2 * metadata/gc.c: GC icalls.
4 * Author: Paolo Molaro <lupus@ximian.com>
6 * Copyright 2002-2003 Ximian, Inc (http://www.ximian.com)
7 * Copyright 2004-2009 Novell, Inc (http://www.novell.com)
8 * Copyright 2012 Xamarin Inc (http://www.xamarin.com)
9 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
16 #include <mono/metadata/gc-internals.h>
17 #include <mono/metadata/mono-gc.h>
18 #include <mono/metadata/threads.h>
19 #include <mono/metadata/tabledefs.h>
20 #include <mono/metadata/exception.h>
21 #include <mono/metadata/profiler-private.h>
22 #include <mono/metadata/domain-internals.h>
23 #include <mono/metadata/class-internals.h>
24 #include <mono/metadata/metadata-internals.h>
25 #include <mono/metadata/mono-mlist.h>
26 #include <mono/metadata/threads-types.h>
27 #include <mono/metadata/threadpool-ms.h>
28 #include <mono/sgen/sgen-conf.h>
29 #include <mono/sgen/sgen-gc.h>
30 #include <mono/utils/mono-logger-internals.h>
31 #include <mono/metadata/gc-internals.h>
32 #include <mono/metadata/marshal.h> /* for mono_delegate_free_ftnptr () */
33 #include <mono/metadata/attach.h>
34 #include <mono/metadata/console-io.h>
35 #include <mono/utils/mono-os-semaphore.h>
36 #include <mono/utils/mono-memory-model.h>
37 #include <mono/utils/mono-counters.h>
38 #include <mono/utils/mono-time.h>
39 #include <mono/utils/dtrace.h>
40 #include <mono/utils/mono-threads.h>
41 #include <mono/utils/atomic.h>
42 #include <mono/utils/mono-coop-semaphore.h>
43 #include <mono/utils/hazard-pointer.h>
49 typedef struct DomainFinalizationReq {
52 } DomainFinalizationReq;
54 static gboolean gc_disabled = FALSE;
56 static gboolean finalizing_root_domain = FALSE;
58 gboolean log_finalizers = FALSE;
59 gboolean mono_do_not_finalize = FALSE;
60 gchar **mono_do_not_finalize_class_names = NULL;
62 #define mono_finalizer_lock() mono_coop_mutex_lock (&finalizer_mutex)
63 #define mono_finalizer_unlock() mono_coop_mutex_unlock (&finalizer_mutex)
64 static MonoCoopMutex finalizer_mutex;
65 static MonoCoopMutex reference_queue_mutex;
67 static GSList *domains_to_finalize= NULL;
68 static MonoMList *threads_to_finalize = NULL;
70 static gboolean finalizer_thread_exited;
71 /* Uses finalizer_mutex */
72 static MonoCoopCond exited_cond;
74 static MonoInternalThread *gc_thread;
76 static void object_register_finalizer (MonoObject *obj, void (*callback)(void *, void*), MonoError *error);
78 static void reference_queue_proccess_all (void);
79 static void mono_reference_queue_cleanup (void);
80 static void reference_queue_clear_for_domain (MonoDomain *domain);
81 static HANDLE pending_done_event;
84 guarded_wait (HANDLE handle, guint32 timeout, gboolean alertable)
88 MONO_PREPARE_BLOCKING;
89 result = WaitForSingleObjectEx (handle, timeout, alertable);
96 add_thread_to_finalize (MonoInternalThread *thread)
98 mono_finalizer_lock ();
99 if (!threads_to_finalize)
100 MONO_GC_REGISTER_ROOT_SINGLE (threads_to_finalize, MONO_ROOT_SOURCE_FINALIZER_QUEUE, "finalizable threads list");
101 threads_to_finalize = mono_mlist_append (threads_to_finalize, (MonoObject*)thread);
102 mono_finalizer_unlock ();
105 static gboolean suspend_finalizers = FALSE;
107 * actually, we might want to queue the finalize requests in a separate thread,
108 * but we need to be careful about the execution domain of the thread...
