex->os_fast_mutex));
#endif
/* If we free the mutex protecting the mutex list (freeing is
not necessary), we have to reset the magic number AFTER removing
it from the list. */
#ifdef UNIV_DEBUG
mutex->magic_n = 0;
#endif /* UNIV_DEBUG */
return;
}
/******************************************************************//**
NOTE! Use the corresponding macro mutex_free(), not directly this function!
Calling this function is obligatory only if the memory buffer containing
the mutex is freed. Removes a priority mutex object from the mutex list. The
mutex is checked to be in the reset state. */
UNIV_INTERN
void
mutex_free_func(
/*============*/
ib_prio_mutex_t* mutex) /*!< in: mutex */
{
ut_a(mutex->high_priority_waiters == 0);
os_event_free(&mutex->high_priority_event, false);
mutex_free_func(&mutex->base_mutex);
}
/********************************************************************//**
NOTE! Use the corresponding macro in the header file, not this function
directly. Tries to lock the mutex for the current thread. If the lock is not
acquired immediately, returns with return value 1.
@return 0 if succeed, 1 if not */
UNIV_INTERN
ulint
mutex_enter_nowait_func(
/*====================*/
ib_mutex_t* mutex, /*!< in: pointer to mutex */
const char* file_name MY_ATTRIBUTE((unused)),
/*!< in: file name where mutex
requested */
ulint line MY_ATTRIBUTE((unused)))
/*!< in: line where requested */
{
ut_ad(mutex_validate(mutex));
if (!ib_mutex_test_and_set(mutex)) {
mutex->thread_id = os_thread_get_curr_id();
#ifdef UNIV_SYNC_DEBUG
mutex_set_debug_info(mutex, file_name, line);
#endif
if (srv_instrument_semaphores) {
mutex->file_name = file_name;
mutex->line = line;
}
return(0); /* Succeeded! */
}
return(1);
}
#ifdef UNIV_DEBUG
/******************************************************************//**
Checks that the mutex has been initialized.
@return TRUE */
UNIV_INTERN
ibool
mutex_validate(
/*===========*/
const ib_mutex_t* mutex) /*!< in: mutex */
{
ut_a(mutex);
if (mutex->magic_n != MUTEX_MAGIC_N) {
ib_logf(IB_LOG_LEVEL_ERROR,
"Mutex %p not initialized file %s line %lu.",
mutex, mutex->cfile_name, mutex->cline);
}
ut_ad(mutex->magic_n == MUTEX_MAGIC_N);
return(TRUE);
}
/******************************************************************//**
Checks that the current thread owns the mutex. Works only in the debug
version.
@return TRUE if owns */
UNIV_INTERN
ibool
mutex_own(
/*======*/
const ib_mutex_t* mutex) /*!< in: mutex */
{
ut_ad(mutex_validate(mutex));
return(mutex_get_lock_word(mutex) == 1
&& os_thread_eq(mutex->thread_id, os_thread_get_curr_id()));
}
/******************************************************************//**
Checks that the current thread owns the priority mutex. Works only
in the debug version.
@return TRUE if owns */
UNIV_INTERN
ibool
mutex_own(
/*======*/
const ib_prio_mutex_t* mutex) /*!< in: priority mutex */
{
return mutex_own(&mutex->base_mutex);
}
#endif /* UNIV_DEBUG */
/******************************************************************//**
Sets the waiters field in a mutex. */
UNIV_INTERN
void
mutex_set_waiters(
/*==============*/
ib_mutex_t* mutex, /*!< in: mutex */
ulint n) /*!< in: value to set */
{
volatile ulint* ptr; /* declared volatile to ensure that
the value is stored to memory */
ut_ad(mutex);
ptr = &(mutex->waiters);
*ptr = n; /* Here we assume that the write of a single
word in memory is atomic */
}
/******************************************************************//**
Reserves a mutex or a priority mutex for the current thread. If the mutex is
reserved, the function spins a preset time (controlled by SYNC_SPIN_ROUNDS),
waiting for the mutex before suspending the thread. */
UNIV_INTERN
void
mutex_spin_wait(
/*============*/
void* _mutex, /*!< in: pointer to mutex */
bool high_priority, /*!< in: whether the mutex is a
priority mutex with high priority
specified */
const char* file_name, /*!< in: file name where mutex
requested */
ulint line) /*!< in: line where requested */
{
ulint i; /* spin round count */
ulint index; /* index of the reserved wait cell */
sync_array_t* sync_arr;
size_t counter_index;
/* The typecast below is performed for some of the priority mutexes
too, when !high_priority. This exploits the fact that regular mutex is
a prefix of the priority mutex in memory. */
ib_mutex_t* mutex = (ib_mutex_t *) _mutex;
ib_prio_mutex_t* prio_mutex = NULL;
counter_index = (size_t) os_thread_get_curr_id();
ut_ad(mutex);
/* This update is not thread safe, but we don't mind if the count
isn't exact. Moved out of ifdef that follows because we are willing
to sacrifice the cost of counting this as the data is valuable.
