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_suspend_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_suspend_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_suspend_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) == MONO_SEM_TIMEDWAIT_RET_SUCCESS)
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
264 mono_hazard_pointer_clear_all (MonoThreadHazardPointers *hp, int retain)
267 mono_hazard_pointer_clear (hp, 0);
269 mono_hazard_pointer_clear (hp, 1);
271 mono_hazard_pointer_clear (hp, 2);
275 If return non null Hazard Pointer 1 holds the return value.
278 mono_thread_info_lookup (MonoNativeThreadId id)
280 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
282 if (!mono_lls_find (&thread_list, hp, (uintptr_t)id)) {
283 mono_hazard_pointer_clear_all (hp, -1);
287 mono_hazard_pointer_clear_all (hp, 1);
288 return (MonoThreadInfo *) mono_hazard_pointer_get_val (hp, 1);
292 mono_thread_info_insert (MonoThreadInfo *info)
294 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
296 if (!mono_lls_insert (&thread_list, hp, (MonoLinkedListSetNode*)info)) {
297 mono_hazard_pointer_clear_all (hp, -1);
301 mono_hazard_pointer_clear_all (hp, -1);
306 mono_thread_info_remove (MonoThreadInfo *info)
308 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
311 THREADS_DEBUG ("removing info %p\n", info);
312 res = mono_lls_remove (&thread_list, hp, (MonoLinkedListSetNode*)info);
313 mono_hazard_pointer_clear_all (hp, -1);
318 free_thread_info (gpointer mem)
320 MonoThreadInfo *info = (MonoThreadInfo *) mem;
322 mono_os_sem_destroy (&info->resume_semaphore);
323 mono_threads_suspend_free (info);
329 mono_thread_info_register_small_id (void)
331 int small_id = mono_thread_small_id_alloc ();
332 #ifdef HAVE_KW_THREAD
333 tls_small_id = small_id;
335 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (small_id + 1));
341 register_thread (MonoThreadInfo *info, gpointer baseptr)
344 guint8 *staddr = NULL;
345 int small_id = mono_thread_info_register_small_id ();
347 mono_thread_info_set_tid (info, mono_native_thread_id_get ());
348 info->small_id = small_id;
350 mono_os_sem_init (&info->resume_semaphore, 0);
352 /*set TLS early so SMR works */
353 mono_native_tls_set_value (thread_info_key, info);
355 THREADS_DEBUG ("registering info %p tid %p small id %x\n", info, mono_thread_info_get_tid (info), info->small_id);
357 if (threads_callbacks.thread_register) {
358 if (threads_callbacks.thread_register (info, baseptr) == NULL) {
359 // g_warning ("thread registation failed\n");
360 mono_native_tls_set_value (thread_info_key, NULL);
366 mono_thread_info_get_stack_bounds (&staddr, &stsize);
369 info->stack_start_limit = staddr;
370 info->stack_end = staddr + stsize;
372 info->stackdata = g_byte_array_new ();
374 mono_threads_platform_register (info);
375 mono_threads_suspend_register (info);
378 Transition it before taking any locks or publishing itself to reduce the chance
379 of others witnessing a detached thread.
380 We can reasonably expect that until this thread gets published, no other thread will
381 try to manipulate it.
383 mono_threads_transition_attach (info);
384 mono_thread_info_suspend_lock ();
385 /*If this fail it means a given thread has been registered twice, which doesn't make sense. */
386 result = mono_thread_info_insert (info);
388 mono_thread_info_suspend_unlock ();
393 mono_thread_info_suspend_lock_with_info (MonoThreadInfo *info);
396 unregister_thread (void *arg)
398 gpointer gc_unsafe_stackdata;
399 MonoThreadInfo *info;
403 info = (MonoThreadInfo *) arg;
405 g_assert (mono_thread_info_is_current (info));
406 g_assert (mono_thread_info_is_live (info));
408 small_id = info->small_id;
410 /* We only enter the GC unsafe region, as when exiting this function, the thread
411 * will be detached, and the current MonoThreadInfo* will be destroyed. */
412 mono_threads_enter_gc_unsafe_region_unbalanced_with_info (info, &gc_unsafe_stackdata);
414 THREADS_DEBUG ("unregistering info %p\n", info);
416 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
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);
445 mono_threads_platform_unregister (info);
446 result = mono_thread_info_remove (info);
448 mono_threads_transition_detach (info);
450 mono_thread_info_suspend_unlock ();
452 g_byte_array_free (info->stackdata, /*free_segment=*/TRUE);
454 /*now it's safe to free the thread info.*/
455 mono_thread_hazardous_try_free (info, free_thread_info);
456 /* Pump the HP queue */
457 mono_thread_hazardous_try_free_some ();
459 mono_thread_small_id_free (small_id);
463 thread_exited_dtor (void *arg)
465 #if defined(__MACH__)
467 * Since we use pthread dtors to clean up thread data, if a thread
468 * is attached to the runtime by another pthread dtor after our dtor
469 * has ran, it will never be detached, leading to various problems
470 * since the thread ids etc. will be reused while they are still in
471 * the threads hashtables etc.
