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src/hotspot/share/runtime/objectMonitor.hpp

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 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   volatile bool _notified;
 56   bool           _is_wait;
 57   bool        _at_reenter;
 58   bool       _interrupted;


 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 notified()           const { return _notified; }
 70   bool at_reenter()         const { return _at_reenter; }
 71   bool at_monitorenter()    const { return !_is_wait || _at_reenter || _notified; }
 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;

182   // Separate _owner and _next_om on different cache lines since
183   // both can have busy multi-threaded access. _previous_owner_tid is only
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 
203   ObjectWaiter* volatile _wait_set; // LL of threads waiting on the monitor - wait()
204   volatile int  _waiters;           // number of waiting threads
205   volatile int _wait_set_lock;      // protects wait set queue - simple spinlock

206 
207  public:
208 
209   static void Initialize();
210   static void Initialize2();
211 
212   static OopHandle& vthread_list_head() { return _vthread_list_head; }
213   static ParkEvent* vthread_unparker_ParkEvent() { return _vthread_unparker_ParkEvent; }
214 
215   static int Knob_SpinLimit;
216 
217   static ByteSize metadata_offset()    { return byte_offset_of(ObjectMonitor, _metadata); }
218   static ByteSize owner_offset()       { return byte_offset_of(ObjectMonitor, _owner); }
219   static ByteSize recursions_offset()  { return byte_offset_of(ObjectMonitor, _recursions); }
220   static ByteSize succ_offset()        { return byte_offset_of(ObjectMonitor, _succ); }
221   static ByteSize entry_list_offset()  { return byte_offset_of(ObjectMonitor, _entry_list); }
222 
223   // ObjectMonitor references can be ORed with markWord::monitor_value
224   // as part of the ObjectMonitor tagging mechanism. When we combine an
225   // ObjectMonitor reference with an offset, we need to remove the tag

308   }
309 
310   bool has_anonymous_owner() const { return owner_raw() == ANONYMOUS_OWNER; }
311   void set_anonymous_owner() {
312     set_owner_from_raw(NO_OWNER, ANONYMOUS_OWNER);
313   }
314   void set_owner_from_anonymous(JavaThread* owner) {
315     set_owner_from(ANONYMOUS_OWNER, owner);
316   }
317 
318   // Simply get _next_om field.
319   ObjectMonitor* next_om() const;
320   // Simply set _next_om field to new_value.
321   void set_next_om(ObjectMonitor* new_value);
322 
323   int       contentions() const;
324   void      add_to_contentions(int value);
325   intx      recursions() const                                         { return _recursions; }
326   void      set_recursions(size_t recursions);
327   void      increment_recursions(JavaThread* current);



328 
329   // JVM/TI GetObjectMonitorUsage() needs this:
330   int waiters() const;
331   ObjectWaiter* first_waiter()                                         { return _wait_set; }
332   ObjectWaiter* next_waiter(ObjectWaiter* o)                           { return o->_next; }
333   JavaThread* thread_of_waiter(ObjectWaiter* o)                        { return o->_thread; }
334 
335   ObjectMonitor(oop object);
336   ~ObjectMonitor();
337 
338   oop       object() const;
339   oop       object_peek() const;
340   bool      object_is_dead() const;
341   bool      object_refers_to(oop obj) const;

342 
343   // Returns true if the specified thread owns the ObjectMonitor. Otherwise
344   // returns false and throws IllegalMonitorStateException (IMSE).
345   bool      check_owner(TRAPS);
346 
347  private:
348   class ExitOnSuspend {
349    protected:
350     ObjectMonitor* _om;
351     bool _om_exited;
352    public:
353     ExitOnSuspend(ObjectMonitor* om) : _om(om), _om_exited(false) {}
354     void operator()(JavaThread* current);
355     bool exited() { return _om_exited; }
356   };
357   class ClearSuccOnSuspend {
358    protected:
359     ObjectMonitor* _om;
360    public:
361     ClearSuccOnSuspend(ObjectMonitor* om) : _om(om)  {}

