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)
13 /* enable pthread extensions */
15 #define _DARWIN_C_SOURCE
18 #include <mono/utils/mono-compiler.h>
19 #include <mono/utils/mono-os-semaphore.h>
20 #include <mono/utils/mono-threads.h>
21 #include <mono/utils/mono-tls.h>
22 #include <mono/utils/hazard-pointer.h>
23 #include <mono/utils/mono-memory-model.h>
24 #include <mono/utils/mono-mmap.h>
25 #include <mono/utils/atomic.h>
26 #include <mono/utils/mono-time.h>
27 #include <mono/utils/mono-lazy-init.h>
28 #include <mono/utils/mono-coop-mutex.h>
29 #include <mono/utils/mono-coop-semaphore.h>
34 #include <mono/utils/mach-support.h>
38 Mutex that makes sure only a single thread can be suspending others.
39 Suspend is a very racy operation since it requires restarting until
40 the target thread is not on an unsafe region.
42 We could implement this using critical regions, but would be much much
43 harder for an operation that is hardly performance critical.
45 The GC has to acquire this lock before starting a STW to make sure
46 a runtime suspend won't make it wronly see a thread in a safepoint
47 when it is in fact not.
49 static MonoCoopSem global_suspend_semaphore;
51 static size_t thread_info_size;
52 static MonoThreadInfoCallbacks threads_callbacks;
53 static MonoThreadInfoRuntimeCallbacks runtime_callbacks;
54 static MonoNativeTlsKey thread_info_key, thread_exited_key;
56 static __thread guint32 tls_small_id MONO_TLS_FAST;
58 static MonoNativeTlsKey small_id_key;
60 static MonoLinkedListSet thread_list;
61 static gboolean mono_threads_inited = FALSE;
63 static MonoSemType suspend_semaphore;
64 static size_t pending_suspends;
65 static gboolean unified_suspend_enabled;
67 #define mono_thread_info_run_state(info) (((MonoThreadInfo*)info)->thread_state & THREAD_STATE_MASK)
70 #define SLEEP_DURATION_BEFORE_WARNING (10)
72 #define SLEEP_DURATION_BEFORE_ABORT 200
74 static int suspend_posts, resume_posts, abort_posts, waits_done, pending_ops;
77 mono_threads_notify_initiator_of_abort (MonoThreadInfo* info)
79 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-ABORT] %p\n", mono_thread_info_get_tid (info));
80 InterlockedIncrement (&abort_posts);
81 mono_os_sem_post (&suspend_semaphore);
85 mono_threads_notify_initiator_of_suspend (MonoThreadInfo* info)
87 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-SUSPEND] %p\n", mono_thread_info_get_tid (info));
88 InterlockedIncrement (&suspend_posts);
89 mono_os_sem_post (&suspend_semaphore);
93 mono_threads_notify_initiator_of_resume (MonoThreadInfo* info)
95 THREADS_SUSPEND_DEBUG ("[INITIATOR-NOTIFY-RESUME] %p\n", mono_thread_info_get_tid (info));
96 InterlockedIncrement (&resume_posts);
97 mono_os_sem_post (&suspend_semaphore);
101 begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
103 if (mono_threads_is_coop_enabled ()) {
104 /* There's nothing else to do after we async request the thread to suspend */
105 mono_threads_add_to_pending_operation_set (info);
109 return mono_threads_core_begin_async_suspend (info, interrupt_kernel);
113 check_async_suspend (MonoThreadInfo *info)
115 if (mono_threads_is_coop_enabled ()) {
116 /* Async suspend can't async fail on coop */
120 return mono_threads_core_check_suspend_result (info);
124 resume_async_suspended (MonoThreadInfo *info)
126 if (mono_threads_is_coop_enabled ())
127 g_assert_not_reached ();
129 g_assert (mono_threads_core_begin_async_resume (info));
133 resume_self_suspended (MonoThreadInfo* info)
135 THREADS_SUSPEND_DEBUG ("**BEGIN self-resume %p\n", mono_thread_info_get_tid (info));
136 mono_os_sem_post (&info->resume_semaphore);
140 mono_thread_info_wait_for_resume (MonoThreadInfo* info)
143 THREADS_SUSPEND_DEBUG ("**WAIT self-resume %p\n", mono_thread_info_get_tid (info));
144 res = mono_os_sem_wait (&info->resume_semaphore, MONO_SEM_FLAGS_NONE);
145 g_assert (res != -1);
149 resume_blocking_suspended (MonoThreadInfo* info)
151 THREADS_SUSPEND_DEBUG ("**BEGIN blocking-resume %p\n", mono_thread_info_get_tid (info));
152 mono_os_sem_post (&info->resume_semaphore);
156 mono_threads_add_to_pending_operation_set (MonoThreadInfo* info)
158 THREADS_SUSPEND_DEBUG ("added %p to pending suspend\n", mono_thread_info_get_tid (info));
160 InterlockedIncrement (&pending_ops);
164 mono_threads_begin_global_suspend (void)
166 size_t ps = pending_suspends;