472 * Dtors are called in a loop until all user tls entries are 0,
473 * but the loop has a maximum count (4), so if we set the tls
474 * variable every time, it will remain set when system tls dtors
475 * are ran. This allows mono_thread_info_is_exiting () to detect
476 * whenever the thread is exiting, even if it is executed from a
477 * system tls dtor (i.e. obj-c dealloc methods).
479 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
484 mono_thread_info_current_unchecked (void)
486 return mono_threads_inited ? (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key) : NULL;
491 mono_thread_info_current (void)
493 MonoThreadInfo *info = (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key);
497 info = mono_thread_info_lookup (mono_native_thread_id_get ()); /*info on HP1*/
500 We might be called during thread cleanup, but we cannot be called after cleanup as happened.
501 The way to distinguish between before, during and after cleanup is the following:
503 -If the TLS key is set, cleanup has not begun;
504 -If the TLS key is clean, but the thread remains registered, cleanup is in progress;
505 -If the thread is nowhere to be found, cleanup has finished.
507 We cannot function after cleanup since there's no way to ensure what will happen.
511 /*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 */
512 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
518 mono_thread_info_get_small_id (void)
520 #ifdef HAVE_KW_THREAD
523 gpointer val = mono_native_tls_get_value (small_id_key);
526 return GPOINTER_TO_INT (val) - 1;
531 mono_thread_info_list_head (void)
537 * mono_threads_attach_tools_thread
539 * Attach the current thread as a tool thread. DON'T USE THIS FUNCTION WITHOUT READING ALL DISCLAIMERS.
541 * A tools thread is a very special kind of thread that needs access to core runtime facilities but should
542 * not be counted as a regular thread for high order facilities such as executing managed code or accessing
545 * This is intended only to tools such as a profiler than needs to be able to use our lock-free support when
546 * doing things like resolving backtraces in their background processing thread.
549 mono_threads_attach_tools_thread (void)
552 MonoThreadInfo *info;
554 /* Must only be called once */
555 g_assert (!mono_native_tls_get_value (thread_info_key));
557 while (!mono_threads_inited) {
558 mono_thread_info_usleep (10);
561 info = mono_thread_info_attach (&dummy);
564 info->tools_thread = TRUE;
568 mono_thread_info_attach (void *baseptr)
570 MonoThreadInfo *info;
571 if (!mono_threads_inited)
574 /* This can happen from DllMain(DLL_THREAD_ATTACH) on Windows, if a
575 * thread is created before an embedding API user initialized Mono. */
576 THREADS_DEBUG ("mono_thread_info_attach called before mono_threads_init\n");
579 g_assert (mono_threads_inited);
582 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
584 info = (MonoThreadInfo *) g_malloc0 (thread_info_size);
585 THREADS_DEBUG ("attaching %p\n", info);
586 if (!register_thread (info, baseptr))
588 } else if (threads_callbacks.thread_attach) {
589 threads_callbacks.thread_attach (info);
595 mono_thread_info_detach (void)
597 MonoThreadInfo *info;
598 if (!mono_threads_inited)
600 /* This can happen from DllMain(THREAD_DETACH) on Windows, if a thread
601 * is created before an embedding API user initialized Mono. */
602 THREADS_DEBUG ("mono_thread_info_detach called before mono_threads_init\n");
605 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
607 THREADS_DEBUG ("detaching %p\n", info);
608 unregister_thread (info);
609 mono_native_tls_set_value (thread_info_key, NULL);
614 * mono_thread_info_is_exiting:
616 * Return whenever the current thread is exiting, i.e. it is running pthread
620 mono_thread_info_is_exiting (void)
622 #if defined(__MACH__)
623 if (mono_native_tls_get_value (thread_exited_key) == GUINT_TO_POINTER (1))
631 thread_info_key_dtor (void *arg)
633 /* Put the MonoThreadInfo back for the duration of the
634 * unregister code. In some circumstances the thread needs to
635 * take the GC lock which may block which requires a coop
636 * state transition. */
637 mono_native_tls_set_value (thread_info_key, arg);
638 unregister_thread (arg);
