/
monitor.c
1159 lines (1019 loc) · 33.1 KB
/
monitor.c
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
/*
* monitor.c: Monitor locking functions
*
* Author:
* Dick Porter (dick@ximian.com)
*
* Copyright 2003 Ximian, Inc (http://www.ximian.com)
* Copyright 2004-2009 Novell, Inc (http://www.novell.com)
*/
#include <config.h>
#include <glib.h>
#include <string.h>
#include <mono/metadata/abi-details.h>
#include <mono/metadata/monitor.h>
#include <mono/metadata/threads-types.h>
#include <mono/metadata/exception.h>
#include <mono/metadata/threads.h>
#include <mono/io-layer/io-layer.h>
#include <mono/metadata/object-internals.h>
#include <mono/metadata/class-internals.h>
#include <mono/metadata/gc-internal.h>
#include <mono/metadata/method-builder.h>
#include <mono/metadata/debug-helpers.h>
#include <mono/metadata/tabledefs.h>
#include <mono/metadata/marshal.h>
#include <mono/utils/mono-threads.h>
#include <mono/metadata/profiler-private.h>
#include <mono/utils/mono-time.h>
#include <mono/utils/atomic.h>
/*
* Pull the list of opcodes
*/
#define OPDEF(a,b,c,d,e,f,g,h,i,j) \
a = i,
enum {
#include "mono/cil/opcode.def"
LAST = 0xff
};
#undef OPDEF
/*#define LOCK_DEBUG(a) do { a; } while (0)*/
#define LOCK_DEBUG(a)
/*
* The monitor implementation here is based on
* http://www.usenix.org/events/jvm01/full_papers/dice/dice.pdf and
* http://www.research.ibm.com/people/d/dfb/papers/Bacon98Thin.ps
*
* The Dice paper describes a technique for saving lock record space
* by returning records to a free list when they become unused. That
* sounds like unnecessary complexity to me, though if it becomes
* clear that unused lock records are taking up lots of space or we
* need to shave more time off by avoiding a malloc then we can always
* implement the free list idea later. The timeout parameter to
* try_enter voids some of the assumptions about the reference count
* field in Dice's implementation too. In his version, the thread
* attempting to lock a contended object will block until it succeeds,
* so the reference count will never be decremented while an object is
* locked.
*
* Bacon's thin locks have a fast path that doesn't need a lock record
* for the common case of locking an unlocked or shallow-nested
* object, but the technique relies on encoding the thread ID in 15
* bits (to avoid too much per-object space overhead.) Unfortunately
* I don't think it's possible to reliably encode a pthread_t into 15
* bits. (The JVM implementation used seems to have a 15-bit
* per-thread identifier available.)
*
* This implementation then combines Dice's basic lock model with
* Bacon's simplification of keeping a lock record for the lifetime of
* an object.
*/
typedef struct _MonitorArray MonitorArray;
struct _MonitorArray {
MonitorArray *next;
int num_monitors;
MonoThreadsSync monitors [MONO_ZERO_LEN_ARRAY];
};
#define mono_monitor_allocator_lock() mono_mutex_lock (&monitor_mutex)
#define mono_monitor_allocator_unlock() mono_mutex_unlock (&monitor_mutex)
static mono_mutex_t monitor_mutex;
static MonoThreadsSync *monitor_freelist;
static MonitorArray *monitor_allocated;
static int array_size = 16;
static inline guint32
mon_status_get_owner (guint32 status)
{
return status & OWNER_MASK;
}
static inline guint32
mon_status_set_owner (guint32 status, guint32 owner)
{
return (status & ENTRY_COUNT_MASK) | owner;
}
static inline gint32
mon_status_get_entry_count (guint32 status)
{