167 if (G_UNLIKELY (ps != 0))
168 g_error ("pending_suspends = %d, but must be 0", ps);
169 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,
170 abort_posts, waits_done, pending_ops);
171 g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
172 mono_threads_coop_begin_global_suspend ();
176 mono_threads_end_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 ("------ END GLOBAL OP sp %d rp %d ap %d wd %d po %d\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_end_global_suspend ();
190 MonoThreadInfo *info;
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" : "" );
214 } END_FOREACH_THREAD_SAFE
218 mono_threads_wait_pending_operations (void)
221 int c = pending_suspends;
223 /* Wait threads to park */
224 THREADS_SUSPEND_DEBUG ("[INITIATOR-WAIT-COUNT] %d\n", c);
225 if (pending_suspends) {
226 MonoStopwatch suspension_time;
227 mono_stopwatch_start (&suspension_time);
228 for (i = 0; i < pending_suspends; ++i) {
229 THREADS_SUSPEND_DEBUG ("[INITIATOR-WAIT-WAITING]\n");
230 InterlockedIncrement (&waits_done);
231 if (!mono_os_sem_timedwait (&suspend_semaphore, SLEEP_DURATION_BEFORE_ABORT, MONO_SEM_FLAGS_NONE))
233 mono_stopwatch_stop (&suspension_time);
237 MOSTLY_ASYNC_SAFE_PRINTF ("WAITING for %d threads, got %d suspended\n", (int)pending_suspends, i);
238 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);
240 mono_stopwatch_stop (&suspension_time);
241 THREADS_SUSPEND_DEBUG ("Suspending %d threads took %d ms.\n", (int)pending_suspends, (int)mono_stopwatch_elapsed_ms (&suspension_time));
245 pending_suspends = 0;
251 //Thread initialization code
253 static void mono_threads_unregister_current_thread (MonoThreadInfo *info);
256 mono_hazard_pointer_clear_all (MonoThreadHazardPointers *hp, int retain)
259 mono_hazard_pointer_clear (hp, 0);
261 mono_hazard_pointer_clear (hp, 1);
263 mono_hazard_pointer_clear (hp, 2);
267 If return non null Hazard Pointer 1 holds the return value.
270 mono_thread_info_lookup (MonoNativeThreadId id)
272 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
274 if (!mono_lls_find (&thread_list, hp, (uintptr_t)id)) {
275 mono_hazard_pointer_clear_all (hp, -1);
279 mono_hazard_pointer_clear_all (hp, 1);
280 return (MonoThreadInfo *) mono_hazard_pointer_get_val (hp, 1);
284 mono_thread_info_insert (MonoThreadInfo *info)
286 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
288 if (!mono_lls_insert (&thread_list, hp, (MonoLinkedListSetNode*)info)) {
289 mono_hazard_pointer_clear_all (hp, -1);
293 mono_hazard_pointer_clear_all (hp, -1);
298 mono_thread_info_remove (MonoThreadInfo *info)
300 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
303 THREADS_DEBUG ("removing info %p\n", info);
304 res = mono_lls_remove (&thread_list, hp, (MonoLinkedListSetNode*)info);
305 mono_hazard_pointer_clear_all (hp, -1);
310 free_thread_info (gpointer mem)
312 MonoThreadInfo *info = (MonoThreadInfo *) mem;
314 mono_os_sem_destroy (&info->resume_semaphore);
315 mono_threads_platform_free (info);
321 mono_thread_info_register_small_id (void)
323 int small_id = mono_thread_small_id_alloc ();
324 #ifdef HAVE_KW_THREAD
325 tls_small_id = small_id;
327 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (small_id + 1));
333 register_thread (MonoThreadInfo *info, gpointer baseptr)
336 guint8 *staddr = NULL;
337 int small_id = mono_thread_info_register_small_id ();
339 mono_thread_info_set_tid (info, mono_native_thread_id_get ());
340 info->small_id = small_id;
342 mono_os_sem_init (&info->resume_semaphore, 0);
344 /*set TLS early so SMR works */
345 mono_native_tls_set_value (thread_info_key, info);
347 THREADS_DEBUG ("registering info %p tid %p small id %x\n", info, mono_thread_info_get_tid (info), info->small_id);
349 if (threads_callbacks.thread_register) {
350 if (threads_callbacks.thread_register (info, baseptr) == NULL) {
351 // g_warning ("thread registation failed\n");
357 mono_thread_info_get_stack_bounds (&staddr, &stsize);
360 info->stack_start_limit = staddr;
361 info->stack_end = staddr + stsize;
363 info->stackdata = g_byte_array_new ();
365 mono_threads_platform_register (info);
368 Transition it before taking any locks or publishing itself to reduce the chance
369 of others witnessing a detached thread.
370 We can reasonably expect that until this thread gets published, no other thread will
371 try to manipulate it.