384   void      print_debug_style_on(outputStream* st) const;
385 #endif
386   void      print_on(outputStream* st) const;
387 
388   // Use the following at your own risk
389   intx      complete_exit(JavaThread* current);
390 
391  private:
392   void      add_to_entry_list(JavaThread* current, ObjectWaiter* node);
393   void      add_waiter(ObjectWaiter* waiter);
394   bool      notify_internal(JavaThread* current);
395   ObjectWaiter* dequeue_waiter();
396   void      dequeue_specific_waiter(ObjectWaiter* waiter);
397   void      enter_internal(JavaThread* current);
398   void      reenter_internal(JavaThread* current, ObjectWaiter* current_node);
399   void      entry_list_build_dll(JavaThread* current);
400   void      unlink_after_acquire(JavaThread* current, ObjectWaiter* current_node);
401   ObjectWaiter* entry_list_tail(JavaThread* current);
402 
403   bool      vthread_monitor_enter(JavaThread* current, ObjectWaiter* node = nullptr);
404   void      vthread_wait(JavaThread* current, jlong millis);
405   bool      vthread_wait_reenter(JavaThread* current, ObjectWaiter* node, ContinuationWrapper& cont);
406   void      vthread_epilog(JavaThread* current, ObjectWaiter* node);
407 
408   enum class TryLockResult { Interference = -1, HasOwner = 0, Success = 1 };
409 
410   bool           try_lock_with_contention_mark(JavaThread* locking_thread, ObjectMonitorContentionMark& contention_mark);
411   bool           try_lock_or_add_to_entry_list(JavaThread* current, ObjectWaiter* node);
412   TryLockResult  try_lock(JavaThread* current);
413 
414   bool      try_spin(JavaThread* current);
415   bool      short_fixed_spin(JavaThread* current, int spin_count, bool adapt);
416   void      exit_epilog(JavaThread* current, ObjectWaiter* Wakee);
417 
418  public:
419   // Deflation support
420   bool      deflate_monitor(Thread* current);
421   void      install_displaced_markword_in_object(const oop obj);
422 
423   // JFR support
424   static bool is_jfr_excluded(const Klass* monitor_klass);

 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   volatile bool _notified;
 56   bool           _is_wait;
 57   bool        _at_reenter;
 58   bool       _interrupted;
 59   bool     _interruptible;
 60   bool     _do_timed_park;
 61   bool            _active;    // Contention monitoring is enabled
 62  public:
 63   ObjectWaiter(JavaThread* current);
 64   ObjectWaiter(oop vthread, ObjectMonitor* mon);
 65   ~ObjectWaiter();
 66   JavaThread* thread()      const { return _thread; }
 67   bool is_vthread()         const { return _thread == nullptr; }
 68   uint8_t state()           const { return TState; }
 69   ObjectMonitor* monitor()  const { return _monitor; }
 70   bool is_wait()            const { return _is_wait; }
 71   bool notified()           const { return _notified; }
 72   bool at_reenter()         const { return _at_reenter; }
 73   bool at_monitorenter()    const { return !_is_wait || _at_reenter || _notified; }
 74   oop vthread() const;
 75   void wait_reenter_begin(ObjectMonitor *mon);
 76   void wait_reenter_end(ObjectMonitor *mon);
 77 
 78   void set_bad_pointers() {
 79 #ifdef ASSERT
 80     this->_prev  = (ObjectWaiter*) badAddressVal;

184   // Separate _owner and _next_om on different cache lines since
185   // both can have busy multi-threaded access. _previous_owner_tid is only
186   // changed by ObjectMonitor::exit() so it is a good choice to share the
187   // cache line with _owner.
188   DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
189                         sizeof(volatile uint64_t));
190   ObjectMonitor* _next_om;          // Next ObjectMonitor* linkage
191   volatile intx _recursions;        // recursion count, 0 for first entry
192   ObjectWaiter* volatile _entry_list;  // Threads blocked on entry or reentry.
193                                        // The list is actually composed of wait-nodes,
194                                        // acting as proxies for Threads.
195   ObjectWaiter* volatile _entry_list_tail; // _entry_list is the head, this is the tail.
196   int64_t volatile _succ;           // Heir presumptive thread - used for futile wakeup throttling
197 
198   volatile int _SpinDuration;
199 
200   int _contentions;                 // Number of active contentions in enter(). It is used by is_busy()
201                                     // along with other fields to determine if an ObjectMonitor can be
202                                     // deflated. It is also used by the async deflation protocol. See
203                                     // ObjectMonitor::deflate_monitor().
204   int64_t _unmounted_vthreads;      // Number of nodes in the _entry_list associated with unmounted vthreads.
205                                     // It might be temporarily more than the actual number but never less.
206   OopHandle _object_strong;         // Used to protect object during preemption on class initialization
207 
208   ObjectWaiter* volatile _wait_set; // LL of threads waiting on the monitor - wait()
209   volatile int  _waiters;           // number of waiting threads
210   volatile int _wait_set_lock;      // protects wait set queue - simple spinlock
211   volatile int _object_strong_lock; // protects setting of _object_strong
212 
213  public:
214 
215   static void Initialize();
216   static void Initialize2();
217 
218   static OopHandle& vthread_list_head() { return _vthread_list_head; }
219   static ParkEvent* vthread_unparker_ParkEvent() { return _vthread_unparker_ParkEvent; }
220 
221   static int Knob_SpinLimit;
222 
223   static ByteSize metadata_offset()    { return byte_offset_of(ObjectMonitor, _metadata); }
224   static ByteSize owner_offset()       { return byte_offset_of(ObjectMonitor, _owner); }
225   static ByteSize recursions_offset()  { return byte_offset_of(ObjectMonitor, _recursions); }
226   static ByteSize succ_offset()        { return byte_offset_of(ObjectMonitor, _succ); }
227   static ByteSize entry_list_offset()  { return byte_offset_of(ObjectMonitor, _entry_list); }
228 
229   // ObjectMonitor references can be ORed with markWord::monitor_value
230   // as part of the ObjectMonitor tagging mechanism. When we combine an
231   // ObjectMonitor reference with an offset, we need to remove the tag

