JvmtiRawMonitor::QNode::QNode(Thread* thread) : _next(NULL), _prev(NULL),

                                                _event(thread->_ParkEvent),

                                                _notified(0), _t_state(TS_RUN) {

}

GrowableArray<JvmtiRawMonitor*>* JvmtiPendingMonitors::_monitors =

  new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JvmtiRawMonitor*>(1, true);

         "Java thread has not been created yet or more than one java thread "

         "is running. Raw monitor transition will not work");

  JavaThread* current_java_thread = JavaThread::current();

  for (int i = 0; i < count(); i++) {

    JvmtiRawMonitor* rmonitor = monitors()->at(i);

    rmonitor->raw_enter(current_java_thread);

JvmtiRawMonitor::JvmtiRawMonitor(const char* name) : _owner(NULL),

                                                     _recursions(0),

                                                     _entry_list(NULL),

                                                     _wait_set(NULL),

                                                     _waiters(0),

                                                     _magic(JVMTI_RM_MAGIC),

                                                     _name(NULL) {

// The JVMTI raw monitor subsystem is entirely distinct from normal

// java-synchronization or jni-synchronization.  JVMTI raw monitors are not

// the raw-monitor implementation on the existing Java ObjectMonitor mechanism.

// Now we just use a simplified form of that ObjectMonitor code.

// is fairly rare, this is not of concern.  The RawMonitor_lock can not

void JvmtiRawMonitor::simple_enter(Thread* self) {

    if (Atomic::replace_if_null(self, &_owner)) {

      return;

    QNode node(self);

    self->_ParkEvent->reset();     // strictly optional

    node._t_state = QNode::TS_ENTER;

    RawMonitor_lock->lock_without_safepoint_check();

    node._next = _entry_list;

    _entry_list = &node;

    OrderAccess::fence();

    if (_owner == NULL && Atomic::replace_if_null(self, &_owner)) {

      _entry_list = node._next;

      RawMonitor_lock->unlock();

      return;

    RawMonitor_lock->unlock();

    while (node._t_state == QNode::TS_ENTER) {

      self->_ParkEvent->park();

void JvmtiRawMonitor::simple_exit(Thread* self) {

  guarantee(_owner == self, "invariant");

  OrderAccess::release_store(&_owner, (Thread*)NULL);

  OrderAccess::fence();

  if (_entry_list == NULL) {

    return;

  }

  RawMonitor_lock->lock_without_safepoint_check();

  QNode* w = _entry_list;

    _entry_list = w->_next;

  RawMonitor_lock->unlock();

    guarantee(w ->_t_state == QNode::TS_ENTER, "invariant");

    // Once we set _t_state to TS_RUN the waiting thread can complete

    // simple_enter and 'w' is pointing into random stack space. So we have

    // to ensure we extract the ParkEvent (which is in type-stable memory)

    // before we set the state, and then don't access 'w'.

    ParkEvent* ev = w->_event;

    OrderAccess::loadstore();

    w->_t_state = QNode::TS_RUN;

    OrderAccess::fence();

    ev->unpark();

  return;

int JvmtiRawMonitor::simple_wait(Thread* self, jlong millis) {

  guarantee(_owner == self  , "invariant");

  guarantee(_recursions == 0, "invariant");

  QNode node(self);

  node._notified = 0;

  node._t_state = QNode::TS_WAIT;

  RawMonitor_lock->lock_without_safepoint_check();

  node._next = _wait_set;

  _wait_set = &node;

  RawMonitor_lock->unlock();

  simple_exit(self);

  guarantee(_owner != self, "invariant");

  int ret = OS_OK;

    self->_ParkEvent->park();

    ret = self->_ParkEvent->park(millis);

  // as _t_state is volatile and the lock-unlock operators are

  if (node._t_state == QNode::TS_WAIT) {

    RawMonitor_lock->lock_without_safepoint_check();

    if (node._t_state == QNode::TS_WAIT) {

      QNode* p;

      QNode* q = NULL;

      for (p = _wait_set; p != &node; p = p->_next) {

        q = p;

      guarantee(p == &node, "invariant");

        guarantee (p == _wait_set, "invariant");

        _wait_set = p->_next;

        guarantee(p == q->_next, "invariant");

        q->_next = p->_next;

      node._t_state = QNode::TS_RUN;

    RawMonitor_lock->unlock();

  guarantee(node._t_state == QNode::TS_RUN, "invariant");

  simple_enter(self);

  guarantee(_owner == self, "invariant");

  guarantee(_recursions == 0, "invariant");

  return ret;

void JvmtiRawMonitor::simple_notify(Thread* self, bool all) {

  guarantee(_owner == self, "invariant");

  if (_wait_set == NULL) {

    return;

  }

  // A. Transfer the threads from the _wait_set to the _entry_list

  // B. Remove the thread from the _wait_set and unpark() it.