111 mono_gc_run_finalize (void *obj, void *data)
114 MonoObject *exc = NULL;
119 MonoMethod* finalizer = NULL;
120 MonoDomain *caller_domain = mono_domain_get ();
122 RuntimeInvokeFunction runtime_invoke;
124 // This function is called from the innards of the GC, so our best alternative for now is to do polling here
125 mono_threads_safepoint ();
127 o = (MonoObject*)((char*)obj + GPOINTER_TO_UINT (data));
129 if (mono_do_not_finalize) {
130 if (!mono_do_not_finalize_class_names)
133 size_t namespace_len = strlen (o->vtable->klass->name_space);
134 for (int i = 0; mono_do_not_finalize_class_names [i]; ++i) {
135 const char *name = mono_do_not_finalize_class_names [i];
136 if (strncmp (name, o->vtable->klass->name_space, namespace_len))
138 if (name [namespace_len] != '.')
140 if (strcmp (name + namespace_len + 1, o->vtable->klass->name))
147 g_log ("mono-gc-finalizers", G_LOG_LEVEL_DEBUG, "<%s at %p> Starting finalizer checks.", o->vtable->klass->name, o);
149 if (suspend_finalizers)
152 domain = o->vtable->domain;
155 mono_domain_finalizers_lock (domain);
157 o2 = (MonoObject *)g_hash_table_lookup (domain->finalizable_objects_hash, o);
159 mono_domain_finalizers_unlock (domain);
162 /* Already finalized somehow */
166 /* make sure the finalizer is not called again if the object is resurrected */
167 object_register_finalizer ((MonoObject *)obj, NULL, &error);
168 mono_error_assert_ok (&error); /* FIXME don't swallow the error */
171 g_log ("mono-gc-finalizers", G_LOG_LEVEL_MESSAGE, "<%s at %p> Registered finalizer as processed.", o->vtable->klass->name, o);
173 if (o->vtable->klass == mono_defaults.internal_thread_class) {
174 MonoInternalThread *t = (MonoInternalThread*)o;
176 if (mono_gc_is_finalizer_internal_thread (t))
177 /* Avoid finalizing ourselves */
180 if (t->threadpool_thread && finalizing_root_domain) {
181 /* Don't finalize threadpool threads when
182 shutting down - they're finalized when the
183 threadpool shuts down. */
184 add_thread_to_finalize (t);
189 if (o->vtable->klass->image == mono_defaults.corlib && !strcmp (o->vtable->klass->name, "DynamicMethod") && finalizing_root_domain) {
191 * These can't be finalized during unloading/shutdown, since that would
192 * free the native code which can still be referenced by other
194 * FIXME: This is not perfect, objects dying at the same time as
195 * dynamic methods can still reference them even when !shutdown.
200 if (mono_runtime_get_no_exec ())
203 /* speedup later... and use a timeout */
204 /* g_print ("Finalize run on %p %s.%s\n", o, mono_object_class (o)->name_space, mono_object_class (o)->name); */
206 /* Use _internal here, since this thread can enter a doomed appdomain */
207 mono_domain_set_internal (mono_object_domain (o));
209 /* delegates that have a native function pointer allocated are
210 * registered for finalization, but they don't have a Finalize
211 * method, because in most cases it's not needed and it's just a waste.
213 if (o->vtable->klass->delegate) {
214 MonoDelegate* del = (MonoDelegate*)o;
215 if (del->delegate_trampoline)
216 mono_delegate_free_ftnptr ((MonoDelegate*)o);
217 mono_domain_set_internal (caller_domain);
221 finalizer = mono_class_get_finalizer (o->vtable->klass);
223 /* If object has a CCW but has no finalizer, it was only
224 * registered for finalization in order to free the CCW.
225 * Else it needs the regular finalizer run.
226 * FIXME: what to do about ressurection and suppression
227 * of finalizer on object with CCW.
