38 class ObjectMonitorContentionMark;
39 class ParkEvent;
40 class BasicLock;
41 class ContinuationWrapper;
42
43
44 class ObjectWaiter : public CHeapObj<mtThread> {
45 public:
46 enum TStates : uint8_t { TS_UNDEF, TS_READY, TS_RUN, TS_WAIT, TS_ENTER };
47 ObjectWaiter* volatile _next;
48 ObjectWaiter* volatile _prev;
49 JavaThread* _thread;
50 OopHandle _vthread;
51 ObjectMonitor* _monitor;
52 uint64_t _notifier_tid;
53 int _recursions;
54 volatile TStates TState;
55 bool _is_wait;
56 bool _at_reenter;
57 bool _interrupted;
58 bool _do_timed_park;
59 bool _active; // Contention monitoring is enabled
60 public:
61 ObjectWaiter(JavaThread* current);
62 ObjectWaiter(oop vthread, ObjectMonitor* mon);
63 ~ObjectWaiter();
64 JavaThread* thread() const { return _thread; }
65 bool is_vthread() const { return _thread == nullptr; }
66 uint8_t state() const { return TState; }
67 ObjectMonitor* monitor() const { return _monitor; }
68 bool is_wait() const { return _is_wait; }
69 bool at_reenter() const { return _at_reenter; }
70 bool at_monitorenter() const { return !_is_wait || TState != TS_WAIT; }
71 oop vthread() const;
72 void wait_reenter_begin(ObjectMonitor *mon);
73 void wait_reenter_end(ObjectMonitor *mon);
74
75 void set_bad_pointers() {
76 #ifdef ASSERT
77 this->_prev = (ObjectWaiter*) badAddressVal;
183 // changed by ObjectMonitor::exit() so it is a good choice to share the
184 // cache line with _owner.
185 DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
186 sizeof(volatile uint64_t));
187 ObjectMonitor* _next_om; // Next ObjectMonitor* linkage
188 volatile intx _recursions; // recursion count, 0 for first entry
189 ObjectWaiter* volatile _entry_list; // Threads blocked on entry or reentry.
190 // The list is actually composed of wait-nodes,
191 // acting as proxies for Threads.
192 ObjectWaiter* volatile _entry_list_tail; // _entry_list is the head, this is the tail.
193 int64_t volatile _succ; // Heir presumptive thread - used for futile wakeup throttling
194
195 volatile int _SpinDuration;
196
197 int _contentions; // Number of active contentions in enter(). It is used by is_busy()
198 // along with other fields to determine if an ObjectMonitor can be
199 // deflated. It is also used by the async deflation protocol. See
200 // ObjectMonitor::deflate_monitor().
201 int64_t _unmounted_vthreads; // Number of nodes in the _entry_list associated with unmounted vthreads.
202 // It might be temporarily more than the actual number but never less.
