-/*
- * mono-threads.c: Low-level threading
+/**
+ * \file
+ * Low-level threading
*
* Author:
* Rodrigo Kumpera (kumpera@gmail.com)
#include <mono/utils/mono-coop-mutex.h>
#include <mono/utils/mono-coop-semaphore.h>
#include <mono/utils/mono-threads-coop.h>
+#include <mono/utils/mono-threads-debug.h>
+#include <mono/utils/os-event.h>
+#include <mono/utils/w32api.h>
#include <errno.h>
static MonoThreadInfoRuntimeCallbacks runtime_callbacks;
static MonoNativeTlsKey thread_info_key, thread_exited_key;
#ifdef HAVE_KW_THREAD
-static __thread guint32 tls_small_id MONO_TLS_FAST;
+static __thread gint32 tls_small_id = -1;
#else
static MonoNativeTlsKey small_id_key;
#endif
static MonoSemType suspend_semaphore;
static size_t pending_suspends;
-static gboolean unified_suspend_enabled;
+
+static mono_mutex_t join_mutex;
#define mono_thread_info_run_state(info) (((MonoThreadInfo*)info)->thread_state & THREAD_STATE_MASK)
g_free (info);
}
+/*
+ * mono_thread_info_register_small_id
+ *
+ * Registers a small ID for the current thread. This is a 16-bit value uniquely
+ * identifying the current thread. If the current thread already has a small ID
+ * assigned, that small ID will be returned; otherwise, the newly assigned small
+ * ID is returned.
+ */
int
mono_thread_info_register_small_id (void)
{
- int small_id = mono_thread_small_id_alloc ();
+ int small_id = mono_thread_info_get_small_id ();
+
+ if (small_id != -1)
+ return small_id;
+
+ small_id = mono_thread_small_id_alloc ();
#ifdef HAVE_KW_THREAD
tls_small_id = small_id;
#else
return small_id;
}
-static void*
-register_thread (MonoThreadInfo *info, gpointer baseptr)
+static void
+thread_handle_destroy (gpointer data)
+{
+ MonoThreadHandle *thread_handle;
+
+ thread_handle = (MonoThreadHandle*) data;
+
+ mono_os_event_destroy (&thread_handle->event);
+ g_free (thread_handle);
+}
+
+static gboolean
+register_thread (MonoThreadInfo *info)
{
size_t stsize = 0;
guint8 *staddr = NULL;
- int small_id = mono_thread_info_register_small_id ();
gboolean result;
+
+ info->small_id = mono_thread_info_register_small_id ();
mono_thread_info_set_tid (info, mono_native_thread_id_get ());
- info->small_id = small_id;
+
+ info->handle = g_new0 (MonoThreadHandle, 1);
+ mono_refcount_init (info->handle, thread_handle_destroy);
+ mono_os_event_init (&info->handle->event, FALSE);
mono_os_sem_init (&info->resume_semaphore, 0);
/*set TLS early so SMR works */
mono_native_tls_set_value (thread_info_key, info);
- THREADS_DEBUG ("registering info %p tid %p small id %x\n", info, mono_thread_info_get_tid (info), info->small_id);
-
- if (threads_callbacks.thread_register) {
- if (threads_callbacks.thread_register (info, baseptr) == NULL) {
- // g_warning ("thread registation failed\n");
- mono_native_tls_set_value (thread_info_key, NULL);
- g_free (info);
- return NULL;
- }
- }
-
mono_thread_info_get_stack_bounds (&staddr, &stsize);
g_assert (staddr);
g_assert (stsize);
info->stackdata = g_byte_array_new ();
- mono_threads_platform_register (info);
+ info->internal_thread_gchandle = G_MAXUINT32;
+
mono_threads_suspend_register (info);
+ THREADS_DEBUG ("registering info %p tid %p small id %x\n", info, mono_thread_info_get_tid (info), info->small_id);
+
+ if (threads_callbacks.thread_attach) {
+ if (!threads_callbacks.thread_attach (info)) {
+ // g_warning ("thread registation failed\n");
+ mono_native_tls_set_value (thread_info_key, NULL);
+ return FALSE;
+ }
+ }
+
/*
Transition it before taking any locks or publishing itself to reduce the chance
of others witnessing a detached thread.