639 mono_native_tls_set_value (thread_info_key, NULL);
644 mono_threads_init (MonoThreadInfoCallbacks *callbacks, size_t info_size)
647 threads_callbacks = *callbacks;
648 thread_info_size = info_size;
649 const char *sleepLimit;
651 res = mono_native_tls_alloc (&thread_info_key, NULL);
652 res = mono_native_tls_alloc (&thread_exited_key, NULL);
654 res = mono_native_tls_alloc (&thread_info_key, (void *) thread_info_key_dtor);
655 res = mono_native_tls_alloc (&thread_exited_key, (void *) thread_exited_dtor);
660 #ifndef HAVE_KW_THREAD
661 res = mono_native_tls_alloc (&small_id_key, NULL);
665 unified_suspend_enabled = g_getenv ("MONO_ENABLE_UNIFIED_SUSPEND") != NULL || mono_threads_is_coop_enabled ();
667 if ((sleepLimit = g_getenv ("MONO_SLEEP_ABORT_LIMIT")) != NULL) {
669 long threshold = strtol(sleepLimit, NULL, 10);
670 if ((errno == 0) && (threshold >= 40)) {
671 sleepAbortDuration = threshold;
672 sleepWarnDuration = threshold / 20;
674 g_warning("MONO_SLEEP_ABORT_LIMIT must be a number >= 40");
677 mono_os_sem_init (&global_suspend_semaphore, 1);
678 mono_os_sem_init (&suspend_semaphore, 0);
680 mono_lls_init (&thread_list, NULL);
681 mono_thread_smr_init ();
682 mono_threads_platform_init ();
683 mono_threads_suspend_init ();
684 mono_threads_coop_init ();
685 mono_threads_abort_syscall_init ();
687 #if defined(__MACH__)
688 mono_mach_init (thread_info_key);
691 mono_threads_inited = TRUE;
693 g_assert (sizeof (MonoNativeThreadId) <= sizeof (uintptr_t));
697 mono_threads_runtime_init (MonoThreadInfoRuntimeCallbacks *callbacks)
699 runtime_callbacks = *callbacks;
702 MonoThreadInfoRuntimeCallbacks *
703 mono_threads_get_runtime_callbacks (void)
705 return &runtime_callbacks;
709 Signal that the current thread wants to be suspended.
710 This function can be called without holding the suspend lock held.
711 To finish suspending, call mono_suspend_check.
714 mono_thread_info_begin_self_suspend (void)
716 MonoThreadInfo *info = mono_thread_info_current_unchecked ();
720 THREADS_SUSPEND_DEBUG ("BEGIN SELF SUSPEND OF %p\n", info);
721 mono_threads_transition_request_self_suspension (info);
725 mono_thread_info_end_self_suspend (void)
727 MonoThreadInfo *info;
729 info = mono_thread_info_current ();
732 THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", info);
734 mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
736 /* commit the saved state and notify others if needed */
737 switch (mono_threads_transition_state_poll (info)) {
738 case SelfSuspendResumed:
740 case SelfSuspendWait:
741 mono_thread_info_wait_for_resume (info);
743 case SelfSuspendNotifyAndWait:
744 mono_threads_notify_initiator_of_suspend (info);
745 mono_thread_info_wait_for_resume (info);
746 mono_threads_notify_initiator_of_resume (info);
752 mono_thread_info_core_resume (MonoThreadInfo *info)
754 gboolean res = FALSE;
756 switch (mono_threads_transition_request_resume (info)) {
763 case ResumeInitSelfResume:
764 resume_self_suspended (info);
767 case ResumeInitAsyncResume:
768 resume_async_suspended (info);
771 case ResumeInitBlockingResume:
772 resume_blocking_suspended (info);
781 mono_thread_info_resume (MonoNativeThreadId tid)
783 gboolean result; /* don't initialize it so the compiler can catch unitilized paths. */
784 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
785 MonoThreadInfo *info;
787 THREADS_SUSPEND_DEBUG ("RESUMING tid %p\n", (void*)tid);
789 mono_thread_info_suspend_lock ();
791 info = mono_thread_info_lookup (tid); /*info on HP1*/
797 result = mono_thread_info_core_resume (info);
799 //Wait for the pending resume to finish
800 mono_threads_wait_pending_operations ();
803 mono_thread_info_suspend_unlock ();
804 mono_hazard_pointer_clear (hp, 1);
809 mono_thread_info_begin_suspend (MonoThreadInfo *info)
811 switch (mono_threads_transition_request_async_suspension (info)) {
812 case AsyncSuspendAlreadySuspended:
813 case AsyncSuspendBlocking:
815 case AsyncSuspendWait:
816 mono_threads_add_to_pending_operation_set (info);
818 case AsyncSuspendInitSuspend:
819 return begin_async_suspend (info, FALSE);
821 g_assert_not_reached ();
826 mono_thread_info_begin_resume (MonoThreadInfo *info)
828 return mono_thread_info_core_resume (info);
