2 * mono-threads.c: Low-level threading
5 * Rodrigo Kumpera (kumpera@gmail.com)
7 * Copyright 2011 Novell, Inc (http://www.novell.com)
8 * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
9 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
14 /* enable pthread extensions */
16 #define _DARWIN_C_SOURCE
19 #include <mono/utils/mono-compiler.h>
20 #include <mono/utils/mono-os-semaphore.h>
21 #include <mono/utils/mono-threads.h>
22 #include <mono/utils/mono-tls.h>
23 #include <mono/utils/hazard-pointer.h>
24 #include <mono/utils/mono-memory-model.h>
25 #include <mono/utils/mono-mmap.h>
26 #include <mono/utils/atomic.h>
27 #include <mono/utils/mono-time.h>
28 #include <mono/utils/mono-lazy-init.h>
29 #include <mono/utils/mono-coop-mutex.h>
30 #include <mono/utils/mono-coop-semaphore.h>
31 #include <mono/utils/mono-threads-coop.h>
36 #include <mono/utils/mach-support.h>
40 Mutex that makes sure only a single thread can be suspending others.
41 Suspend is a very racy operation since it requires restarting until
42 the target thread is not on an unsafe region.
44 We could implement this using critical regions, but would be much much
45 harder for an operation that is hardly performance critical.
47 The GC has to acquire this lock before starting a STW to make sure
48 a runtime suspend won't make it wronly see a thread in a safepoint
49 when it is in fact not.
51 This has to be a naked locking primitive, and not a coop aware one, as
52 it needs to be usable when destroying thread_info_key, the TLS key for
53 the current MonoThreadInfo. In this case, mono_thread_info_current_unchecked,
54 (which is used inside MONO_ENTER_GC_SAFE), would return NULL, leading
55 to an assertion error. We then simply switch state manually in
56 mono_thread_info_suspend_lock_with_info.
58 static MonoSemType global_suspend_semaphore;
60 static size_t thread_info_size;
61 static MonoThreadInfoCallbacks threads_callbacks;
62 static MonoThreadInfoRuntimeCallbacks runtime_callbacks;
63 static MonoNativeTlsKey thread_info_key, thread_exited_key;
65 static __thread guint32 tls_small_id MONO_TLS_FAST;
67 static MonoNativeTlsKey small_id_key;
69 static MonoLinkedListSet thread_list;
70 static gboolean mono_threads_inited = FALSE;
72 static MonoSemType suspend_semaphore;
73 static size_t pending_suspends;
74 static gboolean unified_suspend_enabled;
76 #define mono_thread_info_run_state(info) (((MonoThreadInfo*)info)->thread_state & THREAD_STATE_MASK)
79 #define SLEEP_DURATION_BEFORE_WARNING (50)
81 #define SLEEP_DURATION_BEFORE_ABORT MONO_INFINITE_WAIT
83 static guint32 sleepWarnDuration = SLEEP_DURATION_BEFORE_WARNING,
84 sleepAbortDuration = SLEEP_DURATION_BEFORE_ABORT;
86 static int suspend_posts, resume_posts, abort_posts, waits_done, pending_ops;
89 mono_threads_notify_initiator_of_abort (MonoThreadInfo* info)
91 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-ABORT] %p\n", mono_thread_info_get_tid (info));
92 InterlockedIncrement (&abort_posts);
93 mono_os_sem_post (&suspend_semaphore);
97 mono_threads_notify_initiator_of_suspend (MonoThreadInfo* info)
99 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-SUSPEND] %p\n", mono_thread_info_get_tid (info));
100 InterlockedIncrement (&suspend_posts);
101 mono_os_sem_post (&suspend_semaphore);
105 mono_threads_notify_initiator_of_resume (MonoThreadInfo* info)
107 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-RESUME] %p\n", mono_thread_info_get_tid (info));
108 InterlockedIncrement (&resume_posts);
109 mono_os_sem_post (&suspend_semaphore);
113 begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
115 if (mono_threads_is_coop_enabled ()) {
116 /* There's nothing else to do after we async request the thread to suspend */
117 mono_threads_add_to_pending_operation_set (info);
121 return mono_threads_core_begin_async_suspend (info, interrupt_kernel);
125 check_async_suspend (MonoThreadInfo *info)
127 if (mono_threads_is_coop_enabled ()) {
128 /* Async suspend can't async fail on coop */
132 return mono_threads_core_check_suspend_result (info);
136 resume_async_suspended (MonoThreadInfo *info)
138 if (mono_threads_is_coop_enabled ())
139 g_assert_not_reached ();
141 g_assert (mono_threads_core_begin_async_resume (info));
145 resume_self_suspended (MonoThreadInfo* info)
147 THREADS_SUSPEND_DEBUG ("**BEGIN self-resume %p\n", mono_thread_info_get_tid (info));
148 mono_os_sem_post (&info->resume_semaphore);
152 mono_thread_info_wait_for_resume (MonoThreadInfo* info)
