File: mutex_int.h

package info (click to toggle)
db5.3 5.3.28-12+deb9u1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 163,332 kB
  • ctags: 82,990
  • sloc: ansic: 448,411; java: 111,824; tcl: 80,544; sh: 44,326; cs: 33,697; cpp: 21,604; perl: 14,557; xml: 10,799; makefile: 4,106; yacc: 1,003; awk: 965; sql: 801; erlang: 342; python: 216; php: 24; asm: 14
file content (1074 lines) | stat: -rw-r--r-- 34,080 bytes parent folder | download | duplicates (5)
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
/*
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 2013 Oracle and/or its affiliates.  All rights reserved.
 *
 * $Id$
 */

#ifndef _DB_MUTEX_INT_H_
#define	_DB_MUTEX_INT_H_

#include "dbinc/atomic.h"

#if defined(__cplusplus)
extern "C" {
#endif

/*
 * Mutexes and Shared Latches
 *
 * Mutexes may be test-and-set (spinning & yielding when busy),
 * native versions (pthreads, WaitForSingleObject)
 * or a hybrid which has the lower no-contention overhead of test-and-set
 * mutexes, using operating system calls only to block and wakeup.
 *
 * Hybrid exclusive-only mutexes include a 'tas' field.
 * Hybrid DB_MUTEX_SHARED latches also include a 'shared' field.
 */

/*********************************************************************
 * POSIX.1 pthreads interface.
 *********************************************************************/
#if defined(HAVE_MUTEX_PTHREADS)
/*
 * Pthreads-based mutexes (exclusive-only) and latches (possibly shared)
 * have the same MUTEX_FIELDS union. Different parts of the union are used
 * depending on:
 *    -	whether HAVE_SHARED_LATCHES is defined, and
 *    - if HAVE_SHARED_LATCHES, whether this particular instance of a mutex
 *	is a shared mutexDB_MUTEX_SHARED.
 *
 * The rwlock part of the union is used *only* for non-hybrid shared latches;
 * in all other cases the mutex and cond fields are the only ones used.
 *
 *  configuration &	Who uses the field
 *  mutex
 *			mutex	cond	rwlock	tas
 * Native mutex		y	y
 * Hybrid mutexes	y	y		y
 * Native sharedlatches			y
 * Hybrid sharedlatches	y	y		y
 *
 * They all have a condition variable which is used only for
 * DB_MUTEX_SELF_BLOCK waits.
 *
 * There can be no self-blocking shared latches: the pthread_cond_wait() would
 * require getting a pthread_mutex_t, also it would not make sense.
 */
#define	MUTEX_FIELDS							\
	union {								\
		struct {						\
		    pthread_mutex_t mutex;	/* Mutex */		\
		    pthread_cond_t  cond;	/* Condition variable */ \
		} m;							\
		pthread_rwlock_t rwlock;	/* Read/write lock */	\
	} u;

#if defined(HAVE_SHARED_LATCHES) && !defined(HAVE_MUTEX_HYBRID)
#define	RET_SET_PTHREAD_LOCK(mutexp, ret) do {				\
	if (F_ISSET(mutexp, DB_MUTEX_SHARED))				\
		RET_SET((pthread_rwlock_wrlock(&(mutexp)->u.rwlock)),	\
		    ret);						\
	else								\
		RET_SET((pthread_mutex_lock(&(mutexp)->u.m.mutex)), ret); \
} while (0)
#define	RET_SET_PTHREAD_TRYLOCK(mutexp, ret) do {			\
	if (F_ISSET(mutexp, DB_MUTEX_SHARED))				\
		RET_SET((pthread_rwlock_trywrlock(&(mutexp)->u.rwlock)), \
		    ret);						\
	else								\
		RET_SET((pthread_mutex_trylock(&(mutexp)->u.m.mutex)),	\
		    ret);						\
} while (0)
#else
#define	RET_SET_PTHREAD_LOCK(mutexp, ret)				\
		RET_SET(pthread_mutex_lock(&(mutexp)->u.m.mutex), ret);
#define	RET_SET_PTHREAD_TRYLOCK(mutexp, ret)				\
		RET_SET(pthread_mutex_trylock(&(mutexp)->u.m.mutex), ret);
#endif
#endif

#ifdef HAVE_MUTEX_UI_THREADS
#include <thread.h>
#endif

/*********************************************************************
 * Solaris lwp threads interface.
 *
 * !!!
 * We use LWP mutexes on Solaris instead of UI or POSIX mutexes (both of
 * which are available), for two reasons.  First, the Solaris C library
 * includes versions of the both UI and POSIX thread mutex interfaces, but
 * they are broken in that they don't support inter-process locking, and
 * there's no way to detect it, e.g., calls to configure the mutexes for
 * inter-process locking succeed without error.  So, we use LWP mutexes so
 * that we don't fail in fairly undetectable ways because the application
 * wasn't linked with the appropriate threads library.  Second, there were
 * bugs in SunOS 5.7 (Solaris 7) where if an application loaded the C library
 * before loading the libthread/libpthread threads libraries (e.g., by using
 * dlopen to load the DB library), the pwrite64 interface would be translated
 * into a call to pwrite and DB would drop core.
 *********************************************************************/
#ifdef HAVE_MUTEX_SOLARIS_LWP
/*
 * XXX
 * Don't change <synch.h> to <sys/lwp.h> -- although lwp.h is listed in the
 * Solaris manual page as the correct include to use, it causes the Solaris
 * compiler on SunOS 2.6 to fail.
 */
#include <synch.h>