result = mono_thread_info_insert (info);
g_assert (result);
mono_thread_info_suspend_unlock ();
- return info;
+
+ return TRUE;
}
static void
mono_thread_info_suspend_lock_with_info (MonoThreadInfo *info);
+static void
+mono_threads_signal_thread_handle (MonoThreadHandle* thread_handle);
+
static void
unregister_thread (void *arg)
{
g_assert (mono_thread_info_is_current (info));
g_assert (mono_thread_info_is_live (info));
+ /* Pump the HP queue while the thread is alive.*/
+ mono_thread_hazardous_try_free_some ();
+
small_id = info->small_id;
/* We only enter the GC unsafe region, as when exiting this function, the thread
/* we need to duplicate it, as the info->handle is going
* to be closed when unregistering from the platform */
- handle = mono_threads_platform_duplicate_handle (info);
+ handle = mono_threads_open_thread_handle (info->handle);
/*
First perform the callback that requires no locks.
be done while holding the suspend lock to give no other thread chance
to suspend it.
*/
- if (threads_callbacks.thread_unregister)
- threads_callbacks.thread_unregister (info);
+ if (threads_callbacks.thread_detach_with_lock)
+ threads_callbacks.thread_detach_with_lock (info);
+
+ /* The thread is no longer active, so unref its handle */
+ mono_threads_close_thread_handle (info->handle);
+ info->handle = NULL;
- mono_threads_platform_unregister (info);
result = mono_thread_info_remove (info);
g_assert (result);
mono_threads_transition_detach (info);
/*now it's safe to free the thread info.*/
mono_thread_hazardous_try_free (info, free_thread_info);
- /* Pump the HP queue */
- mono_thread_hazardous_try_free_some ();
mono_thread_small_id_free (small_id);
- /* Signal the w32handle. It can be done as late as here
- * because w32handle does not access the current MonoThreadInfo,
- * neither does it switch state to BLOCKING. */
- mono_threads_platform_set_exited (handle);
+ mono_threads_signal_thread_handle (handle);
+
+ mono_threads_close_thread_handle (handle);
- mono_threads_platform_close_thread_handle (handle);
+ mono_native_tls_set_value (thread_info_key, NULL);
}
static void
return info;
}
+/*
+ * mono_thread_info_get_small_id
+ *
+ * Retrieve the small ID for the current thread. This is a 16-bit value uniquely
+ * identifying the current thread. Returns -1 if the current thread doesn't have
+ * a small ID assigned.
+ *
+ * To ensure that the calling thread has a small ID assigned, call either
+ * mono_thread_info_attach or mono_thread_info_register_small_id.