gint32 entry_count = (gint32)((status & ENTRY_COUNT_MASK) >> ENTRY_COUNT_SHIFT);
gint32 zero = (gint32)(((guint32)ENTRY_COUNT_ZERO) >> ENTRY_COUNT_SHIFT);
return entry_count - zero;
}
static inline guint32
mon_status_init_entry_count (guint32 status)
{
return (status & OWNER_MASK) | ENTRY_COUNT_ZERO;
}
static inline guint32
mon_status_increment_entry_count (guint32 status)
{
return status + (1 << ENTRY_COUNT_SHIFT);
}
static inline guint32
mon_status_decrement_entry_count (guint32 status)
{
return status - (1 << ENTRY_COUNT_SHIFT);
}
static inline gboolean
mon_status_have_waiters (guint32 status)
{
return status & ENTRY_COUNT_WAITERS;
}
void
mono_monitor_init (void)
{
mono_mutex_init_recursive (&monitor_mutex);
}
void
mono_monitor_cleanup (void)
{
MonoThreadsSync *mon;
/* MonitorArray *marray, *next = NULL; */
/*mono_mutex_destroy (&monitor_mutex);*/
/* The monitors on the freelist don't have weak links - mark them */
for (mon = monitor_freelist; mon; mon = mon->data)
mon->wait_list = (gpointer)-1;
/* FIXME: This still crashes with sgen (async_read.exe) */
/*
for (marray = monitor_allocated; marray; marray = next) {
int i;
for (i = 0; i < marray->num_monitors; ++i) {
mon = &marray->monitors [i];
if (mon->wait_list != (gpointer)-1)
mono_gc_weak_link_remove (&mon->data);
}
next = marray->next;
g_free (marray);
}
*/
}
static int
monitor_is_on_freelist (MonoThreadsSync *mon)
{
MonitorArray *marray;
for (marray = monitor_allocated; marray; marray = marray->next) {
if (mon >= marray->monitors && mon < &marray->monitors [marray->num_monitors])
return TRUE;
}
return FALSE;
}
/**
* mono_locks_dump:
* @include_untaken:
*
* Print a report on stdout of the managed locks currently held by
* threads. If @include_untaken is specified, list also inflated locks
* which are unheld.
* This is supposed to be used in debuggers like gdb.
*/
void
mono_locks_dump (gboolean include_untaken)
{
int i;
int used = 0, on_freelist = 0, to_recycle = 0, total = 0, num_arrays = 0;
MonoThreadsSync *mon;
MonitorArray *marray;
for (mon = monitor_freelist; mon; mon = mon->data)
on_freelist++;
for (marray = monitor_allocated; marray; marray = marray->next) {
total += marray->num_monitors;
num_arrays++;
for (i = 0; i < marray->num_monitors; ++i) {
mon = &marray->monitors [i];
if (mon->data == NULL) {
if (i < marray->num_monitors - 1)
to_recycle++;
} else {
if (!monitor_is_on_freelist (mon->data)) {
MonoObject *holder = mono_gc_weak_link_get (&mon->data);
if (mon_status_get_owner (mon->status)) {
g_print ("Lock %p in object %p held by thread %d, nest level: %d\n",
mon, holder, mon_status_get_owner (mon->status), mon->nest);
if (mon->entry_sem)
g_print ("\tWaiting on semaphore %p: %d\n", mon->entry_sem, mon_status_get_entry_count (mon->status));
} else if (include_untaken) {
g_print ("Lock %p in object %p untaken\n", mon, holder);
}
used++;
}
}
}
}
g_print ("Total locks (in %d array(s)): %d, used: %d, on freelist: %d, to recycle: %d\n",
num_arrays, total, used, on_freelist, to_recycle);
}
/* LOCKING: this is called with monitor_mutex held */
static void
mon_finalize (MonoThreadsSync *mon)
{
LOCK_DEBUG (g_message ("%s: Finalizing sync %p", __func__, mon));
if (mon->entry_sem != NULL) {
CloseHandle (mon->entry_sem);
mon->entry_sem = NULL;
}
/* If this isn't empty then something is seriously broken - it
* means a thread is still waiting on the object that owned
* this lock, but the object has been finalized.