#define	MUTEX_FIELDS							\
	lwp_mutex_t mutex;		/* Mutex. */			\
	lwp_cond_t cond;		/* Condition variable. */
#endif

/*********************************************************************
 * Solaris/Unixware threads interface.
 *********************************************************************/
#ifdef HAVE_MUTEX_UI_THREADS
#include <thread.h>
#include <synch.h>

#define	MUTEX_FIELDS							\
	mutex_t mutex;			/* Mutex. */			\
	cond_t  cond;			/* Condition variable. */
#endif

/*********************************************************************
 * AIX C library functions.
 *********************************************************************/
#ifdef HAVE_MUTEX_AIX_CHECK_LOCK
#include <sys/atomic_op.h>
typedef int tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)	0
#define	MUTEX_SET(x)	(!_check_lock(x, 0, 1))
#define	MUTEX_UNSET(x)	_clear_lock(x, 0)
#endif
#endif

/*********************************************************************
 * Apple/Darwin library functions.
 *********************************************************************/
#ifdef HAVE_MUTEX_DARWIN_SPIN_LOCK_TRY
typedef u_int32_t tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
extern int _spin_lock_try(tsl_t *);
extern void _spin_unlock(tsl_t *);
#define	MUTEX_SET(tsl)          _spin_lock_try(tsl)
#define	MUTEX_UNSET(tsl)        _spin_unlock(tsl)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * General C library functions (msemaphore).
 *
 * !!!
 * Check for HPPA as a special case, because it requires unusual alignment,
 * and doesn't support semaphores in malloc(3) or shmget(2) memory.
 *
 * !!!
 * Do not remove the MSEM_IF_NOWAIT flag.  The problem is that if a single
 * process makes two msem_lock() calls in a row, the second one returns an
 * error.  We depend on the fact that we can lock against ourselves in the
 * locking subsystem, where we set up a mutex so that we can block ourselves.
 * Tested on OSF1 v4.0.
 *********************************************************************/
#ifdef HAVE_MUTEX_HPPA_MSEM_INIT
#define	MUTEX_ALIGN	16
#endif

#if defined(HAVE_MUTEX_MSEM_INIT) || defined(HAVE_MUTEX_HPPA_MSEM_INIT)
#include <sys/mman.h>
typedef msemaphore tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)	(msem_init(x, MSEM_UNLOCKED) <= (msemaphore *)0)
#define	MUTEX_SET(x)	(!msem_lock(x, MSEM_IF_NOWAIT))
#define	MUTEX_UNSET(x)	msem_unlock(x, 0)
#endif
#endif

/*********************************************************************
 * Plan 9 library functions.
 *********************************************************************/
#ifdef HAVE_MUTEX_PLAN9
typedef Lock tsl_t;

#define	MUTEX_INIT(x)	(memset(x, 0, sizeof(Lock)), 0)
#define	MUTEX_SET(x)	canlock(x)
#define	MUTEX_UNSET(x)	unlock(x)
#endif

/*********************************************************************
 * Reliant UNIX C library functions.
 *********************************************************************/
#ifdef HAVE_MUTEX_RELIANTUNIX_INITSPIN
#include <ulocks.h>
typedef spinlock_t tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)	(initspin(x, 1), 0)
#define	MUTEX_SET(x)	(cspinlock(x) == 0)
#define	MUTEX_UNSET(x)	spinunlock(x)
#endif
#endif

/*********************************************************************
 * General C library functions (POSIX 1003.1 sema_XXX).
 *
 * !!!
 * Never selected by autoconfig in this release (semaphore calls are known
 * to not work in Solaris 5.5).
 *********************************************************************/
#ifdef HAVE_MUTEX_SEMA_INIT
#include <synch.h>
typedef sema_t tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_DESTROY(x) sema_destroy(x)
#define	MUTEX_INIT(x)	 (sema_init(x, 1, USYNC_PROCESS, NULL) != 0)
#define	MUTEX_SET(x)	 (sema_wait(x) == 0)
#define	MUTEX_UNSET(x)	 sema_post(x)
#endif
#endif

/*********************************************************************
 * SGI C library functions.
 *********************************************************************/
#ifdef HAVE_MUTEX_SGI_INIT_LOCK
#include <abi_mutex.h>
typedef abilock_t tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)	(init_lock(x) != 0)
#define	MUTEX_SET(x)	(!acquire_lock(x))
#define	MUTEX_UNSET(x)	release_lock(x)
#endif
#endif

