104 return value == JVMTI_RM_MAGIC;
105 }
106
107 // -------------------------------------------------------------------------
108 // The JVMTI raw monitor subsystem is entirely distinct from normal
109 // java-synchronization or jni-synchronization. JVMTI raw monitors are not
110 // associated with objects. They can be implemented in any manner
111 // that makes sense. The original implementors decided to piggy-back
112 // the raw-monitor implementation on the existing Java ObjectMonitor mechanism.
113 // Now we just use a simplified form of that ObjectMonitor code.
114 //
115 // Note that we use the single RawMonitor_lock to protect queue operations for
116 // _all_ raw monitors. This is a scalability impediment, but since raw monitor usage
117 // is fairly rare, this is not of concern. The RawMonitor_lock can not
118 // be held indefinitely. The critical sections must be short and bounded.
119 //
120 // -------------------------------------------------------------------------
121
122 void JvmtiRawMonitor::simple_enter(Thread* self) {
123 for (;;) {
124 if (Atomic::replace_if_null(self, &_owner)) {
125 return;
126 }
127
128 QNode node(self);
129 self->_ParkEvent->reset(); // strictly optional
130 node._t_state = QNode::TS_ENTER;
131
132 RawMonitor_lock->lock_without_safepoint_check();
133 node._next = _entry_list;
134 _entry_list = &node;
135 OrderAccess::fence();
136 if (_owner == NULL && Atomic::replace_if_null(self, &_owner)) {
137 _entry_list = node._next;
138 RawMonitor_lock->unlock();
139 return;
140 }
141 RawMonitor_lock->unlock();
142 while (node._t_state == QNode::TS_ENTER) {
143 self->_ParkEvent->park();
144 }
145 }
146 }
147
148 void JvmtiRawMonitor::simple_exit(Thread* self) {
149 guarantee(_owner == self, "invariant");
150 Atomic::release_store(&_owner, (Thread*)NULL);
151 OrderAccess::fence();
152 if (_entry_list == NULL) {
153 return;
154 }
155
156 RawMonitor_lock->lock_without_safepoint_check();
305 ev->unpark();
306 }
307 return;
308 }
309
310 // Any JavaThread will enter here with state _thread_blocked
311 void JvmtiRawMonitor::raw_enter(Thread* self) {
312 void* contended;
313 JavaThread* jt = NULL;
314 // don't enter raw monitor if thread is being externally suspended, it will
315 // surprise the suspender if a "suspended" thread can still enter monitor
316 if (self->is_Java_thread()) {
317 jt = (JavaThread*)self;
318 jt->SR_lock()->lock_without_safepoint_check();
319 while (jt->is_external_suspend()) {
320 jt->SR_lock()->unlock();
321 jt->java_suspend_self();
322 jt->SR_lock()->lock_without_safepoint_check();
323 }
324 // guarded by SR_lock to avoid racing with new external suspend requests.
325 contended = Atomic::cmpxchg(jt, &_owner, (Thread*)NULL);
326 jt->SR_lock()->unlock();
327 } else {
328 contended = Atomic::cmpxchg(self, &_owner, (Thread*)NULL);
329 }
330
331 if (contended == self) {
332 _recursions++;
333 return;
334 }
335
336 if (contended == NULL) {
337 guarantee(_owner == self, "invariant");
338 guarantee(_recursions == 0, "invariant");
339 return;
340 }
341
342 self->set_current_pending_raw_monitor(this);
343
344 if (!self->is_Java_thread()) {
345 simple_enter(self);
346 } else {
347 guarantee(jt->thread_state() == _thread_blocked, "invariant");
348 for (;;) {
|
104 return value == JVMTI_RM_MAGIC;
105 }
106
107 // -------------------------------------------------------------------------
108 // The JVMTI raw monitor subsystem is entirely distinct from normal
109 // java-synchronization or jni-synchronization. JVMTI raw monitors are not
110 // associated with objects. They can be implemented in any manner
111 // that makes sense. The original implementors decided to piggy-back
112 // the raw-monitor implementation on the existing Java ObjectMonitor mechanism.
113 // Now we just use a simplified form of that ObjectMonitor code.
114 //
115 // Note that we use the single RawMonitor_lock to protect queue operations for
116 // _all_ raw monitors. This is a scalability impediment, but since raw monitor usage
117 // is fairly rare, this is not of concern. The RawMonitor_lock can not
118 // be held indefinitely. The critical sections must be short and bounded.
119 //
120 // -------------------------------------------------------------------------
121
122 void JvmtiRawMonitor::simple_enter(Thread* self) {
123 for (;;) {
124 if (Atomic::replace_if_null(&_owner, self)) {
125 return;
126 }
127
128 QNode node(self);
129 self->_ParkEvent->reset(); // strictly optional
130 node._t_state = QNode::TS_ENTER;
131
132 RawMonitor_lock->lock_without_safepoint_check();
133 node._next = _entry_list;
134 _entry_list = &node;
135 OrderAccess::fence();
136 if (_owner == NULL && Atomic::replace_if_null(&_owner, self)) {
137 _entry_list = node._next;
138 RawMonitor_lock->unlock();
139 return;
140 }
141 RawMonitor_lock->unlock();
142 while (node._t_state == QNode::TS_ENTER) {
143 self->_ParkEvent->park();
144 }
145 }
146 }
147
148 void JvmtiRawMonitor::simple_exit(Thread* self) {
149 guarantee(_owner == self, "invariant");
150 Atomic::release_store(&_owner, (Thread*)NULL);
151 OrderAccess::fence();
152 if (_entry_list == NULL) {
153 return;
154 }
155
156 RawMonitor_lock->lock_without_safepoint_check();
305 ev->unpark();
306 }
307 return;
308 }
309
310 // Any JavaThread will enter here with state _thread_blocked
311 void JvmtiRawMonitor::raw_enter(Thread* self) {
312 void* contended;
313 JavaThread* jt = NULL;
314 // don't enter raw monitor if thread is being externally suspended, it will
315 // surprise the suspender if a "suspended" thread can still enter monitor
316 if (self->is_Java_thread()) {
317 jt = (JavaThread*)self;
318 jt->SR_lock()->lock_without_safepoint_check();
319 while (jt->is_external_suspend()) {
320 jt->SR_lock()->unlock();
321 jt->java_suspend_self();
322 jt->SR_lock()->lock_without_safepoint_check();
323 }
324 // guarded by SR_lock to avoid racing with new external suspend requests.
325 contended = Atomic::cmpxchg(&_owner, (Thread*)NULL, jt);
326 jt->SR_lock()->unlock();
327 } else {
328 contended = Atomic::cmpxchg(&_owner, (Thread*)NULL, self);
329 }
330
331 if (contended == self) {
332 _recursions++;
333 return;
334 }
335
336 if (contended == NULL) {
337 guarantee(_owner == self, "invariant");
338 guarantee(_recursions == 0, "invariant");
339 return;
340 }
341
342 self->set_current_pending_raw_monitor(this);
343
344 if (!self->is_Java_thread()) {
345 simple_enter(self);
346 } else {
347 guarantee(jt->thread_state() == _thread_blocked, "invariant");
348 for (;;) {
|