Count the number of calls to mutex_spin_wait. */
mutex_spin_wait_count.add(counter_index, 1);
mutex_loop:
i = 0;
/* Spin waiting for the lock word to become zero. Note that we do
not have to assume that the read access to the lock word is atomic,
as the actual locking is always committed with atomic test-and-set.
In reality, however, all processors probably have an atomic read of
a memory word. */
spin_loop:
HMT_low();
os_rmb;
while (mutex_get_lock_word(mutex) != 0 && i < SYNC_SPIN_ROUNDS) {
if (srv_spin_wait_delay) {
ut_delay(ut_rnd_interval(0, srv_spin_wait_delay));
}
i++;
}
HMT_medium();
if (i >= SYNC_SPIN_ROUNDS) {
os_thread_yield();
}
mutex_spin_round_count.add(counter_index, i);
if (ib_mutex_test_and_set(mutex) == 0) {
/* Succeeded! */
mutex->thread_id = os_thread_get_curr_id();
#ifdef UNIV_SYNC_DEBUG
mutex_set_debug_info(mutex, file_name, line);
#endif
if (srv_instrument_semaphores) {
mutex->file_name = file_name;
mutex->line = line;
}
return;
}
/* We may end up with a situation where lock_word is 0 but the OS
fast mutex is still reserved. On FreeBSD the OS does not seem to
schedule a thread which is constantly calling pthread_mutex_trylock
(in ib_mutex_test_and_set implementation). Then we could end up
spinning here indefinitely. The following 'i++' stops this infinite
spin. */
i++;
if (i < SYNC_SPIN_ROUNDS) {
goto spin_loop;
}
sync_arr = sync_array_get_and_reserve_cell(mutex,
high_priority
? SYNC_PRIO_MUTEX
: SYNC_MUTEX,
file_name, line, &index);
/* The memory order of the array reservation and the change in the
waiters field is important: when we suspend a thread, we first
reserve the cell and then set waiters field to 1. When threads are
released in mutex_exit, the waiters field is first set to zero and
then the event is set to the signaled state. */
if (high_priority) {
prio_mutex = reinterpret_cast<ib_prio_mutex_t *>(_mutex);
os_atomic_increment_ulint(&prio_mutex->high_priority_waiters,
1);
} else {
mutex_set_waiters(mutex, 1);
}
/* Make sure waiters store won't pass over mutex_test_and_set */
#ifdef __powerpc__
os_mb;
#endif
/* Try to reserve still a few times */
for (i = 0; i < 4; i++) {
if (ib_mutex_test_and_set(mutex) == 0) {
/* Succeeded! Free the reserved wait cell */
sync_array_free_cell(sync_arr, index);
mutex->thread_id = os_thread_get_curr_id();
#ifdef UNIV_SYNC_DEBUG
mutex_set_debug_info(mutex, file_name, line);
#endif
if (srv_instrument_semaphores) {
mutex->file_name = file_name;
mutex->line = line;
}
if (prio_mutex) {
os_atomic_decrement_ulint(
&prio_mutex->high_priority_waiters,
1);
}
return;
/* Note that in this case we leave the waiters field
set to 1. We cannot reset it to zero, as we do not
know if there are other waiters. */
}
}
/* Now we know that there has been some thread holding the mutex
after the change in the wait array and the waiters field was made.