*/
g_assert (mon->wait_list == NULL);
/* owner and nest are set in mon_new, no need to zero them out */
mon->data = monitor_freelist;
monitor_freelist = mon;
#ifndef DISABLE_PERFCOUNTERS
mono_perfcounters->gc_sync_blocks--;
#endif
}
/* LOCKING: this is called with monitor_mutex held */
static MonoThreadsSync *
mon_new (gsize id)
{
MonoThreadsSync *new;
if (!monitor_freelist) {
MonitorArray *marray;
int i;
/* see if any sync block has been collected */
new = NULL;
for (marray = monitor_allocated; marray; marray = marray->next) {
for (i = 0; i < marray->num_monitors; ++i) {
if (marray->monitors [i].data == NULL) {
new = &marray->monitors [i];
if (new->wait_list) {
/* Orphaned events left by aborted threads */
while (new->wait_list) {
LOCK_DEBUG (g_message (G_GNUC_PRETTY_FUNCTION ": (%d): Closing orphaned event %d", mono_thread_info_get_small_id (), new->wait_list->data));
CloseHandle (new->wait_list->data);
new->wait_list = g_slist_remove (new->wait_list, new->wait_list->data);
}
}
mono_gc_weak_link_remove (&new->data, TRUE);
new->data = monitor_freelist;
monitor_freelist = new;
}
}
/* small perf tweak to avoid scanning all the blocks */
if (new)
break;
}
/* need to allocate a new array of monitors */
if (!monitor_freelist) {
MonitorArray *last;
LOCK_DEBUG (g_message ("%s: allocating more monitors: %d", __func__, array_size));
marray = g_malloc0 (sizeof (MonoArray) + array_size * sizeof (MonoThreadsSync));
marray->num_monitors = array_size;
array_size *= 2;
/* link into the freelist */
for (i = 0; i < marray->num_monitors - 1; ++i) {
marray->monitors [i].data = &marray->monitors [i + 1];
}
marray->monitors [i].data = NULL; /* the last one */
monitor_freelist = &marray->monitors [0];
/* we happend the marray instead of prepending so that
* the collecting loop above will need to scan smaller arrays first
*/
if (!monitor_allocated) {
monitor_allocated = marray;
} else {
last = monitor_allocated;
while (last->next)
last = last->next;
last->next = marray;
}
}
}
new = monitor_freelist;
monitor_freelist = new->data;
new->status = mon_status_set_owner (0, id);
new->status = mon_status_init_entry_count (new->status);
new->nest = 1;
new->data = NULL;
#ifndef DISABLE_PERFCOUNTERS
mono_perfcounters->gc_sync_blocks++;
#endif
return new;
}
/*
* Format of the lock word:
* thinhash | fathash | data
*
* thinhash is the lower bit: if set data is the shifted hashcode of the object.
* fathash is another bit: if set the hash code is stored in the MonoThreadsSync
* struct pointed to by data
* if neither bit is set and data is non-NULL, data is a MonoThreadsSync
*/
typedef union {
gsize lock_word;
MonoThreadsSync *sync;
} LockWord;
enum {
LOCK_WORD_THIN_HASH = 1,
LOCK_WORD_FAT_HASH = 1 << 1,
LOCK_WORD_BITS_MASK = 0x3,
LOCK_WORD_HASH_SHIFT = 2
};
#define MONO_OBJECT_ALIGNMENT_SHIFT 3
/*
* mono_object_hash:
* @obj: an object
*
* Calculate a hash code for @obj that is constant while @obj is alive.
*/
int
mono_object_hash (MonoObject* obj)
{
#ifdef HAVE_MOVING_COLLECTOR
LockWord lw;
unsigned int hash;
if (!obj)
return 0;
lw.sync = obj->synchronisation;
if (lw.lock_word & LOCK_WORD_THIN_HASH) {
/*g_print ("fast thin hash %d for obj %p store\n", (unsigned int)lw.lock_word >> LOCK_WORD_HASH_SHIFT, obj);*/
return (unsigned int)lw.lock_word >> LOCK_WORD_HASH_SHIFT;
}
if (lw.lock_word & LOCK_WORD_FAT_HASH) {
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
/*g_print ("fast fat hash %d for obj %p store\n", lw.sync->hash_code, obj);*/
return lw.sync->hash_code;
}
/*
* while we are inside this function, the GC will keep this object pinned,
* since we are in the unmanaged stack. Thanks to this and to the hash
* function that depends only on the address, we can ignore the races if
* another thread computes the hash at the same time, because it'll end up
* with the same value.
