2 * monitor.c: Monitor locking functions
5 * Dick Porter (dick@ximian.com)
7 * Copyright 2003 Ximian, Inc (http://www.ximian.com)
8 * Copyright 2004-2009 Novell, Inc (http://www.novell.com)
15 #include <mono/metadata/monitor.h>
16 #include <mono/metadata/threads-types.h>
17 #include <mono/metadata/exception.h>
18 #include <mono/metadata/threads.h>
19 #include <mono/io-layer/io-layer.h>
20 #include <mono/metadata/object-internals.h>
21 #include <mono/metadata/class-internals.h>
22 #include <mono/metadata/gc-internal.h>
23 #include <mono/metadata/method-builder.h>
24 #include <mono/metadata/debug-helpers.h>
25 #include <mono/metadata/tabledefs.h>
26 #include <mono/metadata/marshal.h>
27 #include <mono/metadata/profiler-private.h>
28 #include <mono/utils/mono-time.h>
31 * Pull the list of opcodes
33 #define OPDEF(a,b,c,d,e,f,g,h,i,j) \
37 #include "mono/cil/opcode.def"
42 /*#define LOCK_DEBUG(a) do { a; } while (0)*/
46 * The monitor implementation here is based on
47 * http://www.usenix.org/events/jvm01/full_papers/dice/dice.pdf and
48 * http://www.research.ibm.com/people/d/dfb/papers/Bacon98Thin.ps
50 * The Dice paper describes a technique for saving lock record space
51 * by returning records to a free list when they become unused. That
52 * sounds like unnecessary complexity to me, though if it becomes
53 * clear that unused lock records are taking up lots of space or we
54 * need to shave more time off by avoiding a malloc then we can always
55 * implement the free list idea later. The timeout parameter to
56 * try_enter voids some of the assumptions about the reference count
57 * field in Dice's implementation too. In his version, the thread
58 * attempting to lock a contended object will block until it succeeds,
59 * so the reference count will never be decremented while an object is
62 * Bacon's thin locks have a fast path that doesn't need a lock record
63 * for the common case of locking an unlocked or shallow-nested
64 * object, but the technique relies on encoding the thread ID in 15
65 * bits (to avoid too much per-object space overhead.) Unfortunately
66 * I don't think it's possible to reliably encode a pthread_t into 15
67 * bits. (The JVM implementation used seems to have a 15-bit
68 * per-thread identifier available.)
70 * This implementation then combines Dice's basic lock model with
71 * Bacon's simplification of keeping a lock record for the lifetime of
75 struct _MonoThreadsSync
77 gsize owner; /* thread ID */
79 #ifdef HAVE_MOVING_COLLECTOR
82 volatile gint32 entry_count;
88 typedef struct _MonitorArray MonitorArray;
90 struct _MonitorArray {
93 MonoThreadsSync monitors [MONO_ZERO_LEN_ARRAY];
96 #define mono_monitor_allocator_lock() EnterCriticalSection (&monitor_mutex)
97 #define mono_monitor_allocator_unlock() LeaveCriticalSection (&monitor_mutex)
98 static CRITICAL_SECTION monitor_mutex;
99 static MonoThreadsSync *monitor_freelist;
100 static MonitorArray *monitor_allocated;
101 static int array_size = 16;
103 #ifdef HAVE_KW_THREAD
104 static __thread gsize tls_pthread_self MONO_TLS_FAST;
108 #ifdef HAVE_KW_THREAD
109 #define GetCurrentThreadId() tls_pthread_self
112 * The usual problem: we can't replace GetCurrentThreadId () with a macro because
113 * it is in a public header.
115 #define GetCurrentThreadId() ((gsize)pthread_self ())
120 mono_monitor_init (void)
122 InitializeCriticalSection (&monitor_mutex);
126 mono_monitor_cleanup (void)
128 MonoThreadsSync *mon;
129 /* MonitorArray *marray, *next = NULL; */
131 /*DeleteCriticalSection (&monitor_mutex);*/
133 /* The monitors on the freelist don't have weak links - mark them */
134 for (mon = monitor_freelist; mon; mon = mon->data)
135 mon->wait_list = (gpointer)-1;
137 /* FIXME: This still crashes with sgen (async_read.exe) */
139 for (marray = monitor_allocated; marray; marray = next) {
142 for (i = 0; i < marray->num_monitors; ++i) {
143 mon = &marray->monitors [i];
144 if (mon->wait_list != (gpointer)-1)
145 mono_gc_weak_link_remove (&mon->data);
155 * mono_monitor_init_tls:
157 * Setup TLS variables used by the monitor code for the current thread.
160 mono_monitor_init_tls (void)
162 #if !defined(HOST_WIN32) && defined(HAVE_KW_THREAD)
163 tls_pthread_self = pthread_self ();
168 monitor_is_on_freelist (MonoThreadsSync *mon)
170 MonitorArray *marray;
171 for (marray = monitor_allocated; marray; marray = marray->next) {
172 if (mon >= marray->monitors && mon < &marray->monitors [marray->num_monitors])
182 * Print a report on stdout of the managed locks currently held by
183 * threads. If @include_untaken is specified, list also inflated locks
185 * This is supposed to be used in debuggers like gdb.