+ */
int
mono_thread_info_get_small_id (void)
{
void
mono_threads_attach_tools_thread (void)
{
- int dummy = 0;
MonoThreadInfo *info;
/* Must only be called once */
mono_thread_info_usleep (10);
}
- info = mono_thread_info_attach (&dummy);
+ info = mono_thread_info_attach ();
g_assert (info);
info->tools_thread = TRUE;
}
MonoThreadInfo*
-mono_thread_info_attach (void *baseptr)
+mono_thread_info_attach (void)
{
MonoThreadInfo *info;
+
+#ifdef HOST_WIN32
if (!mono_threads_inited)
{
-#ifdef HOST_WIN32
/* This can happen from DllMain(DLL_THREAD_ATTACH) on Windows, if a
* thread is created before an embedding API user initialized Mono. */
- THREADS_DEBUG ("mono_thread_info_attach called before mono_threads_init\n");
+ THREADS_DEBUG ("mono_thread_info_attach called before mono_thread_info_init\n");
return NULL;
-#else
- g_assert (mono_threads_inited);
-#endif
}
+#endif
+
+ g_assert (mono_threads_inited);
+
info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
if (!info) {
info = (MonoThreadInfo *) g_malloc0 (thread_info_size);
THREADS_DEBUG ("attaching %p\n", info);
- if (!register_thread (info, baseptr))
+ if (!register_thread (info)) {
+ g_free (info);
return NULL;
- } else if (threads_callbacks.thread_attach) {
- threads_callbacks.thread_attach (info);
+ }
}
+
return info;
}
mono_thread_info_detach (void)
{
MonoThreadInfo *info;
+
+#ifdef HOST_WIN32
if (!mono_threads_inited)
{
/* This can happen from DllMain(THREAD_DETACH) on Windows, if a thread
* is created before an embedding API user initialized Mono. */
- THREADS_DEBUG ("mono_thread_info_detach called before mono_threads_init\n");
+ THREADS_DEBUG ("mono_thread_info_detach called before mono_thread_info_init\n");
return;
}
+#endif
+
+ g_assert (mono_threads_inited);
+
info = (MonoThreadInfo *) mono_native_tls_get_value (thread_info_key);
if (info) {
THREADS_DEBUG ("detaching %p\n", info);
unregister_thread (info);
- mono_native_tls_set_value (thread_info_key, NULL);
}
}
+gboolean
+mono_thread_info_try_get_internal_thread_gchandle (MonoThreadInfo *info, guint32 *gchandle)
+{
+ g_assert (info);
+
+ if (info->internal_thread_gchandle == G_MAXUINT32)
+ return FALSE;
+
+ *gchandle = info->internal_thread_gchandle;
+ return TRUE;
+}
+
+void
+mono_thread_info_set_internal_thread_gchandle (MonoThreadInfo *info, guint32 gchandle)
+{
+ g_assert (info);
+ g_assert (gchandle != G_MAXUINT32);
+ info->internal_thread_gchandle = gchandle;
+}
+
+void
+mono_thread_info_unset_internal_thread_gchandle (THREAD_INFO_TYPE *info)
+{
+ g_assert (info);
+ info->internal_thread_gchandle = G_MAXUINT32;
+}
+
/*
* mono_thread_info_is_exiting:
*
#endif
void
-mono_threads_init (MonoThreadInfoCallbacks *callbacks, size_t info_size)
+mono_thread_info_init (size_t info_size)
{
gboolean res;
- threads_callbacks = *callbacks;
thread_info_size = info_size;
- const char *sleepLimit;
+ char *sleepLimit;
#ifdef HOST_WIN32
res = mono_native_tls_alloc (&thread_info_key, NULL);
res = mono_native_tls_alloc (&thread_exited_key, NULL);
#endif
g_assert (res);
- unified_suspend_enabled = g_getenv ("MONO_ENABLE_UNIFIED_SUSPEND") != NULL || mono_threads_is_coop_enabled ();
-
if ((sleepLimit = g_getenv ("MONO_SLEEP_ABORT_LIMIT")) != NULL) {
errno = 0;
long threshold = strtol(sleepLimit, NULL, 10);
sleepWarnDuration = threshold / 20;
} else
g_warning("MONO_SLEEP_ABORT_LIMIT must be a number >= 40");
+ g_free (sleepLimit);
}
mono_os_sem_init (&global_suspend_semaphore, 1);
mono_os_sem_init (&suspend_semaphore, 0);
+ mono_os_mutex_init (&join_mutex);
mono_lls_init (&thread_list, NULL);
mono_thread_smr_init ();
- mono_threads_platform_init ();
mono_threads_suspend_init ();
mono_threads_coop_init ();
- mono_threads_abort_syscall_init ();
+ mono_threads_platform_init ();
#if defined(__MACH__)
mono_mach_init (thread_info_key);
}
void
-mono_threads_runtime_init (MonoThreadInfoRuntimeCallbacks *callbacks)
+mono_thread_info_callbacks_init (MonoThreadInfoCallbacks *callbacks)
{
- runtime_callbacks = *callbacks;
+ threads_callbacks = *callbacks;
}
-MonoThreadInfoRuntimeCallbacks *
-mono_threads_get_runtime_callbacks (void)
+void
+mono_thread_info_signals_init (void)
{
- return &runtime_callbacks;
+ mono_threads_suspend_init_signals ();
}
-/*
-Signal that the current thread wants to be suspended.