373 mono_threads_transition_attach (info);
374 mono_thread_info_suspend_lock ();
375 /*If this fail it means a given thread has been registered twice, which doesn't make sense. */
376 result = mono_thread_info_insert (info);
378 mono_thread_info_suspend_unlock ();
383 unregister_thread (void *arg)
385 MonoThreadInfo *info = (MonoThreadInfo *) arg;
386 int small_id = info->small_id;
389 THREADS_DEBUG ("unregistering info %p\n", info);
391 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
393 mono_threads_core_unregister (info);
396 * TLS destruction order is not reliable so small_id might be cleaned up
399 #ifndef HAVE_KW_THREAD
400 mono_native_tls_set_value (small_id_key, GUINT_TO_POINTER (info->small_id + 1));
404 First perform the callback that requires no locks.
405 This callback has the potential of taking other locks, so we do it before.
406 After it completes, the thread remains functional.
408 if (threads_callbacks.thread_detach)
409 threads_callbacks.thread_detach (info);
411 mono_thread_info_suspend_lock ();
414 Now perform the callback that must be done under locks.
415 This will render the thread useless and non-suspendable, so it must
416 be done while holding the suspend lock to give no other thread chance
419 if (threads_callbacks.thread_unregister)
420 threads_callbacks.thread_unregister (info);
421 mono_threads_unregister_current_thread (info);
422 mono_threads_transition_detach (info);
424 mono_thread_info_suspend_unlock ();
426 g_byte_array_free (info->stackdata, /*free_segment=*/TRUE);
428 /*now it's safe to free the thread info.*/
429 mono_thread_hazardous_free_or_queue (info, free_thread_info, TRUE, FALSE);
430 mono_thread_small_id_free (small_id);
434 thread_exited_dtor (void *arg)
436 #if defined(__MACH__)
438 * Since we use pthread dtors to clean up thread data, if a thread
439 * is attached to the runtime by another pthread dtor after our dtor
440 * has ran, it will never be detached, leading to various problems
441 * since the thread ids etc. will be reused while they are still in
442 * the threads hashtables etc.
443 * Dtors are called in a loop until all user tls entries are 0,
444 * but the loop has a maximum count (4), so if we set the tls
445 * variable every time, it will remain set when system tls dtors
446 * are ran. This allows mono_thread_info_is_exiting () to detect
447 * whenever the thread is exiting, even if it is executed from a
448 * system tls dtor (i.e. obj-c dealloc methods).
450 mono_native_tls_set_value (thread_exited_key, GUINT_TO_POINTER (1));
455 * Removes the current thread from the thread list.
456 * This must be called from the thread unregister callback and nowhere else.
457 * The current thread must be passed as TLS might have already been cleaned up.
460 mono_threads_unregister_current_thread (MonoThreadInfo *info)
463 g_assert (mono_thread_info_get_tid (info) == mono_native_thread_id_get ());
464 result = mono_thread_info_remove (info);
469 mono_thread_info_current_unchecked (void)
471 return mono_threads_inited ? (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key) : NULL;
476 mono_thread_info_current (void)
478 MonoThreadInfo *info = (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key);
482 info = mono_thread_info_lookup (mono_native_thread_id_get ()); /*info on HP1*/
485 We might be called during thread cleanup, but we cannot be called after cleanup as happened.
486 The way to distinguish between before, during and after cleanup is the following:
488 -If the TLS key is set, cleanup has not begun;
489 -If the TLS key is clean, but the thread remains registered, cleanup is in progress;
490 -If the thread is nowhere to be found, cleanup has finished.
492 We cannot function after cleanup since there's no way to ensure what will happen.
496 /*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 */
497 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
503 mono_thread_info_get_small_id (void)
505 #ifdef HAVE_KW_THREAD
508 gpointer val = mono_native_tls_get_value (small_id_key);
511 return GPOINTER_TO_INT (val) - 1;
516 mono_thread_info_list_head (void)
522 * mono_threads_attach_tools_thread
524 * Attach the current thread as a tool thread. DON'T USE THIS FUNCTION WITHOUT READING ALL DISCLAIMERS.
526 * A tools thread is a very special kind of thread that needs access to core runtime facilities but should
527 * not be counted as a regular thread for high order facilities such as executing managed code or accessing
530 * This is intended only to tools such as a profiler than needs to be able to use our lock-free support when
531 * doing things like resolving backtraces in their background processing thread.