*/
hash = (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u;
/* clear the top bits as they can be discarded */
hash &= ~(LOCK_WORD_BITS_MASK << 30);
/* no hash flags were set, so it must be a MonoThreadsSync pointer if not NULL */
if (lw.sync) {
lw.sync->hash_code = hash;
/*g_print ("storing hash code %d for obj %p in sync %p\n", hash, obj, lw.sync);*/
lw.lock_word |= LOCK_WORD_FAT_HASH;
/* this is safe since we don't deflate locks */
obj->synchronisation = lw.sync;
} else {
/*g_print ("storing thin hash code %d for obj %p\n", hash, obj);*/
lw.lock_word = LOCK_WORD_THIN_HASH | (hash << LOCK_WORD_HASH_SHIFT);
if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, lw.sync, NULL) == NULL)
return hash;
/*g_print ("failed store\n");*/
/* someone set the hash flag or someone inflated the object */
lw.sync = obj->synchronisation;
if (lw.lock_word & LOCK_WORD_THIN_HASH)
return hash;
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
lw.sync->hash_code = hash;
lw.lock_word |= LOCK_WORD_FAT_HASH;
/* this is safe since we don't deflate locks */
obj->synchronisation = lw.sync;
}
return hash;
#else
/*
* Wang's address-based hash function:
* http://www.concentric.net/~Ttwang/tech/addrhash.htm
*/
return (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u;
#endif
}
static void
mon_decrement_entry_count (MonoThreadsSync *mon)
{
guint32 old_status, tmp_status, new_status;
/* Decrement entry count */
old_status = mon->status;
for (;;) {
new_status = mon_status_decrement_entry_count (old_status);
tmp_status = InterlockedCompareExchange ((gint32*)&mon->status, new_status, old_status);
if (tmp_status == old_status) {
break;
}
old_status = tmp_status;
}
}
/* If allow_interruption==TRUE, the method will be interrumped if abort or suspend
* is requested. In this case it returns -1.
*/
static inline gint32
mono_monitor_try_enter_internal (MonoObject *obj, guint32 ms, gboolean allow_interruption)
{
MonoThreadsSync *mon;
gsize id = mono_thread_info_get_small_id ();
HANDLE sem;
guint32 then = 0, now, delta;
guint32 waitms;
guint32 ret;
guint32 new_status, old_status, tmp_status;
MonoInternalThread *thread;
gboolean interrupted = FALSE;
LOCK_DEBUG (g_message("%s: (%d) Trying to lock object %p (%d ms)", __func__, id, obj, ms));
if (G_UNLIKELY (!obj)) {
mono_raise_exception (mono_get_exception_argument_null ("obj"));
return FALSE;
}
retry:
mon = obj->synchronisation;
/* If the object has never been locked... */
if (G_UNLIKELY (mon == NULL)) {
mono_monitor_allocator_lock ();
mon = mon_new (id);
if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, mon, NULL) == NULL) {
mono_gc_weak_link_add (&mon->data, obj, TRUE);
mono_monitor_allocator_unlock ();
/* Successfully locked */
return 1;
} else {
#ifdef HAVE_MOVING_COLLECTOR
LockWord lw;
lw.sync = obj->synchronisation;
if (lw.lock_word & LOCK_WORD_THIN_HASH) {
MonoThreadsSync *oldlw = lw.sync;
/* move the already calculated hash */
mon->hash_code = lw.lock_word >> LOCK_WORD_HASH_SHIFT;
lw.sync = mon;
lw.lock_word |= LOCK_WORD_FAT_HASH;
if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, lw.sync, oldlw) == oldlw) {
mono_gc_weak_link_add (&mon->data, obj, TRUE);
mono_monitor_allocator_unlock ();
/* Successfully locked */
return 1;
} else {
mon_finalize (mon);
mono_monitor_allocator_unlock ();
goto retry;
}
} else if (lw.lock_word & LOCK_WORD_FAT_HASH) {
mon_finalize (mon);
mono_monitor_allocator_unlock ();
/* get the old lock without the fat hash bit */
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
mon = lw.sync;
} else {
mon_finalize (mon);
mono_monitor_allocator_unlock ();
mon = obj->synchronisation;
}
#else
mon_finalize (mon);