832 FIXME fix cardtable WB to be out of line and check with the runtime if the target is not the
833 WB trampoline. Another option is to encode wb ranges in MonoJitInfo, but that is somewhat hard.
836 is_thread_in_critical_region (MonoThreadInfo *info)
840 gpointer stack_start;
841 MonoThreadUnwindState *state;
843 /* Are we inside a system critical region? */
844 if (info->inside_critical_region)
847 /* Are we inside a GC critical region? */
848 if (threads_callbacks.mono_thread_in_critical_region && threads_callbacks.mono_thread_in_critical_region (info)) {
852 /* The target thread might be shutting down and the domain might be null, which means no managed code left to run. */
853 state = mono_thread_info_get_suspend_state (info);
854 if (!state->unwind_data [MONO_UNWIND_DATA_DOMAIN])
857 stack_start = MONO_CONTEXT_GET_SP (&state->ctx);
858 /* altstack signal handler, sgen can't handle them, so we treat them as critical */
859 if (stack_start < info->stack_start_limit || stack_start >= info->stack_end)
862 ji = mono_jit_info_table_find (
863 (MonoDomain *) state->unwind_data [MONO_UNWIND_DATA_DOMAIN],
864 (char *) MONO_CONTEXT_GET_IP (&state->ctx));
869 method = mono_jit_info_get_method (ji);
871 return threads_callbacks.mono_method_is_critical (method);
875 mono_thread_info_in_critical_location (MonoThreadInfo *info)
877 return is_thread_in_critical_region (info);
881 The return value is only valid until a matching mono_thread_info_resume is called
883 static MonoThreadInfo*
884 suspend_sync (MonoNativeThreadId tid, gboolean interrupt_kernel)
886 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
887 MonoThreadInfo *info = mono_thread_info_lookup (tid); /*info on HP1*/
891 switch (mono_threads_transition_request_async_suspension (info)) {
892 case AsyncSuspendAlreadySuspended:
893 mono_hazard_pointer_clear (hp, 1); //XXX this is questionable we got to clean the suspend/resume nonsense of critical sections
895 case AsyncSuspendWait:
896 mono_threads_add_to_pending_operation_set (info);
898 case AsyncSuspendInitSuspend:
899 if (!begin_async_suspend (info, interrupt_kernel)) {
900 mono_hazard_pointer_clear (hp, 1);
904 case AsyncSuspendBlocking:
905 if (interrupt_kernel)
906 mono_threads_suspend_abort_syscall (info);
910 g_assert_not_reached ();
913 //Wait for the pending suspend to finish
914 mono_threads_wait_pending_operations ();
916 if (!check_async_suspend (info)) {
917 mono_thread_info_core_resume (info);
918 mono_threads_wait_pending_operations ();
919 mono_hazard_pointer_clear (hp, 1);
925 static MonoThreadInfo*
926 suspend_sync_nolock (MonoNativeThreadId id, gboolean interrupt_kernel)
928 MonoThreadInfo *info = NULL;
929 int sleep_duration = 0;
931 if (!(info = suspend_sync (id, interrupt_kernel))) {
932 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
936 /*WARNING: We now are in interrupt context until we resume the thread. */
937 if (!is_thread_in_critical_region (info))
940 if (!mono_thread_info_core_resume (info)) {
941 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
944 THREADS_SUSPEND_DEBUG ("RESTARTED thread tid %p\n", (void*)id);
946 /* Wait for the pending resume to finish */
947 mono_threads_wait_pending_operations ();
949 if (sleep_duration == 0)
950 mono_thread_info_yield ();
952 g_usleep (sleep_duration);
954 sleep_duration += 10;
960 mono_thread_info_safe_suspend_and_run (MonoNativeThreadId id, gboolean interrupt_kernel, MonoSuspendThreadCallback callback, gpointer user_data)
963 MonoThreadInfo *info = NULL;
964 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
966 THREADS_SUSPEND_DEBUG ("SUSPENDING tid %p\n", (void*)id);
967 /*FIXME: unify this with self-suspend*/
968 g_assert (id != mono_native_thread_id_get ());
970 /* This can block during stw */
971 mono_thread_info_suspend_lock ();
972 mono_threads_begin_global_suspend ();
974 info = suspend_sync_nolock (id, interrupt_kernel);
978 switch (result = callback (info, user_data)) {
979 case MonoResumeThread:
980 mono_hazard_pointer_set (hp, 1, info);
981 mono_thread_info_core_resume (info);
982 mono_threads_wait_pending_operations ();
987 g_error ("Invalid suspend_and_run callback return value %d", result);
991 mono_hazard_pointer_clear (hp, 1);
992 mono_threads_end_global_suspend ();
993 mono_thread_info_suspend_unlock ();
997 Inject an assynchronous call into the target thread. The target thread must be suspended and
998 only a single async call can be setup for a given suspend cycle.