534 mono_threads_attach_tools_thread (void)
537 MonoThreadInfo *info;
539 /* Must only be called once */
540 g_assert (!mono_native_tls_get_value (thread_info_key));
542 while (!mono_threads_inited) {
543 mono_thread_info_usleep (10);
546 info = mono_thread_info_attach (&dummy);
549 info->tools_thread = TRUE;
553 mono_thread_info_attach (void *baseptr)
555 MonoThreadInfo *info;
556 if (!mono_threads_inited)
559 /* This can happen from DllMain(DLL_THREAD_ATTACH) on Windows, if a
560 * thread is created before an embedding API user initialized Mono. */
561 THREADS_DEBUG ("mono_thread_info_attach called before mono_threads_init\n");
564 g_assert (mono_threads_inited);
567 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
569 info = (MonoThreadInfo *) g_malloc0 (thread_info_size);
570 THREADS_DEBUG ("attaching %p\n", info);
571 if (!register_thread (info, baseptr))
573 } else if (threads_callbacks.thread_attach) {
574 threads_callbacks.thread_attach (info);
580 mono_thread_info_detach (void)
582 MonoThreadInfo *info;
583 if (!mono_threads_inited)
585 /* This can happen from DllMain(THREAD_DETACH) on Windows, if a thread
586 * is created before an embedding API user initialized Mono. */
587 THREADS_DEBUG ("mono_thread_info_detach called before mono_threads_init\n");
590 info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
592 THREADS_DEBUG ("detaching %p\n", info);
593 unregister_thread (info);
594 mono_native_tls_set_value (thread_info_key, NULL);
599 * mono_thread_info_is_exiting:
601 * Return whenever the current thread is exiting, i.e. it is running pthread
605 mono_thread_info_is_exiting (void)
607 #if defined(__MACH__)
608 if (mono_native_tls_get_value (thread_exited_key) == GUINT_TO_POINTER (1))
615 mono_threads_init (MonoThreadInfoCallbacks *callbacks, size_t info_size)
618 threads_callbacks = *callbacks;
619 thread_info_size = info_size;
621 res = mono_native_tls_alloc (&thread_info_key, NULL);
622 res = mono_native_tls_alloc (&thread_exited_key, NULL);
624 res = mono_native_tls_alloc (&thread_info_key, (void *) unregister_thread);
625 res = mono_native_tls_alloc (&thread_exited_key, (void *) thread_exited_dtor);
630 #ifndef HAVE_KW_THREAD
631 res = mono_native_tls_alloc (&small_id_key, NULL);
635 unified_suspend_enabled = g_getenv ("MONO_ENABLE_UNIFIED_SUSPEND") != NULL || mono_threads_is_coop_enabled ();
637 mono_coop_sem_init (&global_suspend_semaphore, 1);
638 mono_os_sem_init (&suspend_semaphore, 0);
640 mono_lls_init (&thread_list, NULL);
641 mono_thread_smr_init ();
642 mono_threads_init_platform ();
643 mono_threads_init_coop ();
644 mono_threads_init_abort_syscall ();
646 #if defined(__MACH__)
647 mono_mach_init (thread_info_key);
650 mono_threads_inited = TRUE;
652 g_assert (sizeof (MonoNativeThreadId) <= sizeof (uintptr_t));
656 mono_threads_runtime_init (MonoThreadInfoRuntimeCallbacks *callbacks)
658 runtime_callbacks = *callbacks;
661 MonoThreadInfoRuntimeCallbacks *
662 mono_threads_get_runtime_callbacks (void)
664 return &runtime_callbacks;
668 Signal that the current thread wants to be suspended.
669 This function can be called without holding the suspend lock held.
670 To finish suspending, call mono_suspend_check.
673 mono_thread_info_begin_self_suspend (void)
675 MonoThreadInfo *info = mono_thread_info_current_unchecked ();
679 THREADS_SUSPEND_DEBUG ("BEGIN SELF SUSPEND OF %p\n", info);
680 mono_threads_transition_request_self_suspension (info);
684 mono_thread_info_end_self_suspend (void)
686 MonoThreadInfo *info;
688 info = mono_thread_info_current ();
691 THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", info);
693 mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
695 /* commit the saved state and notify others if needed */
696 switch (mono_threads_transition_state_poll (info)) {
697 case SelfSuspendResumed:
699 case SelfSuspendWait:
700 mono_thread_info_wait_for_resume (info);
702 case SelfSuspendNotifyAndWait:
703 mono_threads_notify_initiator_of_suspend (info);
704 mono_thread_info_wait_for_resume (info);
705 mono_threads_notify_initiator_of_resume (info);
711 mono_thread_info_core_resume (MonoThreadInfo *info)
713 gboolean res = FALSE;
714 if (info->create_suspended) {
715 MonoNativeThreadId tid = mono_thread_info_get_tid (info);
716 /* 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 */
717 info->create_suspended = FALSE;
718 mono_threads_core_resume_created (info, tid);
722 switch (mono_threads_transition_request_resume (info)) {
729 case ResumeInitSelfResume:
730 resume_self_suspended (info);
733 case ResumeInitAsyncResume:
734 resume_async_suspended (info);
737 case ResumeInitBlockingResume:
738 resume_blocking_suspended (info);
747 mono_thread_info_resume (MonoNativeThreadId tid)
749 gboolean result; /* don't initialize it so the compiler can catch unitilized paths. */
750 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
751 MonoThreadInfo *info;
753 THREADS_SUSPEND_DEBUG ("RESUMING tid %p\n", (void*)tid);
755 mono_thread_info_suspend_lock ();
757 info = mono_thread_info_lookup (tid); /*info on HP1*/
763 result = mono_thread_info_core_resume (info);
765 //Wait for the pending resume to finish
766 mono_threads_wait_pending_operations ();
769 mono_thread_info_suspend_unlock ();
770 mono_hazard_pointer_clear (hp, 1);
775 mono_thread_info_begin_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
777 switch (mono_threads_transition_request_async_suspension (info)) {
778 case AsyncSuspendAlreadySuspended:
780 case AsyncSuspendWait:
781 mono_threads_add_to_pending_operation_set (info);
783 case AsyncSuspendInitSuspend:
784 return begin_async_suspend (info, interrupt_kernel);
786 g_assert_not_reached ();
791 mono_thread_info_begin_resume (MonoThreadInfo *info)
793 return mono_thread_info_core_resume (info);
797 mono_thread_info_check_suspend_result (MonoThreadInfo *info)
799 return check_async_suspend (info);