229 if (mono_marshal_free_ccw (o) && !finalizer) {
230 mono_domain_set_internal (caller_domain);
235 * To avoid the locking plus the other overhead of mono_runtime_invoke_checked (),
236 * create and precompile a wrapper which calls the finalize method using
240 g_log ("mono-gc-finalizers", G_LOG_LEVEL_MESSAGE, "<%s at %p> Compiling finalizer.", o->vtable->klass->name, o);
242 if (!domain->finalize_runtime_invoke) {
243 MonoMethod *invoke = mono_marshal_get_runtime_invoke (mono_class_get_method_from_name_flags (mono_defaults.object_class, "Finalize", 0, 0), TRUE);
245 domain->finalize_runtime_invoke = mono_compile_method (invoke);
248 runtime_invoke = (RuntimeInvokeFunction)domain->finalize_runtime_invoke;
250 mono_runtime_class_init_full (o->vtable, &error);
251 mono_error_raise_exception (&error); /* FIXME don't raise here */
253 if (G_UNLIKELY (MONO_GC_FINALIZE_INVOKE_ENABLED ())) {
254 MONO_GC_FINALIZE_INVOKE ((unsigned long)o, mono_object_get_size (o),
255 o->vtable->klass->name_space, o->vtable->klass->name);
259 g_log ("mono-gc-finalizers", G_LOG_LEVEL_MESSAGE, "<%s at %p> Calling finalizer.", o->vtable->klass->name, o);
261 runtime_invoke (o, NULL, &exc, NULL);
264 g_log ("mono-gc-finalizers", G_LOG_LEVEL_MESSAGE, "<%s at %p> Returned from finalizer.", o->vtable->klass->name, o);
267 mono_thread_internal_unhandled_exception (exc);
269 mono_domain_set_internal (caller_domain);
273 mono_gc_finalize_threadpool_threads (void)
276 while (threads_to_finalize) {
277 MonoInternalThread *thread = (MonoInternalThread*) mono_mlist_get_data (threads_to_finalize);
279 /* Force finalization of the thread. */
280 thread->threadpool_thread = FALSE;
281 mono_object_register_finalizer ((MonoObject*)thread, &error);
282 mono_error_assert_ok (&error); /* FIXME don't swallow the error */
284 mono_gc_run_finalize (thread, NULL);
286 threads_to_finalize = mono_mlist_next (threads_to_finalize);
291 mono_gc_out_of_memory (size_t size)
294 * we could allocate at program startup some memory that we could release
295 * back to the system at this point if we're really low on memory (ie, size is
296 * lower than the memory we set apart)
298 mono_raise_exception (mono_domain_get ()->out_of_memory_ex);
304 * Some of our objects may point to a different address than the address returned by GC_malloc()
305 * (because of the GetHashCode hack), but we need to pass the real address to register_finalizer.
306 * This also means that in the callback we need to adjust the pointer to get back the real
308 * We also need to be consistent in the use of the GC_debug* variants of malloc and register_finalizer,
309 * since that, too, can cause the underlying pointer to be offset.
312 object_register_finalizer (MonoObject *obj, void (*callback)(void *, void*), MonoError *error)
316 mono_error_init (error);
319 mono_error_set_argument_null (error, "obj", "");
323 domain = obj->vtable->domain;
326 if (mono_domain_is_unloading (domain) && (callback != NULL))
328 * Can't register finalizers in a dying appdomain, since they
329 * could be invoked after the appdomain has been unloaded.
333 mono_domain_finalizers_lock (domain);
336 g_hash_table_insert (domain->finalizable_objects_hash, obj, obj);
338 g_hash_table_remove (domain->finalizable_objects_hash, obj);
340 mono_domain_finalizers_unlock (domain);
342 mono_gc_register_for_finalization (obj, callback);
343 #elif defined(HAVE_SGEN_GC)
345 * If we register finalizers for domains that are unloading we might
346 * end up running them while or after the domain is being cleared, so
347 * the objects will not be valid anymore.
349 if (!mono_domain_is_unloading (domain))
350 mono_gc_register_for_finalization (obj, callback);
355 * mono_object_register_finalizer:
356 * @obj: object to register
358 * Records that object @obj has a finalizer, this will call the
359 * Finalize method when the garbage collector disposes the object.
363 mono_object_register_finalizer (MonoObject *obj, MonoError *error)
365 /* g_print ("Registered finalizer on %p %s.%s\n", obj, mono_object_class (obj)->name_space, mono_object_class (obj)->name); */
366 object_register_finalizer (obj, mono_gc_run_finalize, error);
370 * mono_domain_finalize:
371 * @domain: the domain to finalize
372 * @timeout: msects to wait for the finalization to complete, -1 to wait indefinitely
374 * Request finalization of all finalizable objects inside @domain. Wait
375 * @timeout msecs for the finalization to complete.