-This function can be called without holding the suspend lock held.
-To finish suspending, call mono_suspend_check.
-*/
void
-mono_thread_info_begin_self_suspend (void)
+mono_thread_info_runtime_init (MonoThreadInfoRuntimeCallbacks *callbacks)
{
- MonoThreadInfo *info = mono_thread_info_current_unchecked ();
- if (!info)
- return;
-
- THREADS_SUSPEND_DEBUG ("BEGIN SELF SUSPEND OF %p\n", info);
- mono_threads_transition_request_self_suspension (info);
+ runtime_callbacks = *callbacks;
}
-void
-mono_thread_info_end_self_suspend (void)
+MonoThreadInfoRuntimeCallbacks *
+mono_threads_get_runtime_callbacks (void)
{
- MonoThreadInfo *info;
-
- info = mono_thread_info_current ();
- if (!info)
- return;
- THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", info);
-
- mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
-
- /* commit the saved state and notify others if needed */
- switch (mono_threads_transition_state_poll (info)) {
- case SelfSuspendResumed:
- return;
- case SelfSuspendWait:
- mono_thread_info_wait_for_resume (info);
- break;
- case SelfSuspendNotifyAndWait:
- mono_threads_notify_initiator_of_suspend (info);
- mono_thread_info_wait_for_resume (info);
- mono_threads_notify_initiator_of_resume (info);
- break;
- }
+ return &runtime_callbacks;
}
static gboolean
static gboolean
is_thread_in_critical_region (MonoThreadInfo *info)
{
- MonoMethod *method;
- MonoJitInfo *ji;
gpointer stack_start;
MonoThreadUnwindState *state;
+ if (mono_threads_platform_in_critical_region (mono_thread_info_get_tid (info)))
+ return TRUE;
+
/* Are we inside a system critical region? */
if (info->inside_critical_region)
return TRUE;
/* Are we inside a GC critical region? */
- if (threads_callbacks.mono_thread_in_critical_region && threads_callbacks.mono_thread_in_critical_region (info)) {
+ if (threads_callbacks.thread_in_critical_region && threads_callbacks.thread_in_critical_region (info)) {
return TRUE;
}
if (stack_start < info->stack_start_limit || stack_start >= info->stack_end)
return TRUE;
- ji = mono_jit_info_table_find (
- (MonoDomain *) state->unwind_data [MONO_UNWIND_DATA_DOMAIN],
- (char *) MONO_CONTEXT_GET_IP (&state->ctx));
-
- if (!ji)
- return FALSE;
-
- method = mono_jit_info_get_method (ji);
+ if (threads_callbacks.ip_in_critical_region)
+ return threads_callbacks.ip_in_critical_region ((MonoDomain *) state->unwind_data [MONO_UNWIND_DATA_DOMAIN], (char *) MONO_CONTEXT_GET_IP (&state->ctx));
- return threads_callbacks.mono_method_is_critical (method);
+ return FALSE;
}
gboolean
mono_threads_wait_pending_operations ();
break;
case KeepSuspended:
+ g_assert (!mono_threads_is_coop_enabled ());
break;
default:
g_error ("Invalid suspend_and_run callback return value %d", result);
void
mono_thread_info_setup_async_call (MonoThreadInfo *info, void (*target_func)(void*), void *user_data)
{
- /* An async call can only be setup on an async suspended thread */
- g_assert (mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED);
+ if (!mono_threads_is_coop_enabled ()) {