155 THREADS_SUSPEND_DEBUG ("**WAIT self-resume %p\n", mono_thread_info_get_tid (info));
156 res = mono_os_sem_wait (&info->resume_semaphore, MONO_SEM_FLAGS_NONE);
157 g_assert (res != -1);
161 resume_blocking_suspended (MonoThreadInfo* info)
163 THREADS_SUSPEND_DEBUG ("**BEGIN blocking-resume %p\n", mono_thread_info_get_tid (info));
164 mono_os_sem_post (&info->resume_semaphore);
168 mono_threads_add_to_pending_operation_set (MonoThreadInfo* info)
170 THREADS_SUSPEND_DEBUG ("added %p to pending suspend\n", mono_thread_info_get_tid (info));
172 InterlockedIncrement (&pending_ops);
176 mono_threads_begin_global_suspend (void)
178 size_t ps = pending_suspends;
179 if (G_UNLIKELY (ps != 0))
180 g_error ("pending_suspends = %d, but must be 0", ps);
181 THREADS_SUSPEND_DEBUG ("------ BEGIN GLOBAL OP sp %d rp %d ap %d wd %d po %d (sp + rp + ap == wd) (wd == po)\n", suspend_posts, resume_posts,
182 abort_posts, waits_done, pending_ops);
183 g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
184 mono_threads_coop_begin_global_suspend ();
188 mono_threads_end_global_suspend (void)
190 size_t ps = pending_suspends;
191 if (G_UNLIKELY (ps != 0))
192 g_error ("pending_suspends = %d, but must be 0", ps);
193 THREADS_SUSPEND_DEBUG ("------ END GLOBAL OP sp %d rp %d ap %d wd %d po %d\n", suspend_posts, resume_posts,
194 abort_posts, waits_done, pending_ops);
195 g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
196 mono_threads_coop_end_global_suspend ();
202 MonoThreadInfo *cur = mono_thread_info_current ();
204 MOSTLY_ASYNC_SAFE_PRINTF ("STATE CUE CARD: (? means a positive number, usually 1 or 2, * means any number)\n");
205 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x0\t- starting (GOOD, unless the thread is running managed code)\n");
206 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x1\t- running (BAD, unless it's the gc thread)\n");
207 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x2\t- detached (GOOD, unless the thread is running managed code)\n");
208 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?03\t- async suspended (GOOD)\n");
209 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?04\t- self suspended (GOOD)\n");
210 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?05\t- async suspend requested (BAD)\n");
211 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?06\t- self suspend requested (BAD)\n");
212 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x*07\t- blocking (GOOD)\n");
213 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?08\t- blocking with pending suspend (GOOD)\n");
215 FOREACH_THREAD_SAFE (info) {
217 char thread_name [256] = { 0 };
218 pthread_getname_np (mono_thread_info_get_tid (info), thread_name, 255);
220 MOSTLY_ASYNC_SAFE_PRINTF ("--thread %p id %p [%p] (%s) state %x %s\n", info, (void *) mono_thread_info_get_tid (info), (void*)(size_t)info->native_handle, thread_name, info->thread_state, info == cur ? "GC INITIATOR" : "" );
222 MOSTLY_ASYNC_SAFE_PRINTF ("--thread %p id %p [%p] state %x %s\n", info, (void *) mono_thread_info_get_tid (info), (void*)(size_t)info->native_handle, info->thread_state, info == cur ? "GC INITIATOR" : "" );
224 } FOREACH_THREAD_SAFE_END
228 mono_threads_wait_pending_operations (void)
231 int c = pending_suspends;
233 /* Wait threads to park */
234 THREADS_SUSPEND_DEBUG ("[INITIATOR-WAIT-COUNT] %d\n", c);
235 if (pending_suspends) {
236 MonoStopwatch suspension_time;
237 mono_stopwatch_start (&suspension_time);
238 for (i = 0; i < pending_suspends; ++i) {
239 THREADS_SUSPEND_DEBUG ("[INITIATOR-WAIT-WAITING]\n");
240 InterlockedIncrement (&waits_done);
241 if (!mono_os_sem_timedwait (&suspend_semaphore, sleepAbortDuration, MONO_SEM_FLAGS_NONE))
243 mono_stopwatch_stop (&suspension_time);
247 MOSTLY_ASYNC_SAFE_PRINTF ("WAITING for %d threads, got %d suspended\n", (int)pending_suspends, i);
248 g_error ("suspend_thread suspend took %d ms, which is more than the allowed %d ms", (int)mono_stopwatch_elapsed_ms (&suspension_time), sleepAbortDuration);
250 mono_stopwatch_stop (&suspension_time);
251 THREADS_SUSPEND_DEBUG ("Suspending %d threads took %d ms.\n", (int)pending_suspends, (int)mono_stopwatch_elapsed_ms (&suspension_time));
255 pending_suspends = 0;
261 //Thread initialization code
263 static void mono_threads_unregister_current_thread (MonoThreadInfo *info);
266 mono_hazard_pointer_clear_all (MonoThreadHazardPointers *hp, int retain)
269 mono_hazard_pointer_clear (hp, 0);
271 mono_hazard_pointer_clear (hp, 1);
273 mono_hazard_pointer_clear (hp, 2);