/*********************************************************************
 * Solaris C library functions.
 *
 * !!!
 * These are undocumented functions, but they're the only ones that work
 * correctly as far as we know.
 *********************************************************************/
#ifdef HAVE_MUTEX_SOLARIS_LOCK_TRY
#include <sys/atomic.h>
#define	MUTEX_MEMBAR(x)	membar_enter()
#define	MEMBAR_ENTER()	membar_enter()
#define	MEMBAR_EXIT()	membar_exit()
#include <sys/machlock.h>
typedef lock_t tsl_t;

/*
 * The functions are declared in <sys/machlock.h>, but under #ifdef KERNEL.
 * Re-declare them here to avoid warnings.
 */
extern  int _lock_try(lock_t *);
extern void _lock_clear(lock_t *);

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)	0
#define	MUTEX_SET(x)	_lock_try(x)
#define	MUTEX_UNSET(x)	_lock_clear(x)
#endif
#endif

/*********************************************************************
 * VMS.
 *********************************************************************/
#ifdef HAVE_MUTEX_VMS
#include <sys/mman.h>
#include <builtins.h>
typedef volatile unsigned char tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#ifdef __ALPHA
#define	MUTEX_SET(tsl)		(!__TESTBITSSI(tsl, 0))
#else /* __VAX */
#define	MUTEX_SET(tsl)		(!(int)_BBSSI(0, tsl))
#endif
#define	MUTEX_UNSET(tsl)	(*(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * VxWorks
 * Use basic binary semaphores in VxWorks, as we currently do not need
 * any special features.  We do need the ability to single-thread the
 * entire system, however, because VxWorks doesn't support the open(2)
 * flag O_EXCL, the mechanism we normally use to single thread access
 * when we're first looking for a DB environment.
 *********************************************************************/
#ifdef HAVE_MUTEX_VXWORKS
#include "taskLib.h"
typedef SEM_ID tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * Uses of this MUTEX_SET() need to have a local 'nowait' variable,
 * which determines whether to return right away when the semaphore
 * is busy or to wait until it is available.
 */
#define	MUTEX_SET(tsl)							\
	(semTake((*(tsl)), nowait ? NO_WAIT : WAIT_FOREVER) == OK)
#define	MUTEX_UNSET(tsl)	(semGive((*tsl)))
#define	MUTEX_INIT(tsl)							\
	((*(tsl) = semBCreate(SEM_Q_FIFO, SEM_FULL)) == NULL)
#define	MUTEX_DESTROY(tsl)	semDelete(*tsl)
#endif
#endif

/*********************************************************************
 * Win16
 *
 * Win16 spinlocks are simple because we cannot possibly be preempted.
 *
 * !!!
 * We should simplify this by always returning a no-need-to-lock lock
 * when we initialize the mutex.
 *********************************************************************/
#ifdef HAVE_MUTEX_WIN16
typedef unsigned int tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)		0
#define	MUTEX_SET(tsl)		(*(tsl) = 1)
#define	MUTEX_UNSET(tsl)	(*(tsl) = 0)
#endif
#endif

/*********************************************************************
 * Win32 - always a hybrid mutex
 *********************************************************************/
#if defined(HAVE_MUTEX_WIN32) || defined(HAVE_MUTEX_WIN32_GCC)
typedef LONG volatile tsl_t;
#define	MUTEX_FIELDS							\
	LONG nwaiters;							\
	u_int32_t id;	/* ID used for creating events */		\

#if defined(LOAD_ACTUAL_MUTEX_CODE)
#define	MUTEX_SET(tsl)		(!InterlockedExchange((PLONG)tsl, 1))
#define	MUTEX_UNSET(tsl)	InterlockedExchange((PLONG)tsl, 0)
#define	MUTEX_INIT(tsl)		MUTEX_UNSET(tsl)

/*
 * From Intel's performance tuning documentation (and see SR #6975):
 * ftp://download.intel.com/design/perftool/cbts/appnotes/sse2/w_spinlock.pdf
 *
 * "For this reason, it is highly recommended that you insert the PAUSE
 * instruction into all spin-wait code immediately. Using the PAUSE
 * instruction does not affect the correctness of programs on existing
 * platforms, and it improves performance on Pentium 4 processor platforms."
 */
#ifdef HAVE_MUTEX_WIN32
#if !defined(_WIN64) && !defined(DB_WINCE)
#define	MUTEX_PAUSE		{__asm{_emit 0xf3}; __asm{_emit 0x90}}
#endif
#endif
#ifdef HAVE_MUTEX_WIN32_GCC
#define	MUTEX_PAUSE		__asm__ volatile ("rep; nop" : : );
#endif
#endif
#endif

