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>
35 #include <mono/utils/mach-support.h>
39 Mutex that makes sure only a single thread can be suspending others.
40 Suspend is a very racy operation since it requires restarting until
41 the target thread is not on an unsafe region.
43 We could implement this using critical regions, but would be much much
44 harder for an operation that is hardly performance critical.
46 The GC has to acquire this lock before starting a STW to make sure
47 a runtime suspend won't make it wronly see a thread in a safepoint
48 when it is in fact not.
50 static MonoCoopSem global_suspend_semaphore;
52 static size_t thread_info_size;
53 static MonoThreadInfoCallbacks threads_callbacks;
54 static MonoThreadInfoRuntimeCallbacks runtime_callbacks;
55 static MonoNativeTlsKey thread_info_key, thread_exited_key;
57 static __thread guint32 tls_small_id MONO_TLS_FAST;
59 static MonoNativeTlsKey small_id_key;
61 static MonoLinkedListSet thread_list;
62 static gboolean mono_threads_inited = FALSE;
64 static MonoSemType suspend_semaphore;
65 static size_t pending_suspends;
66 static gboolean unified_suspend_enabled;
68 #define mono_thread_info_run_state(info) (((MonoThreadInfo*)info)->thread_state & THREAD_STATE_MASK)
71 #define SLEEP_DURATION_BEFORE_WARNING (10)
73 #define SLEEP_DURATION_BEFORE_ABORT 200
75 static int suspend_posts, resume_posts, abort_posts, waits_done, pending_ops;
78 mono_threads_notify_initiator_of_abort (MonoThreadInfo* info)
80 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-ABORT] %p\n", mono_thread_info_get_tid (info));
81 InterlockedIncrement (&abort_posts);
82 mono_os_sem_post (&suspend_semaphore);
86 mono_threads_notify_initiator_of_suspend (MonoThreadInfo* info)
88 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-SUSPEND] %p\n", mono_thread_info_get_tid (info));
89 InterlockedIncrement (&suspend_posts);
90 mono_os_sem_post (&suspend_semaphore);
94 mono_threads_notify_initiator_of_resume (MonoThreadInfo* info)
96 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-RESUME] %p\n", mono_thread_info_get_tid (info));
97 InterlockedIncrement (&resume_posts);
98 mono_os_sem_post (&suspend_semaphore);
102 begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
104 if (mono_threads_is_coop_enabled ()) {
105 /* There's nothing else to do after we async request the thread to suspend */
106 mono_threads_add_to_pending_operation_set (info);
110 return mono_threads_core_begin_async_suspend (info, interrupt_kernel);
114 check_async_suspend (MonoThreadInfo *info)
116 if (mono_threads_is_coop_enabled ()) {
117 /* Async suspend can't async fail on coop */
121 return mono_threads_core_check_suspend_result (info);
125 resume_async_suspended (MonoThreadInfo *info)
127 if (mono_threads_is_coop_enabled ())
128 g_assert_not_reached ();
130 g_assert (mono_threads_core_begin_async_resume (info));
134 resume_self_suspended (MonoThreadInfo* info)
136 THREADS_SUSPEND_DEBUG ("**BEGIN self-resume %p\n", mono_thread_info_get_tid (info));
137 mono_os_sem_post (&info->resume_semaphore);
141 mono_thread_info_wait_for_resume (MonoThreadInfo* info)
144 THREADS_SUSPEND_DEBUG ("**WAIT self-resume %p\n", mono_thread_info_get_tid (info));
145 res = mono_os_sem_wait (&info->resume_semaphore, MONO_SEM_FLAGS_NONE);
146 g_assert (res != -1);
150 resume_blocking_suspended (MonoThreadInfo* info)
152 THREADS_SUSPEND_DEBUG ("**BEGIN blocking-resume %p\n", mono_thread_info_get_tid (info));
153 mono_os_sem_post (&info->resume_semaphore);
157 mono_threads_add_to_pending_operation_set (MonoThreadInfo* info)
159 THREADS_SUSPEND_DEBUG ("added %p to pending suspend\n", mono_thread_info_get_tid (info));
161 InterlockedIncrement (&pending_ops);
165 mono_threads_begin_global_suspend (void)
167 size_t ps = pending_suspends;
168 if (G_UNLIKELY (ps != 0))
169 g_error ("pending_suspends = %d, but must be 0", ps);
170 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,
171 abort_posts, waits_done, pending_ops);
172 g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
173 mono_threads_coop_begin_global_suspend ();
177 mono_threads_end_global_suspend (void)
179 size_t ps = pending_suspends;
180 if (G_UNLIKELY (ps != 0))
181 g_error ("pending_suspends = %d, but must be 0", ps);
182 THREADS_SUSPEND_DEBUG ("------ END GLOBAL OP sp %d rp %d ap %d wd %d po %d\n", suspend_posts, resume_posts,
183 abort_posts, waits_done, pending_ops);
184 g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
185 mono_threads_coop_end_global_suspend ();
191 MonoThreadInfo *cur = mono_thread_info_current ();
193 MOSTLY_ASYNC_SAFE_PRINTF ("STATE CUE CARD: (? means a positive number, usually 1 or 2, * means any number)\n");
194 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x0\t- starting (GOOD, unless the thread is running managed code)\n");