277 If return non null Hazard Pointer 1 holds the return value.
280 mono_thread_info_lookup (MonoNativeThreadId id)
282 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
284 if (!mono_lls_find (&thread_list, hp, (uintptr_t)id, HAZARD_FREE_ASYNC_CTX)) {
285 mono_hazard_pointer_clear_all (hp, -1);
289 mono_hazard_pointer_clear_all (hp, 1);
290 return (MonoThreadInfo *) mono_hazard_pointer_get_val (hp, 1);
294 mono_thread_info_insert (MonoThreadInfo *info)
296 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
298 if (!mono_lls_insert (&thread_list, hp, (MonoLinkedListSetNode*)info, HAZARD_FREE_SAFE_CTX)) {
299 mono_hazard_pointer_clear_all (hp, -1);
303 mono_hazard_pointer_clear_all (hp, -1);
308 mono_thread_info_remove (MonoThreadInfo *info)
310 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
313 THREADS_DEBUG ("removing info %p\n", info);
314 res = mono_lls_remove (&thread_list, hp, (MonoLinkedListSetNode*)info, HAZARD_FREE_SAFE_CTX);
315 mono_hazard_pointer_clear_all (hp, -1);
320 free_thread_info (gpointer mem)
322 MonoThreadInfo *info = (MonoThreadInfo *) mem;
324 mono_os_sem_destroy (&info->resume_semaphore);
325 mono_threads_platform_free (info);
331 mono_thread_info_register_small_id (void)
333 int small_id = mono_thread_small_id_alloc ();
334 #ifdef HAVE_KW_THREAD
335 tls_small_id = small_id;
337 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (small_id + 1));
343 register_thread (MonoThreadInfo *info, gpointer baseptr)
346 guint8 *staddr = NULL;
347 int small_id = mono_thread_info_register_small_id ();
349 mono_thread_info_set_tid (info, mono_native_thread_id_get ());
350 info->small_id = small_id;
352 mono_os_sem_init (&info->resume_semaphore, 0);
354 /*set TLS early so SMR works */
355 mono_native_tls_set_value (thread_info_key, info);
357 THREADS_DEBUG ("registering info %p tid %p small id %x\n", info, mono_thread_info_get_tid (info), info->small_id);
359 if (threads_callbacks.thread_register) {
360 if (threads_callbacks.thread_register (info, baseptr) == NULL) {
361 // g_warning ("thread registation failed\n");
362 mono_native_tls_set_value (thread_info_key, NULL);
368 mono_thread_info_get_stack_bounds (&staddr, &stsize);
371 info->stack_start_limit = staddr;
372 info->stack_end = staddr + stsize;
374 info->stackdata = g_byte_array_new ();
376 mono_threads_platform_register (info);
379 Transition it before taking any locks or publishing itself to reduce the chance
380 of others witnessing a detached thread.
381 We can reasonably expect that until this thread gets published, no other thread will
382 try to manipulate it.
384 mono_threads_transition_attach (info);
385 mono_thread_info_suspend_lock ();
386 /*If this fail it means a given thread has been registered twice, which doesn't make sense. */
387 result = mono_thread_info_insert (info);
389 mono_thread_info_suspend_unlock ();
394 mono_thread_info_suspend_lock_with_info (MonoThreadInfo *info);
397 unregister_thread (void *arg)
399 gpointer gc_unsafe_stackdata;
400 MonoThreadInfo *info;
403 info = (MonoThreadInfo *) arg;
406 small_id = info->small_id;
408 /* We only enter the GC unsafe region, as when exiting this function, the thread
409 * will be detached, and the current MonoThreadInfo* will be destroyed. */
410 mono_threads_enter_gc_unsafe_region_unbalanced_with_info (info, &gc_unsafe_stackdata);
412 THREADS_DEBUG ("unregistering info %p\n", info);
414 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
416 mono_threads_core_unregister (info);
419 * TLS destruction order is not reliable so small_id might be cleaned up
422 #ifndef HAVE_KW_THREAD
423 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (info->small_id + 1));
427 First perform the callback that requires no locks.
428 This callback has the potential of taking other locks, so we do it before.
429 After it completes, the thread remains functional.
431 if (threads_callbacks.thread_detach)
432 threads_callbacks.thread_detach (info);
434 mono_thread_info_suspend_lock_with_info (info);
437 Now perform the callback that must be done under locks.
438 This will render the thread useless and non-suspendable, so it must
439 be done while holding the suspend lock to give no other thread chance
442 if (threads_callbacks.thread_unregister)
443 threads_callbacks.thread_unregister (info);
444 mono_threads_unregister_current_thread (info);
445 mono_threads_transition_detach (info);
447 mono_thread_info_suspend_unlock ();
449 g_byte_array_free (info->stackdata, /*free_segment=*/TRUE);
451 /*now it's safe to free the thread info.*/
452 mono_thread_hazardous_try_free (info, free_thread_info);
453 /* Pump the HP queue */
454 mono_thread_hazardous_try_free_some ();
456 mono_thread_small_id_free (small_id);
460 thread_exited_dtor (void *arg)
462 #if defined(__MACH__)
464 * Since we use pthread dtors to clean up thread data, if a thread
465 * is attached to the runtime by another pthread dtor after our dtor
466 * has ran, it will never be detached, leading to various problems
467 * since the thread ids etc. will be reused while they are still in
468 * the threads hashtables etc.
469 * Dtors are called in a loop until all user tls entries are 0,
470 * but the loop has a maximum count (4), so if we set the tls
471 * variable every time, it will remain set when system tls dtors
472 * are ran. This allows mono_thread_info_is_exiting () to detect
473 * whenever the thread is exiting, even if it is executed from a
474 * system tls dtor (i.e. obj-c dealloc methods).
476 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
481 * Removes the current thread from the thread list.
482 * This must be called from the thread unregister callback and nowhere else.
483 * The current thread must be passed as TLS might have already been cleaned up.
486 mono_threads_unregister_current_thread (MonoThreadInfo *info)
489 g_assert (mono_thread_info_get_tid (info) == mono_native_thread_id_get ());
490 result = mono_thread_info_remove (info);
495 mono_thread_info_current_unchecked (void)
497 return mono_threads_inited ? (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key) : NULL;
502 mono_thread_info_current (void)
504 MonoThreadInfo *info = (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key);
508 info = mono_thread_info_lookup (mono_native_thread_id_get ()); /*info on HP1*/
511 We might be called during thread cleanup, but we cannot be called after cleanup as happened.
512 The way to distinguish between before, during and after cleanup is the following:
514 -If the TLS key is set, cleanup has not begun;
515 -If the TLS key is clean, but the thread remains registered, cleanup is in progress;
516 -If the thread is nowhere to be found, cleanup has finished.