Now there is no risk of infinite wait on the event. */
mutex_os_wait_count.add(counter_index, 1);
mutex->count_os_wait++;
sync_array_wait_event(sync_arr, index);
if (prio_mutex) {
os_atomic_decrement_ulint(&prio_mutex->high_priority_waiters,
1);
}
goto mutex_loop;
}
/******************************************************************//**
Releases the threads waiting in the primary wait array for this mutex. */
UNIV_INTERN
void
mutex_signal_object(
/*================*/
ib_mutex_t* mutex) /*!< in: mutex */
{
mutex_set_waiters(mutex, 0);
/* The memory order of resetting the waiters field and
signaling the object is important. See LEMMA 1 above. */
os_event_set(&mutex->event);
sync_array_object_signalled();
}
#ifdef UNIV_SYNC_DEBUG
/******************************************************************//**
Sets the debug information for a reserved mutex. */
UNIV_INTERN
void
mutex_set_debug_info(
/*=================*/
ib_mutex_t* mutex, /*!< in: mutex */
const char* file_name, /*!< in: file where requested */
ulint line) /*!< in: line where requested */
{
ut_ad(mutex);
ut_ad(file_name);
sync_thread_add_level(mutex, mutex->level, FALSE);
mutex->file_name = file_name;
mutex->line = line;
}
/******************************************************************//**
Gets the debug information for a reserved mutex. */
UNIV_INTERN
void
mutex_get_debug_info(
/*=================*/
ib_mutex_t* mutex, /*!< in: mutex */
const char** file_name, /*!< out: file where requested */
ulint* line, /*!< out: line where requested */
os_thread_id_t* thread_id) /*!< out: id of the thread which owns
the mutex */
{
ut_ad(mutex);
*file_name = mutex->file_name;
*line = mutex->line;
*thread_id = mutex->thread_id;
}
/******************************************************************//**
Prints debug info of currently reserved mutexes. */
static
void
mutex_list_print_info(
/*==================*/
FILE* file) /*!< in: file where to print */
{
ib_mutex_t* mutex;
const char* file_name;
ulint line;
os_thread_id_t thread_id;
ulint count = 0;
fputs("----------\n"
"MUTEX INFO\n"
"----------\n", file);
mutex_enter(&mutex_list_mutex);
mutex = UT_LIST_GET_FIRST(mutex_list);
while (mutex != NULL) {
count++;
if (mutex_get_lock_word(mutex) != 0) {
mutex_get_debug_info(mutex, &file_name, &line,
&thread_id);
fprintf(file,
"Locked mutex: addr %p thread %ld"
" file %s line %ld\n",
(void*) mutex, os_thread_pf(thread_id),
file_name, line);
}
mutex = UT_LIST_GET_NEXT(list, mutex);
}
fprintf(file, "Total number of mutexes %ld\n", count);
mutex_exit(&mutex_list_mutex);
}
/******************************************************************//**
Counts currently reserved mutexes. Works only in the debug version.
@return number of reserved mutexes */
UNIV_INTERN
ulint
mutex_n_reserved(void)
/*==================*/
{
ib_mutex_t* mutex;
ulint count = 0;
mutex_enter(&mutex_list_mutex);
for (mutex = UT_LIST_GET_FIRST(mutex_list);
mutex != NULL;
mutex = UT_LIST_GET_NEXT(list, mutex)) {
if (mutex_get_lock_word(mutex) != 0) {
count++;
}
}
mutex_exit(&mutex_list_mutex);
ut_a(count >= 1);
/* Subtract one, because this function itself was holding
one mutex (mutex_list_mutex) */
return(count - 1);
}
/******************************************************************//**
Returns TRUE if no mutex or rw-lock is currently locked. Works only in
the debug version.
@return TRUE if no mutexes and rw-locks reserved */
UNIV_INTERN
ibool
sync_all_freed(void)
/*================*/
{
return(mutex_n_reserved() + rw_lock_n_locked() == 0);
}
/******************************************************************//**
Looks for the thread slot for the calling thread.
@return pointer to thread slot, NULL if not found */
static
sync_thread_t*
sync_thread_level_arrays_find_slot(void)
/*====================================*/
{
ulint i;
os_thread_id_t id;
id = os_thread_get_curr_id();
for (i = 0; i < OS_THREAD_MAX_N; i++) {
sync_thread_t* slot;
slot = &sync_thread_level_arrays[i];
if (slot->levels && os_thread_eq(slot->id, id)) {
return(slot);
}
}
return(NULL);
}
/******************************************************************//**
Looks for an unused thread slot.
@return pointer to thread slot */
static
sync_thread_t*
sync_thread_level_arrays_find_free(void)
/*====================================*/
{
ulint i;
for (i = 0; i < OS_THREAD_MAX_N; i++) {
sync_thread_t* slot;
slot = &sync_thread_level_arrays[i];
if (slot->levels == NULL) {
return(slot);
}
}
return(NULL);
}
/******************************************************************//**
Print warning. */
static
void
sync_print_warning(
/*===============*/
const sync_level_t* slot) /*!< in: slot for which to
print warning */
{
ib_mutex_t* mutex;
mutex = static_cast<ib_mutex_t*>(slot->latch);
if (mutex->magic_n == MUTEX_MAGIC_N) {
fprintf(stderr,
"Mutex '%s'\n",
mutex->cmutex_name);
if (mutex_get_lock_word(mutex) != 0) {
ulint line;
const char* file_name;
os_thread_id_t thread_id;
mutex_get_debug_info(
mutex, &file_name, &line, &thread_id);
fprintf(stderr,
"InnoDB: Locked mutex:"
" addr %p thread %ld file %s line %ld\n",
(void*) mutex, os_thread_pf(thread_id),
file_name, (ulong) line);
} else {
fputs("Not locked\n", stderr);
}
} else {
rw_lock_t* lock;
lock = static_cast<rw_lock_t*>(slot->latch);
rw_lock_print(lock);
}
}
/******************************************************************//**
Checks if all the level values stored in the level array are greater than
the given limit.