195 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x1\t- running (BAD, unless it's the gc thread)\n");
196 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x2\t- detached (GOOD, unless the thread is running managed code)\n");
197 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?03\t- async suspended (GOOD)\n");
198 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?04\t- self suspended (GOOD)\n");
199 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?05\t- async suspend requested (BAD)\n");
200 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?06\t- self suspend requested (BAD)\n");
201 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x*07\t- blocking (GOOD)\n");
202 MOSTLY_ASYNC_SAFE_PRINTF ("\t0x?08\t- blocking with pending suspend (GOOD)\n");
204 FOREACH_THREAD_SAFE (info) {
206 char thread_name [256] = { 0 };
207 pthread_getname_np (mono_thread_info_get_tid (info), thread_name, 255);
209 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" : "" );
211 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" : "" );
213 } FOREACH_THREAD_SAFE_END
217 mono_threads_wait_pending_operations (void)
220 int c = pending_suspends;
222 /* Wait threads to park */
223 THREADS_SUSPEND_DEBUG ("[INITIATOR-WAIT-COUNT] %d\n", c);
224 if (pending_suspends) {
225 MonoStopwatch suspension_time;
226 mono_stopwatch_start (&suspension_time);
227 for (i = 0; i < pending_suspends; ++i) {
228 THREADS_SUSPEND_DEBUG ("[INITIATOR-WAIT-WAITING]\n");
229 InterlockedIncrement (&waits_done);
230 if (!mono_os_sem_timedwait (&suspend_semaphore, SLEEP_DURATION_BEFORE_ABORT, MONO_SEM_FLAGS_NONE))
232 mono_stopwatch_stop (&suspension_time);
236 MOSTLY_ASYNC_SAFE_PRINTF ("WAITING for %d threads, got %d suspended\n", (int)pending_suspends, i);
237 g_error ("suspend_thread suspend took %d ms, which is more than the allowed %d ms", (int)mono_stopwatch_elapsed_ms (&suspension_time), SLEEP_DURATION_BEFORE_ABORT);
239 mono_stopwatch_stop (&suspension_time);
240 THREADS_SUSPEND_DEBUG ("Suspending %d threads took %d ms.\n", (int)pending_suspends, (int)mono_stopwatch_elapsed_ms (&suspension_time));
244 pending_suspends = 0;
250 //Thread initialization code
252 static void mono_threads_unregister_current_thread (MonoThreadInfo *info);
255 mono_hazard_pointer_clear_all (MonoThreadHazardPointers *hp, int retain)
258 mono_hazard_pointer_clear (hp, 0);
260 mono_hazard_pointer_clear (hp, 1);
262 mono_hazard_pointer_clear (hp, 2);
266 If return non null Hazard Pointer 1 holds the return value.
269 mono_thread_info_lookup (MonoNativeThreadId id)
271 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
273 if (!mono_lls_find (&thread_list, hp, (uintptr_t)id, HAZARD_FREE_ASYNC_CTX)) {
274 mono_hazard_pointer_clear_all (hp, -1);
278 mono_hazard_pointer_clear_all (hp, 1);
279 return (MonoThreadInfo *) mono_hazard_pointer_get_val (hp, 1);
283 mono_thread_info_insert (MonoThreadInfo *info)
285 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
287 if (!mono_lls_insert (&thread_list, hp, (MonoLinkedListSetNode*)info, HAZARD_FREE_SAFE_CTX)) {
288 mono_hazard_pointer_clear_all (hp, -1);
292 mono_hazard_pointer_clear_all (hp, -1);
297 mono_thread_info_remove (MonoThreadInfo *info)
299 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
302 THREADS_DEBUG ("removing info %p\n", info);
303 res = mono_lls_remove (&thread_list, hp, (MonoLinkedListSetNode*)info, HAZARD_FREE_SAFE_CTX);
304 mono_hazard_pointer_clear_all (hp, -1);
309 free_thread_info (gpointer mem)
311 MonoThreadInfo *info = (MonoThreadInfo *) mem;
313 mono_os_sem_destroy (&info->resume_semaphore);
314 mono_threads_platform_free (info);
320 mono_thread_info_register_small_id (void)
322 int small_id = mono_thread_small_id_alloc ();
323 #ifdef HAVE_KW_THREAD
324 tls_small_id = small_id;
326 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (small_id + 1));
332 register_thread (MonoThreadInfo *info, gpointer baseptr)
335 guint8 *staddr = NULL;
336 int small_id = mono_thread_info_register_small_id ();
338 mono_thread_info_set_tid (info, mono_native_thread_id_get ());
339 info->small_id = small_id;
341 mono_os_sem_init (&info->resume_semaphore, 0);
343 /*set TLS early so SMR works */
344 mono_native_tls_set_value (thread_info_key, info);
346 THREADS_DEBUG ("registering info %p tid %p small id %x\n", info, mono_thread_info_get_tid (info), info->small_id);
348 if (threads_callbacks.thread_register) {
349 if (threads_callbacks.thread_register (info, baseptr) == NULL) {
350 // g_warning ("thread registation failed\n");
356 mono_thread_info_get_stack_bounds (&staddr, &stsize);
359 info->stack_start_limit = staddr;
360 info->stack_end = staddr + stsize;
362 info->stackdata = g_byte_array_new ();
364 mono_threads_platform_register (info);
367 Transition it before taking any locks or publishing itself to reduce the chance
368 of others witnessing a detached thread.