518 We cannot function after cleanup since there's no way to ensure what will happen.
522 /*We're looking up the current thread which will not be freed until we finish running, so no need to keep it on a HP */
523 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
529 mono_thread_info_get_small_id (void)
531 #ifdef HAVE_KW_THREAD
534 gpointer val = mono_native_tls_get_value (small_id_key);
537 return GPOINTER_TO_INT (val) - 1;
542 mono_thread_info_list_head (void)
548 * mono_threads_attach_tools_thread
550 * Attach the current thread as a tool thread. DON'T USE THIS FUNCTION WITHOUT READING ALL DISCLAIMERS.
552 * A tools thread is a very special kind of thread that needs access to core runtime facilities but should
553 * not be counted as a regular thread for high order facilities such as executing managed code or accessing
556 * This is intended only to tools such as a profiler than needs to be able to use our lock-free support when
557 * doing things like resolving backtraces in their background processing thread.
560 mono_threads_attach_tools_thread (void)
563 MonoThreadInfo *info;
565 /* Must only be called once */
566 g_assert (!mono_native_tls_get_value (thread_info_key));
568 while (!mono_threads_inited) {
569 mono_thread_info_usleep (10);
572 info = mono_thread_info_attach (&dummy);
575 info->tools_thread = TRUE;
579 mono_thread_info_attach (void *baseptr)
581 MonoThreadInfo *info;
582 if (!mono_threads_inited)
585 /* This can happen from DllMain(DLL_THREAD_ATTACH) on Windows, if a
586 * thread is created before an embedding API user initialized Mono. */
587 THREADS_DEBUG ("mono_thread_info_attach called before mono_threads_init\n");
590 g_assert (mono_threads_inited);
593 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
595 info = (MonoThreadInfo *) g_malloc0 (thread_info_size);
596 THREADS_DEBUG ("attaching %p\n", info);
597 if (!register_thread (info, baseptr))
599 } else if (threads_callbacks.thread_attach) {
600 threads_callbacks.thread_attach (info);
606 mono_thread_info_detach (void)
608 MonoThreadInfo *info;
609 if (!mono_threads_inited)
611 /* This can happen from DllMain(THREAD_DETACH) on Windows, if a thread
612 * is created before an embedding API user initialized Mono. */
613 THREADS_DEBUG ("mono_thread_info_detach called before mono_threads_init\n");
616 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
618 THREADS_DEBUG ("detaching %p\n", info);
619 unregister_thread (info);
620 mono_native_tls_set_value (thread_info_key, NULL);
625 * mono_thread_info_is_exiting:
627 * Return whenever the current thread is exiting, i.e. it is running pthread
631 mono_thread_info_is_exiting (void)
633 #if defined(__MACH__)
634 if (mono_native_tls_get_value (thread_exited_key) == GUINT_TO_POINTER (1))
641 mono_threads_init (MonoThreadInfoCallbacks *callbacks, size_t info_size)
644 threads_callbacks = *callbacks;
645 thread_info_size = info_size;
646 const char *sleepLimit;
648 res = mono_native_tls_alloc (&thread_info_key, NULL);
649 res = mono_native_tls_alloc (&thread_exited_key, NULL);
651 res = mono_native_tls_alloc (&thread_info_key, (void *) unregister_thread);
652 res = mono_native_tls_alloc (&thread_exited_key, (void *) thread_exited_dtor);
657 #ifndef HAVE_KW_THREAD
658 res = mono_native_tls_alloc (&small_id_key, NULL);
662 unified_suspend_enabled = g_getenv ("MONO_ENABLE_UNIFIED_SUSPEND") != NULL || mono_threads_is_coop_enabled ();
664 if ((sleepLimit = g_getenv ("MONO_SLEEP_ABORT_LIMIT")) != NULL) {
666 long threshold = strtol(sleepLimit, NULL, 10);
667 if ((errno == 0) && (threshold >= 40)) {
668 sleepAbortDuration = threshold;
669 sleepWarnDuration = threshold / 20;
671 g_warning("MONO_SLEEP_ABORT_LIMIT must be a number >= 40");
674 mono_os_sem_init (&global_suspend_semaphore, 1);
675 mono_os_sem_init (&suspend_semaphore, 0);
677 mono_lls_init (&thread_list, NULL, HAZARD_FREE_NO_LOCK);
678 mono_thread_smr_init ();
679 mono_threads_init_platform ();
680 mono_threads_init_coop ();
681 mono_threads_init_abort_syscall ();
683 #if defined(__MACH__)
684 mono_mach_init (thread_info_key);
687 mono_threads_inited = TRUE;
689 g_assert (sizeof (MonoNativeThreadId) <= sizeof (uintptr_t));
693 mono_threads_runtime_init (MonoThreadInfoRuntimeCallbacks *callbacks)
695 runtime_callbacks = *callbacks;
698 MonoThreadInfoRuntimeCallbacks *
699 mono_threads_get_runtime_callbacks (void)
701 return &runtime_callbacks;