/*********************************************************************
 * 68K/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_68K_GCC_ASSEMBLY
typedef unsigned char tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/* gcc/68K: 0 is clear, 1 is set. */
#define	MUTEX_SET(tsl) ({						\
	register tsl_t *__l = (tsl);					\
	int __r;							\
	    __asm__ volatile("tas  %1; \n				\
			  seq  %0"					\
		: "=dm" (__r), "=m" (*__l)				\
		: "1" (*__l)						\
		);							\
	__r & 1;							\
})

#define	MUTEX_UNSET(tsl)	(*(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * ALPHA/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_ALPHA_GCC_ASSEMBLY
typedef u_int32_t tsl_t;

#define	MUTEX_ALIGN	4

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * For gcc/alpha.  Should return 0 if could not acquire the lock, 1 if
 * lock was acquired properly.
 */
static inline int
MUTEX_SET(tsl_t *tsl) {
	register tsl_t *__l = tsl;
	register tsl_t __r;
	__asm__ volatile(
		"1:	ldl_l	%0,%2\n"
		"	blbs	%0,2f\n"
		"	or	$31,1,%0\n"
		"	stl_c	%0,%1\n"
		"	beq	%0,3f\n"
		"	mb\n"
		"	br	3f\n"
		"2:	xor	%0,%0\n"
		"3:"
		: "=&r"(__r), "=m"(*__l) : "1"(*__l) : "memory");
	return __r;
}

/*
 * Unset mutex. Judging by Alpha Architecture Handbook, the mb instruction
 * might be necessary before unlocking
 */
static inline int
MUTEX_UNSET(tsl_t *tsl) {
	__asm__ volatile("	mb\n");
	return *tsl = 0;
}

#define	MUTEX_INIT(tsl)		MUTEX_UNSET(tsl)
#endif
#endif

/*********************************************************************
 * Tru64/cc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_TRU64_CC_ASSEMBLY
typedef volatile u_int32_t tsl_t;

#define	MUTEX_ALIGN	4

#ifdef LOAD_ACTUAL_MUTEX_CODE
#include <alpha/builtins.h>
#define	MUTEX_SET(tsl)		(__LOCK_LONG_RETRY((tsl), 1) != 0)
#define	MUTEX_UNSET(tsl)	(__UNLOCK_LONG(tsl))

#define	MUTEX_INIT(tsl)		(MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * ARM/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_ARM_GCC_ASSEMBLY
typedef unsigned char tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/* gcc/arm: 0 is clear, 1 is set. */
#define	MUTEX_SET(tsl) ({						\
	int __r;							\
	__asm__ volatile(						\
		"swpb	%0, %1, [%2]\n\t"				\
		"eor	%0, %0, #1\n\t"					\
	    : "=&r" (__r)						\
	    : "r" (1), "r" (tsl)					\
	    );								\
	__r & 1;							\
})

#define	MUTEX_UNSET(tsl)	(*(volatile tsl_t *)(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * HPPA/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_HPPA_GCC_ASSEMBLY
typedef u_int32_t tsl_t;

#define	MUTEX_ALIGN	16

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * The PA-RISC has a "load and clear" instead of a "test and set" instruction.
 * The 32-bit word used by that instruction must be 16-byte aligned.  We could
 * use the "aligned" attribute in GCC but that doesn't work for stack variables.
 */
#define	MUTEX_SET(tsl) ({						\
	register tsl_t *__l = (tsl);					\
	int __r;							\
	__asm__ volatile("ldcws 0(%1),%0" : "=r" (__r) : "r" (__l));	\
	__r & 1;							\
})

#define	MUTEX_UNSET(tsl)        (*(volatile tsl_t *)(tsl) = -1)
#define	MUTEX_INIT(tsl)		(MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * IA64/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_IA64_GCC_ASSEMBLY
typedef volatile unsigned char tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/* gcc/ia64: 0 is clear, 1 is set. */
#define	MUTEX_SET(tsl) ({						\
	register tsl_t *__l = (tsl);					\
	long __r;							\
	__asm__ volatile("xchg1 %0=%1,%2" :				\
		     "=r"(__r), "+m"(*__l) : "r"(1));			\
	__r ^ 1;							\
})

