< prev index next >

src/hotspot/share/runtime/objectMonitor.hpp

Print this page

 42 
 43 class ObjectWaiter : public StackObj {
 44  public:
 45   enum TStates { TS_UNDEF, TS_READY, TS_RUN, TS_WAIT, TS_ENTER, TS_CXQ };
 46   ObjectWaiter* volatile _next;
 47   ObjectWaiter* volatile _prev;
 48   JavaThread*   _thread;
 49   uint64_t      _notifier_tid;
 50   ParkEvent *   _event;
 51   volatile int  _notified;
 52   volatile TStates TState;
 53   bool          _active;           // Contention monitoring is enabled
 54  public:
 55   ObjectWaiter(JavaThread* current);
 56 
 57   void wait_reenter_begin(ObjectMonitor *mon);
 58   void wait_reenter_end(ObjectMonitor *mon);
 59 };
 60 
 61 // The ObjectMonitor class implements the heavyweight version of a
 62 // JavaMonitor. The lightweight BasicLock/stack lock version has been
 63 // inflated into an ObjectMonitor. This inflation is typically due to
 64 // contention or use of Object.wait().
 65 //
 66 // WARNING: This is a very sensitive and fragile class. DO NOT make any
 67 // changes unless you are fully aware of the underlying semantics.
 68 //
 69 // ObjectMonitor Layout Overview/Highlights/Restrictions:
 70 //
 71 // - The _header field must be at offset 0 because the displaced header
 72 //   from markWord is stored there. We do not want markWord.hpp to include
 73 //   ObjectMonitor.hpp to avoid exposing ObjectMonitor everywhere. This
 74 //   means that ObjectMonitor cannot inherit from any other class nor can
 75 //   it use any virtual member functions. This restriction is critical to
 76 //   the proper functioning of the VM.
 77 // - The _header and _owner fields should be separated by enough space
 78 //   to avoid false sharing due to parallel access by different threads.
 79 //   This is an advisory recommendation.
 80 // - The general layout of the fields in ObjectMonitor is:
 81 //     _header
 82 //     <lightly_used_fields>

129 class ObjectMonitor : public CHeapObj<mtObjectMonitor> {
130   friend class ObjectSynchronizer;
131   friend class ObjectWaiter;
132   friend class VMStructs;
133   JVMCI_ONLY(friend class JVMCIVMStructs;)
134 
135   static OopStorage* _oop_storage;
136 
137   // The sync code expects the header field to be at offset zero (0).
138   // Enforced by the assert() in header_addr().
139   volatile markWord _header;        // displaced object header word - mark
140   WeakHandle _object;               // backward object pointer
141   // Separate _header and _owner on different cache lines since both can
142   // have busy multi-threaded access. _header and _object are set at initial
143   // inflation. The _object does not change, so it is a good choice to share
144   // its cache line with _header.
145   DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE, sizeof(volatile markWord) +
146                         sizeof(WeakHandle));
147   // Used by async deflation as a marker in the _owner field:
148   #define DEFLATER_MARKER reinterpret_cast<void*>(-1)
149   void* volatile _owner;            // pointer to owning thread OR BasicLock

150   volatile uint64_t _previous_owner_tid;  // thread id of the previous owner of the monitor
151   // Separate _owner and _next_om on different cache lines since
152   // both can have busy multi-threaded access. _previous_owner_tid is only
153   // changed by ObjectMonitor::exit() so it is a good choice to share the
154   // cache line with _owner.
155   DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
156                         sizeof(volatile uint64_t));
157   ObjectMonitor* _next_om;          // Next ObjectMonitor* linkage
158   volatile intx _recursions;        // recursion count, 0 for first entry
159   ObjectWaiter* volatile _EntryList;  // Threads blocked on entry or reentry.
160                                       // The list is actually composed of WaitNodes,
161                                       // acting as proxies for Threads.
162 
163   ObjectWaiter* volatile _cxq;      // LL of recently-arrived threads blocked on entry.
164   JavaThread* volatile _succ;       // Heir presumptive thread - used for futile wakeup throttling
165   JavaThread* volatile _Responsible;
166 
167   volatile int _Spinner;            // for exit->spinner handoff optimization
168   volatile int _SpinDuration;
169 