377 * Returns: TRUE if succeeded, FALSE if there was a timeout
381 mono_domain_finalize (MonoDomain *domain, guint32 timeout)
383 DomainFinalizationReq *req;
386 MonoInternalThread *thread = mono_thread_internal_current ();
388 #if defined(__native_client__)
392 if (mono_thread_internal_current () == gc_thread)
393 /* We are called from inside a finalizer, not much we can do here */
397 * No need to create another thread 'cause the finalizer thread
398 * is still working and will take care of running the finalizers
404 /* We don't support domain finalization without a GC */
405 if (mono_gc_is_null ())
408 mono_gc_collect (mono_gc_max_generation ());
410 done_event = CreateEvent (NULL, TRUE, FALSE, NULL);
411 if (done_event == NULL) {
415 req = g_new0 (DomainFinalizationReq, 1);
416 req->domain = domain;
417 req->done_event = done_event;
419 if (domain == mono_get_root_domain ())
420 finalizing_root_domain = TRUE;
422 mono_finalizer_lock ();
424 domains_to_finalize = g_slist_append (domains_to_finalize, req);
426 mono_finalizer_unlock ();
428 /* Tell the finalizer thread to finalize this appdomain */
429 mono_gc_finalize_notify ();
435 res = guarded_wait (done_event, timeout, TRUE);
436 /* printf ("WAIT RES: %d.\n", res); */
438 if (res == WAIT_IO_COMPLETION) {
439 if ((thread->state & (ThreadState_StopRequested | ThreadState_SuspendRequested)) != 0)
441 } else if (res == WAIT_TIMEOUT) {
442 /* We leak the handle here */
449 CloseHandle (done_event);
451 if (domain == mono_get_root_domain ()) {
452 mono_threadpool_ms_cleanup ();
453 mono_gc_finalize_threadpool_threads ();
460 ves_icall_System_GC_InternalCollect (int generation)
462 mono_gc_collect (generation);
466 ves_icall_System_GC_GetTotalMemory (MonoBoolean forceCollection)
469 mono_gc_collect (mono_gc_max_generation ());
470 return mono_gc_get_used_size ();
474 ves_icall_System_GC_KeepAlive (MonoObject *obj)
482 ves_icall_System_GC_ReRegisterForFinalize (MonoObject *obj)
486 MONO_CHECK_ARG_NULL (obj,);
488 object_register_finalizer (obj, mono_gc_run_finalize, &error);
489 mono_error_set_pending_exception (&error);
493 ves_icall_System_GC_SuppressFinalize (MonoObject *obj)
497 MONO_CHECK_ARG_NULL (obj,);
499 /* delegates have no finalizers, but we register them to deal with the
500 * unmanaged->managed trampoline. We don't let the user suppress it
501 * otherwise we'd leak it.
503 if (obj->vtable->klass->delegate)
506 /* FIXME: Need to handle case where obj has COM Callable Wrapper
507 * generated for it that needs cleaned up, but user wants to suppress
508 * their derived object finalizer. */
510 object_register_finalizer (obj, NULL, &error);
511 mono_error_set_pending_exception (&error);
515 ves_icall_System_GC_WaitForPendingFinalizers (void)
517 if (mono_gc_is_null ())
520 if (!mono_gc_pending_finalizers ())
523 if (mono_thread_internal_current () == gc_thread)
524 /* Avoid deadlocks */
528 If the finalizer thread is not live, lets pretend no finalizers are pending since the current thread might
529 be the one responsible for starting it up.
531 if (gc_thread == NULL)
534 ResetEvent (pending_done_event);
535 mono_gc_finalize_notify ();
536 /* g_print ("Waiting for pending finalizers....\n"); */
537 guarded_wait (pending_done_event, INFINITE, TRUE);
538 /* g_print ("Done pending....\n"); */
542 ves_icall_System_GC_register_ephemeron_array (MonoObject *array)
545 if (!mono_gc_ephemeron_array_add (array)) {
546 mono_set_pending_exception (mono_object_domain (array)->out_of_memory_ex);
553 ves_icall_System_GC_get_ephemeron_tombstone (void)
555 return mono_domain_get ()->ephemeron_tombstone;
559 ves_icall_System_GCHandle_GetTarget (guint32 handle)
561 return mono_gchandle_get_target (handle);
565 * if type == -1, change the target of the handle, otherwise allocate a new handle.