803 FIXME fix cardtable WB to be out of line and check with the runtime if the target is not the
804 WB trampoline. Another option is to encode wb ranges in MonoJitInfo, but that is somewhat hard.
807 is_thread_in_critical_region (MonoThreadInfo *info)
811 gpointer stack_start;
812 MonoThreadUnwindState *state;
814 /* Are we inside a system critical region? */
815 if (info->inside_critical_region)
818 /* Are we inside a GC critical region? */
819 if (threads_callbacks.mono_thread_in_critical_region && threads_callbacks.mono_thread_in_critical_region (info)) {
823 /* The target thread might be shutting down and the domain might be null, which means no managed code left to run. */
824 state = mono_thread_info_get_suspend_state (info);
825 if (!state->unwind_data [MONO_UNWIND_DATA_DOMAIN])
828 stack_start = MONO_CONTEXT_GET_SP (&state->ctx);
829 /* altstack signal handler, sgen can't handle them, so we treat them as critical */
830 if (stack_start < info->stack_start_limit || stack_start >= info->stack_end)
833 ji = mono_jit_info_table_find (
834 (MonoDomain *) state->unwind_data [MONO_UNWIND_DATA_DOMAIN],
835 (char *) MONO_CONTEXT_GET_IP (&state->ctx));
840 method = mono_jit_info_get_method (ji);
842 return threads_callbacks.mono_method_is_critical (method);
846 mono_thread_info_in_critical_location (MonoThreadInfo *info)
848 return is_thread_in_critical_region (info);
852 The return value is only valid until a matching mono_thread_info_resume is called
854 static MonoThreadInfo*
855 suspend_sync (MonoNativeThreadId tid, gboolean interrupt_kernel)
857 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
858 MonoThreadInfo *info = mono_thread_info_lookup (tid); /*info on HP1*/
862 switch (mono_threads_transition_request_async_suspension (info)) {
863 case AsyncSuspendAlreadySuspended:
864 mono_hazard_pointer_clear (hp, 1); //XXX this is questionable we got to clean the suspend/resume nonsense of critical sections
866 case AsyncSuspendWait:
867 mono_threads_add_to_pending_operation_set (info);
869 case AsyncSuspendInitSuspend:
870 if (!begin_async_suspend (info, interrupt_kernel)) {
871 mono_hazard_pointer_clear (hp, 1);
876 //Wait for the pending suspend to finish
877 mono_threads_wait_pending_operations ();
879 if (!check_async_suspend (info)) {
880 mono_hazard_pointer_clear (hp, 1);
886 static MonoThreadInfo*
887 suspend_sync_nolock (MonoNativeThreadId id, gboolean interrupt_kernel)
889 MonoThreadInfo *info = NULL;
890 int sleep_duration = 0;
892 if (!(info = suspend_sync (id, interrupt_kernel))) {
893 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
897 /*WARNING: We now are in interrupt context until we resume the thread. */
898 if (!is_thread_in_critical_region (info))
901 if (!mono_thread_info_core_resume (info)) {
902 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
905 THREADS_SUSPEND_DEBUG ("RESTARTED thread tid %p\n", (void*)id);
907 /* Wait for the pending resume to finish */
908 mono_threads_wait_pending_operations ();
910 if (sleep_duration == 0)
911 mono_thread_info_yield ();
913 g_usleep (sleep_duration);
915 sleep_duration += 10;
921 mono_thread_info_safe_suspend_and_run (MonoNativeThreadId id, gboolean interrupt_kernel, MonoSuspendThreadCallback callback, gpointer user_data)
924 MonoThreadInfo *info = NULL;
925 MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
927 THREADS_SUSPEND_DEBUG ("SUSPENDING tid %p\n", (void*)id);
928 /*FIXME: unify this with self-suspend*/
929 g_assert (id != mono_native_thread_id_get ());
931 /* This can block during stw */
932 mono_thread_info_suspend_lock ();
933 mono_threads_begin_global_suspend ();
935 info = suspend_sync_nolock (id, interrupt_kernel);
939 switch (result = callback (info, user_data)) {
940 case MonoResumeThread:
941 mono_hazard_pointer_set (hp, 1, info);
942 mono_thread_info_core_resume (info);
943 mono_threads_wait_pending_operations ();
948 g_error ("Invalid suspend_and_run callback return value %d", result);
952 mono_hazard_pointer_clear (hp, 1);
953 mono_threads_end_global_suspend ();
954 mono_thread_info_suspend_unlock ();
958 Inject an assynchronous call into the target thread. The target thread must be suspended and
959 only a single async call can be setup for a given suspend cycle.
960 This async call must cause stack unwinding as the current implementation doesn't save enough state
961 to resume execution of the top-of-stack function. It's an acceptable limitation since this is
962 currently used only to deliver exceptions.
965 mono_thread_info_setup_async_call (MonoThreadInfo *info, void (*target_func)(void*), void *user_data)
967 /* An async call can only be setup on an async suspended thread */
968 g_assert (mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED);
969 /*FIXME this is a bad assert, we probably should do proper locking and fail if one is already set*/
970 g_assert (!info->async_target);
971 info->async_target = target_func;
972 /* This is not GC tracked */
973 info->user_data = user_data;
977 The suspend lock is held during any suspend in progress.
978 A GC that has safepoints must take this lock as part of its
979 STW to make sure no unsafe pending suspend is in progress.
982 mono_thread_info_suspend_lock (void)
984 int res = mono_coop_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
985 g_assert (res != -1);
989 mono_thread_info_suspend_unlock (void)
991 mono_coop_sem_post (&global_suspend_semaphore);
995 * This is a very specific function whose only purpose is to
996 * break a given thread from socket syscalls.