705 Signal that the current thread wants to be suspended.
706 This function can be called without holding the suspend lock held.
707 To finish suspending, call mono_suspend_check.
710 mono_thread_info_begin_self_suspend (void)
712 MonoThreadInfo *info = mono_thread_info_current_unchecked ();
716 THREADS_SUSPEND_DEBUG ("BEGIN SELF SUSPEND OF %p\n", info);
717 mono_threads_transition_request_self_suspension (info);
721 mono_thread_info_end_self_suspend (void)
723 MonoThreadInfo *info;
725 info = mono_thread_info_current ();
728 THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", info);
730 mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
732 /* commit the saved state and notify others if needed */
733 switch (mono_threads_transition_state_poll (info)) {
734 case SelfSuspendResumed:
736 case SelfSuspendWait:
737 mono_thread_info_wait_for_resume (info);
739 case SelfSuspendNotifyAndWait:
740 mono_threads_notify_initiator_of_suspend (info);
741 mono_thread_info_wait_for_resume (info);
742 mono_threads_notify_initiator_of_resume (info);
748 mono_thread_info_core_resume (MonoThreadInfo *info)
750 gboolean res = FALSE;
751 if (info->create_suspended) {
752 MonoNativeThreadId tid = mono_thread_info_get_tid (info);
753 /* Have to special case this, as the normal suspend/resume pair are racy, they don't work if he resume is received before the suspend */
754 info->create_suspended = FALSE;
755 mono_threads_core_resume_created (info, tid);
759 switch (mono_threads_transition_request_resume (info)) {
766 case ResumeInitSelfResume:
767 resume_self_suspended (info);
770 case ResumeInitAsyncResume:
771 resume_async_suspended (info);
774 case ResumeInitBlockingResume:
775 resume_blocking_suspended (info);
784 mono_thread_info_resume (MonoNativeThreadId tid)
786 gboolean result; /* don't initialize it so the compiler can catch unitilized paths. */
787 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
788 MonoThreadInfo *info;
790 THREADS_SUSPEND_DEBUG ("RESUMING tid %p\n", (void*)tid);
792 mono_thread_info_suspend_lock ();
794 info = mono_thread_info_lookup (tid); /*info on HP1*/
800 result = mono_thread_info_core_resume (info);
802 //Wait for the pending resume to finish
803 mono_threads_wait_pending_operations ();
806 mono_thread_info_suspend_unlock ();
807 mono_hazard_pointer_clear (hp, 1);
812 mono_thread_info_begin_suspend (MonoThreadInfo *info)
814 switch (mono_threads_transition_request_async_suspension (info)) {
815 case AsyncSuspendAlreadySuspended:
816 case AsyncSuspendBlocking:
818 case AsyncSuspendWait:
819 mono_threads_add_to_pending_operation_set (info);
821 case AsyncSuspendInitSuspend:
822 return begin_async_suspend (info, FALSE);
824 g_assert_not_reached ();
829 mono_thread_info_begin_resume (MonoThreadInfo *info)
831 return mono_thread_info_core_resume (info);
835 FIXME fix cardtable WB to be out of line and check with the runtime if the target is not the
836 WB trampoline. Another option is to encode wb ranges in MonoJitInfo, but that is somewhat hard.
839 is_thread_in_critical_region (MonoThreadInfo *info)
843 gpointer stack_start;
844 MonoThreadUnwindState *state;
846 /* Are we inside a system critical region? */
847 if (info->inside_critical_region)
850 /* Are we inside a GC critical region? */
851 if (threads_callbacks.mono_thread_in_critical_region && threads_callbacks.mono_thread_in_critical_region (info)) {
855 /* The target thread might be shutting down and the domain might be null, which means no managed code left to run. */
856 state = mono_thread_info_get_suspend_state (info);
857 if (!state->unwind_data [MONO_UNWIND_DATA_DOMAIN])
860 stack_start = MONO_CONTEXT_GET_SP (&state->ctx);
861 /* altstack signal handler, sgen can't handle them, so we treat them as critical */
862 if (stack_start < info->stack_start_limit || stack_start >= info->stack_end)
865 ji = mono_jit_info_table_find (
866 (MonoDomain *) state->unwind_data [MONO_UNWIND_DATA_DOMAIN],
867 (char *) MONO_CONTEXT_GET_IP (&state->ctx));
872 method = mono_jit_info_get_method (ji);
874 return threads_callbacks.mono_method_is_critical (method);
878 mono_thread_info_in_critical_location (MonoThreadInfo *info)
880 return is_thread_in_critical_region (info);
884 The return value is only valid until a matching mono_thread_info_resume is called
886 static MonoThreadInfo*
887 suspend_sync (MonoNativeThreadId tid, gboolean interrupt_kernel)
889 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
890 MonoThreadInfo *info = mono_thread_info_lookup (tid); /*info on HP1*/
894 switch (mono_threads_transition_request_async_suspension (info)) {
895 case AsyncSuspendAlreadySuspended:
896 mono_hazard_pointer_clear (hp, 1); //XXX this is questionable we got to clean the suspend/resume nonsense of critical sections
898 case AsyncSuspendWait:
899 mono_threads_add_to_pending_operation_set (info);
901 case AsyncSuspendInitSuspend:
902 if (!begin_async_suspend (info, interrupt_kernel)) {
903 mono_hazard_pointer_clear (hp, 1);
907 case AsyncSuspendBlocking:
908 if (interrupt_kernel)
909 mono_threads_core_abort_syscall (info);
913 g_assert_not_reached ();
916 //Wait for the pending suspend to finish
917 mono_threads_wait_pending_operations ();
919 if (!check_async_suspend (info)) {
920 mono_thread_info_core_resume (info);
921 mono_threads_wait_pending_operations ();
922 mono_hazard_pointer_clear (hp, 1);
928 static MonoThreadInfo*
929 suspend_sync_nolock (MonoNativeThreadId id, gboolean interrupt_kernel)
931 MonoThreadInfo *info = NULL;
932 int sleep_duration = 0;
934 if (!(info = suspend_sync (id, interrupt_kernel))) {
935 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
939 /*WARNING: We now are in interrupt context until we resume the thread. */
940 if (!is_thread_in_critical_region (info))
943 if (!mono_thread_info_core_resume (info)) {
944 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
947 THREADS_SUSPEND_DEBUG ("RESTARTED thread tid %p\n", (void*)id);
949 /* Wait for the pending resume to finish */
950 mono_threads_wait_pending_operations ();
952 if (sleep_duration == 0)
953 mono_thread_info_yield ();
955 g_usleep (sleep_duration);
957 sleep_duration += 10;
963 mono_thread_info_safe_suspend_and_run (MonoNativeThreadId id, gboolean interrupt_kernel, MonoSuspendThreadCallback callback, gpointer user_data)
966 MonoThreadInfo *info = NULL;
967 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
969 THREADS_SUSPEND_DEBUG ("SUSPENDING tid %p\n", (void*)id);
970 /*FIXME: unify this with self-suspend*/
971 g_assert (id != mono_native_thread_id_get ());
973 /* This can block during stw */
974 mono_thread_info_suspend_lock ();
975 mono_threads_begin_global_suspend ();
977 info = suspend_sync_nolock (id, interrupt_kernel);
981 switch (result = callback (info, user_data)) {
982 case MonoResumeThread:
983 mono_hazard_pointer_set (hp, 1, info);
984 mono_thread_info_core_resume (info);
985 mono_threads_wait_pending_operations ();
990 g_error ("Invalid suspend_and_run callback return value %d", result);
994 mono_hazard_pointer_clear (hp, 1);
995 mono_threads_end_global_suspend ();
996 mono_thread_info_suspend_unlock ();
1000 Inject an assynchronous call into the target thread. The target thread must be suspended and
1001 only a single async call can be setup for a given suspend cycle.