568 ves_icall_System_GCHandle_GetTargetHandle (MonoObject *obj, guint32 handle, gint32 type)
571 mono_gchandle_set_target (handle, obj);
572 /* the handle doesn't change */
577 return mono_gchandle_new_weakref (obj, FALSE);
578 case HANDLE_WEAK_TRACK:
579 return mono_gchandle_new_weakref (obj, TRUE);
581 return mono_gchandle_new (obj, FALSE);
583 return mono_gchandle_new (obj, TRUE);
585 g_assert_not_reached ();
591 ves_icall_System_GCHandle_FreeHandle (guint32 handle)
593 mono_gchandle_free (handle);
597 ves_icall_System_GCHandle_GetAddrOfPinnedObject (guint32 handle)
601 if (MONO_GC_HANDLE_TYPE (handle) != HANDLE_PINNED)
603 obj = mono_gchandle_get_target (handle);
605 MonoClass *klass = mono_object_class (obj);
606 if (klass == mono_defaults.string_class) {
607 return mono_string_chars ((MonoString*)obj);
608 } else if (klass->rank) {
609 return mono_array_addr ((MonoArray*)obj, char, 0);
611 /* the C# code will check and throw the exception */
612 /* FIXME: missing !klass->blittable test, see bug #61134 */
613 if ((klass->flags & TYPE_ATTRIBUTE_LAYOUT_MASK) == TYPE_ATTRIBUTE_AUTO_LAYOUT)
615 return (char*)obj + sizeof (MonoObject);
622 mono_gc_GCHandle_CheckCurrentDomain (guint32 gchandle)
624 return mono_gchandle_is_in_domain (gchandle, mono_domain_get ());
627 static MonoCoopSem finalizer_sem;
628 static volatile gboolean finished=FALSE;
631 mono_gc_finalize_notify (void)
634 g_message ( "%s: prodding finalizer", __func__);
637 if (mono_gc_is_null ())
640 mono_coop_sem_post (&finalizer_sem);
644 This is the number of entries allowed in the hazard free queue before
645 we explicitly cycle the finalizer thread to trigger pumping the queue.
647 It was picked empirically by running the corlib test suite in a stress
648 scenario where all hazard entries are queued.
650 In this extreme scenario we double the number of times we cycle the finalizer
651 thread compared to just GC calls.
653 Entries are usually in the order of 100's of bytes each, so we're limiting
654 floating garbage to be in the order of a dozen kb.
656 static gboolean finalizer_thread_pulsed;
657 #define HAZARD_QUEUE_OVERFLOW_SIZE 20
660 hazard_free_queue_is_too_big (size_t size)
662 if (size < HAZARD_QUEUE_OVERFLOW_SIZE)
665 if (finalizer_thread_pulsed || InterlockedCompareExchange (&finalizer_thread_pulsed, TRUE, FALSE))
668 mono_gc_finalize_notify ();
672 hazard_free_queue_pump (void)
674 mono_thread_hazardous_try_free_all ();
675 finalizer_thread_pulsed = FALSE;
681 collect_objects (gpointer key, gpointer value, gpointer user_data)
683 GPtrArray *arr = (GPtrArray*)user_data;
684 g_ptr_array_add (arr, key);
690 * finalize_domain_objects:
692 * Run the finalizers of all finalizable objects in req->domain.
695 finalize_domain_objects (DomainFinalizationReq *req)
697 MonoDomain *domain = req->domain;
700 #define NUM_FOBJECTS 64
701 MonoObject *to_finalize [NUM_FOBJECTS];
705 /* Process finalizers which are already in the queue */
706 mono_gc_invoke_finalizers ();
709 while (g_hash_table_size (domain->finalizable_objects_hash) > 0) {
713 * Since the domain is unloading, nobody is allowed to put
714 * new entries into the hash table. But finalize_object might
715 * remove entries from the hash table, so we make a copy.