@return TRUE if all greater */
static
ibool
sync_thread_levels_g(
/*=================*/
sync_arr_t* arr, /*!< in: pointer to level array for an OS
thread */
ulint limit, /*!< in: level limit */
ulint warn) /*!< in: TRUE=display a diagnostic message */
{
ulint i;
for (i = 0; i < arr->size(); i++) {
const sync_level_t* slot;
slot = (const sync_level_t*)&(arr->at(i));
if (slot->latch != NULL && slot->level <= limit) {
if (warn) {
fprintf(stderr,
"InnoDB: sync levels should be"
" > %lu but a level is %lu\n",
(ulong) limit, (ulong) slot->level);
sync_print_warning(slot);
}
return(FALSE);
}
}
return(TRUE);
}
/******************************************************************//**
Checks if the level value is stored in the level array.
@return slot if found or NULL */
static
const sync_level_t*
sync_thread_levels_contain(
/*=======================*/
sync_arr_t* arr, /*!< in: pointer to level array for an OS
thread */
ulint level) /*!< in: level */
{
ulint i;
for (i = 0; i < arr->size(); i++) {
const sync_level_t* slot;
slot = (const sync_level_t*)&(arr->at(i));
if (slot->latch != NULL && slot->level == level) {
return(slot);
}
}
return(NULL);
}
/******************************************************************//**
Checks if the level array for the current thread contains a
mutex or rw-latch at the specified level.
@return a matching latch, or NULL if not found */
UNIV_INTERN
void*
sync_thread_levels_contains(
/*========================*/
ulint level) /*!< in: latching order level
(SYNC_DICT, ...)*/
{
ulint i;
sync_arr_t* arr;
sync_thread_t* thread_slot;
if (!sync_order_checks_on) {
return(NULL);
}
mutex_enter(&sync_thread_mutex);
thread_slot = sync_thread_level_arrays_find_slot();
if (thread_slot == NULL) {
mutex_exit(&sync_thread_mutex);
return(NULL);
}
arr = thread_slot->levels;
for (i = 0; i < arr->size(); i++) {
sync_level_t* slot;
slot = (sync_level_t*)&(arr->at(i));
if (slot->latch != NULL && slot->level == level) {
mutex_exit(&sync_thread_mutex);
return(slot->latch);
}
}
mutex_exit(&sync_thread_mutex);
return(NULL);
}
/******************************************************************//**
Checks that the level array for the current thread is empty.
@return a latch, or NULL if empty except the exceptions specified below */
UNIV_INTERN
void*
sync_thread_levels_nonempty_gen(
/*============================*/
ibool dict_mutex_allowed) /*!< in: TRUE if dictionary mutex is
allowed to be owned by the thread */
{
ulint i;
sync_arr_t* arr;
sync_thread_t* thread_slot;
if (!sync_order_checks_on) {
return(NULL);
}
mutex_enter(&sync_thread_mutex);
thread_slot = sync_thread_level_arrays_find_slot();
if (thread_slot == NULL) {
mutex_exit(&sync_thread_mutex);
return(NULL);
}
arr = thread_slot->levels;
for (i = 0; i < arr->size(); ++i) {
const sync_level_t* slot;
slot = (const sync_level_t*)&(arr->at(i));
if (slot->latch != NULL
&& (!dict_mutex_allowed
|| (slot->level != SYNC_DICT
&& slot->level != SYNC_DICT_OPERATION
&& slot->level != SYNC_FTS_CACHE))) {
mutex_exit(&sync_thread_mutex);
ut_error;
return(slot->latch);
}
}
mutex_exit(&sync_thread_mutex);
return(NULL);
}
/******************************************************************//**
Checks if the level array for the current thread is empty,
except for the btr_search_latch.