+ /* In non-coop mode, an async call can only be setup on an async suspended thread, but in coop mode, a thread
+ * may be in blocking state, and will execute the async call when leaving the safepoint, leaving a gc safe
+ * region or entering a gc unsafe region */
+ g_assert (mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED);
+ }
/*FIXME this is a bad assert, we probably should do proper locking and fail if one is already set*/
g_assert (!info->async_target);
info->async_target = target_func;
static void
mono_thread_info_suspend_lock_with_info (MonoThreadInfo *info)
{
- g_assert (info);
- g_assert (mono_thread_info_is_current (info));
- g_assert (mono_thread_info_is_live (info));
+ if (mono_threads_is_coop_enabled ()) {
+ g_assert (info);
+ g_assert (mono_thread_info_is_current (info));
+ g_assert (mono_thread_info_is_live (info));
- MONO_ENTER_GC_SAFE_WITH_INFO(info);
+ MONO_ENTER_GC_SAFE_WITH_INFO(info);
- int res = mono_os_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
- g_assert (res != -1);
+ int res = mono_os_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
+ g_assert (res != -1);
- MONO_EXIT_GC_SAFE_WITH_INFO;
+ MONO_EXIT_GC_SAFE_WITH_INFO;
+ } else {
+ int res = mono_os_sem_wait (&global_suspend_semaphore, MONO_SEM_FLAGS_NONE);
+ g_assert (res != -1);
+ }
}
void
MonoThreadHazardPointers *hp;
MonoThreadInfo *info;
- if (tid == mono_native_thread_id_get () || !mono_threads_suspend_needs_abort_syscall ())
+ if (tid == mono_native_thread_id_get ())
return;
hp = mono_hazard_pointer_get ();
mono_thread_info_suspend_unlock ();
}
-gboolean
-mono_thread_info_unified_management_enabled (void)
-{
- return unified_suspend_enabled;
-}
-
/*
* mono_thread_info_set_is_async_context:
*
return FALSE;
}
-typedef struct {
- gint32 ref;
- MonoThreadStart start_routine;
- gpointer start_routine_arg;
- gint32 priority;
- MonoCoopSem registered;
- gpointer handle;
-} CreateThreadData;
-
-static gsize WINAPI
-inner_start_thread (gpointer data)
-{
- CreateThreadData *thread_data;
- MonoThreadInfo *info;
- MonoThreadStart start_routine;
- gpointer start_routine_arg;
- guint32 start_routine_res;
- gsize dummy;
-
- thread_data = (CreateThreadData*) data;
- g_assert (thread_data);
-
- start_routine = thread_data->start_routine;
- start_routine_arg = thread_data->start_routine_arg;
-
- info = mono_thread_info_attach (&dummy);
- info->runtime_thread = TRUE;
-
- thread_data->handle = mono_thread_info_duplicate_handle (info);
-
- mono_coop_sem_post (&thread_data->registered);
-
- if (InterlockedDecrement (&thread_data->ref) == 0) {
- mono_coop_sem_destroy (&thread_data->registered);
- g_free (thread_data);
- }
-
- /* thread_data is not valid anymore */
- thread_data = NULL;
-
- /* Run the actual main function of the thread */
- start_routine_res = start_routine (start_routine_arg);
-
- mono_threads_platform_exit (start_routine_res);
-
- g_assert_not_reached ();
-}
-
-/*
- * mono_threads_create_thread:
- *
- * Create a new thread executing START with argument ARG. Store its id into OUT_TID.
- * Returns: a windows or io-layer handle for the thread.