999 This async call must cause stack unwinding as the current implementation doesn't save enough state
1000 to resume execution of the top-of-stack function. It's an acceptable limitation since this is
1001 currently used only to deliver exceptions.
1004 mono_thread_info_setup_async_call (MonoThreadInfo *info, void (*target_func)(void*), void *user_data)
1006 /* An async call can only be setup on an async suspended thread */
1007 g_assert (mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED);
1008 /*FIXME this is a bad assert, we probably should do proper locking and fail if one is already set*/
1009 g_assert (!info->async_target);
1010 info->async_target = target_func;
1011 /* This is not GC tracked */
1012 info->user_data = user_data;
1016 The suspend lock is held during any suspend in progress.
1017 A GC that has safepoints must take this lock as part of its
1018 STW to make sure no unsafe pending suspend is in progress.
1022 mono_thread_info_suspend_lock_with_info (MonoThreadInfo *info)
1025 g_assert (mono_thread_info_is_current (info));
1026 g_assert (mono_thread_info_is_live (info));
1028 MONO_ENTER_GC_SAFE_WITH_INFO(info);
1030 int res = mono_os_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
1031 g_assert (res != -1);
1033 MONO_EXIT_GC_SAFE_WITH_INFO;
1037 mono_thread_info_suspend_lock (void)
1039 mono_thread_info_suspend_lock_with_info (mono_thread_info_current_unchecked ());
1043 mono_thread_info_suspend_unlock (void)
1045 mono_os_sem_post (&global_suspend_semaphore);
1049 * This is a very specific function whose only purpose is to
1050 * break a given thread from socket syscalls.
1052 * This only exists because linux won't fail a call to connect
1053 * if the underlying is closed.
1055 * TODO We should cleanup and unify this with the other syscall abort
1059 mono_thread_info_abort_socket_syscall_for_close (MonoNativeThreadId tid)
1061 MonoThreadHazardPointers *hp;
1062 MonoThreadInfo *info;
1064 if (tid == mono_native_thread_id_get () || !mono_threads_suspend_needs_abort_syscall ())
1067 hp = mono_hazard_pointer_get ();
1068 info = mono_thread_info_lookup (tid);
1072 if (mono_thread_info_run_state (info) == STATE_DETACHED) {
1073 mono_hazard_pointer_clear (hp, 1);
1077 mono_thread_info_suspend_lock ();
1078 mono_threads_begin_global_suspend ();
1080 mono_threads_suspend_abort_syscall (info);
1081 mono_threads_wait_pending_operations ();
1083 mono_hazard_pointer_clear (hp, 1);
1085 mono_threads_end_global_suspend ();
1086 mono_thread_info_suspend_unlock ();
1090 mono_thread_info_unified_management_enabled (void)
1092 return unified_suspend_enabled;
1096 * mono_thread_info_set_is_async_context:
1098 * Set whenever the current thread is in an async context. Some runtime functions might behave
1099 * differently while in an async context in order to be async safe.
1102 mono_thread_info_set_is_async_context (gboolean async_context)
1104 MonoThreadInfo *info = mono_thread_info_current ();
1107 info->is_async_context = async_context;
1111 mono_thread_info_is_async_context (void)
1113 MonoThreadInfo *info = mono_thread_info_current ();
1116 return info->is_async_context;
1123 MonoThreadStart start_routine;
1124 gpointer start_routine_arg;
1126 MonoCoopSem registered;
1131 inner_start_thread (gpointer data)
1133 CreateThreadData *thread_data;
1134 MonoThreadInfo *info;
1135 MonoThreadStart start_routine;
1136 gpointer start_routine_arg;
1137 guint32 start_routine_res;
1140 thread_data = (CreateThreadData*) data;
1141 g_assert (thread_data);
1143 start_routine = thread_data->start_routine;
1144 start_routine_arg = thread_data->start_routine_arg;
1146 info = mono_thread_info_attach (&dummy);
1147 info->runtime_thread = TRUE;
1149 thread_data->handle = mono_thread_info_duplicate_handle (info);
1151 mono_coop_sem_post (&thread_data->registered);
1153 if (InterlockedDecrement (&thread_data->ref) == 0) {
1154 mono_coop_sem_destroy (&thread_data->registered);
1155 g_free (thread_data);
1158 /* thread_data is not valid anymore */
1161 /* Run the actual main function of the thread */
1162 start_routine_res = start_routine (start_routine_arg);
1164 mono_threads_platform_exit (start_routine_res);
1166 g_assert_not_reached ();
1170 * mono_threads_create_thread:
1172 * Create a new thread executing START with argument ARG. Store its id into OUT_TID.