717 objs = g_ptr_array_new ();
718 g_hash_table_foreach (domain->finalizable_objects_hash, collect_objects, objs);
719 /* printf ("FINALIZING %d OBJECTS.\n", objs->len); */
721 for (i = 0; i < objs->len; ++i) {
722 MonoObject *o = (MonoObject*)g_ptr_array_index (objs, i);
723 /* FIXME: Avoid finalizing threads, etc */
724 mono_gc_run_finalize (o, 0);
727 g_ptr_array_free (objs, TRUE);
729 #elif defined(HAVE_SGEN_GC)
730 while ((count = mono_gc_finalizers_for_domain (domain, to_finalize, NUM_FOBJECTS))) {
732 for (i = 0; i < count; ++i) {
733 mono_gc_run_finalize (to_finalize [i], 0);
738 /* cleanup the reference queue */
739 reference_queue_clear_for_domain (domain);
741 /* printf ("DONE.\n"); */
742 SetEvent (req->done_event);
744 /* The event is closed in mono_domain_finalize if we get here */
749 finalizer_thread (gpointer unused)
751 mono_thread_set_name_internal (mono_thread_internal_current (), mono_string_new (mono_get_root_domain (), "Finalizer"), FALSE);
753 gboolean wait = TRUE;
755 /* Register a hazard free queue pump callback */
756 mono_hazard_pointer_install_free_queue_size_callback (hazard_free_queue_is_too_big);
759 /* Wait to be notified that there's at least one
763 g_assert (mono_domain_get () == mono_get_root_domain ());
764 mono_gc_set_skip_thread (TRUE);
767 /* An alertable wait is required so this thread can be suspended on windows */
768 mono_coop_sem_wait (&finalizer_sem, MONO_SEM_FLAGS_ALERTABLE);
772 mono_gc_set_skip_thread (FALSE);
774 mono_threads_perform_thread_dump ();
776 mono_console_handle_async_ops ();
778 mono_attach_maybe_start ();
780 if (domains_to_finalize) {
781 mono_finalizer_lock ();
782 if (domains_to_finalize) {
783 DomainFinalizationReq *req = (DomainFinalizationReq *)domains_to_finalize->data;
784 domains_to_finalize = g_slist_remove (domains_to_finalize, req);
785 mono_finalizer_unlock ();
787 finalize_domain_objects (req);
789 mono_finalizer_unlock ();
793 /* If finished == TRUE, mono_gc_cleanup has been called (from mono_runtime_cleanup),
794 * before the domain is unloaded.
796 mono_gc_invoke_finalizers ();
798 mono_threads_join_threads ();
800 reference_queue_proccess_all ();
802 hazard_free_queue_pump ();
804 /* Avoid posting the pending done event until there are pending finalizers */
805 if (mono_coop_sem_timedwait (&finalizer_sem, 0, MONO_SEM_FLAGS_NONE) == 0) {
806 /* Don't wait again at the start of the loop */
809 SetEvent (pending_done_event);
813 mono_finalizer_lock ();
814 finalizer_thread_exited = TRUE;
815 mono_coop_cond_signal (&exited_cond);
816 mono_finalizer_unlock ();
821 #ifndef LAZY_GC_THREAD_CREATION
825 mono_gc_init_finalizer_thread (void)
827 gc_thread = mono_thread_create_internal (mono_domain_get (), finalizer_thread, NULL, FALSE, 0);
833 mono_coop_mutex_init_recursive (&finalizer_mutex);
834 mono_coop_mutex_init_recursive (&reference_queue_mutex);
836 mono_counters_register ("Minor GC collections", MONO_COUNTER_GC | MONO_COUNTER_UINT, &gc_stats.minor_gc_count);
837 mono_counters_register ("Major GC collections", MONO_COUNTER_GC | MONO_COUNTER_UINT, &gc_stats.major_gc_count);
838 mono_counters_register ("Minor GC time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &gc_stats.minor_gc_time);
839 mono_counters_register ("Major GC time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &gc_stats.major_gc_time);
840 mono_counters_register ("Major GC time concurrent", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &gc_stats.major_gc_time_concurrent);
842 mono_gc_base_init ();
844 if (mono_gc_is_disabled ()) {
849 pending_done_event = CreateEvent (NULL, TRUE, FALSE, NULL);
850 g_assert (pending_done_event);