mono_monitor_allocator_unlock ();
mon = obj->synchronisation;
#endif
}
} else {
#ifdef HAVE_MOVING_COLLECTOR
LockWord lw;
lw.sync = mon;
if (lw.lock_word & LOCK_WORD_THIN_HASH) {
MonoThreadsSync *oldlw = lw.sync;
mono_monitor_allocator_lock ();
mon = mon_new (id);
/* move the already calculated hash */
mon->hash_code = lw.lock_word >> LOCK_WORD_HASH_SHIFT;
lw.sync = mon;
lw.lock_word |= LOCK_WORD_FAT_HASH;
if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, lw.sync, oldlw) == oldlw) {
mono_gc_weak_link_add (&mon->data, obj, TRUE);
mono_monitor_allocator_unlock ();
/* Successfully locked */
return 1;
} else {
mon_finalize (mon);
mono_monitor_allocator_unlock ();
goto retry;
}
}
#endif
}
#ifdef HAVE_MOVING_COLLECTOR
{
LockWord lw;
lw.sync = mon;
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
mon = lw.sync;
}
#endif
/* If the object has previously been locked but isn't now... */
/* This case differs from Dice's case 3 because we don't
* deflate locks or cache unused lock records
*/
old_status = mon->status;
if (G_LIKELY (mon_status_get_owner (old_status) == 0)) {
/* Try to install our ID in the owner field, nest
* should have been left at 1 by the previous unlock
* operation
*/
new_status = mon_status_set_owner (old_status, id);
tmp_status = InterlockedCompareExchange ((gint32*)&mon->status, new_status, old_status);
if (G_LIKELY (tmp_status == old_status)) {
/* Success */
g_assert (mon->nest == 1);
return 1;
} else {
/* Trumped again! */
goto retry;
}
}
/* If the object is currently locked by this thread... */
if (mon_status_get_owner (old_status) == id) {
mon->nest++;
return 1;
}
/* The object must be locked by someone else... */
#ifndef DISABLE_PERFCOUNTERS
mono_perfcounters->thread_contentions++;
#endif
/* If ms is 0 we don't block, but just fail straight away */
if (ms == 0) {
LOCK_DEBUG (g_message ("%s: (%d) timed out, returning FALSE", __func__, id));
return 0;
}
mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_CONTENTION);
/* The slow path begins here. */
retry_contended:
/* a small amount of duplicated code, but it allows us to insert the profiler
* callbacks without impacting the fast path: from here on we don't need to go back to the
* retry label, but to retry_contended. At this point mon is already installed in the object
* header.
*/
/* This case differs from Dice's case 3 because we don't
* deflate locks or cache unused lock records
*/
old_status = mon->status;
if (G_LIKELY (mon_status_get_owner (old_status) == 0)) {
/* Try to install our ID in the owner field, nest
* should have been left at 1 by the previous unlock
* operation
*/
new_status = mon_status_set_owner (old_status, id);
tmp_status = InterlockedCompareExchange ((gint32*)&mon->status, new_status, old_status);
if (G_LIKELY (tmp_status == old_status)) {
/* Success */
g_assert (mon->nest == 1);
mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_DONE);
return 1;
}
}
/* If the object is currently locked by this thread... */
if (mon_status_get_owner (old_status) == id) {
mon->nest++;
mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_DONE);
return 1;
}
/* We need to make sure there's a semaphore handle (creating it if
* necessary), and block on it
*/
if (mon->entry_sem == NULL) {
/* Create the semaphore */
sem = CreateSemaphore (NULL, 0, 0x7fffffff, NULL);
g_assert (sem != NULL);
if (InterlockedCompareExchangePointer ((gpointer*)&mon->entry_sem, sem, NULL) != NULL) {
/* Someone else just put a handle here */
CloseHandle (sem);
}
}
/*
* We need to register ourselves as waiting if it is the first time we are waiting,
* of if we were signaled and failed to acquire the lock.