188 mono_locks_dump (gboolean include_untaken)
191 int used = 0, on_freelist = 0, to_recycle = 0, total = 0, num_arrays = 0;
192 MonoThreadsSync *mon;
193 MonitorArray *marray;
194 for (mon = monitor_freelist; mon; mon = mon->data)
196 for (marray = monitor_allocated; marray; marray = marray->next) {
197 total += marray->num_monitors;
199 for (i = 0; i < marray->num_monitors; ++i) {
200 mon = &marray->monitors [i];
201 if (mon->data == NULL) {
202 if (i < marray->num_monitors - 1)
205 if (!monitor_is_on_freelist (mon->data)) {
206 MonoObject *holder = mono_gc_weak_link_get (&mon->data);
208 g_print ("Lock %p in object %p held by thread %p, nest level: %d\n",
209 mon, holder, (void*)mon->owner, mon->nest);
211 g_print ("\tWaiting on semaphore %p: %d\n", mon->entry_sem, mon->entry_count);
212 } else if (include_untaken) {
213 g_print ("Lock %p in object %p untaken\n", mon, holder);
220 g_print ("Total locks (in %d array(s)): %d, used: %d, on freelist: %d, to recycle: %d\n",
221 num_arrays, total, used, on_freelist, to_recycle);
224 /* LOCKING: this is called with monitor_mutex held */
226 mon_finalize (MonoThreadsSync *mon)
228 LOCK_DEBUG (g_message ("%s: Finalizing sync %p", __func__, mon));
230 if (mon->entry_sem != NULL) {
231 CloseHandle (mon->entry_sem);
232 mon->entry_sem = NULL;
234 /* If this isn't empty then something is seriously broken - it
235 * means a thread is still waiting on the object that owned
236 * this lock, but the object has been finalized.
238 g_assert (mon->wait_list == NULL);
240 mon->entry_count = 0;
241 /* owner and nest are set in mon_new, no need to zero them out */
243 mon->data = monitor_freelist;
244 monitor_freelist = mon;
245 #ifndef DISABLE_PERFCOUNTERS
246 mono_perfcounters->gc_sync_blocks--;
250 /* LOCKING: this is called with monitor_mutex held */
251 static MonoThreadsSync *
254 MonoThreadsSync *new;
256 if (!monitor_freelist) {
257 MonitorArray *marray;
259 /* see if any sync block has been collected */
261 for (marray = monitor_allocated; marray; marray = marray->next) {
262 for (i = 0; i < marray->num_monitors; ++i) {
263 if (marray->monitors [i].data == NULL) {
264 new = &marray->monitors [i];
265 if (new->wait_list) {
266 /* Orphaned events left by aborted threads */
267 while (new->wait_list) {
268 LOCK_DEBUG (g_message (G_GNUC_PRETTY_FUNCTION ": (%d): Closing orphaned event %d", GetCurrentThreadId (), new->wait_list->data));
269 CloseHandle (new->wait_list->data);
270 new->wait_list = g_slist_remove (new->wait_list, new->wait_list->data);
273 mono_gc_weak_link_remove (&new->data);
274 new->data = monitor_freelist;
275 monitor_freelist = new;
278 /* small perf tweak to avoid scanning all the blocks */
282 /* need to allocate a new array of monitors */
283 if (!monitor_freelist) {
285 LOCK_DEBUG (g_message ("%s: allocating more monitors: %d", __func__, array_size));
286 marray = g_malloc0 (sizeof (MonoArray) + array_size * sizeof (MonoThreadsSync));
287 marray->num_monitors = array_size;
289 /* link into the freelist */
290 for (i = 0; i < marray->num_monitors - 1; ++i) {
291 marray->monitors [i].data = &marray->monitors [i + 1];
293 marray->monitors [i].data = NULL; /* the last one */
294 monitor_freelist = &marray->monitors [0];
295 /* we happend the marray instead of prepending so that
296 * the collecting loop above will need to scan smaller arrays first
298 if (!monitor_allocated) {
299 monitor_allocated = marray;
301 last = monitor_allocated;
309 new = monitor_freelist;
310 monitor_freelist = new->data;
315 #ifndef DISABLE_PERFCOUNTERS
316 mono_perfcounters->gc_sync_blocks++;
322 * Format of the lock word:
323 * thinhash | fathash | data
325 * thinhash is the lower bit: if set data is the shifted hashcode of the object.
326 * fathash is another bit: if set the hash code is stored in the MonoThreadsSync
327 * struct pointed to by data
328 * if neither bit is set and data is non-NULL, data is a MonoThreadsSync
332 MonoThreadsSync *sync;
336 LOCK_WORD_THIN_HASH = 1,
337 LOCK_WORD_FAT_HASH = 1 << 1,
338 LOCK_WORD_BITS_MASK = 0x3,
339 LOCK_WORD_HASH_SHIFT = 2
342 #define MONO_OBJECT_ALIGNMENT_SHIFT 3
348 * Calculate a hash code for @obj that is constant while @obj is alive.
351 mono_object_hash (MonoObject* obj)
353 #ifdef HAVE_MOVING_COLLECTOR
358 lw.sync = obj->synchronisation;
359 if (lw.lock_word & LOCK_WORD_THIN_HASH) {
360 /*g_print ("fast thin hash %d for obj %p store\n", (unsigned int)lw.lock_word >> LOCK_WORD_HASH_SHIFT, obj);*/
361 return (unsigned int)lw.lock_word >> LOCK_WORD_HASH_SHIFT;
363 if (lw.lock_word & LOCK_WORD_FAT_HASH) {
364 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
365 /*g_print ("fast fat hash %d for obj %p store\n", lw.sync->hash_code, obj);*/
366 return lw.sync->hash_code;
369 * while we are inside this function, the GC will keep this object pinned,
370 * since we are in the unmanaged stack. Thanks to this and to the hash
371 * function that depends only on the address, we can ignore the races if
372 * another thread computes the hash at the same time, because it'll end up
373 * with the same value.
375 hash = (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u;
376 /* clear the top bits as they can be discarded */
377 hash &= ~(LOCK_WORD_BITS_MASK << 30);
378 /* no hash flags were set, so it must be a MonoThreadsSync pointer if not NULL */
380 lw.sync->hash_code = hash;
381 /*g_print ("storing hash code %d for obj %p in sync %p\n", hash, obj, lw.sync);*/
382 lw.lock_word |= LOCK_WORD_FAT_HASH;
383 /* this is safe since we don't deflate locks */
384 obj->synchronisation = lw.sync;
386 /*g_print ("storing thin hash code %d for obj %p\n", hash, obj);*/
387 lw.lock_word = LOCK_WORD_THIN_HASH | (hash << LOCK_WORD_HASH_SHIFT);
388 if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, lw.sync, NULL) == NULL)
390 /*g_print ("failed store\n");*/
391 /* someone set the hash flag or someone inflated the object */
392 lw.sync = obj->synchronisation;
393 if (lw.lock_word & LOCK_WORD_THIN_HASH)
395 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
396 lw.sync->hash_code = hash;
397 lw.lock_word |= LOCK_WORD_FAT_HASH;
398 /* this is safe since we don't deflate locks */
399 obj->synchronisation = lw.sync;
404 * Wang's address-based hash function:
405 * http://www.concentric.net/~Ttwang/tech/addrhash.htm
407 return (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u;
411 /* If allow_interruption==TRUE, the method will be interrumped if abort or suspend
412 * is requested. In this case it returns -1.