@return a latch, or NULL if empty except the exceptions specified below */
UNIV_INTERN
void*
sync_thread_levels_nonempty_trx(
/*============================*/
ibool has_search_latch)
/*!< in: TRUE if and only if the thread
is supposed to hold btr_search_latch */
{
ulint i;
sync_arr_t* arr;
sync_thread_t* thread_slot;
if (!sync_order_checks_on) {
return(NULL);
}
ut_a(!has_search_latch
|| sync_thread_levels_contains(SYNC_SEARCH_SYS));
mutex_enter(&sync_thread_mutex);
thread_slot = sync_thread_level_arrays_find_slot();
if (thread_slot == NULL) {
mutex_exit(&sync_thread_mutex);
return(NULL);
}
arr = thread_slot->levels;
for (i = 0; i < arr->size(); ++i) {
const sync_level_t* slot;
slot = (const sync_level_t*)&(arr->at(i));
if (slot->latch != NULL
&& (!has_search_latch
|| slot->level != SYNC_SEARCH_SYS)) {
mutex_exit(&sync_thread_mutex);
ut_error;
return(slot->latch);
}
}
mutex_exit(&sync_thread_mutex);
return(NULL);
}
/******************************************************************//**
Adds a latch and its level in the thread level array. Allocates the memory
for the array if called first time for this OS thread. Makes the checks
against other latch levels stored in the array for this thread. */
UNIV_INTERN
void
sync_thread_add_level(
/*==================*/
void* latch, /*!< in: pointer to a mutex or an rw-lock */
ulint level, /*!< in: level in the latching order; if
SYNC_LEVEL_VARYING, nothing is done */
ibool relock) /*!< in: TRUE if re-entering an x-lock */
{
sync_arr_t* array;
sync_thread_t* thread_slot;
sync_level_t sync_level;
if (!sync_order_checks_on) {
return;
}
if ((latch == (void*) &sync_thread_mutex)
|| (latch == (void*) &mutex_list_mutex)
|| (latch == (void*) &rw_lock_debug_mutex)
|| (latch == (void*) &rw_lock_list_mutex)) {
return;
}
if (level == SYNC_LEVEL_VARYING) {
return;
}
mutex_enter(&sync_thread_mutex);
thread_slot = sync_thread_level_arrays_find_slot();
if (thread_slot == NULL) {
/* We have to allocate the level array for a new thread */
array = new sync_arr_t();
ut_a(array != NULL);
thread_slot = sync_thread_level_arrays_find_free();
thread_slot->levels = array;
thread_slot->id = os_thread_get_curr_id();
}
array = thread_slot->levels;
if (relock) {
goto levels_ok;
}
/* NOTE that there is a problem with _NODE and _LEAF levels: if the
B-tree height changes, then a leaf can change to an internal node
or the other way around. We do not know at present if this can cause
unnecessary assertion failures below. */
switch (level) {
case SYNC_NO_ORDER_CHECK:
case SYNC_EXTERN_STORAGE:
case SYNC_TREE_NODE_FROM_HASH:
/* Do no order checking */
break;
case SYNC_TRX_SYS_HEADER:
if (srv_is_being_started) {
/* This is violated during trx_sys_create_rsegs()
when creating additional rollback segments when
upgrading in innobase_start_or_create_for_mysql(). */
break;
}
case SYNC_MEM_POOL:
case SYNC_MEM_HASH:
case SYNC_RECV:
case SYNC_FTS_BG_THREADS:
case SYNC_WORK_QUEUE:
case SYNC_FTS_TOKENIZE:
case SYNC_FTS_OPTIMIZE:
case SYNC_FTS_CACHE:
case SYNC_FTS_CACHE_INIT:
case SYNC_LOG_ONLINE:
case SYNC_LOG:
case SYNC_LOG_FLUSH_ORDER:
case SYNC_ANY_LATCH:
case SYNC_FILE_FORMAT_TAG:
case SYNC_DOUBLEWRITE:
case SYNC_THREADS:
case SYNC_LOCK_SYS:
case SYNC_LOCK_WAIT_SYS:
case SYNC_TRX_SYS:
case SYNC_IBUF_BITMAP_MUTEX:
case SYNC_RSEG:
case SYNC_TRX_UNDO:
case SYNC_PURGE_LATCH:
case SYNC_PURGE_QUEUE:
case SYNC_DICT_AUTOINC_MUTEX:
case SYNC_DICT_OPERATION:
case SYNC_DICT_HEADER:
case SYNC_TRX_I_S_RWLOCK:
case SYNC_TRX_I_S_LAST_READ:
case SYNC_IBUF_MUTEX:
case SYNC_INDEX_ONLINE_LOG:
case SYNC_STATS_AUTO_RECALC:
case SYNC_STATS_DEFRAG:
if (!sync_thread_levels_g(array, level, TRUE)) {
fprintf(stderr,
"InnoDB: sync_thread_levels_g(array, %lu)"
" does not hold!\n", level);
ut_error;
}
break;
case SYNC_TRX:
/* Either the thread must own the lock_sys->mutex, or
it is allowed to own only ONE trx->mutex. */
if (!sync_thread_levels_g(array, level, FALSE)) {
ut_a(sync_thread_levels_g(array, level - 1, TRUE));
ut_a(sync_thread_levels_contain(array, SYNC_LOCK_SYS));
}
break;
case SYNC_SEARCH_SYS: {
/* Verify the lock order inside the split btr_search_latch
array */
bool found_current = false;
for (ulint i = 0; i < btr_search_index_num; i++) {
if (&btr_search_latch_arr[i] == latch) {
found_current = true;
} else if (found_current) {
ut_ad(!rw_lock_own(&btr_search_latch_arr[i],
RW_LOCK_SHARED));
ut_ad(!rw_lock_own(&btr_search_latch_arr[i],