998 * This only exists because linux won't fail a call to connect
999 * if the underlying is closed.
1001 * TODO We should cleanup and unify this with the other syscall abort
1005 mono_thread_info_abort_socket_syscall_for_close (MonoNativeThreadId tid)
1007 MonoThreadHazardPointers *hp;
1008 MonoThreadInfo *info;
1010 if (tid == mono_native_thread_id_get () || !mono_threads_core_needs_abort_syscall ())
1013 hp = mono_hazard_pointer_get ();
1014 info = mono_thread_info_lookup (tid);
1018 if (mono_thread_info_run_state (info) == STATE_DETACHED) {
1019 mono_hazard_pointer_clear (hp, 1);
1023 mono_thread_info_suspend_lock ();
1024 mono_threads_begin_global_suspend ();
1026 mono_threads_core_abort_syscall (info);
1027 mono_threads_wait_pending_operations ();
1029 mono_hazard_pointer_clear (hp, 1);
1031 mono_threads_end_global_suspend ();
1032 mono_thread_info_suspend_unlock ();
1036 mono_thread_info_unified_management_enabled (void)
1038 return unified_suspend_enabled;
1042 * mono_thread_info_set_is_async_context:
1044 * Set whenever the current thread is in an async context. Some runtime functions might behave
1045 * differently while in an async context in order to be async safe.
1048 mono_thread_info_set_is_async_context (gboolean async_context)
1050 MonoThreadInfo *info = mono_thread_info_current ();
1053 info->is_async_context = async_context;
1057 mono_thread_info_is_async_context (void)
1059 MonoThreadInfo *info = mono_thread_info_current ();
1062 return info->is_async_context;
1068 * mono_threads_create_thread:
1070 * Create a new thread executing START with argument ARG. Store its id into OUT_TID.
1071 * Returns: a windows or io-layer handle for the thread.
1074 mono_threads_create_thread (LPTHREAD_START_ROUTINE start, gpointer arg, guint32 stack_size, guint32 creation_flags, MonoNativeThreadId *out_tid)
1076 return mono_threads_core_create_thread (start, arg, stack_size, creation_flags, out_tid);
1080 * mono_thread_info_get_stack_bounds:
1082 * Return the address and size of the current threads stack. Return NULL as the
1083 * stack address if the stack address cannot be determined.
1086 mono_thread_info_get_stack_bounds (guint8 **staddr, size_t *stsize)
1088 guint8 *current = (guint8 *)&stsize;
1089 mono_threads_core_get_stack_bounds (staddr, stsize);
1093 /* Sanity check the result */
1094 g_assert ((current > *staddr) && (current < *staddr + *stsize));
1096 /* When running under emacs, sometimes staddr is not aligned to a page size */
1097 *staddr = (guint8*)((gssize)*staddr & ~(mono_pagesize () - 1));
1101 mono_thread_info_yield (void)
1103 return mono_threads_core_yield ();
1105 static mono_lazy_init_t sleep_init = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
1106 static MonoCoopMutex sleep_mutex;
1107 static MonoCoopCond sleep_cond;
1110 sleep_initialize (void)
1112 mono_coop_mutex_init (&sleep_mutex);
1113 mono_coop_cond_init (&sleep_cond);
1117 sleep_interrupt (gpointer data)
1119 mono_coop_mutex_lock (&sleep_mutex);
1120 mono_coop_cond_broadcast (&sleep_cond);
1121 mono_coop_mutex_unlock (&sleep_mutex);
1124 static inline guint32
1125 sleep_interruptable (guint32 ms, gboolean *alerted)
1127 guint32 start, now, end;
1129 g_assert (INFINITE == G_MAXUINT32);
1134 start = mono_msec_ticks ();
1136 if (start < G_MAXUINT32 - ms) {
1139 /* start + ms would overflow guint32 */
1143 mono_lazy_initialize (&sleep_init, sleep_initialize);
1145 mono_coop_mutex_lock (&sleep_mutex);
1147 for (now = mono_msec_ticks (); ms == INFINITE || now - start < ms; now = mono_msec_ticks ()) {
1148 mono_thread_info_install_interrupt (sleep_interrupt, NULL, alerted);
1150 mono_coop_mutex_unlock (&sleep_mutex);
1151 return WAIT_IO_COMPLETION;
1155 mono_coop_cond_timedwait (&sleep_cond, &sleep_mutex, end - now);
1157 mono_coop_cond_wait (&sleep_cond, &sleep_mutex);
1159 mono_thread_info_uninstall_interrupt (alerted);
1161 mono_coop_mutex_unlock (&sleep_mutex);
1162 return WAIT_IO_COMPLETION;
1166 mono_coop_mutex_unlock (&sleep_mutex);
1172 mono_thread_info_sleep (guint32 ms, gboolean *alerted)
1175 MonoThreadInfo *info;
1177 mono_thread_info_yield ();
1179 info = mono_thread_info_current ();
1180 if (info && mono_thread_info_is_interrupt_state (info))
1181 return WAIT_IO_COMPLETION;
1187 return sleep_interruptable (ms, alerted);
1189 MONO_PREPARE_BLOCKING;
1191 if (ms == INFINITE) {
1194 Sleep (G_MAXUINT32);
1196 sleep (G_MAXUINT32);