369 We can reasonably expect that until this thread gets published, no other thread will
370 try to manipulate it.
372 mono_threads_transition_attach (info);
373 mono_thread_info_suspend_lock ();
374 /*If this fail it means a given thread has been registered twice, which doesn't make sense. */
375 result = mono_thread_info_insert (info);
377 mono_thread_info_suspend_unlock ();
382 unregister_thread (void *arg)
384 MonoThreadInfo *info = (MonoThreadInfo *) arg;
385 int small_id = info->small_id;
388 THREADS_DEBUG ("unregistering info %p\n", info);
390 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
392 mono_threads_core_unregister (info);
395 * TLS destruction order is not reliable so small_id might be cleaned up
398 #ifndef HAVE_KW_THREAD
399 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (info->small_id + 1));
403 First perform the callback that requires no locks.
404 This callback has the potential of taking other locks, so we do it before.
405 After it completes, the thread remains functional.
407 if (threads_callbacks.thread_detach)
408 threads_callbacks.thread_detach (info);
410 mono_thread_info_suspend_lock ();
413 Now perform the callback that must be done under locks.
414 This will render the thread useless and non-suspendable, so it must
415 be done while holding the suspend lock to give no other thread chance
418 if (threads_callbacks.thread_unregister)
419 threads_callbacks.thread_unregister (info);
420 mono_threads_unregister_current_thread (info);
421 mono_threads_transition_detach (info);
423 mono_thread_info_suspend_unlock ();
425 g_byte_array_free (info->stackdata, /*free_segment=*/TRUE);
427 /*now it's safe to free the thread info.*/
428 mono_thread_hazardous_try_free (info, free_thread_info);
429 /* Pump the HP queue */
430 mono_thread_hazardous_try_free_some ();
432 mono_thread_small_id_free (small_id);
436 thread_exited_dtor (void *arg)
438 #if defined(__MACH__)
440 * Since we use pthread dtors to clean up thread data, if a thread
441 * is attached to the runtime by another pthread dtor after our dtor
442 * has ran, it will never be detached, leading to various problems
443 * since the thread ids etc. will be reused while they are still in
444 * the threads hashtables etc.
445 * Dtors are called in a loop until all user tls entries are 0,
446 * but the loop has a maximum count (4), so if we set the tls
447 * variable every time, it will remain set when system tls dtors
448 * are ran. This allows mono_thread_info_is_exiting () to detect
449 * whenever the thread is exiting, even if it is executed from a
450 * system tls dtor (i.e. obj-c dealloc methods).
452 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
457 * Removes the current thread from the thread list.
458 * This must be called from the thread unregister callback and nowhere else.
459 * The current thread must be passed as TLS might have already been cleaned up.
462 mono_threads_unregister_current_thread (MonoThreadInfo *info)
465 g_assert (mono_thread_info_get_tid (info) == mono_native_thread_id_get ());
466 result = mono_thread_info_remove (info);
471 mono_thread_info_current_unchecked (void)
473 return mono_threads_inited ? (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key) : NULL;
478 mono_thread_info_current (void)
480 MonoThreadInfo *info = (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key);
484 info = mono_thread_info_lookup (mono_native_thread_id_get ()); /*info on HP1*/
487 We might be called during thread cleanup, but we cannot be called after cleanup as happened.
488 The way to distinguish between before, during and after cleanup is the following:
490 -If the TLS key is set, cleanup has not begun;
491 -If the TLS key is clean, but the thread remains registered, cleanup is in progress;
492 -If the thread is nowhere to be found, cleanup has finished.
494 We cannot function after cleanup since there's no way to ensure what will happen.
498 /*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 */
499 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
505 mono_thread_info_get_small_id (void)
507 #ifdef HAVE_KW_THREAD
510 gpointer val = mono_native_tls_get_value (small_id_key);
513 return GPOINTER_TO_INT (val) - 1;
518 mono_thread_info_list_head (void)
524 * mono_threads_attach_tools_thread
526 * Attach the current thread as a tool thread. DON'T USE THIS FUNCTION WITHOUT READING ALL DISCLAIMERS.
528 * A tools thread is a very special kind of thread that needs access to core runtime facilities but should
529 * not be counted as a regular thread for high order facilities such as executing managed code or accessing
532 * This is intended only to tools such as a profiler than needs to be able to use our lock-free support when
533 * doing things like resolving backtraces in their background processing thread.