415 mono_monitor_try_enter_internal (MonoObject *obj, guint32 ms, gboolean allow_interruption)
417 MonoThreadsSync *mon;
418 gsize id = GetCurrentThreadId ();
420 guint32 then = 0, now, delta;
423 MonoInternalThread *thread;
425 LOCK_DEBUG (g_message("%s: (%d) Trying to lock object %p (%d ms)", __func__, id, obj, ms));
427 if (G_UNLIKELY (!obj)) {
428 mono_raise_exception (mono_get_exception_argument_null ("obj"));
433 mon = obj->synchronisation;
435 /* If the object has never been locked... */
436 if (G_UNLIKELY (mon == NULL)) {
437 mono_monitor_allocator_lock ();
439 if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, mon, NULL) == NULL) {
440 mono_gc_weak_link_add (&mon->data, obj, FALSE);
441 mono_monitor_allocator_unlock ();
442 /* Successfully locked */
445 #ifdef HAVE_MOVING_COLLECTOR
447 lw.sync = obj->synchronisation;
448 if (lw.lock_word & LOCK_WORD_THIN_HASH) {
449 MonoThreadsSync *oldlw = lw.sync;
450 /* move the already calculated hash */
451 mon->hash_code = lw.lock_word >> LOCK_WORD_HASH_SHIFT;
453 lw.lock_word |= LOCK_WORD_FAT_HASH;
454 if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, lw.sync, oldlw) == oldlw) {
455 mono_gc_weak_link_add (&mon->data, obj, FALSE);
456 mono_monitor_allocator_unlock ();
457 /* Successfully locked */
461 mono_monitor_allocator_unlock ();
464 } else if (lw.lock_word & LOCK_WORD_FAT_HASH) {
466 mono_monitor_allocator_unlock ();
467 /* get the old lock without the fat hash bit */
468 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
472 mono_monitor_allocator_unlock ();
473 mon = obj->synchronisation;
477 mono_monitor_allocator_unlock ();
478 mon = obj->synchronisation;
482 #ifdef HAVE_MOVING_COLLECTOR
485 if (lw.lock_word & LOCK_WORD_THIN_HASH) {
486 MonoThreadsSync *oldlw = lw.sync;
487 mono_monitor_allocator_lock ();
489 /* move the already calculated hash */
490 mon->hash_code = lw.lock_word >> LOCK_WORD_HASH_SHIFT;
492 lw.lock_word |= LOCK_WORD_FAT_HASH;
493 if (InterlockedCompareExchangePointer ((gpointer*)&obj->synchronisation, lw.sync, oldlw) == oldlw) {
494 mono_gc_weak_link_add (&mon->data, obj, TRUE);
495 mono_monitor_allocator_unlock ();
496 /* Successfully locked */
500 mono_monitor_allocator_unlock ();
507 #ifdef HAVE_MOVING_COLLECTOR
511 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
516 /* If the object has previously been locked but isn't now... */
518 /* This case differs from Dice's case 3 because we don't
519 * deflate locks or cache unused lock records
521 if (G_LIKELY (mon->owner == 0)) {
522 /* Try to install our ID in the owner field, nest
523 * should have been left at 1 by the previous unlock
526 if (G_LIKELY (InterlockedCompareExchangePointer ((gpointer *)&mon->owner, (gpointer)id, 0) == 0)) {
528 g_assert (mon->nest == 1);
536 /* If the object is currently locked by this thread... */
537 if (mon->owner == id) {
542 /* The object must be locked by someone else... */
543 #ifndef DISABLE_PERFCOUNTERS
544 mono_perfcounters->thread_contentions++;
547 /* If ms is 0 we don't block, but just fail straight away */
549 LOCK_DEBUG (g_message ("%s: (%d) timed out, returning FALSE", __func__, id));
553 mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_CONTENTION);
555 /* The slow path begins here. */
557 /* a small amount of duplicated code, but it allows us to insert the profiler
558 * callbacks without impacting the fast path: from here on we don't need to go back to the
559 * retry label, but to retry_contended. At this point mon is already installed in the object
562 /* This case differs from Dice's case 3 because we don't
563 * deflate locks or cache unused lock records
565 if (G_LIKELY (mon->owner == 0)) {
566 /* Try to install our ID in the owner field, nest
567 * should have been left at 1 by the previous unlock
570 if (G_LIKELY (InterlockedCompareExchangePointer ((gpointer *)&mon->owner, (gpointer)id, 0) == 0)) {
572 g_assert (mon->nest == 1);
573 mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_DONE);
578 /* If the object is currently locked by this thread... */
579 if (mon->owner == id) {
581 mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_DONE);
585 /* We need to make sure there's a semaphore handle (creating it if
586 * necessary), and block on it
588 if (mon->entry_sem == NULL) {
589 /* Create the semaphore */
590 sem = CreateSemaphore (NULL, 0, 0x7fffffff, NULL);
591 g_assert (sem != NULL);
592 if (InterlockedCompareExchangePointer ((gpointer*)&mon->entry_sem, sem, NULL) != NULL) {
593 /* Someone else just put a handle here */
598 /* If we need to time out, record a timestamp and adjust ms,
599 * because WaitForSingleObject doesn't tell us how long it
602 * Don't block forever here, because theres a chance the owner
603 * thread released the lock while we were creating the
604 * semaphore: we would not get the wakeup. Using the event
605 * handle technique from pulse/wait would involve locking the
606 * lock struct and therefore slowing down the fast path.