1201 #if defined (__linux__) && !defined(PLATFORM_ANDROID)
1202 struct timespec start, target;
1204 /* Use clock_nanosleep () to prevent time drifting problems when nanosleep () is interrupted by signals */
1205 ret = clock_gettime (CLOCK_MONOTONIC, &start);
1206 g_assert (ret == 0);
1209 target.tv_sec += ms / 1000;
1210 target.tv_nsec += (ms % 1000) * 1000000;
1211 if (target.tv_nsec > 999999999) {
1212 target.tv_nsec -= 999999999;
1217 ret = clock_nanosleep (CLOCK_MONOTONIC, TIMER_ABSTIME, &target, NULL);
1222 struct timespec req, rem;
1224 req.tv_sec = ms / 1000;
1225 req.tv_nsec = (ms % 1000) * 1000000;
1228 memset (&rem, 0, sizeof (rem));
1229 ret = nanosleep (&req, &rem);
1231 #endif /* __linux__ */
1234 MONO_FINISH_BLOCKING;
1240 mono_thread_info_usleep (guint64 us)
1242 MONO_PREPARE_BLOCKING;
1244 MONO_FINISH_BLOCKING;
1249 mono_thread_info_tls_get (THREAD_INFO_TYPE *info, MonoTlsKey key)
1251 return ((MonoThreadInfo*)info)->tls [key];
1255 * mono_threads_info_tls_set:
1257 * Set the TLS key to VALUE in the info structure. This can be used to obtain
1258 * values of TLS variables for threads other than the current thread.
1259 * This should only be used for infrequently changing TLS variables, and it should
1260 * be paired with setting the real TLS variable since this provides no GC tracking.
1263 mono_thread_info_tls_set (THREAD_INFO_TYPE *info, MonoTlsKey key, gpointer value)
1265 ((MonoThreadInfo*)info)->tls [key] = value;
1269 * mono_thread_info_exit:
1271 * Exit the current thread.
1272 * This function doesn't return.
1275 mono_thread_info_exit (void)
1277 mono_threads_core_exit (0);
1281 * mono_thread_info_open_handle:
1283 * Return a io-layer/win32 handle for the current thread.
1284 * The handle need to be closed by calling CloseHandle () when it is no
1288 mono_thread_info_open_handle (void)
1290 return mono_threads_core_open_handle ();
1294 * mono_threads_open_thread_handle:
1296 * Return a io-layer/win32 handle for the thread identified by HANDLE/TID.
1297 * The handle need to be closed by calling CloseHandle () when it is no
1301 mono_threads_open_thread_handle (HANDLE handle, MonoNativeThreadId tid)
1303 return mono_threads_core_open_thread_handle (handle, tid);
1307 mono_thread_info_set_name (MonoNativeThreadId tid, const char *name)
1309 mono_threads_core_set_name (tid, name);
1312 #define INTERRUPT_STATE ((MonoThreadInfoInterruptToken*) (size_t) -1)
1314 struct _MonoThreadInfoInterruptToken {
1315 void (*callback) (gpointer data);
1320 * mono_thread_info_install_interrupt: install an interruption token for the current thread.
1322 * - @callback: must be able to be called from another thread and always cancel the wait
1323 * - @data: passed to the callback
1324 * - @interrupted: will be set to TRUE if a token is already installed, FALSE otherwise
1325 * if set to TRUE, it must mean that the thread is in interrupted state
1328 mono_thread_info_install_interrupt (void (*callback) (gpointer data), gpointer data, gboolean *interrupted)
1330 MonoThreadInfo *info;
1331 MonoThreadInfoInterruptToken *previous_token, *token;
1333 g_assert (callback);
1335 g_assert (interrupted);
1336 *interrupted = FALSE;
1338 info = mono_thread_info_current ();
1341 /* The memory of this token can be freed at 2 places:
1342 * - if the token is not interrupted: it will be freed in uninstall, as info->interrupt_token has not been replaced
1343 * by the INTERRUPT_STATE flag value, and it still contains the pointer to the memory location
1344 * - if the token is interrupted: it will be freed in finish, as the token is now owned by the prepare/finish
1345 * functions, and info->interrupt_token does not contains a pointer to the memory anymore */
1346 token = g_new0 (MonoThreadInfoInterruptToken, 1);
1347 token->callback = callback;
1350 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, token, NULL);
1352 if (previous_token) {
1353 if (previous_token != INTERRUPT_STATE)
1354 g_error ("mono_thread_info_install_interrupt: previous_token should be INTERRUPT_STATE (%p), but it was %p", INTERRUPT_STATE, previous_token);
1358 *interrupted = TRUE;
1361 THREADS_INTERRUPT_DEBUG ("interrupt install tid %p token %p previous_token %p interrupted %s\n",
1362 mono_thread_info_get_tid (info), token, previous_token, *interrupted ? "TRUE" : "FALSE");
1366 mono_thread_info_uninstall_interrupt (gboolean *interrupted)
1368 MonoThreadInfo *info;
1369 MonoThreadInfoInterruptToken *previous_token;