1002 This async call must cause stack unwinding as the current implementation doesn't save enough state
1003 to resume execution of the top-of-stack function. It's an acceptable limitation since this is
1004 currently used only to deliver exceptions.
1007 mono_thread_info_setup_async_call (MonoThreadInfo *info, void (*target_func)(void*), void *user_data)
1009 /* An async call can only be setup on an async suspended thread */
1010 g_assert (mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED);
1011 /*FIXME this is a bad assert, we probably should do proper locking and fail if one is already set*/
1012 g_assert (!info->async_target);
1013 info->async_target = target_func;
1014 /* This is not GC tracked */
1015 info->user_data = user_data;
1019 The suspend lock is held during any suspend in progress.
1020 A GC that has safepoints must take this lock as part of its
1021 STW to make sure no unsafe pending suspend is in progress.
1025 mono_thread_info_suspend_lock_with_info (MonoThreadInfo *info)
1029 MONO_ENTER_GC_SAFE_WITH_INFO(info);
1031 int res = mono_os_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
1032 g_assert (res != -1);
1034 MONO_EXIT_GC_SAFE_WITH_INFO;
1038 mono_thread_info_suspend_lock (void)
1040 mono_thread_info_suspend_lock_with_info (mono_thread_info_current_unchecked ());
1044 mono_thread_info_suspend_unlock (void)
1046 mono_os_sem_post (&global_suspend_semaphore);
1050 * This is a very specific function whose only purpose is to
1051 * break a given thread from socket syscalls.
1053 * This only exists because linux won't fail a call to connect
1054 * if the underlying is closed.
1056 * TODO We should cleanup and unify this with the other syscall abort
1060 mono_thread_info_abort_socket_syscall_for_close (MonoNativeThreadId tid)
1062 MonoThreadHazardPointers *hp;
1063 MonoThreadInfo *info;
1065 if (tid == mono_native_thread_id_get () || !mono_threads_core_needs_abort_syscall ())
1068 hp = mono_hazard_pointer_get ();
1069 info = mono_thread_info_lookup (tid);
1073 if (mono_thread_info_run_state (info) == STATE_DETACHED) {
1074 mono_hazard_pointer_clear (hp, 1);
1078 mono_thread_info_suspend_lock ();
1079 mono_threads_begin_global_suspend ();
1081 mono_threads_core_abort_syscall (info);
1082 mono_threads_wait_pending_operations ();
1084 mono_hazard_pointer_clear (hp, 1);
1086 mono_threads_end_global_suspend ();
1087 mono_thread_info_suspend_unlock ();
1091 mono_thread_info_unified_management_enabled (void)
1093 return unified_suspend_enabled;
1097 * mono_thread_info_set_is_async_context:
1099 * Set whenever the current thread is in an async context. Some runtime functions might behave
1100 * differently while in an async context in order to be async safe.
1103 mono_thread_info_set_is_async_context (gboolean async_context)
1105 MonoThreadInfo *info = mono_thread_info_current ();
1108 info->is_async_context = async_context;
1112 mono_thread_info_is_async_context (void)
1114 MonoThreadInfo *info = mono_thread_info_current ();
1117 return info->is_async_context;
1123 * mono_threads_create_thread:
1125 * Create a new thread executing START with argument ARG. Store its id into OUT_TID.
1126 * Returns: a windows or io-layer handle for the thread.
1129 mono_threads_create_thread (LPTHREAD_START_ROUTINE start, gpointer arg, MonoThreadParm *tp, MonoNativeThreadId *out_tid)
1131 return mono_threads_core_create_thread (start, arg, tp, out_tid);
1135 * mono_thread_info_get_stack_bounds:
1137 * Return the address and size of the current threads stack. Return NULL as the
1138 * stack address if the stack address cannot be determined.