1173 * Returns: a windows or io-layer handle for the thread.
1176 mono_threads_create_thread (MonoThreadStart start, gpointer arg, gsize stack_size, MonoNativeThreadId *out_tid)
1178 CreateThreadData *thread_data;
1182 thread_data = g_new0 (CreateThreadData, 1);
1183 thread_data->ref = 2;
1184 thread_data->start_routine = start;
1185 thread_data->start_routine_arg = arg;
1186 mono_coop_sem_init (&thread_data->registered, 0);
1188 res = mono_threads_platform_create_thread (inner_start_thread, (gpointer) thread_data, stack_size, out_tid);
1190 /* ref is not going to be decremented in inner_start_thread */
1191 InterlockedDecrement (&thread_data->ref);
1196 res = mono_coop_sem_wait (&thread_data->registered, MONO_SEM_FLAGS_NONE);
1197 g_assert (res == 0);
1199 ret = thread_data->handle;
1203 if (InterlockedDecrement (&thread_data->ref) == 0) {
1204 mono_coop_sem_destroy (&thread_data->registered);
1205 g_free (thread_data);
1212 * mono_thread_info_get_stack_bounds:
1214 * Return the address and size of the current threads stack. Return NULL as the
1215 * stack address if the stack address cannot be determined.
1218 mono_thread_info_get_stack_bounds (guint8 **staddr, size_t *stsize)
1220 guint8 *current = (guint8 *)&stsize;
1221 mono_threads_platform_get_stack_bounds (staddr, stsize);
1225 /* Sanity check the result */
1226 g_assert ((current > *staddr) && (current < *staddr + *stsize));
1228 /* When running under emacs, sometimes staddr is not aligned to a page size */
1229 *staddr = (guint8*)((gssize)*staddr & ~(mono_pagesize () - 1));
1233 mono_thread_info_yield (void)
1235 return mono_threads_platform_yield ();
1237 static mono_lazy_init_t sleep_init = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
1238 static MonoCoopMutex sleep_mutex;
1239 static MonoCoopCond sleep_cond;
1242 sleep_initialize (void)
1244 mono_coop_mutex_init (&sleep_mutex);
1245 mono_coop_cond_init (&sleep_cond);
1249 sleep_interrupt (gpointer data)
1251 mono_coop_mutex_lock (&sleep_mutex);
1252 mono_coop_cond_broadcast (&sleep_cond);
1253 mono_coop_mutex_unlock (&sleep_mutex);
1256 static inline guint32
1257 sleep_interruptable (guint32 ms, gboolean *alerted)
1261 g_assert (INFINITE == G_MAXUINT32);
1267 end = mono_msec_ticks() + ms;
1269 mono_lazy_initialize (&sleep_init, sleep_initialize);
1271 mono_coop_mutex_lock (&sleep_mutex);
1274 if (ms != INFINITE) {
1275 now = mono_msec_ticks();
1280 mono_thread_info_install_interrupt (sleep_interrupt, NULL, alerted);
1282 mono_coop_mutex_unlock (&sleep_mutex);
1283 return WAIT_IO_COMPLETION;
1287 mono_coop_cond_timedwait (&sleep_cond, &sleep_mutex, end - now);
1289 mono_coop_cond_wait (&sleep_cond, &sleep_mutex);
1291 mono_thread_info_uninstall_interrupt (alerted);
1293 mono_coop_mutex_unlock (&sleep_mutex);
1294 return WAIT_IO_COMPLETION;
1298 mono_coop_mutex_unlock (&sleep_mutex);
1304 mono_thread_info_sleep (guint32 ms, gboolean *alerted)
1307 MonoThreadInfo *info;
1309 mono_thread_info_yield ();
1311 info = mono_thread_info_current ();
1312 if (info && mono_thread_info_is_interrupt_state (info))
1313 return WAIT_IO_COMPLETION;
1319 return sleep_interruptable (ms, alerted);
1323 if (ms == INFINITE) {
1326 Sleep (G_MAXUINT32);
1328 sleep (G_MAXUINT32);
1333 #if defined (__linux__) && !defined(PLATFORM_ANDROID)
1334 struct timespec start, target;
1336 /* Use clock_nanosleep () to prevent time drifting problems when nanosleep () is interrupted by signals */
1337 ret = clock_gettime (CLOCK_MONOTONIC, &start);
1338 g_assert (ret == 0);
1341 target.tv_sec += ms / 1000;
1342 target.tv_nsec += (ms % 1000) * 1000000;
1343 if (target.tv_nsec > 999999999) {
1344 target.tv_nsec -= 999999999;
1349 ret = clock_nanosleep (CLOCK_MONOTONIC, TIMER_ABSTIME, &target, NULL);
1354 struct timespec req, rem;
1356 req.tv_sec = ms / 1000;
1357 req.tv_nsec = (ms % 1000) * 1000000;
1360 memset (&rem, 0, sizeof (rem));
1361 ret = nanosleep (&req, &rem);
1363 #endif /* __linux__ */
1372 mono_thread_info_usleep (guint64 us)
1381 mono_thread_info_tls_get (THREAD_INFO_TYPE *info, MonoTlsKey key)
1383 return ((MonoThreadInfo*)info)->tls [key];
1387 * mono_threads_info_tls_set:
1389 * Set the TLS key to VALUE in the info structure. This can be used to obtain
1390 * values of TLS variables for threads other than the current thread.