- */
-HANDLE
-mono_threads_create_thread (MonoThreadStart start, gpointer arg, gsize * const stack_size, MonoNativeThreadId *out_tid)
-{
- CreateThreadData *thread_data;
- gint res;
- gpointer ret;
-
- thread_data = g_new0 (CreateThreadData, 1);
- thread_data->ref = 2;
- thread_data->start_routine = start;
- thread_data->start_routine_arg = arg;
- mono_coop_sem_init (&thread_data->registered, 0);
-
- res = mono_threads_platform_create_thread (inner_start_thread, (gpointer) thread_data, stack_size, out_tid);
- if (res != 0) {
- /* ref is not going to be decremented in inner_start_thread */
- InterlockedDecrement (&thread_data->ref);
- ret = NULL;
- goto done;
- }
-
- res = mono_coop_sem_wait (&thread_data->registered, MONO_SEM_FLAGS_NONE);
- g_assert (res == 0);
-
- ret = thread_data->handle;
- g_assert (ret);
-
-done:
- if (InterlockedDecrement (&thread_data->ref) == 0) {
- mono_coop_sem_destroy (&thread_data->registered);
- g_free (thread_data);
- }
-
- return ret;
-}
-
/*
* mono_thread_info_get_stack_bounds:
*
{
return mono_threads_platform_yield ();
}
+
static mono_lazy_init_t sleep_init = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
static MonoCoopMutex sleep_mutex;
static MonoCoopCond sleep_cond;
{
gint64 now, end;
- g_assert (INFINITE == G_MAXUINT32);
+ g_assert (MONO_INFINITE_WAIT == G_MAXUINT32);
g_assert (alerted);
*alerted = FALSE;
- if (ms != INFINITE)
+ if (ms != MONO_INFINITE_WAIT)
end = mono_msec_ticks() + ms;
mono_lazy_initialize (&sleep_init, sleep_initialize);
mono_coop_mutex_lock (&sleep_mutex);
for (;;) {
- if (ms != INFINITE) {
+ if (ms != MONO_INFINITE_WAIT) {
now = mono_msec_ticks();
if (now >= end)
break;
return WAIT_IO_COMPLETION;
}
- if (ms != INFINITE)
+ if (ms != MONO_INFINITE_WAIT)
mono_coop_cond_timedwait (&sleep_cond, &sleep_mutex, end - now);
else
mono_coop_cond_wait (&sleep_cond, &sleep_mutex);
MONO_ENTER_GC_SAFE;
- if (ms == INFINITE) {
+ if (ms == MONO_INFINITE_WAIT) {
do {
#ifdef HOST_WIN32
Sleep (G_MAXUINT32);
* This function doesn't return.
*/
void
-mono_thread_info_exit (void)
+mono_thread_info_exit (gsize exit_code)
{
+ mono_thread_info_detach ();
+
mono_threads_platform_exit (0);
}
/*
* mono_threads_open_thread_handle:
*
- * Return a io-layer/win32 handle for the thread identified by HANDLE/TID.
- * The handle need to be closed by calling CloseHandle () when it is no
- * longer needed.
+ * Duplicate the handle. The handle needs to be closed by calling
+ * mono_threads_close_thread_handle () when it is no longer needed.