203
204 ObjectWaiter* volatile _wait_set; // LL of threads waiting on the monitor - wait()
205 volatile int _waiters; // number of waiting threads
206 volatile int _wait_set_lock; // protects wait set queue - simple spinlock
207
208 public:
209
210 static void Initialize();
211 static void Initialize2();
212
213 static OopHandle& vthread_list_head() { return _vthread_list_head; }
214 static ParkEvent* vthread_unparker_ParkEvent() { return _vthread_unparker_ParkEvent; }
215
216 static int Knob_SpinLimit;
217
218 static ByteSize metadata_offset() { return byte_offset_of(ObjectMonitor, _metadata); }
219 static ByteSize owner_offset() { return byte_offset_of(ObjectMonitor, _owner); }
220 static ByteSize recursions_offset() { return byte_offset_of(ObjectMonitor, _recursions); }
221 static ByteSize succ_offset() { return byte_offset_of(ObjectMonitor, _succ); }
222 static ByteSize entry_list_offset() { return byte_offset_of(ObjectMonitor, _entry_list); }
223
224 // ObjectMonitor references can be ORed with markWord::monitor_value
225 // as part of the ObjectMonitor tagging mechanism. When we combine an
226 // ObjectMonitor reference with an offset, we need to remove the tag
326 intx recursions() const { return _recursions; }
327 void set_recursions(size_t recursions);
328 void increment_recursions(JavaThread* current);
329 void inc_unmounted_vthreads();
330 void dec_unmounted_vthreads();
331 bool has_unmounted_vthreads() const;
332
333 // JVM/TI GetObjectMonitorUsage() needs this:
334 int waiters() const;
335 ObjectWaiter* first_waiter() { return _wait_set; }
336 ObjectWaiter* next_waiter(ObjectWaiter* o) { return o->_next; }
337 JavaThread* thread_of_waiter(ObjectWaiter* o) { return o->_thread; }
338
339 ObjectMonitor(oop object);
340 ~ObjectMonitor();
341
342 oop object() const;
343 oop object_peek() const;
344 bool object_is_dead() const;
345 bool object_refers_to(oop obj) const;
346
347 // Returns true if the specified thread owns the ObjectMonitor. Otherwise
348 // returns false and throws IllegalMonitorStateException (IMSE).
349 bool check_owner(TRAPS);
350
351 private:
352 class ExitOnSuspend {
353 protected:
354 ObjectMonitor* _om;
355 bool _om_exited;
356 public:
357 ExitOnSuspend(ObjectMonitor* om) : _om(om), _om_exited(false) {}
358 void operator()(JavaThread* current);
359 bool exited() { return _om_exited; }
360 };
361 class ClearSuccOnSuspend {
362 protected:
363 ObjectMonitor* _om;
364 public:
365 ClearSuccOnSuspend(ObjectMonitor* om) : _om(om) {}
388 void print_debug_style_on(outputStream* st) const;
389 #endif
390 void print_on(outputStream* st) const;
391
392 // Use the following at your own risk
393 intx complete_exit(JavaThread* current);
394
395 private:
396 void add_to_entry_list(JavaThread* current, ObjectWaiter* node);
397 void add_waiter(ObjectWaiter* waiter);
398 bool notify_internal(JavaThread* current);
399 ObjectWaiter* dequeue_waiter();
400 void dequeue_specific_waiter(ObjectWaiter* waiter);
401 void enter_internal(JavaThread* current);
402 void reenter_internal(JavaThread* current, ObjectWaiter* current_node);
403 void entry_list_build_dll(JavaThread* current);
404 void unlink_after_acquire(JavaThread* current, ObjectWaiter* current_node);
405 ObjectWaiter* entry_list_tail(JavaThread* current);
406
407 bool vthread_monitor_enter(JavaThread* current, ObjectWaiter* node = nullptr);
408 void vthread_wait(JavaThread* current, jlong millis);
409 bool vthread_wait_reenter(JavaThread* current, ObjectWaiter* node, ContinuationWrapper& cont);
410 void vthread_epilog(JavaThread* current, ObjectWaiter* node);
411
412 enum class TryLockResult { Interference = -1, HasOwner = 0, Success = 1 };
413
414 bool try_lock_with_contention_mark(JavaThread* locking_thread, ObjectMonitorContentionMark& contention_mark);
415 bool try_lock_or_add_to_entry_list(JavaThread* current, ObjectWaiter* node);