536 mono_threads_attach_tools_thread (void)
539 MonoThreadInfo *info;
541 /* Must only be called once */
542 g_assert (!mono_native_tls_get_value (thread_info_key));
544 while (!mono_threads_inited) {
545 mono_thread_info_usleep (10);
548 info = mono_thread_info_attach (&dummy);
551 info->tools_thread = TRUE;
555 mono_thread_info_attach (void *baseptr)
557 MonoThreadInfo *info;
558 if (!mono_threads_inited)
561 /* This can happen from DllMain(DLL_THREAD_ATTACH) on Windows, if a
562 * thread is created before an embedding API user initialized Mono. */
563 THREADS_DEBUG ("mono_thread_info_attach called before mono_threads_init\n");
566 g_assert (mono_threads_inited);
569 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
571 info = (MonoThreadInfo *) g_malloc0 (thread_info_size);
572 THREADS_DEBUG ("attaching %p\n", info);
573 if (!register_thread (info, baseptr))
575 } else if (threads_callbacks.thread_attach) {
576 threads_callbacks.thread_attach (info);
582 mono_thread_info_detach (void)
584 MonoThreadInfo *info;
585 if (!mono_threads_inited)
587 /* This can happen from DllMain(THREAD_DETACH) on Windows, if a thread
588 * is created before an embedding API user initialized Mono. */
589 THREADS_DEBUG ("mono_thread_info_detach called before mono_threads_init\n");
592 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
594 THREADS_DEBUG ("detaching %p\n", info);
595 unregister_thread (info);
596 mono_native_tls_set_value (thread_info_key, NULL);
601 * mono_thread_info_is_exiting:
603 * Return whenever the current thread is exiting, i.e. it is running pthread
607 mono_thread_info_is_exiting (void)
609 #if defined(__MACH__)
610 if (mono_native_tls_get_value (thread_exited_key) == GUINT_TO_POINTER (1))
617 mono_threads_init (MonoThreadInfoCallbacks *callbacks, size_t info_size)
620 threads_callbacks = *callbacks;
621 thread_info_size = info_size;
623 res = mono_native_tls_alloc (&thread_info_key, NULL);
624 res = mono_native_tls_alloc (&thread_exited_key, NULL);
626 res = mono_native_tls_alloc (&thread_info_key, (void *) unregister_thread);
627 res = mono_native_tls_alloc (&thread_exited_key, (void *) thread_exited_dtor);
632 #ifndef HAVE_KW_THREAD
633 res = mono_native_tls_alloc (&small_id_key, NULL);
637 unified_suspend_enabled = g_getenv ("MONO_ENABLE_UNIFIED_SUSPEND") != NULL || mono_threads_is_coop_enabled ();
639 mono_coop_sem_init (&global_suspend_semaphore, 1);
640 mono_os_sem_init (&suspend_semaphore, 0);
642 mono_lls_init (&thread_list, NULL, HAZARD_FREE_NO_LOCK);
643 mono_thread_smr_init ();
644 mono_threads_init_platform ();
645 mono_threads_init_coop ();
646 mono_threads_init_abort_syscall ();
648 #if defined(__MACH__)
649 mono_mach_init (thread_info_key);
652 mono_threads_inited = TRUE;
654 g_assert (sizeof (MonoNativeThreadId) <= sizeof (uintptr_t));
658 mono_threads_runtime_init (MonoThreadInfoRuntimeCallbacks *callbacks)
660 runtime_callbacks = *callbacks;
663 MonoThreadInfoRuntimeCallbacks *
664 mono_threads_get_runtime_callbacks (void)
666 return &runtime_callbacks;
670 Signal that the current thread wants to be suspended.
671 This function can be called without holding the suspend lock held.
672 To finish suspending, call mono_suspend_check.
675 mono_thread_info_begin_self_suspend (void)
677 MonoThreadInfo *info = mono_thread_info_current_unchecked ();
681 THREADS_SUSPEND_DEBUG ("BEGIN SELF SUSPEND OF %p\n", info);
682 mono_threads_transition_request_self_suspension (info);
686 mono_thread_info_end_self_suspend (void)
688 MonoThreadInfo *info;
690 info = mono_thread_info_current ();
693 THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", info);
695 mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
697 /* commit the saved state and notify others if needed */
698 switch (mono_threads_transition_state_poll (info)) {
699 case SelfSuspendResumed:
701 case SelfSuspendWait:
702 mono_thread_info_wait_for_resume (info);
704 case SelfSuspendNotifyAndWait:
705 mono_threads_notify_initiator_of_suspend (info);
706 mono_thread_info_wait_for_resume (info);
707 mono_threads_notify_initiator_of_resume (info);
713 mono_thread_info_core_resume (MonoThreadInfo *info)
715 gboolean res = FALSE;
716 if (info->create_suspended) {
717 MonoNativeThreadId tid = mono_thread_info_get_tid (info);
718 /* 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 */
719 info->create_suspended = FALSE;
720 mono_threads_core_resume_created (info, tid);
724 switch (mono_threads_transition_request_resume (info)) {
731 case ResumeInitSelfResume:
732 resume_self_suspended (info);
735 case ResumeInitAsyncResume:
736 resume_async_suspended (info);
739 case ResumeInitBlockingResume:
740 resume_blocking_suspended (info);
749 mono_thread_info_resume (MonoNativeThreadId tid)
751 gboolean result; /* don't initialize it so the compiler can catch unitilized paths. */
752 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
753 MonoThreadInfo *info;
755 THREADS_SUSPEND_DEBUG ("RESUMING tid %p\n", (void*)tid);
757 mono_thread_info_suspend_lock ();
759 info = mono_thread_info_lookup (tid); /*info on HP1*/
765 result = mono_thread_info_core_resume (info);
767 //Wait for the pending resume to finish
768 mono_threads_wait_pending_operations ();
771 mono_thread_info_suspend_unlock ();
772 mono_hazard_pointer_clear (hp, 1);
777 mono_thread_info_begin_suspend (MonoThreadInfo *info)
779 switch (mono_threads_transition_request_async_suspension (info)) {
780 case AsyncSuspendAlreadySuspended:
781 case AsyncSuspendBlocking:
783 case AsyncSuspendWait:
784 mono_threads_add_to_pending_operation_set (info);
786 case AsyncSuspendInitSuspend:
787 return begin_async_suspend (info, FALSE);
789 g_assert_not_reached ();
794 mono_thread_info_begin_resume (MonoThreadInfo *info)
796 return mono_thread_info_core_resume (info);
800 mono_thread_info_check_suspend_result (MonoThreadInfo *info)
802 return check_async_suspend (info);