851 mono_coop_cond_init (&exited_cond);
852 mono_coop_sem_init (&finalizer_sem, 0);
854 #ifndef LAZY_GC_THREAD_CREATION
855 mono_gc_init_finalizer_thread ();
860 mono_gc_cleanup (void)
863 g_message ("%s: cleaning up finalizer", __func__);
866 if (mono_gc_is_null ())
871 if (mono_thread_internal_current () != gc_thread) {
872 gboolean timed_out = FALSE;
873 guint32 start_ticks = mono_msec_ticks ();
874 guint32 end_ticks = start_ticks + 2000;
876 mono_gc_finalize_notify ();
877 /* Finishing the finalizer thread, so wait a little bit... */
878 /* MS seems to wait for about 2 seconds */
879 while (!finalizer_thread_exited) {
880 guint32 current_ticks = mono_msec_ticks ();
883 if (current_ticks >= end_ticks)
886 timeout = end_ticks - current_ticks;
887 mono_finalizer_lock ();
888 if (!finalizer_thread_exited)
889 mono_coop_cond_timedwait (&exited_cond, &finalizer_mutex, timeout);
890 mono_finalizer_unlock ();
893 if (!finalizer_thread_exited) {
896 /* Set a flag which the finalizer thread can check */
897 suspend_finalizers = TRUE;
899 /* Try to abort the thread, in the hope that it is running managed code */
900 mono_thread_internal_stop (gc_thread);
902 /* Wait for it to stop */
903 ret = guarded_wait (gc_thread->handle, 100, TRUE);
905 if (ret == WAIT_TIMEOUT) {
907 * The finalizer thread refused to die. There is not much we
908 * can do here, since the runtime is shutting down so the
909 * state the finalizer thread depends on will vanish.
911 g_warning ("Shutting down finalizer thread timed out.");
919 /* Wait for the thread to actually exit */
920 ret = guarded_wait (gc_thread->handle, INFINITE, TRUE);
921 g_assert (ret == WAIT_OBJECT_0);
923 mono_thread_join (GUINT_TO_POINTER (gc_thread->tid));
925 g_assert (finalizer_thread_exited);
928 mono_gc_base_cleanup ();
931 mono_reference_queue_cleanup ();
933 mono_coop_mutex_destroy (&finalizer_mutex);
934 mono_coop_mutex_destroy (&reference_queue_mutex);
938 mono_gc_is_finalizer_internal_thread (MonoInternalThread *thread)
940 return thread == gc_thread;
944 * mono_gc_is_finalizer_thread:
945 * @thread: the thread to test.
947 * In Mono objects are finalized asynchronously on a separate thread.
948 * This routine tests whether the @thread argument represents the
949 * finalization thread.
951 * Returns: TRUE if @thread is the finalization thread.
954 mono_gc_is_finalizer_thread (MonoThread *thread)
956 return mono_gc_is_finalizer_internal_thread (thread->internal_thread);
959 #if defined(__MACH__)
960 static pthread_t mach_exception_thread;
963 mono_gc_register_mach_exception_thread (pthread_t thread)
965 mach_exception_thread = thread;
969 mono_gc_get_mach_exception_thread (void)
971 return mach_exception_thread;
975 static MonoReferenceQueue *ref_queues;
978 ref_list_remove_element (RefQueueEntry **prev, RefQueueEntry *element)
981 /* Guard if head is changed concurrently. */
982 while (*prev != element)
983 prev = &(*prev)->next;
984 } while (prev && InterlockedCompareExchangePointer ((volatile gpointer *)prev, element->next, element) != element);
988 ref_list_push (RefQueueEntry **head, RefQueueEntry *value)
990 RefQueueEntry *current;
993 value->next = current;
994 STORE_STORE_FENCE; /*Must make sure the previous store is visible before the CAS. */
995 } while (InterlockedCompareExchangePointer ((volatile gpointer *)head, value, current) != current);
999 reference_queue_proccess (MonoReferenceQueue *queue)
1001 RefQueueEntry **iter = &queue->queue;
1002 RefQueueEntry *entry;
1003 while ((entry = *iter)) {
1004 if (queue->should_be_deleted || !mono_gchandle_get_target (entry->gchandle)) {