/*
 * Store through a "volatile" pointer so we get a store with "release"
 * semantics.
 */
#define	MUTEX_UNSET(tsl)	(*(tsl_t *)(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * PowerPC/gcc assembly.
 *********************************************************************/
#if defined(HAVE_MUTEX_PPC_GCC_ASSEMBLY)
typedef u_int32_t tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * The PowerPC does a sort of pseudo-atomic locking.  You set up a
 * 'reservation' on a chunk of memory containing a mutex by loading the
 * mutex value with LWARX.  If the mutex has an 'unlocked' (arbitrary)
 * value, you then try storing into it with STWCX.  If no other process or
 * thread broke your 'reservation' by modifying the memory containing the
 * mutex, then the STCWX succeeds; otherwise it fails and you try to get
 * a reservation again.
 *
 * While mutexes are explicitly 4 bytes, a 'reservation' applies to an
 * entire cache line, normally 32 bytes, aligned naturally.  If the mutex
 * lives near data that gets changed a lot, there's a chance that you'll
 * see more broken reservations than you might otherwise.  The only
 * situation in which this might be a problem is if one processor is
 * beating on a variable in the same cache block as the mutex while another
 * processor tries to acquire the mutex.  That's bad news regardless
 * because of the way it bashes caches, but if you can't guarantee that a
 * mutex will reside in a relatively quiescent cache line, you might
 * consider padding the mutex to force it to live in a cache line by
 * itself.  No, you aren't guaranteed that cache lines are 32 bytes.  Some
 * embedded processors use 16-byte cache lines, while some 64-bit
 * processors use 128-bit cache lines.  But assuming a 32-byte cache line
 * won't get you into trouble for now.
 *
 * If mutex locking is a bottleneck, then you can speed it up by adding a
 * regular LWZ load before the LWARX load, so that you can test for the
 * common case of a locked mutex without wasting cycles making a reservation.
 *
 * gcc/ppc: 0 is clear, 1 is set.
 */
static inline int
MUTEX_SET(int *tsl)  {
	int __r;
	__asm__ volatile (
"0:                             \n\t"
"       lwarx   %0,0,%1         \n\t"
"       cmpwi   %0,0            \n\t"
"       bne-    1f              \n\t"
"       stwcx.  %1,0,%1         \n\t"
"       isync                   \n\t"
"       beq+    2f              \n\t"
"       b       0b              \n\t"
"1:                             \n\t"
"       li      %1,0            \n\t"
"2:                             \n\t"
	 : "=&r" (__r), "+r" (tsl)
	 :
	 : "cr0", "memory");
	 return (int)tsl;
}

static inline int
MUTEX_UNSET(tsl_t *tsl) {
	 __asm__ volatile("sync" : : : "memory");
	 return *tsl = 0;
}
#define	MUTEX_INIT(tsl)		MUTEX_UNSET(tsl)
#endif
#endif

/*********************************************************************
 * OS/390 C.
 *********************************************************************/
#ifdef HAVE_MUTEX_S390_CC_ASSEMBLY
typedef int tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * cs() is declared in <stdlib.h> but is built in to the compiler.
 * Must use LANGLVL(EXTENDED) to get its declaration.
 */
#define	MUTEX_SET(tsl)		(!cs(&zero, (tsl), 1))
#define	MUTEX_UNSET(tsl)	(*(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * S/390 32-bit assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_S390_GCC_ASSEMBLY
typedef int tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/* gcc/S390: 0 is clear, 1 is set. */
static inline int
MUTEX_SET(tsl_t *tsl) {							\
	register tsl_t *__l = (tsl);					\
	int __r;							\
  __asm__ volatile(							\
       "    la    1,%1\n"						\
       "    lhi   0,1\n"						\
       "    l     %0,%1\n"						\
       "0:  cs    %0,0,0(1)\n"						\
       "    jl    0b"							\
       : "=&d" (__r), "+m" (*__l)					\
       : : "0", "1", "cc");						\
	return !__r;							\
}

#define	MUTEX_UNSET(tsl)	(*(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * SCO/cc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_SCO_X86_CC_ASSEMBLY
typedef unsigned char tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * UnixWare has threads in libthread, but OpenServer doesn't (yet).
 *
 * cc/x86: 0 is clear, 1 is set.
 */
#if defined(__USLC__)
asm int
_tsl_set(void *tsl)
{
%mem tsl
	movl	tsl, %ecx
	movl	$1, %eax
	lock
	xchgb	(%ecx),%al
	xorl	$1,%eax
}
#endif

#define	MUTEX_SET(tsl)		_tsl_set(tsl)
#define	MUTEX_UNSET(tsl)	(*(tsl) = 0)
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#endif
#endif

/*********************************************************************
 * Sparc/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_SPARC_GCC_ASSEMBLY
typedef unsigned char tsl_t;

#define	MUTEX_ALIGN	8

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * The ldstub instruction takes the location specified by its first argument
 * (a register containing a memory address) and loads its contents into its
 * second argument (a register) and atomically sets the contents the location
 * specified by its first argument to a byte of 1s.  (The value in the second
 * argument is never read, but only overwritten.)
 *
 * Hybrid mutexes require membar #StoreLoad and #LoadStore ordering on multi-
 * processor v9 systems.
 *
 * gcc/sparc: 0 is clear, 1 is set.
 */
#define	MUTEX_SET(tsl) ({						\
	register tsl_t *__l = (tsl);					\
	register tsl_t __r;						\
	__asm__ volatile						\
	    ("ldstub [%1],%0; stbar"					\
	    : "=r"( __r) : "r" (__l));					\
	!__r;								\
})