806 FIXME fix cardtable WB to be out of line and check with the runtime if the target is not the
807 WB trampoline. Another option is to encode wb ranges in MonoJitInfo, but that is somewhat hard.
810 is_thread_in_critical_region (MonoThreadInfo *info)
814 gpointer stack_start;
815 MonoThreadUnwindState *state;
817 /* Are we inside a system critical region? */
818 if (info->inside_critical_region)
821 /* Are we inside a GC critical region? */
822 if (threads_callbacks.mono_thread_in_critical_region && threads_callbacks.mono_thread_in_critical_region (info)) {
826 /* The target thread might be shutting down and the domain might be null, which means no managed code left to run. */
827 state = mono_thread_info_get_suspend_state (info);
828 if (!state->unwind_data [MONO_UNWIND_DATA_DOMAIN])
831 stack_start = MONO_CONTEXT_GET_SP (&state->ctx);
832 /* altstack signal handler, sgen can't handle them, so we treat them as critical */
833 if (stack_start < info->stack_start_limit || stack_start >= info->stack_end)
836 ji = mono_jit_info_table_find (
837 (MonoDomain *) state->unwind_data [MONO_UNWIND_DATA_DOMAIN],
838 (char *) MONO_CONTEXT_GET_IP (&state->ctx));
843 method = mono_jit_info_get_method (ji);
845 return threads_callbacks.mono_method_is_critical (method);
849 mono_thread_info_in_critical_location (MonoThreadInfo *info)
851 return is_thread_in_critical_region (info);
855 The return value is only valid until a matching mono_thread_info_resume is called
857 static MonoThreadInfo*
858 suspend_sync (MonoNativeThreadId tid, gboolean interrupt_kernel)
860 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
861 MonoThreadInfo *info = mono_thread_info_lookup (tid); /*info on HP1*/
865 switch (mono_threads_transition_request_async_suspension (info)) {
866 case AsyncSuspendAlreadySuspended:
867 mono_hazard_pointer_clear (hp, 1); //XXX this is questionable we got to clean the suspend/resume nonsense of critical sections
869 case AsyncSuspendWait:
870 mono_threads_add_to_pending_operation_set (info);
872 case AsyncSuspendInitSuspend:
873 if (!begin_async_suspend (info, interrupt_kernel)) {
874 mono_hazard_pointer_clear (hp, 1);
878 case AsyncSuspendBlocking:
879 if (interrupt_kernel)
880 mono_threads_core_abort_syscall (info);
884 g_assert_not_reached ();
887 //Wait for the pending suspend to finish
888 mono_threads_wait_pending_operations ();
890 if (!check_async_suspend (info)) {
891 mono_hazard_pointer_clear (hp, 1);
897 static MonoThreadInfo*
898 suspend_sync_nolock (MonoNativeThreadId id, gboolean interrupt_kernel)
900 MonoThreadInfo *info = NULL;
901 int sleep_duration = 0;
903 if (!(info = suspend_sync (id, interrupt_kernel))) {
904 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
908 /*WARNING: We now are in interrupt context until we resume the thread. */
909 if (!is_thread_in_critical_region (info))
912 if (!mono_thread_info_core_resume (info)) {
913 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
916 THREADS_SUSPEND_DEBUG ("RESTARTED thread tid %p\n", (void*)id);
918 /* Wait for the pending resume to finish */
919 mono_threads_wait_pending_operations ();
921 if (sleep_duration == 0)
922 mono_thread_info_yield ();
924 g_usleep (sleep_duration);
926 sleep_duration += 10;
932 mono_thread_info_safe_suspend_and_run (MonoNativeThreadId id, gboolean interrupt_kernel, MonoSuspendThreadCallback callback, gpointer user_data)
935 MonoThreadInfo *info = NULL;
936 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
938 THREADS_SUSPEND_DEBUG ("SUSPENDING tid %p\n", (void*)id);
939 /*FIXME: unify this with self-suspend*/
940 g_assert (id != mono_native_thread_id_get ());
942 /* This can block during stw */
943 mono_thread_info_suspend_lock ();
944 mono_threads_begin_global_suspend ();
946 info = suspend_sync_nolock (id, interrupt_kernel);
950 switch (result = callback (info, user_data)) {
951 case MonoResumeThread:
952 mono_hazard_pointer_set (hp, 1, info);
953 mono_thread_info_core_resume (info);
954 mono_threads_wait_pending_operations ();
959 g_error ("Invalid suspend_and_run callback return value %d", result);
963 mono_hazard_pointer_clear (hp, 1);
964 mono_threads_end_global_suspend ();
965 mono_thread_info_suspend_unlock ();
969 Inject an assynchronous call into the target thread. The target thread must be suspended and
970 only a single async call can be setup for a given suspend cycle.