1005 mono_gchandle_free ((guint32)entry->gchandle);
1006 ref_list_remove_element (iter, entry);
1007 queue->callback (entry->user_data);
1010 iter = &entry->next;
1016 reference_queue_proccess_all (void)
1018 MonoReferenceQueue **iter;
1019 MonoReferenceQueue *queue = ref_queues;
1020 for (; queue; queue = queue->next)
1021 reference_queue_proccess (queue);
1024 mono_coop_mutex_lock (&reference_queue_mutex);
1025 for (iter = &ref_queues; *iter;) {
1027 if (!queue->should_be_deleted) {
1028 iter = &queue->next;
1032 mono_coop_mutex_unlock (&reference_queue_mutex);
1033 reference_queue_proccess (queue);
1036 *iter = queue->next;
1039 mono_coop_mutex_unlock (&reference_queue_mutex);
1043 mono_reference_queue_cleanup (void)
1045 MonoReferenceQueue *queue = ref_queues;
1046 for (; queue; queue = queue->next)
1047 queue->should_be_deleted = TRUE;
1048 reference_queue_proccess_all ();
1052 reference_queue_clear_for_domain (MonoDomain *domain)
1054 MonoReferenceQueue *queue = ref_queues;
1055 for (; queue; queue = queue->next) {
1056 RefQueueEntry **iter = &queue->queue;
1057 RefQueueEntry *entry;
1058 while ((entry = *iter)) {
1059 if (entry->domain == domain) {
1060 mono_gchandle_free ((guint32)entry->gchandle);
1061 ref_list_remove_element (iter, entry);
1062 queue->callback (entry->user_data);
1065 iter = &entry->next;
1071 * mono_gc_reference_queue_new:
1072 * @callback callback used when processing collected entries.
1074 * Create a new reference queue used to process collected objects.
1075 * A reference queue let you add a pair of (managed object, user data)
1076 * using the mono_gc_reference_queue_add method.
1078 * Once the managed object is collected @callback will be called
1079 * in the finalizer thread with 'user data' as argument.
1081 * The callback is called from the finalizer thread without any locks held.
1082 * When a AppDomain is unloaded, all callbacks for objects belonging to it
1085 * @returns the new queue.
1088 mono_gc_reference_queue_new (mono_reference_queue_callback callback)
1090 MonoReferenceQueue *res = g_new0 (MonoReferenceQueue, 1);
1091 res->callback = callback;
1093 mono_coop_mutex_lock (&reference_queue_mutex);
1094 res->next = ref_queues;
1096 mono_coop_mutex_unlock (&reference_queue_mutex);
1102 * mono_gc_reference_queue_add:
1103 * @queue the queue to add the reference to.
1104 * @obj the object to be watched for collection
1105 * @user_data parameter to be passed to the queue callback
1107 * Queue an object to be watched for collection, when the @obj is
1108 * collected, the callback that was registered for the @queue will
1109 * be invoked with @user_data as argument.
1111 * @returns false if the queue is scheduled to be freed.
1114 mono_gc_reference_queue_add (MonoReferenceQueue *queue, MonoObject *obj, void *user_data)
1117 RefQueueEntry *entry;
1118 if (queue->should_be_deleted)
1121 entry = g_new0 (RefQueueEntry, 1);
1122 entry->user_data = user_data;
1123 entry->domain = mono_object_domain (obj);
1125 entry->gchandle = mono_gchandle_new_weakref (obj, TRUE);
1126 mono_object_register_finalizer (obj, &error);
1127 mono_error_assert_ok (&error);
1129 ref_list_push (&queue->queue, entry);
1134 * mono_gc_reference_queue_free:
1135 * @queue the queue that should be freed.
1137 * This operation signals that @queue should be freed. This operation is deferred
1138 * as it happens on the finalizer thread.
1140 * After this call, no further objects can be queued. It's the responsibility of the
1141 * caller to make sure that no further attempt to access queue will be made.
1144 mono_gc_reference_queue_free (MonoReferenceQueue *queue)
1146 queue->should_be_deleted = TRUE;