416 TryLockResult try_lock(JavaThread* current);
417
418 bool try_spin(JavaThread* current);
419 bool short_fixed_spin(JavaThread* current, int spin_count, bool adapt);
420 void exit_epilog(JavaThread* current, ObjectWaiter* Wakee);
421
422 public:
423 // Deflation support
424 bool deflate_monitor(Thread* current);
425 void install_displaced_markword_in_object(const oop obj);
426
427 // JFR support
428 static bool is_jfr_excluded(const Klass* monitor_klass);
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38 class ObjectMonitorContentionMark;
39 class ParkEvent;
40 class BasicLock;
41 class ContinuationWrapper;
42
43
44 class ObjectWaiter : public CHeapObj<mtThread> {
45 public:
46 enum TStates : uint8_t { TS_UNDEF, TS_READY, TS_RUN, TS_WAIT, TS_ENTER };
47 ObjectWaiter* volatile _next;
48 ObjectWaiter* volatile _prev;
49 JavaThread* _thread;
50 OopHandle _vthread;
51 ObjectMonitor* _monitor;
52 uint64_t _notifier_tid;
53 int _recursions;
54 volatile TStates TState;
55 bool _is_wait;
56 bool _at_reenter;
57 bool _interrupted;
58 bool _interruptible;
59 bool _do_timed_park;
60 bool _active; // Contention monitoring is enabled
61 public:
62 ObjectWaiter(JavaThread* current);
63 ObjectWaiter(oop vthread, ObjectMonitor* mon);
64 ~ObjectWaiter();
65 JavaThread* thread() const { return _thread; }
66 bool is_vthread() const { return _thread == nullptr; }
67 uint8_t state() const { return TState; }
68 ObjectMonitor* monitor() const { return _monitor; }
69 bool is_wait() const { return _is_wait; }
70 bool at_reenter() const { return _at_reenter; }
71 bool at_monitorenter() const { return !_is_wait || TState != TS_WAIT; }
72 oop vthread() const;
73 void wait_reenter_begin(ObjectMonitor *mon);
74 void wait_reenter_end(ObjectMonitor *mon);
75
76 void set_bad_pointers() {
77 #ifdef ASSERT
78 this->_prev = (ObjectWaiter*) badAddressVal;
184 // changed by ObjectMonitor::exit() so it is a good choice to share the
185 // cache line with _owner.
186 DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
187 sizeof(volatile uint64_t));
188 ObjectMonitor* _next_om; // Next ObjectMonitor* linkage
189 volatile intx _recursions; // recursion count, 0 for first entry
190 ObjectWaiter* volatile _entry_list; // Threads blocked on entry or reentry.
191 // The list is actually composed of wait-nodes,
192 // acting as proxies for Threads.
193 ObjectWaiter* volatile _entry_list_tail; // _entry_list is the head, this is the tail.
194 int64_t volatile _succ; // Heir presumptive thread - used for futile wakeup throttling
195
196 volatile int _SpinDuration;
197
198 int _contentions; // Number of active contentions in enter(). It is used by is_busy()
199 // along with other fields to determine if an ObjectMonitor can be
200 // deflated. It is also used by the async deflation protocol. See
201 // ObjectMonitor::deflate_monitor().
202 int64_t _unmounted_vthreads; // Number of nodes in the _entry_list associated with unmounted vthreads.
203 // It might be temporarily more than the actual number but never less.
204 OopHandle _object_strong; // Used to protect object during preemption on class initialization
205
206 ObjectWaiter* volatile _wait_set; // LL of threads waiting on the monitor - wait()
207 volatile int _waiters; // number of waiting threads
208 volatile int _wait_set_lock; // protects wait set queue - simple spinlock
209 volatile int _object_strong_lock; // protects setting of _object_strong
210
211 public:
212
213 static void Initialize();
214 static void Initialize2();
215
216 static OopHandle& vthread_list_head() { return _vthread_list_head; }
217 static ParkEvent* vthread_unparker_ParkEvent() { return _vthread_unparker_ParkEvent; }
218
219 static int Knob_SpinLimit;
220
221 static ByteSize metadata_offset() { return byte_offset_of(ObjectMonitor, _metadata); }