1141 mono_thread_info_get_stack_bounds (guint8 **staddr, size_t *stsize)
1143 guint8 *current = (guint8 *)&stsize;
1144 mono_threads_core_get_stack_bounds (staddr, stsize);
1148 /* Sanity check the result */
1149 g_assert ((current > *staddr) && (current < *staddr + *stsize));
1151 /* When running under emacs, sometimes staddr is not aligned to a page size */
1152 *staddr = (guint8*)((gssize)*staddr & ~(mono_pagesize () - 1));
1156 mono_thread_info_yield (void)
1158 return mono_threads_core_yield ();
1160 static mono_lazy_init_t sleep_init = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
1161 static MonoCoopMutex sleep_mutex;
1162 static MonoCoopCond sleep_cond;
1165 sleep_initialize (void)
1167 mono_coop_mutex_init (&sleep_mutex);
1168 mono_coop_cond_init (&sleep_cond);
1172 sleep_interrupt (gpointer data)
1174 mono_coop_mutex_lock (&sleep_mutex);
1175 mono_coop_cond_broadcast (&sleep_cond);
1176 mono_coop_mutex_unlock (&sleep_mutex);
1179 static inline guint32
1180 sleep_interruptable (guint32 ms, gboolean *alerted)
1184 g_assert (INFINITE == G_MAXUINT32);
1190 end = mono_100ns_ticks () + (ms * 1000 * 10);
1192 mono_lazy_initialize (&sleep_init, sleep_initialize);
1194 mono_coop_mutex_lock (&sleep_mutex);
1197 if (ms != INFINITE) {
1198 now = mono_100ns_ticks ();
1203 mono_thread_info_install_interrupt (sleep_interrupt, NULL, alerted);
1205 mono_coop_mutex_unlock (&sleep_mutex);
1206 return WAIT_IO_COMPLETION;
1210 mono_coop_cond_timedwait (&sleep_cond, &sleep_mutex, (end - now) / 10 / 1000);
1212 mono_coop_cond_wait (&sleep_cond, &sleep_mutex);
1214 mono_thread_info_uninstall_interrupt (alerted);
1216 mono_coop_mutex_unlock (&sleep_mutex);
1217 return WAIT_IO_COMPLETION;
1221 mono_coop_mutex_unlock (&sleep_mutex);
1227 mono_thread_info_sleep (guint32 ms, gboolean *alerted)
1230 MonoThreadInfo *info;
1232 mono_thread_info_yield ();
1234 info = mono_thread_info_current ();
1235 if (info && mono_thread_info_is_interrupt_state (info))
1236 return WAIT_IO_COMPLETION;
1242 return sleep_interruptable (ms, alerted);
1246 if (ms == INFINITE) {
1249 Sleep (G_MAXUINT32);
1251 sleep (G_MAXUINT32);
1256 #if defined (__linux__) && !defined(PLATFORM_ANDROID)
1257 struct timespec start, target;
1259 /* Use clock_nanosleep () to prevent time drifting problems when nanosleep () is interrupted by signals */
1260 ret = clock_gettime (CLOCK_MONOTONIC, &start);
1261 g_assert (ret == 0);
1264 target.tv_sec += ms / 1000;
1265 target.tv_nsec += (ms % 1000) * 1000000;
1266 if (target.tv_nsec > 999999999) {
1267 target.tv_nsec -= 999999999;
1272 ret = clock_nanosleep (CLOCK_MONOTONIC, TIMER_ABSTIME, &target, NULL);
1277 struct timespec req, rem;
1279 req.tv_sec = ms / 1000;
1280 req.tv_nsec = (ms % 1000) * 1000000;
1283 memset (&rem, 0, sizeof (rem));
1284 ret = nanosleep (&req, &rem);
1286 #endif /* __linux__ */
1295 mono_thread_info_usleep (guint64 us)
1304 mono_thread_info_tls_get (THREAD_INFO_TYPE *info, MonoTlsKey key)
1306 return ((MonoThreadInfo*)info)->tls [key];
1310 * mono_threads_info_tls_set:
1312 * Set the TLS key to VALUE in the info structure. This can be used to obtain
1313 * values of TLS variables for threads other than the current thread.
1314 * This should only be used for infrequently changing TLS variables, and it should
1315 * be paired with setting the real TLS variable since this provides no GC tracking.
1318 mono_thread_info_tls_set (THREAD_INFO_TYPE *info, MonoTlsKey key, gpointer value)
1320 ((MonoThreadInfo*)info)->tls [key] = value;
1324 * mono_thread_info_exit:
1326 * Exit the current thread.
1327 * This function doesn't return.
1330 mono_thread_info_exit (void)
1332 mono_threads_core_exit (0);
1336 * mono_thread_info_open_handle:
1338 * Return a io-layer/win32 handle for the current thread.
1339 * The handle need to be closed by calling CloseHandle () when it is no
1343 mono_thread_info_open_handle (void)
1345 return mono_threads_core_open_handle ();
1349 * mono_threads_open_thread_handle:
1351 * Return a io-layer/win32 handle for the thread identified by HANDLE/TID.
1352 * The handle need to be closed by calling CloseHandle () when it is no
1356 mono_threads_open_thread_handle (HANDLE handle, MonoNativeThreadId tid)
1358 return mono_threads_core_open_thread_handle (handle, tid);
1361 #define INTERRUPT_STATE ((MonoThreadInfoInterruptToken*) (size_t) -1)
1363 struct _MonoThreadInfoInterruptToken {
1364 void (*callback) (gpointer data);
1369 * mono_thread_info_install_interrupt: install an interruption token for the current thread.