971 This async call must cause stack unwinding as the current implementation doesn't save enough state
972 to resume execution of the top-of-stack function. It's an acceptable limitation since this is
973 currently used only to deliver exceptions.
976 mono_thread_info_setup_async_call (MonoThreadInfo *info, void (*target_func)(void*), void *user_data)
978 /* An async call can only be setup on an async suspended thread */
979 g_assert (mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED);
980 /*FIXME this is a bad assert, we probably should do proper locking and fail if one is already set*/
981 g_assert (!info->async_target);
982 info->async_target = target_func;
983 /* This is not GC tracked */
984 info->user_data = user_data;
988 The suspend lock is held during any suspend in progress.
989 A GC that has safepoints must take this lock as part of its
990 STW to make sure no unsafe pending suspend is in progress.
993 mono_thread_info_suspend_lock (void)
995 int res = mono_coop_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
996 g_assert (res != -1);
1000 mono_thread_info_suspend_unlock (void)
1002 mono_coop_sem_post (&global_suspend_semaphore);
1006 * This is a very specific function whose only purpose is to
1007 * break a given thread from socket syscalls.
1009 * This only exists because linux won't fail a call to connect
1010 * if the underlying is closed.
1012 * TODO We should cleanup and unify this with the other syscall abort
1016 mono_thread_info_abort_socket_syscall_for_close (MonoNativeThreadId tid)
1018 MonoThreadHazardPointers *hp;
1019 MonoThreadInfo *info;
1021 if (tid == mono_native_thread_id_get () || !mono_threads_core_needs_abort_syscall ())
1024 hp = mono_hazard_pointer_get ();
1025 info = mono_thread_info_lookup (tid);
1029 if (mono_thread_info_run_state (info) == STATE_DETACHED) {
1030 mono_hazard_pointer_clear (hp, 1);
1034 mono_thread_info_suspend_lock ();
1035 mono_threads_begin_global_suspend ();
1037 mono_threads_core_abort_syscall (info);
1038 mono_threads_wait_pending_operations ();
1040 mono_hazard_pointer_clear (hp, 1);
1042 mono_threads_end_global_suspend ();
1043 mono_thread_info_suspend_unlock ();
1047 mono_thread_info_unified_management_enabled (void)
1049 return unified_suspend_enabled;
1053 * mono_thread_info_set_is_async_context:
1055 * Set whenever the current thread is in an async context. Some runtime functions might behave
1056 * differently while in an async context in order to be async safe.
1059 mono_thread_info_set_is_async_context (gboolean async_context)
1061 MonoThreadInfo *info = mono_thread_info_current ();
1064 info->is_async_context = async_context;
1068 mono_thread_info_is_async_context (void)
1070 MonoThreadInfo *info = mono_thread_info_current ();
1073 return info->is_async_context;
1079 * mono_threads_create_thread:
1081 * Create a new thread executing START with argument ARG. Store its id into OUT_TID.
1082 * Returns: a windows or io-layer handle for the thread.
1085 mono_threads_create_thread (LPTHREAD_START_ROUTINE start, gpointer arg, guint32 stack_size, guint32 creation_flags, MonoNativeThreadId *out_tid)
1087 return mono_threads_core_create_thread (start, arg, stack_size, creation_flags, out_tid);
1091 * mono_thread_info_get_stack_bounds:
1093 * Return the address and size of the current threads stack. Return NULL as the
1094 * stack address if the stack address cannot be determined.