239     }
240     if (!owner_is_DEFLATER_MARKER()) {
241       ret_code |= intptr_t(owner_raw());
242     }
243     return ret_code != 0;
244   }
245   const char* is_busy_to_string(stringStream* ss);
246 
247   intptr_t  is_entered(JavaThread* current) const;
248 
249   void*     owner() const;  // Returns NULL if DEFLATER_MARKER is observed.
250   void*     owner_raw() const;
251   // Returns true if owner field == DEFLATER_MARKER and false otherwise.
252   bool      owner_is_DEFLATER_MARKER() const;
253   // Returns true if 'this' is being async deflated and false otherwise.
254   bool      is_being_async_deflated();
255   // Clear _owner field; current value must match old_value.
256   void      release_clear_owner(void* old_value);
257   // Simply set _owner field to new_value; current value must match old_value.
258   void      set_owner_from(void* old_value, void* new_value);
259   // Simply set _owner field to current; current value must match basic_lock_p.
260   void      set_owner_from_BasicLock(void* basic_lock_p, JavaThread* current);
261   // Try to set _owner field to new_value if the current value matches
262   // old_value, using Atomic::cmpxchg(). Otherwise, does not change the
263   // _owner field. Returns the prior value of the _owner field.
264   void*     try_set_owner_from(void* old_value, void* new_value);
265 
266   // Simply get _next_om field.
267   ObjectMonitor* next_om() const;
268   // Get _next_om field with acquire semantics.
269   ObjectMonitor* next_om_acquire() const;
270   // Simply set _next_om field to new_value.
271   void set_next_om(ObjectMonitor* new_value);
272   // Set _next_om field to new_value with release semantics.
273   void release_set_next_om(ObjectMonitor* new_value);
274   // Try to set _next_om field to new_value if the current value matches
275   // old_value, using Atomic::cmpxchg(). Otherwise, does not change the
276   // _next_om field. Returns the prior value of the _next_om field.
277   ObjectMonitor* try_set_next_om(ObjectMonitor* old_value, ObjectMonitor* new_value);
278 












279   int       waiters() const;
280 
281   int       contentions() const;
282   void      add_to_contentions(int value);
283   intx      recursions() const                                         { return _recursions; }
284 
285   // JVM/TI GetObjectMonitorUsage() needs this:
286   ObjectWaiter* first_waiter()                                         { return _WaitSet; }
287   ObjectWaiter* next_waiter(ObjectWaiter* o)                           { return o->_next; }
288   JavaThread* thread_of_waiter(ObjectWaiter* o)                        { return o->_thread; }
289 
290   ObjectMonitor(oop object);
291   ~ObjectMonitor();
292 
293   oop       object() const;
294   oop       object_peek() const;
295 
296   // Returns true if the specified thread owns the ObjectMonitor. Otherwise
297   // returns false and throws IllegalMonitorStateException (IMSE).
298   bool      check_owner(TRAPS);

314     ClearSuccOnSuspend(ObjectMonitor* om) : _om(om)  {}
315     void operator()(JavaThread* current);
316   };
317  public:
318   bool      enter(JavaThread* current);
319   void      exit(JavaThread* current, bool not_suspended = true);
320   void      wait(jlong millis, bool interruptible, TRAPS);
321   void      notify(TRAPS);
322   void      notifyAll(TRAPS);
323 
324   void      print() const;
325 #ifdef ASSERT
326   void      print_debug_style_on(outputStream* st) const;
327 #endif
328   void      print_on(outputStream* st) const;
329 
330   // Use the following at your own risk
331   intx      complete_exit(JavaThread* current);
332   bool      reenter(intx recursions, JavaThread* current);
333 


334  private:
335   void      AddWaiter(ObjectWaiter* waiter);
336   void      INotify(JavaThread* current);
337   ObjectWaiter* DequeueWaiter();
338   void      DequeueSpecificWaiter(ObjectWaiter* waiter);
339   void      EnterI(JavaThread* current);
340   void      ReenterI(JavaThread* current, ObjectWaiter* current_node);
341   void      UnlinkAfterAcquire(JavaThread* current, ObjectWaiter* current_node);
342   int       TryLock(JavaThread* current);
343   int       NotRunnable(JavaThread* current, JavaThread* Owner);
344   int       TrySpin(JavaThread* current);
345   void      ExitEpilog(JavaThread* current, ObjectWaiter* Wakee);
346 
347   // Deflation support
348   bool      deflate_monitor();
349   void      install_displaced_markword_in_object(const oop obj);
350 };
351 
352 #endif // SHARE_RUNTIME_OBJECTMONITOR_HPP