*/
if (!interrupted) {
old_status = mon->status;
for (;;) {
if (mon_status_get_owner (old_status) == 0)
goto retry_contended;
new_status = mon_status_increment_entry_count (old_status);
tmp_status = InterlockedCompareExchange ((gint32*)&mon->status, new_status, old_status);
if (tmp_status == old_status) {
break;
}
old_status = tmp_status;
}
}
if (ms != INFINITE) {
then = mono_msec_ticks ();
}
waitms = ms;
#ifndef DISABLE_PERFCOUNTERS
mono_perfcounters->thread_queue_len++;
mono_perfcounters->thread_queue_max++;
#endif
thread = mono_thread_internal_current ();
mono_thread_set_state (thread, ThreadState_WaitSleepJoin);
/*
* We pass TRUE instead of allow_interruption since we have to check for the
* StopRequested case below.
*/
ret = WaitForSingleObjectEx (mon->entry_sem, waitms, TRUE);
mono_thread_clr_state (thread, ThreadState_WaitSleepJoin);
#ifndef DISABLE_PERFCOUNTERS
mono_perfcounters->thread_queue_len--;
#endif
if (ret == WAIT_IO_COMPLETION && !allow_interruption) {
interrupted = TRUE;
/*
* We have to obey a stop/suspend request even if
* allow_interruption is FALSE to avoid hangs at shutdown.
*/
if (!mono_thread_test_state (mono_thread_internal_current (), (ThreadState_StopRequested|ThreadState_SuspendRequested))) {
if (ms != INFINITE) {
now = mono_msec_ticks ();
if (now < then) {
LOCK_DEBUG (g_message ("%s: wrapped around! now=0x%x then=0x%x", __func__, now, then));
now += (0xffffffff - then);
then = 0;
LOCK_DEBUG (g_message ("%s: wrap rejig: now=0x%x then=0x%x delta=0x%x", __func__, now, then, now-then));
}
delta = now - then;
if (delta >= ms) {
ms = 0;
} else {
ms -= delta;
}
}
/* retry from the top */
goto retry_contended;
}
} else if (ret == WAIT_OBJECT_0) {
interrupted = FALSE;
/* retry from the top */
goto retry_contended;
} else if (ret == WAIT_TIMEOUT) {
/* we're done */
}
/* Timed out or interrupted */
mon_decrement_entry_count (mon);
mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_FAIL);
if (ret == WAIT_IO_COMPLETION) {
LOCK_DEBUG (g_message ("%s: (%d) interrupted waiting, returning -1", __func__, id));
return -1;
} else if (ret == WAIT_TIMEOUT) {
LOCK_DEBUG (g_message ("%s: (%d) timed out waiting, returning FALSE", __func__, id));
return 0;
} else {
g_assert_not_reached ();
return 0;
}
}
gboolean
mono_monitor_enter (MonoObject *obj)
{
return mono_monitor_try_enter_internal (obj, INFINITE, FALSE) == 1;
}
gboolean
mono_monitor_try_enter (MonoObject *obj, guint32 ms)
{
return mono_monitor_try_enter_internal (obj, ms, FALSE) == 1;
}
void
mono_monitor_exit (MonoObject *obj)
{
MonoThreadsSync *mon;
guint32 nest;
guint32 new_status, old_status, tmp_status;
LOCK_DEBUG (g_message ("%s: (%d) Unlocking %p", __func__, mono_thread_info_get_small_id (), obj));
if (G_UNLIKELY (!obj)) {
mono_raise_exception (mono_get_exception_argument_null ("obj"));
return;
}
mon = obj->synchronisation;
#ifdef HAVE_MOVING_COLLECTOR
{
LockWord lw;
lw.sync = mon;
if (lw.lock_word & LOCK_WORD_THIN_HASH)
return;
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
mon = lw.sync;
}
#endif
if (G_UNLIKELY (mon == NULL)) {
/* No one ever used Enter. Just ignore the Exit request as MS does */
return;
}
old_status = mon->status;
if (G_UNLIKELY (mon_status_get_owner (old_status) != mono_thread_info_get_small_id ())) {
return;
}
nest = mon->nest - 1;
if (nest == 0) {
/*
* Release lock and do the wakeup stuff. It's possible that
* the last blocking thread gave up waiting just before we
* release the semaphore resulting in a negative entry count
* and a futile wakeup next time there's contention for this
* object.