1097 mono_thread_info_get_stack_bounds (guint8 **staddr, size_t *stsize)
1099 guint8 *current = (guint8 *)&stsize;
1100 mono_threads_core_get_stack_bounds (staddr, stsize);
1104 /* Sanity check the result */
1105 g_assert ((current > *staddr) && (current < *staddr + *stsize));
1107 /* When running under emacs, sometimes staddr is not aligned to a page size */
1108 *staddr = (guint8*)((gssize)*staddr & ~(mono_pagesize () - 1));
1112 mono_thread_info_yield (void)
1114 return mono_threads_core_yield ();
1116 static mono_lazy_init_t sleep_init = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
1117 static MonoCoopMutex sleep_mutex;
1118 static MonoCoopCond sleep_cond;
1121 sleep_initialize (void)
1123 mono_coop_mutex_init (&sleep_mutex);
1124 mono_coop_cond_init (&sleep_cond);
1128 sleep_interrupt (gpointer data)
1130 mono_coop_mutex_lock (&sleep_mutex);
1131 mono_coop_cond_broadcast (&sleep_cond);
1132 mono_coop_mutex_unlock (&sleep_mutex);
1135 static inline guint32
1136 sleep_interruptable (guint32 ms, gboolean *alerted)
1140 g_assert (INFINITE == G_MAXUINT32);
1146 end = mono_100ns_ticks () + (ms * 1000 * 10);
1148 mono_lazy_initialize (&sleep_init, sleep_initialize);
1150 mono_coop_mutex_lock (&sleep_mutex);
1153 if (ms != INFINITE) {
1154 now = mono_100ns_ticks ();
1159 mono_thread_info_install_interrupt (sleep_interrupt, NULL, alerted);
1161 mono_coop_mutex_unlock (&sleep_mutex);
1162 return WAIT_IO_COMPLETION;
1166 mono_coop_cond_timedwait (&sleep_cond, &sleep_mutex, (end - now) / 10 / 1000);
1168 mono_coop_cond_wait (&sleep_cond, &sleep_mutex);
1170 mono_thread_info_uninstall_interrupt (alerted);
1172 mono_coop_mutex_unlock (&sleep_mutex);
1173 return WAIT_IO_COMPLETION;
1177 mono_coop_mutex_unlock (&sleep_mutex);
1183 mono_thread_info_sleep (guint32 ms, gboolean *alerted)
1186 MonoThreadInfo *info;
1188 mono_thread_info_yield ();
1190 info = mono_thread_info_current ();
1191 if (info && mono_thread_info_is_interrupt_state (info))
1192 return WAIT_IO_COMPLETION;
1198 return sleep_interruptable (ms, alerted);
1200 MONO_PREPARE_BLOCKING;
1202 if (ms == INFINITE) {
1205 Sleep (G_MAXUINT32);
1207 sleep (G_MAXUINT32);
1212 #if defined (__linux__) && !defined(PLATFORM_ANDROID)
1213 struct timespec start, target;
1215 /* Use clock_nanosleep () to prevent time drifting problems when nanosleep () is interrupted by signals */
1216 ret = clock_gettime (CLOCK_MONOTONIC, &start);
1217 g_assert (ret == 0);
1220 target.tv_sec += ms / 1000;
1221 target.tv_nsec += (ms % 1000) * 1000000;
1222 if (target.tv_nsec > 999999999) {
1223 target.tv_nsec -= 999999999;
1228 ret = clock_nanosleep (CLOCK_MONOTONIC, TIMER_ABSTIME, &target, NULL);
1233 struct timespec req, rem;
1235 req.tv_sec = ms / 1000;
1236 req.tv_nsec = (ms % 1000) * 1000000;
1239 memset (&rem, 0, sizeof (rem));
1240 ret = nanosleep (&req, &rem);
1242 #endif /* __linux__ */
1245 MONO_FINISH_BLOCKING;
1251 mono_thread_info_usleep (guint64 us)
1253 MONO_PREPARE_BLOCKING;
1255 MONO_FINISH_BLOCKING;
1260 mono_thread_info_tls_get (THREAD_INFO_TYPE *info, MonoTlsKey key)
1262 return ((MonoThreadInfo*)info)->tls [key];
1266 * mono_threads_info_tls_set:
1268 * Set the TLS key to VALUE in the info structure. This can be used to obtain
1269 * values of TLS variables for threads other than the current thread.
1270 * This should only be used for infrequently changing TLS variables, and it should
1271 * be paired with setting the real TLS variable since this provides no GC tracking.
1274 mono_thread_info_tls_set (THREAD_INFO_TYPE *info, MonoTlsKey key, gpointer value)
1276 ((MonoThreadInfo*)info)->tls [key] = value;
1280 * mono_thread_info_exit:
1282 * Exit the current thread.
1283 * This function doesn't return.
1286 mono_thread_info_exit (void)
1288 mono_threads_core_exit (0);
1292 * mono_thread_info_open_handle:
1294 * Return a io-layer/win32 handle for the current thread.
1295 * The handle need to be closed by calling CloseHandle () when it is no
1299 mono_thread_info_open_handle (void)
1301 return mono_threads_core_open_handle ();
1305 * mono_threads_open_thread_handle:
1307 * Return a io-layer/win32 handle for the thread identified by HANDLE/TID.
1308 * The handle need to be closed by calling CloseHandle () when it is no
1312 mono_threads_open_thread_handle (HANDLE handle, MonoNativeThreadId tid)
1314 return mono_threads_core_open_thread_handle (handle, tid);
1318 mono_thread_info_set_name (MonoNativeThreadId tid, const char *name)
1320 mono_threads_core_set_name (tid, name);
1323 #define INTERRUPT_STATE ((MonoThreadInfoInterruptToken*) (size_t) -1)
1325 struct _MonoThreadInfoInterruptToken {
1326 void (*callback) (gpointer data);
1331 * mono_thread_info_install_interrupt: install an interruption token for the current thread.