*/
-HANDLE
-mono_threads_open_thread_handle (HANDLE handle, MonoNativeThreadId tid)
+MonoThreadHandle*
+mono_threads_open_thread_handle (MonoThreadHandle *thread_handle)
{
- return mono_threads_platform_open_thread_handle (handle, tid);
+ return mono_refcount_inc (thread_handle);
}
void
-mono_threads_close_thread_handle (HANDLE handle)
+mono_threads_close_thread_handle (MonoThreadHandle *thread_handle)
+{
+ mono_refcount_dec (thread_handle);
+}
+
+static void
+mono_threads_signal_thread_handle (MonoThreadHandle* thread_handle)
{
- return mono_threads_platform_close_thread_handle (handle);
+ mono_os_event_set (&thread_handle->event);
}
#define INTERRUPT_STATE ((MonoThreadInfoInterruptToken*) (size_t) -1)
return mono_thread_info_get_tid (info) == mono_native_thread_id_get ();
}
-void
-mono_thread_info_set_exited (THREAD_INFO_TYPE *info)
+MonoThreadInfoWaitRet
+mono_thread_info_wait_one_handle (MonoThreadHandle *thread_handle, guint32 timeout, gboolean alertable)
{
- g_assert (mono_thread_info_is_current (info));
+ MonoOSEventWaitRet res;
- g_assert (info->handle);
- mono_threads_platform_set_exited (info->handle);
+ res = mono_os_event_wait_one (&thread_handle->event, timeout, alertable);
+ if (res == MONO_OS_EVENT_WAIT_RET_SUCCESS_0)
+ return MONO_THREAD_INFO_WAIT_RET_SUCCESS_0;
+ else if (res == MONO_OS_EVENT_WAIT_RET_ALERTED)
+ return MONO_THREAD_INFO_WAIT_RET_ALERTED;
+ else if (res == MONO_OS_EVENT_WAIT_RET_TIMEOUT)
+ return MONO_THREAD_INFO_WAIT_RET_TIMEOUT;
+ else
+ g_error ("%s: unknown res value %d", __func__, res);
}
-gpointer
-mono_thread_info_duplicate_handle (MonoThreadInfo *info)
+MonoThreadInfoWaitRet
+mono_thread_info_wait_multiple_handle (MonoThreadHandle **thread_handles, gsize nhandles, MonoOSEvent *background_change_event, gboolean waitall, guint32 timeout, gboolean alertable)
{
- g_assert (mono_thread_info_is_current (info));
- return mono_threads_platform_duplicate_handle (info);
+ MonoOSEventWaitRet res;
+ MonoOSEvent *thread_events [MONO_OS_EVENT_WAIT_MAXIMUM_OBJECTS];
+ gint i;
+
+ g_assert (nhandles <= MONO_OS_EVENT_WAIT_MAXIMUM_OBJECTS);
+ if (background_change_event)
+ g_assert (nhandles <= MONO_OS_EVENT_WAIT_MAXIMUM_OBJECTS - 1);
+
+ for (i = 0; i < nhandles; ++i)
+ thread_events [i] = &thread_handles [i]->event;
+
+ if (background_change_event)
+ thread_events [nhandles ++] = background_change_event;
+
+ res = mono_os_event_wait_multiple (thread_events, nhandles, waitall, timeout, alertable);
+ if (res >= MONO_OS_EVENT_WAIT_RET_SUCCESS_0 && res <= MONO_OS_EVENT_WAIT_RET_SUCCESS_0 + nhandles - 1)
+ return MONO_THREAD_INFO_WAIT_RET_SUCCESS_0 + (res - MONO_OS_EVENT_WAIT_RET_SUCCESS_0);
+ else if (res == MONO_OS_EVENT_WAIT_RET_ALERTED)
+ return MONO_THREAD_INFO_WAIT_RET_ALERTED;
+ else if (res == MONO_OS_EVENT_WAIT_RET_TIMEOUT)
+ return MONO_THREAD_INFO_WAIT_RET_TIMEOUT;
+ else
+ g_error ("%s: unknown res value %d", __func__, res);
+}
+
+/*
+ * mono_threads_join_mutex:
+ *
+ * This mutex is used to avoid races between pthread_create () and pthread_join () on osx, see
+ * https://bugzilla.xamarin.com/show_bug.cgi?id=50529
+ * The code inside the lock should not block.
+ */
+void
+mono_threads_join_lock (void)
+{
+#ifdef TARGET_OSX
+ mono_os_mutex_lock (&join_mutex);
+#endif
+}
+
+void
+mono_threads_join_unlock (void)
+{
+#ifdef TARGET_OSX
+ mono_os_mutex_unlock (&join_mutex);
+#endif
}