222 static ByteSize owner_offset() { return byte_offset_of(ObjectMonitor, _owner); }
223 static ByteSize recursions_offset() { return byte_offset_of(ObjectMonitor, _recursions); }
224 static ByteSize succ_offset() { return byte_offset_of(ObjectMonitor, _succ); }
225 static ByteSize entry_list_offset() { return byte_offset_of(ObjectMonitor, _entry_list); }
226
227 // ObjectMonitor references can be ORed with markWord::monitor_value
228 // as part of the ObjectMonitor tagging mechanism. When we combine an
229 // ObjectMonitor reference with an offset, we need to remove the tag
329 intx recursions() const { return _recursions; }
330 void set_recursions(size_t recursions);
331 void increment_recursions(JavaThread* current);
332 void inc_unmounted_vthreads();
333 void dec_unmounted_vthreads();
334 bool has_unmounted_vthreads() const;
335
336 // JVM/TI GetObjectMonitorUsage() needs this:
337 int waiters() const;
338 ObjectWaiter* first_waiter() { return _wait_set; }
339 ObjectWaiter* next_waiter(ObjectWaiter* o) { return o->_next; }
340 JavaThread* thread_of_waiter(ObjectWaiter* o) { return o->_thread; }
341
342 ObjectMonitor(oop object);
343 ~ObjectMonitor();
344
345 oop object() const;
346 oop object_peek() const;
347 bool object_is_dead() const;
348 bool object_refers_to(oop obj) const;
349 void set_object_strong();
350
351 // Returns true if the specified thread owns the ObjectMonitor. Otherwise
352 // returns false and throws IllegalMonitorStateException (IMSE).
353 bool check_owner(TRAPS);
354
355 private:
356 class ExitOnSuspend {
357 protected:
358 ObjectMonitor* _om;
359 bool _om_exited;
360 public:
361 ExitOnSuspend(ObjectMonitor* om) : _om(om), _om_exited(false) {}
362 void operator()(JavaThread* current);
363 bool exited() { return _om_exited; }
364 };
365 class ClearSuccOnSuspend {
366 protected:
367 ObjectMonitor* _om;
368 public:
369 ClearSuccOnSuspend(ObjectMonitor* om) : _om(om) {}
392 void print_debug_style_on(outputStream* st) const;
393 #endif
394 void print_on(outputStream* st) const;
395
396 // Use the following at your own risk
397 intx complete_exit(JavaThread* current);
398
399 private:
400 void add_to_entry_list(JavaThread* current, ObjectWaiter* node);
401 void add_waiter(ObjectWaiter* waiter);
402 bool notify_internal(JavaThread* current);
403 ObjectWaiter* dequeue_waiter();
404 void dequeue_specific_waiter(ObjectWaiter* waiter);
405 void enter_internal(JavaThread* current);
406 void reenter_internal(JavaThread* current, ObjectWaiter* current_node);
407 void entry_list_build_dll(JavaThread* current);
408 void unlink_after_acquire(JavaThread* current, ObjectWaiter* current_node);
409 ObjectWaiter* entry_list_tail(JavaThread* current);
410
411 bool vthread_monitor_enter(JavaThread* current, ObjectWaiter* node = nullptr);
412 void vthread_wait(JavaThread* current, jlong millis, bool interruptible);
413 bool vthread_wait_reenter(JavaThread* current, ObjectWaiter* node, ContinuationWrapper& cont);
414 void vthread_epilog(JavaThread* current, ObjectWaiter* node);
415
416 enum class TryLockResult { Interference = -1, HasOwner = 0, Success = 1 };
417
418 bool try_lock_with_contention_mark(JavaThread* locking_thread, ObjectMonitorContentionMark& contention_mark);
419 bool try_lock_or_add_to_entry_list(JavaThread* current, ObjectWaiter* node);
420 TryLockResult try_lock(JavaThread* current);
421
422 bool try_spin(JavaThread* current);
423 bool short_fixed_spin(JavaThread* current, int spin_count, bool adapt);
424 void exit_epilog(JavaThread* current, ObjectWaiter* Wakee);
425
426 public:
427 // Deflation support
428 bool deflate_monitor(Thread* current);
429 void install_displaced_markword_in_object(const oop obj);
430
431 // JFR support
432 static bool is_jfr_excluded(const Klass* monitor_klass);
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