RW_LOCK_EX));
}
}
ut_ad(found_current);
/* fallthrough */
}
case SYNC_BUF_FLUSH_LIST:
case SYNC_BUF_LRU_LIST:
case SYNC_BUF_FREE_LIST:
case SYNC_BUF_ZIP_FREE:
case SYNC_BUF_ZIP_HASH:
case SYNC_BUF_FLUSH_STATE:
/* We can have multiple mutexes of this type therefore we
can only check whether the greater than condition holds. */
if (!sync_thread_levels_g(array, level-1, TRUE)) {
fprintf(stderr,
"InnoDB: sync_thread_levels_g(array, %lu)"
" does not hold!\n", level-1);
ut_error;
}
break;
case SYNC_BUF_PAGE_HASH:
/* Multiple page_hash locks are only allowed during
buf_validate. */
/* Fall through */
case SYNC_BUF_BLOCK:
if (!sync_thread_levels_g(array, level, FALSE)) {
ut_a(sync_thread_levels_g(array, level - 1, TRUE));
}
break;
case SYNC_REC_LOCK:
if (sync_thread_levels_contain(array, SYNC_LOCK_SYS)) {
ut_a(sync_thread_levels_g(array, SYNC_REC_LOCK - 1,
TRUE));
} else {
ut_a(sync_thread_levels_g(array, SYNC_REC_LOCK, TRUE));
}
break;
case SYNC_IBUF_BITMAP:
/* Either the thread must own the master mutex to all
the bitmap pages, or it is allowed to latch only ONE
bitmap page. */
if (sync_thread_levels_contain(array,
SYNC_IBUF_BITMAP_MUTEX)) {
ut_a(sync_thread_levels_g(array, SYNC_IBUF_BITMAP - 1,
TRUE));
} else {
/* This is violated during trx_sys_create_rsegs()
when creating additional rollback segments when
upgrading in innobase_start_or_create_for_mysql(). */
ut_a(srv_is_being_started
|| sync_thread_levels_g(array, SYNC_IBUF_BITMAP,
TRUE));
}
break;
case SYNC_FSP_PAGE:
ut_a(sync_thread_levels_contain(array, SYNC_FSP));
break;
case SYNC_FSP:
ut_a(sync_thread_levels_contain(array, SYNC_FSP)
|| sync_thread_levels_g(array, SYNC_FSP, TRUE));
break;
case SYNC_TRX_UNDO_PAGE:
/* Purge is allowed to read in as many UNDO pages as it likes,
there was a bogus rule here earlier that forced the caller to
acquire the purge_sys_t::mutex. The purge mutex did not really
protect anything because it was only ever acquired by the
single purge thread. The purge thread can read the UNDO pages
without any covering mutex. */
ut_a(sync_thread_levels_contain(array, SYNC_TRX_UNDO)
|| sync_thread_levels_contain(array, SYNC_RSEG)
|| sync_thread_levels_g(array, level - 1, TRUE));
break;
case SYNC_RSEG_HEADER:
ut_a(sync_thread_levels_contain(array, SYNC_RSEG));
break;
case SYNC_RSEG_HEADER_NEW:
ut_a(sync_thread_levels_contain(array, SYNC_FSP_PAGE));
break;
case SYNC_TREE_NODE:
ut_a(sync_thread_levels_contain(array, SYNC_INDEX_TREE)
|| sync_thread_levels_contain(array, SYNC_DICT_OPERATION)
|| sync_thread_levels_g(array, SYNC_TREE_NODE - 1, TRUE));
break;
case SYNC_TREE_NODE_NEW:
ut_a(sync_thread_levels_contain(array, SYNC_FSP_PAGE));
break;
case SYNC_INDEX_TREE:
ut_a(sync_thread_levels_g(array, SYNC_TREE_NODE - 1, TRUE));
break;
case SYNC_IBUF_TREE_NODE:
ut_a(sync_thread_levels_contain(array, SYNC_IBUF_INDEX_TREE)
|| sync_thread_levels_g(array, SYNC_IBUF_TREE_NODE - 1,
TRUE));
break;
case SYNC_IBUF_TREE_NODE_NEW:
/* ibuf_add_free_page() allocates new pages for the
change buffer while only holding the tablespace
x-latch. These pre-allocated new pages may only be
taken in use while holding ibuf_mutex, in
btr_page_alloc_for_ibuf(). */
ut_a(sync_thread_levels_contain(array, SYNC_IBUF_MUTEX)
|| sync_thread_levels_contain(array, SYNC_FSP));
break;
case SYNC_IBUF_INDEX_TREE:
if (sync_thread_levels_contain(array, SYNC_FSP)) {
ut_a(sync_thread_levels_g(array, level - 1, TRUE));
} else {
ut_a(sync_thread_levels_g(
array, SYNC_IBUF_TREE_NODE - 1, TRUE));
}
break;
case SYNC_IBUF_PESS_INSERT_MUTEX:
ut_a(sync_thread_levels_g(array, SYNC_FSP - 1, TRUE));
ut_a(!sync_thread_levels_contain(array, SYNC_IBUF_MUTEX));
break;
case SYNC_IBUF_HEADER:
ut_a(sync_thread_levels_g(array, SYNC_FSP - 1, TRUE));
ut_a(!sync_thread_levels_contain(array, SYNC_IBUF_MUTEX));
ut_a(!sync_thread_levels_contain(array,
SYNC_IBUF_PESS_INSERT_MUTEX));
break;
case SYNC_DICT:
#ifdef UNIV_DEBUG
ut_a(buf_debug_prints
|| sync_thread_levels_g(array, SYNC_DICT, TRUE));
#else /* UNIV_DEBUG */
ut_a(sync_thread_levels_g(array, SYNC_DICT, TRUE));
#endif /* UNIV_DEBUG */
break;
default:
ut_error;
}
levels_ok:
sync_level.latch = latch;
sync_level.level = level;
array->push_back(sync_level);
mutex_exit(&sync_thread_mutex);
}
/******************************************************************//**
Removes a latch from the thread level array if it is found there.