  ParkEvent* ev = NULL;       // consider using a small auto array ...

  RawMonitor_lock->lock_without_safepoint_check();

    QNode* w = _wait_set;

    if (w == NULL) break;

    _wait_set = w->_next;

    if (ev != NULL) {

      ev->unpark();

      ev = NULL;

    }

    ev = w->_event;

    OrderAccess::loadstore();

    w->_t_state = QNode::TS_RUN;

    OrderAccess::storeload();

    if (!all) {

      break;

    }

  RawMonitor_lock->unlock();

  if (ev != NULL) {

    ev->unpark();

  }

  return;

void JvmtiRawMonitor::raw_enter(Thread* self) {

  void* contended;

  JavaThread* jt = NULL;

  if (self->is_Java_thread()) {

    jt = (JavaThread*)self;

    contended = Atomic::cmpxchg(jt, &_owner, (Thread*)NULL);

    contended = Atomic::cmpxchg(self, &_owner, (Thread*)NULL);

  if (contended == self) {

    _recursions++;

    return;

  if (contended == NULL) {

    guarantee(_owner == self, "invariant");

    guarantee(_recursions == 0, "invariant");

    return;

  self->set_current_pending_raw_monitor(this);

  if (!self->is_Java_thread()) {

    simple_enter(self);

  } else {

    guarantee(jt->thread_state() == _thread_blocked, "invariant");

    for (;;) {

      jt->set_suspend_equivalent();

      // cleared by handle_special_suspend_equivalent_condition() or

      // java_suspend_self()

      simple_enter(jt);

      // were we externally suspended while we were waiting?

      if (!jt->handle_special_suspend_equivalent_condition()) {

        break;

      }

      // This thread was externally suspended

      // We have reentered the contended monitor, but while we were

      // waiting another thread suspended us. We don't want to reenter

      // the monitor while suspended because that would surprise the

      // thread that suspended us.

      //

      // Drop the lock

      simple_exit(jt);

      jt->java_suspend_self();

    }

  self->set_current_pending_raw_monitor(NULL);

  guarantee(_owner == self, "invariant");

  guarantee(_recursions == 0, "invariant");

int JvmtiRawMonitor::raw_exit(Thread* self) {

  if (self != _owner) {

    return M_ILLEGAL_MONITOR_STATE;

    _recursions--;

  } else {

    simple_exit(self);

  return M_OK;

int JvmtiRawMonitor::raw_wait(jlong millis, bool interruptible, Thread* self) {

  if (self != _owner) {

    return M_ILLEGAL_MONITOR_STATE;

  // To avoid spurious wakeups we reset the parkevent. This is strictly optional.

  self->_ParkEvent->reset();

  OrderAccess::fence();

  JavaThread* jt = NULL;

  if (interruptible) {

    assert(self->is_Java_thread(), "Only JavaThreads can be interruptible");

    jt = (JavaThread*)self;

    if (jt->is_interrupted(true)) {

      return M_INTERRUPTED;

    }

  } else {

    assert(!self->is_Java_thread(), "JavaThreads must be interuptible");

  intptr_t save = _recursions;

  _recursions = 0;

  _waiters++;

  if (self->is_Java_thread()) {

    guarantee(jt->thread_state() == _thread_blocked, "invariant");

    jt->set_suspend_equivalent();

  int rv = simple_wait(self, millis);

  _recursions = save;

  _waiters--;

  guarantee(self == _owner, "invariant");

  if (self->is_Java_thread()) {

    for (;;) {

      if (!jt->handle_special_suspend_equivalent_condition()) {

        break;

      }

      simple_exit(jt);

      jt->java_suspend_self();

      simple_enter(jt);

      jt->set_suspend_equivalent();

    }

    guarantee(jt == _owner, "invariant");

  if (interruptible && jt->is_interrupted(true)) {

    return M_INTERRUPTED;

  return M_OK;

int JvmtiRawMonitor::raw_notify(Thread* self) {

  if (self != _owner) {

    return M_ILLEGAL_MONITOR_STATE;

  simple_notify(self, false);

  return M_OK;

int JvmtiRawMonitor::raw_notifyAll(Thread* self) {

  if (self != _owner) {

    return M_ILLEGAL_MONITOR_STATE;

  simple_notify(self, true);

  return M_OK;