1391 * This should only be used for infrequently changing TLS variables, and it should
1392 * be paired with setting the real TLS variable since this provides no GC tracking.
1395 mono_thread_info_tls_set (THREAD_INFO_TYPE *info, MonoTlsKey key, gpointer value)
1397 ((MonoThreadInfo*)info)->tls [key] = value;
1401 * mono_thread_info_exit:
1403 * Exit the current thread.
1404 * This function doesn't return.
1407 mono_thread_info_exit (void)
1409 mono_threads_platform_exit (0);
1413 * mono_threads_open_thread_handle:
1415 * Return a io-layer/win32 handle for the thread identified by HANDLE/TID.
1416 * The handle need to be closed by calling CloseHandle () when it is no
1420 mono_threads_open_thread_handle (HANDLE handle, MonoNativeThreadId tid)
1422 return mono_threads_platform_open_thread_handle (handle, tid);
1426 mono_threads_close_thread_handle (HANDLE handle)
1428 return mono_threads_platform_close_thread_handle (handle);
1431 #define INTERRUPT_STATE ((MonoThreadInfoInterruptToken*) (size_t) -1)
1433 struct _MonoThreadInfoInterruptToken {
1434 void (*callback) (gpointer data);
1439 * mono_thread_info_install_interrupt: install an interruption token for the current thread.
1441 * - @callback: must be able to be called from another thread and always cancel the wait
1442 * - @data: passed to the callback
1443 * - @interrupted: will be set to TRUE if a token is already installed, FALSE otherwise
1444 * if set to TRUE, it must mean that the thread is in interrupted state
1447 mono_thread_info_install_interrupt (void (*callback) (gpointer data), gpointer data, gboolean *interrupted)
1449 MonoThreadInfo *info;
1450 MonoThreadInfoInterruptToken *previous_token, *token;
1452 g_assert (callback);
1454 g_assert (interrupted);
1455 *interrupted = FALSE;
1457 info = mono_thread_info_current ();
1460 /* The memory of this token can be freed at 2 places:
1461 * - if the token is not interrupted: it will be freed in uninstall, as info->interrupt_token has not been replaced
1462 * by the INTERRUPT_STATE flag value, and it still contains the pointer to the memory location
1463 * - if the token is interrupted: it will be freed in finish, as the token is now owned by the prepare/finish
1464 * functions, and info->interrupt_token does not contains a pointer to the memory anymore */
1465 token = g_new0 (MonoThreadInfoInterruptToken, 1);
1466 token->callback = callback;
1469 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, token, NULL);
1471 if (previous_token) {
1472 if (previous_token != INTERRUPT_STATE)
1473 g_error ("mono_thread_info_install_interrupt: previous_token should be INTERRUPT_STATE (%p), but it was %p", INTERRUPT_STATE, previous_token);
1477 *interrupted = TRUE;
1480 THREADS_INTERRUPT_DEBUG ("interrupt install tid %p token %p previous_token %p interrupted %s\n",
1481 mono_thread_info_get_tid (info), token, previous_token, *interrupted ? "TRUE" : "FALSE");
1485 mono_thread_info_uninstall_interrupt (gboolean *interrupted)
1487 MonoThreadInfo *info;
1488 MonoThreadInfoInterruptToken *previous_token;
1490 g_assert (interrupted);
1491 *interrupted = FALSE;
1493 info = mono_thread_info_current ();
1496 previous_token = (MonoThreadInfoInterruptToken *)InterlockedExchangePointer ((gpointer*) &info->interrupt_token, NULL);
1498 /* only the installer can uninstall the token */
1499 g_assert (previous_token);
1501 if (previous_token == INTERRUPT_STATE) {
1502 /* if it is interrupted, then it is going to be freed in finish interrupt */
1503 *interrupted = TRUE;
1505 g_free (previous_token);
1508 THREADS_INTERRUPT_DEBUG ("interrupt uninstall tid %p previous_token %p interrupted %s\n",