#define	MUTEX_UNSET(tsl)	(*(tsl) = 0, MUTEX_MEMBAR(tsl))
#define	MUTEX_INIT(tsl)         (MUTEX_UNSET(tsl), 0)
#define	MUTEX_MEMBAR(x)	\
	({ __asm__ volatile ("membar #StoreStore|#StoreLoad|#LoadStore"); })
#define	MEMBAR_ENTER() \
	({ __asm__ volatile ("membar #StoreStore|#StoreLoad"); })
#define	MEMBAR_EXIT() \
	({ __asm__ volatile ("membar #StoreStore|#LoadStore"); })
#endif
#endif

/*********************************************************************
 * UTS/cc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_UTS_CC_ASSEMBLY
typedef int tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
#define	MUTEX_INIT(x)	0
#define	MUTEX_SET(x)	(!uts_lock(x, 1))
#define	MUTEX_UNSET(x)	(*(x) = 0)
#endif
#endif

/*********************************************************************
 * MIPS/gcc assembly.
 *********************************************************************/
#ifdef HAVE_MUTEX_MIPS_GCC_ASSEMBLY
typedef u_int32_t tsl_t;

#define	MUTEX_ALIGN	4

#ifdef LOAD_ACTUAL_MUTEX_CODE
/*
 * For gcc/MIPS.  Should return 0 if could not acquire the lock, 1 if
 * lock was acquired properly.
 */
static inline int
MUTEX_SET(tsl_t *tsl) {
       register tsl_t *__l = tsl;
       register tsl_t __r, __t;
       __asm__ volatile(
	       "       .set push           \n"
	       "       .set mips2          \n"
	       "       .set noreorder      \n"
	       "       .set nomacro        \n"
	       "1:     ll      %0, %3      \n"
	       "       ori     %2, %0, 1   \n"
	       "       sc      %2, %1      \n"
	       "       beqzl   %2, 1b      \n"
	       "       nop                 \n"
	       "       andi    %2, %0, 1   \n"
	       "       sync                \n"
	       "       .set reorder        \n"
	       "       .set pop            \n"
	       : "=&r" (__t), "=m" (*tsl), "=&r" (__r)
	       : "m" (*tsl)
	       : "memory");
       return (!__r);
}

static inline void
MUTEX_UNSET(tsl_t *tsl) {
	__asm__ volatile(
	       "       .set noreorder      \n"
	       "       sync                \n"
	       "       sw      $0, %0      \n"
	       "       .set reorder        \n"
	       : "=m" (*tsl)
	       : "m" (*tsl)
	       : "memory");
}

#define	       MUTEX_INIT(tsl)         (*(tsl) = 0)
#endif
#endif

/*********************************************************************
 * x86/gcc (32- and 64-bit) assembly.
 *********************************************************************/
#if defined(HAVE_MUTEX_X86_GCC_ASSEMBLY) || \
    defined(HAVE_MUTEX_X86_64_GCC_ASSEMBLY)
typedef volatile unsigned char tsl_t;

#ifdef LOAD_ACTUAL_MUTEX_CODE
/* gcc/x86: 0 is clear, 1 is set. */
#define	MUTEX_SET(tsl) ({						\
	tsl_t __r;							\
	__asm__ volatile("movb $1, %b0\n\t"				\
		"xchgb %b0,%1"						\
	    : "=&q" (__r)						\
	    : "m" (*(tsl_t *)(tsl))					\
	    : "memory", "cc");						\
	!__r;	/* return 1 on success, 0 on failure */			\
})

#define	MUTEX_UNSET(tsl)        (*(tsl_t *)(tsl) = 0)
#define	MUTEX_INIT(tsl)		(MUTEX_UNSET(tsl), 0)
/*
 * We need to pass a valid address to generate the memory barrier
 * otherwise PURIFY will complain.  Use something referenced recently
 * and initialized.
 */
#if defined(HAVE_MUTEX_X86_GCC_ASSEMBLY)
#define	MUTEX_MEMBAR(addr)						\
    ({ __asm__ volatile ("lock; addl $0, %0" ::"m" (addr): "memory"); 1; })
#else
#define	MUTEX_MEMBAR(addr)						\
    ({ __asm__ volatile ("mfence" ::: "memory"); 1; })
#endif

/*
 * From Intel's performance tuning documentation (and see SR #6975):
 * ftp://download.intel.com/design/perftool/cbts/appnotes/sse2/w_spinlock.pdf
 *
 * "For this reason, it is highly recommended that you insert the PAUSE
 * instruction into all spin-wait code immediately. Using the PAUSE
 * instruction does not affect the correctness of programs on existing
 * platforms, and it improves performance on Pentium 4 processor platforms."
 */
#define	MUTEX_PAUSE		__asm__ volatile ("rep; nop" : : );
#endif
#endif

/* End of operating system & hardware architecture-specific definitions */

/*
 * Mutex alignment defaults to sizeof(unsigned int).
 *
 * !!!
 * Various systems require different alignments for mutexes (the worst we've
 * seen so far is 16-bytes on some HP architectures).  Malloc(3) is assumed
 * to return reasonable alignment, all other mutex users must ensure proper
 * alignment locally.
 */
#ifndef	MUTEX_ALIGN
# if defined(__linux__) && defined(__sparc__)
# define	MUTEX_ALIGN	8
# else
# define	MUTEX_ALIGN	sizeof(unsigned int)
# endif
#endif