314   }
315 
316   bool has_anonymous_owner() const { return owner_raw() == ANONYMOUS_OWNER; }
317   void set_anonymous_owner() {
318     set_owner_from_raw(NO_OWNER, ANONYMOUS_OWNER);
319   }
320   void set_owner_from_anonymous(JavaThread* owner) {
321     set_owner_from(ANONYMOUS_OWNER, owner);
322   }
323 
324   // Simply get _next_om field.
325   ObjectMonitor* next_om() const;
326   // Simply set _next_om field to new_value.
327   void set_next_om(ObjectMonitor* new_value);
328 
329   int       contentions() const;
330   void      add_to_contentions(int value);
331   intx      recursions() const                                         { return _recursions; }
332   void      set_recursions(size_t recursions);
333   void      increment_recursions(JavaThread* current);
334   void      inc_unmounted_vthreads();
335   void      dec_unmounted_vthreads();
336   bool      has_unmounted_vthreads() const;
337 
338   // JVM/TI GetObjectMonitorUsage() needs this:
339   int waiters() const;
340   ObjectWaiter* first_waiter()                                         { return _wait_set; }
341   ObjectWaiter* next_waiter(ObjectWaiter* o)                           { return o->_next; }
342   JavaThread* thread_of_waiter(ObjectWaiter* o)                        { return o->_thread; }
343 
344   ObjectMonitor(oop object);
345   ~ObjectMonitor();
346 
347   oop       object() const;
348   oop       object_peek() const;
349   bool      object_is_dead() const;
350   bool      object_refers_to(oop obj) const;
351   void      set_object_strong();
352 
353   // Returns true if the specified thread owns the ObjectMonitor. Otherwise
354   // returns false and throws IllegalMonitorStateException (IMSE).
355   bool      check_owner(TRAPS);
356 
357  private:
358   class ExitOnSuspend {
359    protected:
360     ObjectMonitor* _om;
361     bool _om_exited;
362    public:
363     ExitOnSuspend(ObjectMonitor* om) : _om(om), _om_exited(false) {}
364     void operator()(JavaThread* current);
365     bool exited() { return _om_exited; }
366   };
367   class ClearSuccOnSuspend {
368    protected:
369     ObjectMonitor* _om;
370    public:
371     ClearSuccOnSuspend(ObjectMonitor* om) : _om(om)  {}

394   void      print_debug_style_on(outputStream* st) const;
395 #endif
396   void      print_on(outputStream* st) const;
397 
398   // Use the following at your own risk
399   intx      complete_exit(JavaThread* current);
400 
401  private:
402   void      add_to_entry_list(JavaThread* current, ObjectWaiter* node);
403   void      add_waiter(ObjectWaiter* waiter);
404   bool      notify_internal(JavaThread* current);
405   ObjectWaiter* dequeue_waiter();
406   void      dequeue_specific_waiter(ObjectWaiter* waiter);
407   void      enter_internal(JavaThread* current);
408   void      reenter_internal(JavaThread* current, ObjectWaiter* current_node);
409   void      entry_list_build_dll(JavaThread* current);
410   void      unlink_after_acquire(JavaThread* current, ObjectWaiter* current_node);
411   ObjectWaiter* entry_list_tail(JavaThread* current);
412 
413   bool      vthread_monitor_enter(JavaThread* current, ObjectWaiter* node = nullptr);
414   void      vthread_wait(JavaThread* current, jlong millis, bool interruptible);
415   bool      vthread_wait_reenter(JavaThread* current, ObjectWaiter* node, ContinuationWrapper& cont);
416   void      vthread_epilog(JavaThread* current, ObjectWaiter* node);
417 
418   enum class TryLockResult { Interference = -1, HasOwner = 0, Success = 1 };
419 
420   bool           try_lock_with_contention_mark(JavaThread* locking_thread, ObjectMonitorContentionMark& contention_mark);
421   bool           try_lock_or_add_to_entry_list(JavaThread* current, ObjectWaiter* node);
422   TryLockResult  try_lock(JavaThread* current);
423 
424   bool      try_spin(JavaThread* current);
425   bool      short_fixed_spin(JavaThread* current, int spin_count, bool adapt);
426   void      exit_epilog(JavaThread* current, ObjectWaiter* Wakee);
427 
428  public:
429   // Deflation support
430   bool      deflate_monitor(Thread* current);
431   void      install_displaced_markword_in_object(const oop obj);
432 
433   // JFR support
434   static bool is_jfr_excluded(const Klass* monitor_klass);
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