*/
for (;;) {
gboolean have_waiters = mon_status_have_waiters (old_status);
new_status = mon_status_set_owner (old_status, 0);
if (have_waiters)
new_status = mon_status_decrement_entry_count (new_status);
tmp_status = InterlockedCompareExchange ((gint32*)&mon->status, new_status, old_status);
if (tmp_status == old_status) {
if (have_waiters)
ReleaseSemaphore (mon->entry_sem, 1, NULL);
break;
}
old_status = tmp_status;
}
LOCK_DEBUG (g_message ("%s: (%d) Object %p is now unlocked", __func__, mono_thread_info_get_small_id (), obj));
/* object is now unlocked, leave nest==1 so we don't
* need to set it when the lock is reacquired
*/
} else {
LOCK_DEBUG (g_message ("%s: (%d) Object %p is now locked %d times", __func__, mono_thread_info_get_small_id (), obj, nest));
mon->nest = nest;
}
}
void**
mono_monitor_get_object_monitor_weak_link (MonoObject *object)
{
LockWord lw;
MonoThreadsSync *sync = NULL;
lw.sync = object->synchronisation;
if (lw.lock_word & LOCK_WORD_FAT_HASH) {
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
sync = lw.sync;
} else if (!(lw.lock_word & LOCK_WORD_THIN_HASH)) {
sync = lw.sync;
}
if (sync && sync->data)
return &sync->data;
return NULL;
}
/*
* mono_monitor_threads_sync_member_offset:
* @status_offset: returns size and offset of the "status" member
* @nest_offset: returns size and offset of the "nest" member
*
* Returns the offsets and sizes of two members of the
* MonoThreadsSync struct. The Monitor ASM fastpaths need this.
*/
void
mono_monitor_threads_sync_members_offset (int *status_offset, int *nest_offset)
{
MonoThreadsSync ts;
#define ENCODE_OFF_SIZE(o,s) (((o) << 8) | ((s) & 0xff))
*status_offset = ENCODE_OFF_SIZE (MONO_STRUCT_OFFSET (MonoThreadsSync, status), sizeof (ts.status));
*nest_offset = ENCODE_OFF_SIZE (MONO_STRUCT_OFFSET (MonoThreadsSync, nest), sizeof (ts.nest));
}
gboolean
ves_icall_System_Threading_Monitor_Monitor_try_enter (MonoObject *obj, guint32 ms)
{
gint32 res;
do {
res = mono_monitor_try_enter_internal (obj, ms, TRUE);
if (res == -1)
mono_thread_interruption_checkpoint ();
} while (res == -1);
return res == 1;
}
void
ves_icall_System_Threading_Monitor_Monitor_try_enter_with_atomic_var (MonoObject *obj, guint32 ms, char *lockTaken)
{
gint32 res;
do {
res = mono_monitor_try_enter_internal (obj, ms, TRUE);
/*This means we got interrupted during the wait and didn't got the monitor.*/
if (res == -1)
mono_thread_interruption_checkpoint ();
} while (res == -1);
/*It's safe to do it from here since interruption would happen only on the wrapper.*/
*lockTaken = res == 1;
}
void
mono_monitor_enter_v4 (MonoObject *obj, char *lock_taken)
{
if (*lock_taken == 1)
mono_raise_exception (mono_get_exception_argument ("lockTaken", "lockTaken is already true"));
ves_icall_System_Threading_Monitor_Monitor_try_enter_with_atomic_var (obj, INFINITE, lock_taken);
}
gboolean