608 if (ms != INFINITE) {
609 then = mono_msec_ticks ();
619 InterlockedIncrement (&mon->entry_count);
621 #ifndef DISABLE_PERFCOUNTERS
622 mono_perfcounters->thread_queue_len++;
623 mono_perfcounters->thread_queue_max++;
625 thread = mono_thread_internal_current ();
627 mono_thread_set_state (thread, ThreadState_WaitSleepJoin);
630 * We pass TRUE instead of allow_interruption since we have to check for the
631 * StopRequested case below.
633 ret = WaitForSingleObjectEx (mon->entry_sem, waitms, TRUE);
635 mono_thread_clr_state (thread, ThreadState_WaitSleepJoin);
637 InterlockedDecrement (&mon->entry_count);
638 #ifndef DISABLE_PERFCOUNTERS
639 mono_perfcounters->thread_queue_len--;
642 if (ms != INFINITE) {
643 now = mono_msec_ticks ();
646 /* The counter must have wrapped around */
647 LOCK_DEBUG (g_message ("%s: wrapped around! now=0x%x then=0x%x", __func__, now, then));
649 now += (0xffffffff - then);
652 LOCK_DEBUG (g_message ("%s: wrap rejig: now=0x%x then=0x%x delta=0x%x", __func__, now, then, now-then));
662 if ((ret == WAIT_TIMEOUT || (ret == WAIT_IO_COMPLETION && !allow_interruption)) && ms > 0) {
664 goto retry_contended;
667 if (ret == WAIT_TIMEOUT || (ret == WAIT_IO_COMPLETION && !allow_interruption)) {
668 if (ret == WAIT_IO_COMPLETION && (mono_thread_test_state (mono_thread_internal_current (), (ThreadState_StopRequested|ThreadState_SuspendRequested)))) {
670 * We have to obey a stop/suspend request even if
671 * allow_interruption is FALSE to avoid hangs at shutdown.
673 mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_FAIL);
676 /* Infinite wait, so just try again */
677 goto retry_contended;
681 if (ret == WAIT_OBJECT_0) {
682 /* retry from the top */
683 goto retry_contended;
686 /* We must have timed out */
687 LOCK_DEBUG (g_message ("%s: (%d) timed out waiting, returning FALSE", __func__, id));
689 mono_profiler_monitor_event (obj, MONO_PROFILER_MONITOR_FAIL);
691 if (ret == WAIT_IO_COMPLETION)
698 mono_monitor_enter (MonoObject *obj)
700 return mono_monitor_try_enter_internal (obj, INFINITE, FALSE) == 1;
704 mono_monitor_try_enter (MonoObject *obj, guint32 ms)
706 return mono_monitor_try_enter_internal (obj, ms, FALSE) == 1;
710 mono_monitor_exit (MonoObject *obj)
712 MonoThreadsSync *mon;
715 LOCK_DEBUG (g_message ("%s: (%d) Unlocking %p", __func__, GetCurrentThreadId (), obj));
717 if (G_UNLIKELY (!obj)) {
718 mono_raise_exception (mono_get_exception_argument_null ("obj"));
722 mon = obj->synchronisation;
724 #ifdef HAVE_MOVING_COLLECTOR
728 if (lw.lock_word & LOCK_WORD_THIN_HASH)
730 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
734 if (G_UNLIKELY (mon == NULL)) {
735 /* No one ever used Enter. Just ignore the Exit request as MS does */
738 if (G_UNLIKELY (mon->owner != GetCurrentThreadId ())) {
742 nest = mon->nest - 1;
744 LOCK_DEBUG (g_message ("%s: (%d) Object %p is now unlocked", __func__, GetCurrentThreadId (), obj));
746 /* object is now unlocked, leave nest==1 so we don't
747 * need to set it when the lock is reacquired
751 /* Do the wakeup stuff. It's possible that the last
752 * blocking thread gave up waiting just before we
753 * release the semaphore resulting in a futile wakeup
754 * next time there's contention for this object, but
755 * it means we don't have to waste time locking the
758 if (mon->entry_count > 0) {
759 ReleaseSemaphore (mon->entry_sem, 1, NULL);
762 LOCK_DEBUG (g_message ("%s: (%d) Object %p is now locked %d times", __func__, GetCurrentThreadId (), obj, nest));
768 mono_monitor_get_object_monitor_weak_link (MonoObject *object)
771 MonoThreadsSync *sync = NULL;
773 lw.sync = object->synchronisation;
774 if (lw.lock_word & LOCK_WORD_FAT_HASH) {
775 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
777 } else if (!(lw.lock_word & LOCK_WORD_THIN_HASH)) {
781 if (sync && sync->data)
787 emit_obj_syncp_check (MonoMethodBuilder *mb, int syncp_loc, int *obj_null_branch, int *true_locktaken_branch, int *syncp_true_false_branch,
788 int *thin_hash_branch, gboolean branch_on_true)
795 mono_mb_emit_byte (mb, CEE_LDARG_0);
796 *obj_null_branch = mono_mb_emit_short_branch (mb, CEE_BRFALSE_S);
801 brtrue.s true_locktaken
803 if (true_locktaken_branch) {
804 mono_mb_emit_byte (mb, CEE_LDARG_1);
805 mono_mb_emit_byte (mb, CEE_LDIND_I1);
806 *true_locktaken_branch = mono_mb_emit_short_branch (mb, CEE_BRTRUE_S);
812 ldc.i4 G_STRUCT_OFFSET(MonoObject, synchronisation) objp off
817 brtrue/false.s syncp_true_false
820 mono_mb_emit_byte (mb, CEE_LDARG_0);
821 mono_mb_emit_byte (mb, CEE_CONV_I);
822 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
823 mono_mb_emit_byte (mb, CEE_ADD);
824 mono_mb_emit_byte (mb, CEE_LDIND_I);
825 mono_mb_emit_stloc (mb, syncp_loc);
828 if (mono_gc_is_moving ()) {