1333 * - @callback: must be able to be called from another thread and always cancel the wait
1334 * - @data: passed to the callback
1335 * - @interrupted: will be set to TRUE if a token is already installed, FALSE otherwise
1336 * if set to TRUE, it must mean that the thread is in interrupted state
1339 mono_thread_info_install_interrupt (void (*callback) (gpointer data), gpointer data, gboolean *interrupted)
1341 MonoThreadInfo *info;
1342 MonoThreadInfoInterruptToken *previous_token, *token;
1344 g_assert (callback);
1346 g_assert (interrupted);
1347 *interrupted = FALSE;
1349 info = mono_thread_info_current ();
1352 /* The memory of this token can be freed at 2 places:
1353 * - if the token is not interrupted: it will be freed in uninstall, as info->interrupt_token has not been replaced
1354 * by the INTERRUPT_STATE flag value, and it still contains the pointer to the memory location
1355 * - if the token is interrupted: it will be freed in finish, as the token is now owned by the prepare/finish
1356 * functions, and info->interrupt_token does not contains a pointer to the memory anymore */
1357 token = g_new0 (MonoThreadInfoInterruptToken, 1);
1358 token->callback = callback;
1361 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, token, NULL);
1363 if (previous_token) {
1364 if (previous_token != INTERRUPT_STATE)
1365 g_error ("mono_thread_info_install_interrupt: previous_token should be INTERRUPT_STATE (%p), but it was %p", INTERRUPT_STATE, previous_token);
1369 *interrupted = TRUE;
1372 THREADS_INTERRUPT_DEBUG ("interrupt install tid %p token %p previous_token %p interrupted %s\n",
1373 mono_thread_info_get_tid (info), token, previous_token, *interrupted ? "TRUE" : "FALSE");
1377 mono_thread_info_uninstall_interrupt (gboolean *interrupted)
1379 MonoThreadInfo *info;
1380 MonoThreadInfoInterruptToken *previous_token;
1382 g_assert (interrupted);
1383 *interrupted = FALSE;
1385 info = mono_thread_info_current ();
1388 previous_token = (MonoThreadInfoInterruptToken *)InterlockedExchangePointer ((gpointer*) &info->interrupt_token, NULL);
1390 /* only the installer can uninstall the token */
1391 g_assert (previous_token);
1393 if (previous_token == INTERRUPT_STATE) {
1394 /* if it is interrupted, then it is going to be freed in finish interrupt */
1395 *interrupted = TRUE;
1397 g_free (previous_token);
1400 THREADS_INTERRUPT_DEBUG ("interrupt uninstall tid %p previous_token %p interrupted %s\n",
1401 mono_thread_info_get_tid (info), previous_token, *interrupted ? "TRUE" : "FALSE");
1404 static MonoThreadInfoInterruptToken*
1405 set_interrupt_state (MonoThreadInfo *info)
1407 MonoThreadInfoInterruptToken *token, *previous_token;
1411 /* Atomically obtain the token the thread is
1412 * waiting on, and change it to a flag value. */
1415 previous_token = info->interrupt_token;
1417 /* Already interrupted */
1418 if (previous_token == INTERRUPT_STATE) {
1423 token = previous_token;
1424 } while (InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, INTERRUPT_STATE, previous_token) != previous_token);
1430 * mono_thread_info_prepare_interrupt:
1432 * The state of the thread info interrupt token is set to 'interrupted' which means that :
1433 * - if the thread calls one of the WaitFor functions, the function will return with
1434 * WAIT_IO_COMPLETION instead of waiting
1435 * - if the thread was waiting when this function was called, the wait will be broken
1437 * It is possible that the wait functions return WAIT_IO_COMPLETION, but the target thread
1438 * didn't receive the interrupt signal yet, in this case it should call the wait function
1439 * again. This essentially means that the target thread will busy wait until it is ready to
1440 * process the interruption.
1442 MonoThreadInfoInterruptToken*
1443 mono_thread_info_prepare_interrupt (MonoThreadInfo *info)
1445 MonoThreadInfoInterruptToken *token;
1447 token = set_interrupt_state (info);
1449 THREADS_INTERRUPT_DEBUG ("interrupt prepare tid %p token %p\n",
1450 mono_thread_info_get_tid (info), token);
1456 mono_thread_info_finish_interrupt (MonoThreadInfoInterruptToken *token)
1458 THREADS_INTERRUPT_DEBUG ("interrupt finish token %p\n", token);
1463 g_assert (token->callback);
1465 token->callback (token->data);
1471 mono_thread_info_self_interrupt (void)
1473 MonoThreadInfo *info;
1474 MonoThreadInfoInterruptToken *token;
1476 info = mono_thread_info_current ();
1479 token = set_interrupt_state (info);
1482 THREADS_INTERRUPT_DEBUG ("interrupt self tid %p\n",
1483 mono_thread_info_get_tid (info));
1486 /* Clear the interrupted flag of the current thread, set with
1487 * mono_thread_info_self_interrupt, so it can wait again */
1489 mono_thread_info_clear_self_interrupt ()
1491 MonoThreadInfo *info;
1492 MonoThreadInfoInterruptToken *previous_token;
1494 info = mono_thread_info_current ();
1497 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, NULL, INTERRUPT_STATE);
1498 g_assert (previous_token == NULL || previous_token == INTERRUPT_STATE);
1500 THREADS_INTERRUPT_DEBUG ("interrupt clear self tid %p previous_token %p\n", mono_thread_info_get_tid (info), previous_token);
1504 mono_thread_info_is_interrupt_state (MonoThreadInfo *info)
1507 return InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE;
1511 mono_thread_info_describe_interrupt_token (MonoThreadInfo *info, GString *text)
1515 if (!InterlockedReadPointer ((gpointer*) &info->interrupt_token))
1516 g_string_append_printf (text, "not waiting");
1517 else if (InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE)
1518 g_string_append_printf (text, "interrupted state");
1520 g_string_append_printf (text, "waiting");