 42 
 43 class ObjectWaiter : public StackObj {
 44  public:
 45   enum TStates { TS_UNDEF, TS_READY, TS_RUN, TS_WAIT, TS_ENTER, TS_CXQ };
 46   ObjectWaiter* volatile _next;
 47   ObjectWaiter* volatile _prev;
 48   JavaThread*   _thread;
 49   uint64_t      _notifier_tid;
 50   ParkEvent *   _event;
 51   volatile int  _notified;
 52   volatile TStates TState;
 53   bool          _active;           // Contention monitoring is enabled
 54  public:
 55   ObjectWaiter(JavaThread* current);
 56 
 57   void wait_reenter_begin(ObjectMonitor *mon);
 58   void wait_reenter_end(ObjectMonitor *mon);
 59 };
 60 
 61 // The ObjectMonitor class implements the heavyweight version of a
 62 // JavaMonitor. The lightweight fast-lock version has been
 63 // inflated into an ObjectMonitor. This inflation is typically due to
 64 // contention or use of Object.wait().
 65 //
 66 // WARNING: This is a very sensitive and fragile class. DO NOT make any
 67 // changes unless you are fully aware of the underlying semantics.
 68 //
 69 // ObjectMonitor Layout Overview/Highlights/Restrictions:
 70 //
 71 // - The _header field must be at offset 0 because the displaced header
 72 //   from markWord is stored there. We do not want markWord.hpp to include
 73 //   ObjectMonitor.hpp to avoid exposing ObjectMonitor everywhere. This
 74 //   means that ObjectMonitor cannot inherit from any other class nor can
 75 //   it use any virtual member functions. This restriction is critical to
 76 //   the proper functioning of the VM.
 77 // - The _header and _owner fields should be separated by enough space
 78 //   to avoid false sharing due to parallel access by different threads.
 79 //   This is an advisory recommendation.
 80 // - The general layout of the fields in ObjectMonitor is:
 81 //     _header
 82 //     <lightly_used_fields>

129 class ObjectMonitor : public CHeapObj<mtObjectMonitor> {
130   friend class ObjectSynchronizer;
131   friend class ObjectWaiter;
132   friend class VMStructs;
133   JVMCI_ONLY(friend class JVMCIVMStructs;)
134 
135   static OopStorage* _oop_storage;
136 
137   // The sync code expects the header field to be at offset zero (0).
138   // Enforced by the assert() in header_addr().
139   volatile markWord _header;        // displaced object header word - mark
140   WeakHandle _object;               // backward object pointer
141   // Separate _header and _owner on different cache lines since both can
142   // have busy multi-threaded access. _header and _object are set at initial
143   // inflation. The _object does not change, so it is a good choice to share
144   // its cache line with _header.
145   DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE, sizeof(volatile markWord) +
146                         sizeof(WeakHandle));
147   // Used by async deflation as a marker in the _owner field:
148   #define DEFLATER_MARKER reinterpret_cast<void*>(-1)
149   #define ANONYMOUS_OWNER reinterpret_cast<void*>(1)
150   void* volatile _owner;            // pointer to owning thread
151   volatile uint64_t _previous_owner_tid;  // thread id of the previous owner of the monitor
152   // Separate _owner and _next_om on different cache lines since
153   // both can have busy multi-threaded access. _previous_owner_tid is only
154   // changed by ObjectMonitor::exit() so it is a good choice to share the
155   // cache line with _owner.
156   DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
157                         sizeof(volatile uint64_t));
158   ObjectMonitor* _next_om;          // Next ObjectMonitor* linkage
159   volatile intx _recursions;        // recursion count, 0 for first entry
160   ObjectWaiter* volatile _EntryList;  // Threads blocked on entry or reentry.
161                                       // The list is actually composed of WaitNodes,
162                                       // acting as proxies for Threads.
163 
164   ObjectWaiter* volatile _cxq;      // LL of recently-arrived threads blocked on entry.
165   JavaThread* volatile _succ;       // Heir presumptive thread - used for futile wakeup throttling
166   JavaThread* volatile _Responsible;
167 
168   volatile int _Spinner;            // for exit->spinner handoff optimization
169   volatile int _SpinDuration;
170 