829 /*check for a thin hash*/
830 mono_mb_emit_ldloc (mb, syncp_loc);
831 mono_mb_emit_icon (mb, 0x01);
832 mono_mb_emit_byte (mb, CEE_CONV_I);
833 mono_mb_emit_byte (mb, CEE_AND);
834 *thin_hash_branch = mono_mb_emit_short_branch (mb, CEE_BRTRUE_S);
837 mono_mb_emit_ldloc (mb, syncp_loc);
838 mono_mb_emit_icon (mb, ~0x3);
839 mono_mb_emit_byte (mb, CEE_CONV_I);
840 mono_mb_emit_byte (mb, CEE_AND);
841 mono_mb_emit_stloc (mb, syncp_loc);
843 *thin_hash_branch = 0;
846 mono_mb_emit_ldloc (mb, syncp_loc);
847 *syncp_true_false_branch = mono_mb_emit_short_branch (mb, branch_on_true ? CEE_BRTRUE_S : CEE_BRFALSE_S);
850 static MonoMethod* monitor_il_fastpaths[3];
853 mono_monitor_is_il_fastpath_wrapper (MonoMethod *method)
856 for (i = 0; i < 3; ++i) {
857 if (monitor_il_fastpaths [i] == method)
871 register_fastpath (MonoMethod *method, int idx)
873 mono_memory_barrier ();
874 monitor_il_fastpaths [idx] = method;
879 mono_monitor_get_fast_enter_method (MonoMethod *monitor_enter_method)
881 MonoMethodBuilder *mb;
883 static MonoMethod *compare_exchange_method;
884 int obj_null_branch, true_locktaken_branch = 0, syncp_null_branch, has_owner_branch, other_owner_branch, tid_branch, thin_hash_branch;
885 int tid_loc, syncp_loc, owner_loc;
886 int thread_tls_offset;
887 gboolean is_v4 = mono_method_signature (monitor_enter_method)->param_count == 2;
888 int fast_path_idx = is_v4 ? FASTPATH_ENTERV4 : FASTPATH_ENTER;
891 /* The !is_v4 version is not used/tested */
894 thread_tls_offset = mono_thread_get_tls_offset ();
895 if (thread_tls_offset == -1)
898 if (monitor_il_fastpaths [fast_path_idx])
899 return monitor_il_fastpaths [fast_path_idx];
901 if (!compare_exchange_method) {
902 MonoMethodDesc *desc;
905 desc = mono_method_desc_new ("Interlocked:CompareExchange(intptr&,intptr,intptr)", FALSE);
906 class = mono_class_from_name (mono_defaults.corlib, "System.Threading", "Interlocked");
907 compare_exchange_method = mono_method_desc_search_in_class (desc, class);
908 mono_method_desc_free (desc);
910 if (!compare_exchange_method)
914 mb = mono_mb_new (mono_defaults.monitor_class, is_v4 ? "FastMonitorEnterV4" : "FastMonitorEnter", MONO_WRAPPER_UNKNOWN);
916 mb->method->slot = -1;
917 mb->method->flags = METHOD_ATTRIBUTE_PUBLIC | METHOD_ATTRIBUTE_STATIC |
918 METHOD_ATTRIBUTE_HIDE_BY_SIG | METHOD_ATTRIBUTE_FINAL;
920 tid_loc = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
921 syncp_loc = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
922 owner_loc = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
924 emit_obj_syncp_check (mb, syncp_loc, &obj_null_branch, is_v4 ? &true_locktaken_branch : NULL, &syncp_null_branch, &thin_hash_branch, FALSE);
927 mono. tls thread_tls_offset threadp
928 ldc.i4 G_STRUCT_OFFSET(MonoThread, tid) threadp off
933 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, owner) syncp off
941 mono_mb_emit_byte (mb, MONO_CUSTOM_PREFIX);
942 mono_mb_emit_byte (mb, CEE_MONO_TLS);
943 mono_mb_emit_i4 (mb, thread_tls_offset);
944 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoInternalThread, tid));
945 mono_mb_emit_byte (mb, CEE_ADD);
946 mono_mb_emit_byte (mb, CEE_LDIND_I);
947 mono_mb_emit_stloc (mb, tid_loc);
948 mono_mb_emit_ldloc (mb, syncp_loc);
949 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, owner));
950 mono_mb_emit_byte (mb, CEE_ADD);
951 mono_mb_emit_byte (mb, CEE_LDIND_I);
952 mono_mb_emit_stloc (mb, owner_loc);
953 mono_mb_emit_ldloc (mb, owner_loc);
954 tid_branch = mono_mb_emit_short_branch (mb, CEE_BRTRUE_S);
958 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, owner) syncp off
961 ldc.i4 0 &owner tid 0
962 call System.Threading.Interlocked.CompareExchange oldowner
967 mono_mb_emit_ldloc (mb, syncp_loc);
968 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, owner));
969 mono_mb_emit_byte (mb, CEE_ADD);
970 mono_mb_emit_ldloc (mb, tid_loc);
971 mono_mb_emit_byte (mb, CEE_LDC_I4_0);
972 mono_mb_emit_managed_call (mb, compare_exchange_method, NULL);
973 has_owner_branch = mono_mb_emit_short_branch (mb, CEE_BRTRUE_S);
976 mono_mb_emit_byte (mb, CEE_LDARG_1);
977 mono_mb_emit_byte (mb, CEE_LDC_I4_1);
978 mono_mb_emit_byte (mb, CEE_STIND_I1);
980 mono_mb_emit_byte (mb, CEE_RET);
988 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, nest) syncp off
992 ldc.i4 1 &nest nest 1
998 mono_mb_patch_short_branch (mb, tid_branch);
999 mono_mb_emit_ldloc (mb, owner_loc);
1000 mono_mb_emit_ldloc (mb, tid_loc);
1001 other_owner_branch = mono_mb_emit_short_branch (mb, CEE_BNE_UN_S);
1002 mono_mb_emit_ldloc (mb, syncp_loc);
1003 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, nest));
1004 mono_mb_emit_byte (mb, CEE_ADD);
1005 mono_mb_emit_byte (mb, CEE_DUP);
1006 mono_mb_emit_byte (mb, CEE_LDIND_I4);
1007 mono_mb_emit_byte (mb, CEE_LDC_I4_1);