1371 * - @callback: must be able to be called from another thread and always cancel the wait
1372 * - @data: passed to the callback
1373 * - @interrupted: will be set to TRUE if a token is already installed, FALSE otherwise
1374 * if set to TRUE, it must mean that the thread is in interrupted state
1377 mono_thread_info_install_interrupt (void (*callback) (gpointer data), gpointer data, gboolean *interrupted)
1379 MonoThreadInfo *info;
1380 MonoThreadInfoInterruptToken *previous_token, *token;
1382 g_assert (callback);
1384 g_assert (interrupted);
1385 *interrupted = FALSE;
1387 info = mono_thread_info_current ();
1390 /* The memory of this token can be freed at 2 places:
1391 * - if the token is not interrupted: it will be freed in uninstall, as info->interrupt_token has not been replaced
1392 * by the INTERRUPT_STATE flag value, and it still contains the pointer to the memory location
1393 * - if the token is interrupted: it will be freed in finish, as the token is now owned by the prepare/finish
1394 * functions, and info->interrupt_token does not contains a pointer to the memory anymore */
1395 token = g_new0 (MonoThreadInfoInterruptToken, 1);
1396 token->callback = callback;
1399 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, token, NULL);
1401 if (previous_token) {
1402 if (previous_token != INTERRUPT_STATE)
1403 g_error ("mono_thread_info_install_interrupt: previous_token should be INTERRUPT_STATE (%p), but it was %p", INTERRUPT_STATE, previous_token);
1407 *interrupted = TRUE;
1410 THREADS_INTERRUPT_DEBUG ("interrupt install tid %p token %p previous_token %p interrupted %s\n",
1411 mono_thread_info_get_tid (info), token, previous_token, *interrupted ? "TRUE" : "FALSE");
1415 mono_thread_info_uninstall_interrupt (gboolean *interrupted)
1417 MonoThreadInfo *info;
1418 MonoThreadInfoInterruptToken *previous_token;
1420 g_assert (interrupted);
1421 *interrupted = FALSE;
1423 info = mono_thread_info_current ();
1426 previous_token = (MonoThreadInfoInterruptToken *)InterlockedExchangePointer ((gpointer*) &info->interrupt_token, NULL);
1428 /* only the installer can uninstall the token */
1429 g_assert (previous_token);
1431 if (previous_token == INTERRUPT_STATE) {
1432 /* if it is interrupted, then it is going to be freed in finish interrupt */
1433 *interrupted = TRUE;
1435 g_free (previous_token);
1438 THREADS_INTERRUPT_DEBUG ("interrupt uninstall tid %p previous_token %p interrupted %s\n",
1439 mono_thread_info_get_tid (info), previous_token, *interrupted ? "TRUE" : "FALSE");
1442 static MonoThreadInfoInterruptToken*
1443 set_interrupt_state (MonoThreadInfo *info)
1445 MonoThreadInfoInterruptToken *token, *previous_token;
1449 /* Atomically obtain the token the thread is
1450 * waiting on, and change it to a flag value. */
1453 previous_token = info->interrupt_token;
1455 /* Already interrupted */
1456 if (previous_token == INTERRUPT_STATE) {
1461 token = previous_token;
1462 } while (InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, INTERRUPT_STATE, previous_token) != previous_token);
1468 * mono_thread_info_prepare_interrupt:
1470 * The state of the thread info interrupt token is set to 'interrupted' which means that :
1471 * - if the thread calls one of the WaitFor functions, the function will return with
1472 * WAIT_IO_COMPLETION instead of waiting
1473 * - if the thread was waiting when this function was called, the wait will be broken
1475 * It is possible that the wait functions return WAIT_IO_COMPLETION, but the target thread
1476 * didn't receive the interrupt signal yet, in this case it should call the wait function
1477 * again. This essentially means that the target thread will busy wait until it is ready to
1478 * process the interruption.
1480 MonoThreadInfoInterruptToken*
1481 mono_thread_info_prepare_interrupt (MonoThreadInfo *info)
1483 MonoThreadInfoInterruptToken *token;
1485 token = set_interrupt_state (info);
1487 THREADS_INTERRUPT_DEBUG ("interrupt prepare tid %p token %p\n",
1488 mono_thread_info_get_tid (info), token);
1494 mono_thread_info_finish_interrupt (MonoThreadInfoInterruptToken *token)
1496 THREADS_INTERRUPT_DEBUG ("interrupt finish token %p\n", token);
1501 g_assert (token->callback);
1503 token->callback (token->data);
1509 mono_thread_info_self_interrupt (void)
1511 MonoThreadInfo *info;
1512 MonoThreadInfoInterruptToken *token;
1514 info = mono_thread_info_current ();
1517 token = set_interrupt_state (info);
1520 THREADS_INTERRUPT_DEBUG ("interrupt self tid %p\n",
1521 mono_thread_info_get_tid (info));
1524 /* Clear the interrupted flag of the current thread, set with
1525 * mono_thread_info_self_interrupt, so it can wait again */
1527 mono_thread_info_clear_self_interrupt ()
1529 MonoThreadInfo *info;
1530 MonoThreadInfoInterruptToken *previous_token;
1532 info = mono_thread_info_current ();
1535 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, NULL, INTERRUPT_STATE);
1536 g_assert (previous_token == NULL || previous_token == INTERRUPT_STATE);
1538 THREADS_INTERRUPT_DEBUG ("interrupt clear self tid %p previous_token %p\n", mono_thread_info_get_tid (info), previous_token);
1542 mono_thread_info_is_interrupt_state (MonoThreadInfo *info)
1545 return InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE;
1549 mono_thread_info_describe_interrupt_token (MonoThreadInfo *info, GString *text)
1553 if (!InterlockedReadPointer ((gpointer*) &info->interrupt_token))
1554 g_string_append_printf (text, "not waiting");
1555 else if (InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE)
1556 g_string_append_printf (text, "interrupted state");
1558 g_string_append_printf (text, "waiting");
1562 mono_thread_info_is_current (MonoThreadInfo *info)
1564 return mono_thread_info_get_tid (info) == mono_native_thread_id_get ();