240     }
241     if (!owner_is_DEFLATER_MARKER()) {
242       ret_code |= intptr_t(owner_raw());
243     }
244     return ret_code != 0;
245   }
246   const char* is_busy_to_string(stringStream* ss);
247 
248   intptr_t  is_entered(JavaThread* current) const;
249 
250   void*     owner() const;  // Returns NULL if DEFLATER_MARKER is observed.
251   void*     owner_raw() const;
252   // Returns true if owner field == DEFLATER_MARKER and false otherwise.
253   bool      owner_is_DEFLATER_MARKER() const;
254   // Returns true if 'this' is being async deflated and false otherwise.
255   bool      is_being_async_deflated();
256   // Clear _owner field; current value must match old_value.
257   void      release_clear_owner(void* old_value);
258   // Simply set _owner field to new_value; current value must match old_value.
259   void      set_owner_from(void* old_value, void* new_value);


260   // Try to set _owner field to new_value if the current value matches
261   // old_value, using Atomic::cmpxchg(). Otherwise, does not change the
262   // _owner field. Returns the prior value of the _owner field.
263   void*     try_set_owner_from(void* old_value, void* new_value);
264 
265   // Simply get _next_om field.
266   ObjectMonitor* next_om() const;
267   // Get _next_om field with acquire semantics.
268   ObjectMonitor* next_om_acquire() const;
269   // Simply set _next_om field to new_value.
270   void set_next_om(ObjectMonitor* new_value);
271   // Set _next_om field to new_value with release semantics.
272   void release_set_next_om(ObjectMonitor* new_value);
273   // Try to set _next_om field to new_value if the current value matches
274   // old_value, using Atomic::cmpxchg(). Otherwise, does not change the
275   // _next_om field. Returns the prior value of the _next_om field.
276   ObjectMonitor* try_set_next_om(ObjectMonitor* old_value, ObjectMonitor* new_value);
277 
278   void set_owner_anonymous() {
279     set_owner_from(NULL, ANONYMOUS_OWNER);
280   }
281 
282   bool is_owner_anonymous() const {
283     return _owner == ANONYMOUS_OWNER;
284   }
285 
286   void set_owner_from_anonymous(Thread* owner) {
287     set_owner_from(ANONYMOUS_OWNER, owner);
288   }
289 
290   int       waiters() const;
291 
292   int       contentions() const;
293   void      add_to_contentions(int value);
294   intx      recursions() const                                         { return _recursions; }
295 
296   // JVM/TI GetObjectMonitorUsage() needs this:
297   ObjectWaiter* first_waiter()                                         { return _WaitSet; }
298   ObjectWaiter* next_waiter(ObjectWaiter* o)                           { return o->_next; }
299   JavaThread* thread_of_waiter(ObjectWaiter* o)                        { return o->_thread; }
300 
301   ObjectMonitor(oop object);
302   ~ObjectMonitor();
303 
304   oop       object() const;
305   oop       object_peek() const;
306 
307   // Returns true if the specified thread owns the ObjectMonitor. Otherwise
308   // returns false and throws IllegalMonitorStateException (IMSE).
309   bool      check_owner(TRAPS);

325     ClearSuccOnSuspend(ObjectMonitor* om) : _om(om)  {}
326     void operator()(JavaThread* current);
327   };
328  public:
329   bool      enter(JavaThread* current);
330   void      exit(JavaThread* current, bool not_suspended = true);
331   void      wait(jlong millis, bool interruptible, TRAPS);
332   void      notify(TRAPS);
333   void      notifyAll(TRAPS);
334 
335   void      print() const;
336 #ifdef ASSERT
337   void      print_debug_style_on(outputStream* st) const;
338 #endif
339   void      print_on(outputStream* st) const;
340 
341   // Use the following at your own risk
342   intx      complete_exit(JavaThread* current);
343   bool      reenter(intx recursions, JavaThread* current);
344 
345   static void maybe_deflate_dead(oop* p);
346 
347  private:
348   void      AddWaiter(ObjectWaiter* waiter);
349   void      INotify(JavaThread* current);
350   ObjectWaiter* DequeueWaiter();
351   void      DequeueSpecificWaiter(ObjectWaiter* waiter);
352   void      EnterI(JavaThread* current);
353   void      ReenterI(JavaThread* current, ObjectWaiter* current_node);
354   void      UnlinkAfterAcquire(JavaThread* current, ObjectWaiter* current_node);
355   int       TryLock(JavaThread* current);
356   int       NotRunnable(JavaThread* current, JavaThread* Owner);
357   int       TrySpin(JavaThread* current);
358   void      ExitEpilog(JavaThread* current, ObjectWaiter* Wakee);
359 
360   // Deflation support
361   bool      deflate_monitor();
362   void      install_displaced_markword_in_object(const oop obj);
363 };
364 
365 #endif // SHARE_RUNTIME_OBJECTMONITOR_HPP
< prev index next >