1371 g_assert (interrupted);
1372 *interrupted = FALSE;
1374 info = mono_thread_info_current ();
1377 previous_token = (MonoThreadInfoInterruptToken *)InterlockedExchangePointer ((gpointer*) &info->interrupt_token, NULL);
1379 /* only the installer can uninstall the token */
1380 g_assert (previous_token);
1382 if (previous_token == INTERRUPT_STATE) {
1383 /* if it is interrupted, then it is going to be freed in finish interrupt */
1384 *interrupted = TRUE;
1386 g_free (previous_token);
1389 THREADS_INTERRUPT_DEBUG ("interrupt uninstall tid %p previous_token %p interrupted %s\n",
1390 mono_thread_info_get_tid (info), previous_token, *interrupted ? "TRUE" : "FALSE");
1393 static MonoThreadInfoInterruptToken*
1394 set_interrupt_state (MonoThreadInfo *info)
1396 MonoThreadInfoInterruptToken *token, *previous_token;
1400 /* Atomically obtain the token the thread is
1401 * waiting on, and change it to a flag value. */
1404 previous_token = info->interrupt_token;
1406 /* Already interrupted */
1407 if (previous_token == INTERRUPT_STATE) {
1412 token = previous_token;
1413 } while (InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, INTERRUPT_STATE, previous_token) != previous_token);
1419 * mono_thread_info_prepare_interrupt:
1421 * The state of the thread info interrupt token is set to 'interrupted' which means that :
1422 * - if the thread calls one of the WaitFor functions, the function will return with
1423 * WAIT_IO_COMPLETION instead of waiting
1424 * - if the thread was waiting when this function was called, the wait will be broken
1426 * It is possible that the wait functions return WAIT_IO_COMPLETION, but the target thread
1427 * didn't receive the interrupt signal yet, in this case it should call the wait function
1428 * again. This essentially means that the target thread will busy wait until it is ready to
1429 * process the interruption.
1431 MonoThreadInfoInterruptToken*
1432 mono_thread_info_prepare_interrupt (MonoThreadInfo *info)
1434 MonoThreadInfoInterruptToken *token;
1436 token = set_interrupt_state (info);
1438 THREADS_INTERRUPT_DEBUG ("interrupt prepare tid %p token %p\n",
1439 mono_thread_info_get_tid (info), token);
1445 mono_thread_info_finish_interrupt (MonoThreadInfoInterruptToken *token)
1447 THREADS_INTERRUPT_DEBUG ("interrupt finish token %p\n", token);
1452 g_assert (token->callback);
1454 token->callback (token->data);
1460 mono_thread_info_self_interrupt (void)
1462 MonoThreadInfo *info;
1463 MonoThreadInfoInterruptToken *token;
1465 info = mono_thread_info_current ();
1468 token = set_interrupt_state (info);
1471 THREADS_INTERRUPT_DEBUG ("interrupt self tid %p\n",
1472 mono_thread_info_get_tid (info));
1475 /* Clear the interrupted flag of the current thread, set with
1476 * mono_thread_info_self_interrupt, so it can wait again */
1478 mono_thread_info_clear_self_interrupt ()
1480 MonoThreadInfo *info;
1481 MonoThreadInfoInterruptToken *previous_token;
1483 info = mono_thread_info_current ();
1486 previous_token = (MonoThreadInfoInterruptToken *)InterlockedCompareExchangePointer ((gpointer*) &info->interrupt_token, NULL, INTERRUPT_STATE);
1487 g_assert (previous_token == NULL || previous_token == INTERRUPT_STATE);
1489 THREADS_INTERRUPT_DEBUG ("interrupt clear self tid %p previous_token %p\n", mono_thread_info_get_tid (info), previous_token);
1493 mono_thread_info_is_interrupt_state (MonoThreadInfo *info)
1496 return InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE;
1500 mono_thread_info_describe_interrupt_token (MonoThreadInfo *info, GString *text)
1504 if (!InterlockedReadPointer ((gpointer*) &info->interrupt_token))
1505 g_string_append_printf (text, "not waiting");
1506 else if (InterlockedReadPointer ((gpointer*) &info->interrupt_token) == INTERRUPT_STATE)
1507 g_string_append_printf (text, "interrupted state");
1509 g_string_append_printf (text, "waiting");
1512 /* info must be self or be held in a hazard pointer. */
1514 mono_threads_add_async_job (MonoThreadInfo *info, MonoAsyncJob job)
1516 MonoAsyncJob old_job;
1518 old_job = (MonoAsyncJob) info->service_requests;
1521 } while (InterlockedCompareExchange (&info->service_requests, old_job | job, old_job) != old_job);
1526 mono_threads_consume_async_jobs (void)
1528 MonoThreadInfo *info = (MonoThreadInfo*)mono_native_tls_get_value (thread_info_key);
1531 return (MonoAsyncJob) 0;
1533 return (MonoAsyncJob) InterlockedExchange (&info->service_requests, 0);