1008 mono_mb_emit_byte (mb, CEE_ADD);
1009 mono_mb_emit_byte (mb, CEE_STIND_I4);
1012 mono_mb_emit_byte (mb, CEE_LDARG_1);
1013 mono_mb_emit_byte (mb, CEE_LDC_I4_1);
1014 mono_mb_emit_byte (mb, CEE_STIND_I1);
1017 mono_mb_emit_byte (mb, CEE_RET);
1020 obj_null, syncp_null, has_owner, other_owner:
1022 call System.Threading.Monitor.Enter
1026 if (thin_hash_branch)
1027 mono_mb_patch_short_branch (mb, thin_hash_branch);
1028 mono_mb_patch_short_branch (mb, obj_null_branch);
1029 mono_mb_patch_short_branch (mb, syncp_null_branch);
1030 mono_mb_patch_short_branch (mb, has_owner_branch);
1031 mono_mb_patch_short_branch (mb, other_owner_branch);
1032 if (true_locktaken_branch)
1033 mono_mb_patch_short_branch (mb, true_locktaken_branch);
1034 mono_mb_emit_byte (mb, CEE_LDARG_0);
1036 mono_mb_emit_byte (mb, CEE_LDARG_1);
1037 mono_mb_emit_managed_call (mb, monitor_enter_method, NULL);
1038 mono_mb_emit_byte (mb, CEE_RET);
1040 res = register_fastpath (mono_mb_create_method (mb, mono_signature_no_pinvoke (monitor_enter_method), 5), fast_path_idx);
1042 info = mono_image_alloc0 (mono_defaults.corlib, sizeof (WrapperInfo));
1043 info->subtype = is_v4 ? WRAPPER_SUBTYPE_FAST_MONITOR_ENTER_V4 : WRAPPER_SUBTYPE_FAST_MONITOR_ENTER;
1044 mono_marshal_set_wrapper_info (res, info);
1051 mono_monitor_get_fast_exit_method (MonoMethod *monitor_exit_method)
1053 MonoMethodBuilder *mb;
1055 int obj_null_branch, has_waiting_branch, has_syncp_branch, owned_branch, nested_branch, thin_hash_branch;
1056 int thread_tls_offset;
1060 thread_tls_offset = mono_thread_get_tls_offset ();
1061 if (thread_tls_offset == -1)
1064 if (monitor_il_fastpaths [FASTPATH_EXIT])
1065 return monitor_il_fastpaths [FASTPATH_EXIT];
1067 mb = mono_mb_new (mono_defaults.monitor_class, "FastMonitorExit", MONO_WRAPPER_UNKNOWN);
1069 mb->method->slot = -1;
1070 mb->method->flags = METHOD_ATTRIBUTE_PUBLIC | METHOD_ATTRIBUTE_STATIC |
1071 METHOD_ATTRIBUTE_HIDE_BY_SIG | METHOD_ATTRIBUTE_FINAL;
1073 syncp_loc = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
1075 emit_obj_syncp_check (mb, syncp_loc, &obj_null_branch, NULL, &has_syncp_branch, &thin_hash_branch, TRUE);
1081 mono_mb_emit_byte (mb, CEE_RET);
1086 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, owner) syncp off
1089 mono. tls thread_tls_offset owner threadp
1090 ldc.i4 G_STRUCT_OFFSET(MonoThread, tid) owner threadp off
1096 mono_mb_patch_short_branch (mb, has_syncp_branch);
1097 mono_mb_emit_ldloc (mb, syncp_loc);
1098 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, owner));
1099 mono_mb_emit_byte (mb, CEE_ADD);
1100 mono_mb_emit_byte (mb, CEE_LDIND_I);
1101 mono_mb_emit_byte (mb, MONO_CUSTOM_PREFIX);
1102 mono_mb_emit_byte (mb, CEE_MONO_TLS);
1103 mono_mb_emit_i4 (mb, thread_tls_offset);
1104 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoInternalThread, tid));
1105 mono_mb_emit_byte (mb, CEE_ADD);
1106 mono_mb_emit_byte (mb, CEE_LDIND_I);
1107 owned_branch = mono_mb_emit_short_branch (mb, CEE_BEQ_S);
1113 mono_mb_emit_byte (mb, CEE_RET);
1118 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, nest) syncp off
1123 ldc.i4 1 &nest nest nest 1
1124 bgt.un.s nested &nest nest
1127 mono_mb_patch_short_branch (mb, owned_branch);
1128 mono_mb_emit_ldloc (mb, syncp_loc);
1129 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, nest));
1130 mono_mb_emit_byte (mb, CEE_ADD);
1131 mono_mb_emit_byte (mb, CEE_DUP);
1132 mono_mb_emit_byte (mb, CEE_LDIND_I4);
1133 mono_mb_emit_byte (mb, CEE_DUP);
1134 mono_mb_emit_byte (mb, CEE_LDC_I4_1);
1135 nested_branch = mono_mb_emit_short_branch (mb, CEE_BGT_UN_S);
1141 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, entry_count) syncp off
1144 brtrue.s has_waiting
1147 mono_mb_emit_byte (mb, CEE_POP);
1148 mono_mb_emit_byte (mb, CEE_POP);
1149 mono_mb_emit_ldloc (mb, syncp_loc);
1150 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, entry_count));
1151 mono_mb_emit_byte (mb, CEE_ADD);
1152 mono_mb_emit_byte (mb, CEE_LDIND_I4);
1153 has_waiting_branch = mono_mb_emit_short_branch (mb, CEE_BRTRUE_S);
1157 ldc.i4 G_STRUCT_OFFSET(MonoThreadsSync, owner) syncp off
1164 mono_mb_emit_ldloc (mb, syncp_loc);
1165 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoThreadsSync, owner));
1166 mono_mb_emit_byte (mb, CEE_ADD);
1167 mono_mb_emit_byte (mb, CEE_LDNULL);
1168 mono_mb_emit_byte (mb, CEE_STIND_I);
1169 mono_mb_emit_byte (mb, CEE_RET);
1173 ldc.i4 1 &nest nest 1
1179 mono_mb_patch_short_branch (mb, nested_branch);
1180 mono_mb_emit_byte (mb, CEE_LDC_I4_1);
1181 mono_mb_emit_byte (mb, CEE_SUB);
1182 mono_mb_emit_byte (mb, CEE_STIND_I4);
1183 mono_mb_emit_byte (mb, CEE_RET);
1186 obj_null, has_waiting:
1188 call System.Threading.Monitor.Exit
1192 if (thin_hash_branch)