/*
 * Mutex destruction defaults to a no-op.
 */
#ifndef	MUTEX_DESTROY
#define	MUTEX_DESTROY(x)
#endif

/*
 * Mutex pause defaults to a no-op.
 */
#ifndef	MUTEX_PAUSE
#define	MUTEX_PAUSE
#endif

/*
 * If no native atomic support is available then use mutexes to
 * emulate atomic increment, decrement, and compare-and-exchange.
 * The address of the atomic value selects which of a small number
 * of mutexes to use to protect the updates.
 * The number of mutexes should be somewhat larger than the number of
 * processors in the system in order to minimize unnecessary contention.
 * It defaults to 8 to handle most small (1-4) cpu systems, if it hasn't
 * already been defined (e.g. in db_config.h)
 */
#if !defined(HAVE_ATOMIC_SUPPORT) && defined(HAVE_MUTEX_SUPPORT) && \
    !defined(MAX_ATOMIC_MUTEXES)
#define	MAX_ATOMIC_MUTEXES	1
#endif

/*
 * DB_MUTEXMGR --
 *	The mutex manager encapsulates the mutex system.
 */
struct __db_mutexmgr {
	/* These fields are never updated after creation, so not protected. */
	DB_ENV	*dbenv;			/* Environment */
	REGINFO	 reginfo;		/* Region information */

	void	*mutex_array;		/* Base of the mutex array */
};

/* Macros to lock/unlock the mutex region as a whole. */
#define	MUTEX_SYSTEM_LOCK(dbenv)					\
	MUTEX_LOCK(dbenv, ((DB_MUTEXREGION *)				\
	    (dbenv)->mutex_handle->reginfo.primary)->mtx_region)
#define	MUTEX_SYSTEM_UNLOCK(dbenv)					\
	MUTEX_UNLOCK(dbenv, ((DB_MUTEXREGION *)				\
	    (dbenv)->mutex_handle->reginfo.primary)->mtx_region)

/*
 * DB_MUTEXREGION --
 *	The primary mutex data structure in the shared memory region.
 */
typedef struct __db_mutexregion { /* SHARED */
	/* These fields are initialized at create time and never modified. */
	roff_t		mutex_off_alloc;/* Offset of mutex array */
	roff_t		mutex_off;	/* Adjusted offset of mutex array */
	db_size_t	mutex_size;	/* Size of the aligned mutex */
	roff_t		thread_off;	/* Offset of the thread area. */

	db_mutex_t	mtx_region;	/* Region mutex. */

	/* Protected using the region mutex. */
	db_mutex_t	mutex_next;	/* Next free mutex */

#if !defined(HAVE_ATOMIC_SUPPORT) && defined(HAVE_MUTEX_SUPPORT)
	/* Mutexes for emulating atomic operations. */
	db_mutex_t	mtx_atomic[MAX_ATOMIC_MUTEXES];
#endif

	DB_MUTEX_STAT	stat;		/* Mutex statistics */
} DB_MUTEXREGION;

#ifdef HAVE_MUTEX_SUPPORT
struct __db_mutex_t { /* SHARED */	/* Mutex. */
#ifdef MUTEX_FIELDS
	MUTEX_FIELDS			/* Opaque thread mutex structures. */
#endif
#ifndef HAVE_MUTEX_FCNTL
#if defined(HAVE_MUTEX_HYBRID) || \
    (defined(HAVE_SHARED_LATCHES) && !defined(HAVE_MUTEX_PTHREADS))
	/*
	 * For hybrid and test-and-set shared latches it is a counter:
	 * 0 means it is free,
	 * -1 is exclusively locked,
	 * > 0 is the number of shared readers.
	 * Pthreads shared latches use pthread_rwlock instead.
	 */
	tsl_t		tas;
	db_atomic_t	sharecount;
#elif !defined(MUTEX_FIELDS)
	/*
	 * This is the Test and Set flag for exclusive latches (mutexes):
	 * there is a free value (often 0, 1, or -1) and a set value.
	 */
	tsl_t		tas;
#endif
#endif
#ifdef HAVE_MUTEX_HYBRID
	volatile u_int32_t wait;	/* Count of waiters. */
#endif
	pid_t		pid;		/* Process owning mutex */
	db_threadid_t	tid;		/* Thread owning mutex */

	db_mutex_t mutex_next_link;	/* Linked list of free mutexes. */

#ifdef HAVE_STATISTICS
	int	  alloc_id;		/* Allocation ID. */

	u_int32_t mutex_set_wait;	/* Granted after wait. */
	u_int32_t mutex_set_nowait;	/* Granted without waiting. */
#ifdef HAVE_SHARED_LATCHES
	u_int32_t mutex_set_rd_wait;	/* Granted shared lock after wait. */
	u_int32_t mutex_set_rd_nowait;	/* Granted shared lock w/out waiting. */
#endif
#ifdef HAVE_MUTEX_HYBRID
	u_int32_t hybrid_wait;
	u_int32_t hybrid_wakeup;	/* for counting spurious wakeups */
#endif
#endif