@return TRUE if found in the array; it is no error if the latch is
not found, as we presently are not able to determine the level for
every latch reservation the program does */
UNIV_INTERN
ibool
sync_thread_reset_level(
/*====================*/
void* latch) /*!< in: pointer to a mutex or an rw-lock */
{
sync_arr_t* array;
sync_thread_t* thread_slot;
if (!sync_order_checks_on) {
return(FALSE);
}
if ((latch == (void*) &sync_thread_mutex)
|| (latch == (void*) &mutex_list_mutex)
|| (latch == (void*) &rw_lock_debug_mutex)
|| (latch == (void*) &rw_lock_list_mutex)) {
return(FALSE);
}
mutex_enter(&sync_thread_mutex);
thread_slot = sync_thread_level_arrays_find_slot();
if (thread_slot == NULL) {
ut_error;
mutex_exit(&sync_thread_mutex);
return(FALSE);
}
array = thread_slot->levels;
for (std::vector<sync_level_t>::iterator it = array->begin(); it != array->end(); ++it) {
sync_level_t level = *it;
if (level.latch != latch) {
continue;
}
array->erase(it);
mutex_exit(&sync_thread_mutex);
return(TRUE);
}
if (((ib_mutex_t*) latch)->magic_n != MUTEX_MAGIC_N) {
rw_lock_t* rw_lock;
rw_lock = (rw_lock_t*) latch;
if (rw_lock->level == SYNC_LEVEL_VARYING) {
mutex_exit(&sync_thread_mutex);
return(TRUE);
}
}
ut_error;
mutex_exit(&sync_thread_mutex);
return(FALSE);
}
#endif /* UNIV_SYNC_DEBUG */
/******************************************************************//**
Initializes the synchronization data structures. */
UNIV_INTERN
void
sync_init(void)
/*===========*/
{
ut_a(sync_initialized == FALSE);
sync_initialized = TRUE;
sync_array_init(OS_THREAD_MAX_N);
#ifdef UNIV_SYNC_DEBUG
/* Create the thread latch level array where the latch levels
are stored for each OS thread */
sync_thread_level_arrays = static_cast<sync_thread_t*>(
calloc(sizeof(sync_thread_t), OS_THREAD_MAX_N));
ut_a(sync_thread_level_arrays != NULL);
#endif /* UNIV_SYNC_DEBUG */
/* Init the mutex list and create the mutex to protect it. */
UT_LIST_INIT(mutex_list);
mutex_create(mutex_list_mutex_key, &mutex_list_mutex,
SYNC_NO_ORDER_CHECK);
#ifdef UNIV_SYNC_DEBUG
mutex_create(sync_thread_mutex_key, &sync_thread_mutex,
SYNC_NO_ORDER_CHECK);
#endif /* UNIV_SYNC_DEBUG */
/* Init the rw-lock list and create the mutex to protect it. */
UT_LIST_INIT(rw_lock_list);
mutex_create(rw_lock_list_mutex_key, &rw_lock_list_mutex,
SYNC_NO_ORDER_CHECK);
#ifdef UNIV_SYNC_DEBUG
os_fast_mutex_init(rw_lock_debug_mutex_key, &rw_lock_debug_mutex);
#endif /* UNIV_SYNC_DEBUG */
}
#ifdef UNIV_SYNC_DEBUG
/******************************************************************//**
Frees all debug memory. */
static
void
sync_thread_level_arrays_free(void)
/*===============================*/
{
ulint i;
for (i = 0; i < OS_THREAD_MAX_N; i++) {
sync_thread_t* slot;
slot = &sync_thread_level_arrays[i];
/* If this slot was allocated then free the slot memory too. */
if (slot->levels != NULL) {
delete slot->levels;
}
}
free(sync_thread_level_arrays);
sync_thread_level_arrays = NULL;
}
#endif /* UNIV_SYNC_DEBUG */
/******************************************************************//**