1193 mono_mb_patch_short_branch (mb, thin_hash_branch);
1194 mono_mb_patch_short_branch (mb, obj_null_branch);
1195 mono_mb_patch_short_branch (mb, has_waiting_branch);
1196 mono_mb_emit_byte (mb, CEE_LDARG_0);
1197 mono_mb_emit_managed_call (mb, monitor_exit_method, NULL);
1198 mono_mb_emit_byte (mb, CEE_RET);
1200 res = register_fastpath (mono_mb_create_method (mb, mono_signature_no_pinvoke (monitor_exit_method), 5), FASTPATH_EXIT);
1203 info = mono_image_alloc0 (mono_defaults.corlib, sizeof (WrapperInfo));
1204 info->subtype = WRAPPER_SUBTYPE_FAST_MONITOR_EXIT;
1205 mono_marshal_set_wrapper_info (res, info);
1211 mono_monitor_get_fast_path (MonoMethod *enter_or_exit)
1213 if (strcmp (enter_or_exit->name, "Enter") == 0)
1214 return mono_monitor_get_fast_enter_method (enter_or_exit);
1215 if (strcmp (enter_or_exit->name, "Exit") == 0)
1216 return mono_monitor_get_fast_exit_method (enter_or_exit);
1217 g_assert_not_reached ();
1222 * mono_monitor_threads_sync_member_offset:
1223 * @owner_offset: returns size and offset of the "owner" member
1224 * @nest_offset: returns size and offset of the "nest" member
1225 * @entry_count_offset: returns size and offset of the "entry_count" member
1227 * Returns the offsets and sizes of three members of the
1228 * MonoThreadsSync struct. The Monitor ASM fastpaths need this.
1231 mono_monitor_threads_sync_members_offset (int *owner_offset, int *nest_offset, int *entry_count_offset)
1235 #define ENCODE_OFF_SIZE(o,s) (((o) << 8) | ((s) & 0xff))
1237 *owner_offset = ENCODE_OFF_SIZE (G_STRUCT_OFFSET (MonoThreadsSync, owner), sizeof (ts.owner));
1238 *nest_offset = ENCODE_OFF_SIZE (G_STRUCT_OFFSET (MonoThreadsSync, nest), sizeof (ts.nest));
1239 *entry_count_offset = ENCODE_OFF_SIZE (G_STRUCT_OFFSET (MonoThreadsSync, entry_count), sizeof (ts.entry_count));
1243 ves_icall_System_Threading_Monitor_Monitor_try_enter (MonoObject *obj, guint32 ms)
1248 res = mono_monitor_try_enter_internal (obj, ms, TRUE);
1250 mono_thread_interruption_checkpoint ();
1251 } while (res == -1);
1257 ves_icall_System_Threading_Monitor_Monitor_try_enter_with_atomic_var (MonoObject *obj, guint32 ms, char *lockTaken)
1261 res = mono_monitor_try_enter_internal (obj, ms, TRUE);
1262 /*This means we got interrupted during the wait and didn't got the monitor.*/
1264 mono_thread_interruption_checkpoint ();
1265 } while (res == -1);
1266 /*It's safe to do it from here since interruption would happen only on the wrapper.*/
1267 *lockTaken = res == 1;
1271 ves_icall_System_Threading_Monitor_Monitor_test_owner (MonoObject *obj)
1273 MonoThreadsSync *mon;
1275 LOCK_DEBUG (g_message ("%s: Testing if %p is owned by thread %d", __func__, obj, GetCurrentThreadId()));
1277 mon = obj->synchronisation;
1278 #ifdef HAVE_MOVING_COLLECTOR
1282 if (lw.lock_word & LOCK_WORD_THIN_HASH)
1284 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
1292 if(mon->owner==GetCurrentThreadId ()) {
1300 ves_icall_System_Threading_Monitor_Monitor_test_synchronised (MonoObject *obj)
1302 MonoThreadsSync *mon;
1304 LOCK_DEBUG (g_message("%s: (%d) Testing if %p is owned by any thread", __func__, GetCurrentThreadId (), obj));
1306 mon = obj->synchronisation;
1307 #ifdef HAVE_MOVING_COLLECTOR
1311 if (lw.lock_word & LOCK_WORD_THIN_HASH)
1313 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
1321 if (mon->owner != 0) {
1328 /* All wait list manipulation in the pulse, pulseall and wait
1329 * functions happens while the monitor lock is held, so we don't need
1330 * any extra struct locking
1334 ves_icall_System_Threading_Monitor_Monitor_pulse (MonoObject *obj)
1336 MonoThreadsSync *mon;
1338 LOCK_DEBUG (g_message ("%s: (%d) Pulsing %p", __func__, GetCurrentThreadId (), obj));
1340 mon = obj->synchronisation;
1341 #ifdef HAVE_MOVING_COLLECTOR
1345 if (lw.lock_word & LOCK_WORD_THIN_HASH) {
1346 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked"));
1349 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
1354 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked"));
1357 if (mon->owner != GetCurrentThreadId ()) {
1358 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked by this thread"));
1362 LOCK_DEBUG (g_message ("%s: (%d) %d threads waiting", __func__, GetCurrentThreadId (), g_slist_length (mon->wait_list)));
1364 if (mon->wait_list != NULL) {
1365 LOCK_DEBUG (g_message ("%s: (%d) signalling and dequeuing handle %p", __func__, GetCurrentThreadId (), mon->wait_list->data));
1367 SetEvent (mon->wait_list->data);
1368 mon->wait_list = g_slist_remove (mon->wait_list, mon->wait_list->data);
1373 ves_icall_System_Threading_Monitor_Monitor_pulse_all (MonoObject *obj)
1375 MonoThreadsSync *mon;
1377 LOCK_DEBUG (g_message("%s: (%d) Pulsing all %p", __func__, GetCurrentThreadId (), obj));