	/*
	 * A subset of the flag arguments for __mutex_alloc().
	 *
	 * Flags should be an unsigned integer even if it's not required by
	 * the possible flags values, getting a single byte on some machines
	 * is expensive, and the mutex structure is a MP hot spot.
	 */
	volatile u_int32_t flags;		/* MUTEX_XXX */
};
#endif

/* Macro to get a reference to a specific mutex. */
#define	MUTEXP_SET(env, indx)						\
	(F_ISSET(env, ENV_PRIVATE) ? (DB_MUTEX *) indx :		\
	(DB_MUTEX *)((u_int8_t *)env->mutex_handle->mutex_array +	\
	    (indx) *							\
	    ((DB_MUTEXREGION *)env->mutex_handle->reginfo.primary)->mutex_size))

/*
 * Check that a particular mutex is exclusively held at least by someone, not
 * necessarily the current thread.
 */
#ifdef HAVE_MUTEX_SUPPORT
#define	MUTEX_IS_OWNED(env, mutex)					\
	(mutex == MUTEX_INVALID || !MUTEX_ON(env) ||			\
	F_ISSET(env->dbenv, DB_ENV_NOLOCKING) ||			\
	F_ISSET(MUTEXP_SET(env, mutex), DB_MUTEX_LOCKED))
#else
#define	MUTEX_IS_OWNED(env, mutex)	0
#endif

#if defined(HAVE_MUTEX_HYBRID) ||  defined(DB_WIN32) ||		\
	(defined(HAVE_SHARED_LATCHES) && !defined(HAVE_MUTEX_PTHREADS))
#define	MUTEXP_IS_BUSY(mutexp)					\
	(F_ISSET(mutexp, DB_MUTEX_SHARED) ?			\
	(atomic_read(&(mutexp)->sharecount) != 0) :		\
	F_ISSET(mutexp, DB_MUTEX_LOCKED))
#define	MUTEXP_BUSY_FIELD(mutexp)		\
	(F_ISSET(mutexp, DB_MUTEX_SHARED) ?	\
	(atomic_read(&(mutexp)->sharecount)) : (mutexp)->flags)
#else
/* Pthread_rwlocks don't have an low-cost 'is it being shared?' predicate. */
#define	MUTEXP_IS_BUSY(mutexp)	(F_ISSET((mutexp), DB_MUTEX_LOCKED))
#define	MUTEXP_BUSY_FIELD(mutexp)	((mutexp)->flags)
#endif

#define	MUTEX_IS_BUSY(env, mutex)					\
	(mutex == MUTEX_INVALID || !MUTEX_ON(env) ||			\
	F_ISSET(env->dbenv, DB_ENV_NOLOCKING) ||			\
	MUTEXP_IS_BUSY(MUTEXP_SET(env, mutex)))

#define	MUTEX_REQUIRED(env, mutex)					\
	DB_ASSERT(env, MUTEX_IS_OWNED(env, mutex))

#define	MUTEX_REQUIRED_READ(env, mutex)					\
	DB_ASSERT(env, MUTEX_IS_OWNED(env, mutex) || MUTEX_IS_BUSY(env, mutex))

/*
 * Test and set (and thus hybrid) shared latches use compare & exchange
 * to acquire; the others the mutex-setting primitive defined above.
 */
#ifdef LOAD_ACTUAL_MUTEX_CODE

#if defined(HAVE_SHARED_LATCHES)
/* This is the value of the 'sharecount' of an exclusively held tas latch.
 * The particular value is not special; it is just unlikely to be caused
 * by releasing or acquiring a shared latch too many times.
 */
#define	MUTEX_SHARE_ISEXCLUSIVE	(-1024)

/*
 * Get an exclusive lock on a possibly sharable latch. We use the native
 * MUTEX_SET() operation for non-sharable latches; it usually is faster.
 */
#define	MUTEXP_ACQUIRE(mutexp)	\
	(F_ISSET(mutexp, DB_MUTEX_SHARED) ?			\
	atomic_compare_exchange(env,				\
	    &(mutexp)->sharecount, 0, MUTEX_SHARE_ISEXCLUSIVE) :	\
	MUTEX_SET(&(mutexp)->tas))
#else
#define	MUTEXP_ACQUIRE(mutexp)		MUTEX_SET(&(mutexp)->tas)
#endif

#ifndef MEMBAR_ENTER
#define	MEMBAR_ENTER()
#define	MEMBAR_EXIT()
#endif

#endif

#if defined(__cplusplus)
}
#endif
#endif /* !_DB_MUTEX_INT_H_ */