Frees the resources in InnoDB's own synchronization data structures. */
UNIV_INTERN
void
sync_close(void)
/*===========*/
{
ib_mutex_t* mutex;
sync_array_close();
mutex_free(&rw_lock_list_mutex);
for (mutex = UT_LIST_GET_FIRST(mutex_list);
mutex != NULL;
/* No op */) {
#ifdef UNIV_MEM_DEBUG
if (mutex == &mem_hash_mutex) {
mutex = UT_LIST_GET_NEXT(list, mutex);
continue;
}
#endif /* UNIV_MEM_DEBUG */
mutex_free(mutex);
mutex = UT_LIST_GET_FIRST(mutex_list);
}
#ifdef UNIV_SYNC_DEBUG
mutex_free(&sync_thread_mutex);
/* Switch latching order checks on in sync0sync.cc */
sync_order_checks_on = FALSE;
sync_thread_level_arrays_free();
os_fast_mutex_free(&rw_lock_debug_mutex);
#endif /* UNIV_SYNC_DEBUG */
mutex_free(&mutex_list_mutex);
sync_initialized = FALSE;
}
/*******************************************************************//**
Prints wait info of the sync system. */
UNIV_INTERN
void
sync_print_wait_info(
/*=================*/
FILE* file) /*!< in: file where to print */
{
// Sum counter values once
ib_int64_t mutex_spin_wait_count_val
= static_cast<ib_int64_t>(mutex_spin_wait_count);
ib_int64_t mutex_spin_round_count_val
= static_cast<ib_int64_t>(mutex_spin_round_count);
ib_int64_t mutex_os_wait_count_val
= static_cast<ib_int64_t>(mutex_os_wait_count);
ib_int64_t rw_s_spin_wait_count_val
= static_cast<ib_int64_t>(rw_lock_stats.rw_s_spin_wait_count);
ib_int64_t rw_s_spin_round_count_val
= static_cast<ib_int64_t>(rw_lock_stats.rw_s_spin_round_count);
ib_int64_t rw_s_os_wait_count_val
= static_cast<ib_int64_t>(rw_lock_stats.rw_s_os_wait_count);
ib_int64_t rw_x_spin_wait_count_val
= static_cast<ib_int64_t>(rw_lock_stats.rw_x_spin_wait_count);
ib_int64_t rw_x_spin_round_count_val
= static_cast<ib_int64_t>(rw_lock_stats.rw_x_spin_round_count);
ib_int64_t rw_x_os_wait_count_val
= static_cast<ib_int64_t>(rw_lock_stats.rw_x_os_wait_count);
fprintf(file,
"Mutex spin waits " INT64PF ", rounds " INT64PF ", "
"OS waits " INT64PF "\n"
"RW-shared spins " INT64PF ", rounds " INT64PF ", "
"OS waits " INT64PF "\n"
"RW-excl spins " INT64PF ", rounds " INT64PF ", "
"OS waits " INT64PF "\n",
mutex_spin_wait_count_val, mutex_spin_round_count_val,
mutex_os_wait_count_val,
rw_s_spin_wait_count_val, rw_s_spin_round_count_val,
rw_s_os_wait_count_val,
rw_x_spin_wait_count_val, rw_x_spin_round_count_val,
rw_x_os_wait_count_val);
fprintf(file,
"Spin rounds per wait: %.2f mutex, %.2f RW-shared, "
"%.2f RW-excl\n",
(double) mutex_spin_round_count_val /
(mutex_spin_wait_count_val ? mutex_spin_wait_count_val : 1LL),
(double) rw_s_spin_round_count_val /
(rw_s_spin_wait_count_val ? rw_s_spin_wait_count_val : 1LL),
(double) rw_x_spin_round_count_val /
(rw_x_spin_wait_count_val ? rw_x_spin_wait_count_val : 1LL));
}
/*******************************************************************//**
Prints info of the sync system. */
UNIV_INTERN
void
sync_print(
/*=======*/
FILE* file) /*!< in: file where to print */
{
#ifdef UNIV_SYNC_DEBUG
mutex_list_print_info(file);
rw_lock_list_print_info(file);
#endif /* UNIV_SYNC_DEBUG */
sync_array_print(file);
sync_print_wait_info(file);
}
|