ves_icall_System_Threading_Monitor_Monitor_test_owner (MonoObject *obj)
{
MonoThreadsSync *mon;
LOCK_DEBUG (g_message ("%s: Testing if %p is owned by thread %d", __func__, obj, mono_thread_info_get_small_id()));
mon = obj->synchronisation;
#ifdef HAVE_MOVING_COLLECTOR
{
LockWord lw;
lw.sync = mon;
if (lw.lock_word & LOCK_WORD_THIN_HASH)
return FALSE;
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
mon = lw.sync;
}
#endif
if (mon == NULL) {
return FALSE;
}
if (mon_status_get_owner (mon->status) == mono_thread_info_get_small_id ()) {
return(TRUE);
}
return(FALSE);
}
gboolean
ves_icall_System_Threading_Monitor_Monitor_test_synchronised (MonoObject *obj)
{
MonoThreadsSync *mon;
LOCK_DEBUG (g_message("%s: (%d) Testing if %p is owned by any thread", __func__, mono_thread_info_get_small_id (), obj));
mon = obj->synchronisation;
#ifdef HAVE_MOVING_COLLECTOR
{
LockWord lw;
lw.sync = mon;
if (lw.lock_word & LOCK_WORD_THIN_HASH)
return FALSE;
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
mon = lw.sync;
}
#endif
if (mon == NULL) {
return FALSE;
}
if (mon_status_get_owner (mon->status) != 0) {
return TRUE;
}
return FALSE;
}
/* All wait list manipulation in the pulse, pulseall and wait
* functions happens while the monitor lock is held, so we don't need
* any extra struct locking
*/
void
ves_icall_System_Threading_Monitor_Monitor_pulse (MonoObject *obj)
{
MonoThreadsSync *mon;
LOCK_DEBUG (g_message ("%s: (%d) Pulsing %p", __func__, mono_thread_info_get_small_id (), obj));
mon = obj->synchronisation;
#ifdef HAVE_MOVING_COLLECTOR
{
LockWord lw;
lw.sync = mon;
if (lw.lock_word & LOCK_WORD_THIN_HASH) {
mono_set_pending_exception (mono_get_exception_synchronization_lock ("Not locked"));
return;
}
lw.lock_word &= ~LOCK_WORD_BITS_MASK;
mon = lw.sync;
}
#endif
if (mon == NULL) {
mono_set_pending_exception (mono_get_exception_synchronization_lock ("Not locked"));
return;
}
if (mon_status_get_owner (mon->status) != mono_thread_info_get_small_id ()) {
mono_set_pending_exception (mono_get_exception_synchronization_lock ("Not locked by this thread"));
return;
}
LOCK_DEBUG (g_message ("%s: (%d) %d threads waiting", __func__, mono_thread_info_get_small_id (), g_slist_length (mon->wait_list)));
if (mon->wait_list != NULL) {
LOCK_DEBUG (g_message ("%s: (%d) signalling and dequeuing handle %p", __func__, mono_thread_info_get_small_id (), mon->wait_list->data));
SetEvent (mon->wait_list->data);
mon->wait_list = g_slist_remove (mon->wait_list, mon->wait_list->data);
}
}
void
ves_icall_System_Threading_Monitor_Monitor_pulse_all (MonoObject *obj)
{
MonoThreadsSync *mon;
LOCK_DEBUG (g_message("%s: (%d) Pulsing all %p", __func__, mono_thread_info_get_small_id (), obj));
mon = obj->synchronisation;
#ifdef HAVE_MOVING_COLLECTOR
{
LockWord lw;
lw.sync = mon;
if (lw.lock_word & LOCK_WORD_THIN_HASH) {
mono_set_pending_exception (mono_get_exception_synchronization_lock ("Not locked"));
return;