1379 mon = obj->synchronisation;
1380 #ifdef HAVE_MOVING_COLLECTOR
1384 if (lw.lock_word & LOCK_WORD_THIN_HASH) {
1385 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked"));
1388 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
1393 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked"));
1396 if (mon->owner != GetCurrentThreadId ()) {
1397 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked by this thread"));
1401 LOCK_DEBUG (g_message ("%s: (%d) %d threads waiting", __func__, GetCurrentThreadId (), g_slist_length (mon->wait_list)));
1403 while (mon->wait_list != NULL) {
1404 LOCK_DEBUG (g_message ("%s: (%d) signalling and dequeuing handle %p", __func__, GetCurrentThreadId (), mon->wait_list->data));
1406 SetEvent (mon->wait_list->data);
1407 mon->wait_list = g_slist_remove (mon->wait_list, mon->wait_list->data);
1412 ves_icall_System_Threading_Monitor_Monitor_wait (MonoObject *obj, guint32 ms)
1414 MonoThreadsSync *mon;
1418 gboolean success = FALSE;
1420 MonoInternalThread *thread = mono_thread_internal_current ();
1422 LOCK_DEBUG (g_message ("%s: (%d) Trying to wait for %p with timeout %dms", __func__, GetCurrentThreadId (), obj, ms));
1424 mon = obj->synchronisation;
1425 #ifdef HAVE_MOVING_COLLECTOR
1429 if (lw.lock_word & LOCK_WORD_THIN_HASH) {
1430 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked"));
1433 lw.lock_word &= ~LOCK_WORD_BITS_MASK;
1438 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked"));
1441 if (mon->owner != GetCurrentThreadId ()) {
1442 mono_raise_exception (mono_get_exception_synchronization_lock ("Not locked by this thread"));
1446 /* Do this WaitSleepJoin check before creating the event handle */
1447 mono_thread_current_check_pending_interrupt ();
1449 event = CreateEvent (NULL, FALSE, FALSE, NULL);
1450 if (event == NULL) {
1451 mono_raise_exception (mono_get_exception_synchronization_lock ("Failed to set up wait event"));
1455 LOCK_DEBUG (g_message ("%s: (%d) queuing handle %p", __func__, GetCurrentThreadId (), event));
1457 mono_thread_current_check_pending_interrupt ();
1459 mono_thread_set_state (thread, ThreadState_WaitSleepJoin);
1461 mon->wait_list = g_slist_append (mon->wait_list, event);
1463 /* Save the nest count, and release the lock */
1466 mono_monitor_exit (obj);
1468 LOCK_DEBUG (g_message ("%s: (%d) Unlocked %p lock %p", __func__, GetCurrentThreadId (), obj, mon));
1470 /* There's no race between unlocking mon and waiting for the
1471 * event, because auto reset events are sticky, and this event
1472 * is private to this thread. Therefore even if the event was
1473 * signalled before we wait, we still succeed.
1475 ret = WaitForSingleObjectEx (event, ms, TRUE);
1477 /* Reset the thread state fairly early, so we don't have to worry
1478 * about the monitor error checking
1480 mono_thread_clr_state (thread, ThreadState_WaitSleepJoin);
1482 if (mono_thread_interruption_requested ()) {
1484 * Can't remove the event from wait_list, since the monitor is not locked by
1485 * us. So leave it there, mon_new () will delete it when the mon structure
1486 * is placed on the free list.
1487 * FIXME: The caller expects to hold the lock after the wait returns, but it
1488 * doesn't happen in this case:
1489 * http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=97268
1494 /* Regain the lock with the previous nest count */
1496 regain = mono_monitor_try_enter_internal (obj, INFINITE, TRUE);
1498 mono_thread_interruption_checkpoint ();
1499 } while (regain == -1);
1502 /* Something went wrong, so throw a
1503 * SynchronizationLockException
1505 CloseHandle (event);
1506 mono_raise_exception (mono_get_exception_synchronization_lock ("Failed to regain lock"));
1512 LOCK_DEBUG (g_message ("%s: (%d) Regained %p lock %p", __func__, GetCurrentThreadId (), obj, mon));
1514 if (ret == WAIT_TIMEOUT) {
1515 /* Poll the event again, just in case it was signalled
1516 * while we were trying to regain the monitor lock
1518 ret = WaitForSingleObjectEx (event, 0, FALSE);
1521 /* Pulse will have popped our event from the queue if it signalled
1522 * us, so we only do it here if the wait timed out.
1524 * This avoids a race condition where the thread holding the
1525 * lock can Pulse several times before the WaitForSingleObject
1526 * returns. If we popped the queue here then this event might
1527 * be signalled more than once, thereby starving another
1531 if (ret == WAIT_OBJECT_0) {
1532 LOCK_DEBUG (g_message ("%s: (%d) Success", __func__, GetCurrentThreadId ()));
1535 LOCK_DEBUG (g_message ("%s: (%d) Wait failed, dequeuing handle %p", __func__, GetCurrentThreadId (), event));
1536 /* No pulse, so we have to remove ourself from the
1539 mon->wait_list = g_slist_remove (mon->wait_list, event);
1541 CloseHandle (event);