1509 mono_thread_info_get_tid (info), previous_token, *interrupted ? "TRUE" : "FALSE");
1512 static MonoThreadInfoInterruptToken*
1513 set_interrupt_state (MonoThreadInfo *info)
1515 MonoThreadInfoInterruptToken *token, *previous_token;
1519 /* Atomically obtain the token the thread is
1520 * waiting on, and change it to a flag value. */
1523 previous_token = info->interrupt_token;
1525 /* Already interrupted */
1526 if (previous_token == INTERRUPT_STATE) {
1531 token = previous_token;
1532 } while (InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, INTERRUPT_STATE, previous_token) != previous_token);
1538 * mono_thread_info_prepare_interrupt:
1540 * The state of the thread info interrupt token is set to 'interrupted' which means that :
1541 * - if the thread calls one of the WaitFor functions, the function will return with
1542 * WAIT_IO_COMPLETION instead of waiting
1543 * - if the thread was waiting when this function was called, the wait will be broken
1545 * It is possible that the wait functions return WAIT_IO_COMPLETION, but the target thread
1546 * didn't receive the interrupt signal yet, in this case it should call the wait function
1547 * again. This essentially means that the target thread will busy wait until it is ready to
1548 * process the interruption.
1550 MonoThreadInfoInterruptToken*
1551 mono_thread_info_prepare_interrupt (MonoThreadInfo *info)
1553 MonoThreadInfoInterruptToken *token;
1555 token = set_interrupt_state (info);
1557 THREADS_INTERRUPT_DEBUG ("interrupt prepare tid %p token %p\n",
1558 mono_thread_info_get_tid (info), token);
1564 mono_thread_info_finish_interrupt (MonoThreadInfoInterruptToken *token)
1566 THREADS_INTERRUPT_DEBUG ("interrupt finish token %p\n", token);
1571 g_assert (token->callback);
1573 token->callback (token->data);
1579 mono_thread_info_self_interrupt (void)
1581 MonoThreadInfo *info;
1582 MonoThreadInfoInterruptToken *token;
1584 info = mono_thread_info_current ();
1587 token = set_interrupt_state (info);
1590 THREADS_INTERRUPT_DEBUG ("interrupt self tid %p\n",
1591 mono_thread_info_get_tid (info));
1594 /* Clear the interrupted flag of the current thread, set with
1595 * mono_thread_info_self_interrupt, so it can wait again */
1597 mono_thread_info_clear_self_interrupt ()
1599 MonoThreadInfo *info;
1600 MonoThreadInfoInterruptToken *previous_token;
1602 info = mono_thread_info_current ();
1605 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, NULL, INTERRUPT_STATE);
1606 g_assert (previous_token == NULL || previous_token == INTERRUPT_STATE);
1608 THREADS_INTERRUPT_DEBUG ("interrupt clear self tid %p previous_token %p\n", mono_thread_info_get_tid (info), previous_token);
1612 mono_thread_info_is_interrupt_state (MonoThreadInfo *info)
1615 return InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE;
1619 mono_thread_info_describe_interrupt_token (MonoThreadInfo *info, GString *text)
1623 if (!InterlockedReadPointer ((gpointer*) &info->interrupt_token))
1624 g_string_append_printf (text, "not waiting");
1625 else if (InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE)
1626 g_string_append_printf (text, "interrupted state");
1628 g_string_append_printf (text, "waiting");
1632 mono_thread_info_is_current (MonoThreadInfo *info)
1634 return mono_thread_info_get_tid (info) == mono_native_thread_id_get ();
1638 mono_thread_info_set_exited (THREAD_INFO_TYPE *info)
1640 g_assert (mono_thread_info_is_current (info));
1641 mono_threads_platform_set_exited (info);
1645 mono_thread_info_duplicate_handle (MonoThreadInfo *info)
1647 g_assert (mono_thread_info_is_current (info));
1648 return mono_threads_platform_duplicate_handle (info);