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src/hotspot/share/runtime/objectMonitor.hpp

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








150   void* volatile _owner;            // pointer to owning thread OR BasicLock
151   volatile jlong _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 jlong));
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;

229 
230   markWord           header() const;
231   volatile markWord* header_addr();
232   void               set_header(markWord hdr);
233 
234   bool is_busy() const {
235     // TODO-FIXME: assert _owner == null implies _recursions = 0
236     intptr_t ret_code = _waiters | intptr_t(_cxq) | intptr_t(_EntryList);
237     if (contentions() > 0) {
238       ret_code |= contentions();
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   jint      waiters() const;
280 
281   jint      contentions() const;
282   void      add_to_contentions(jint value);
283   intx      recursions() const                                         { return _recursions; }
284 
285   // JVM/TI GetObjectMonitorUsage() needs this:

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

128 #endif
129 
130 class ObjectMonitor : public CHeapObj<mtObjectMonitor> {
131   friend class ObjectSynchronizer;
132   friend class ObjectWaiter;
133   friend class VMStructs;
134   JVMCI_ONLY(friend class JVMCIVMStructs;)
135 
136   static OopStorage* _oop_storage;
137 
138   // The sync code expects the header field to be at offset zero (0).
139   // Enforced by the assert() in header_addr().
140   volatile markWord _header;        // displaced object header word - mark
141   WeakHandle _object;               // backward object pointer
142   // Separate _header and _owner on different cache lines since both can
143   // have busy multi-threaded access. _header and _object are set at initial
144   // inflation. The _object does not change, so it is a good choice to share
145   // its cache line with _header.
146   DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE, sizeof(volatile markWord) +
147                         sizeof(WeakHandle));
148   // Used by async deflation as a marker in the _owner field.
149   // Note that the choice of the two markers is peculiar:
150   // - They need to represent values that cannot be pointers. In particular,
151   //   we achieve this by using the lowest two bits
152   // - ANONYMOUS_OWNER should be a small value, it is used in generated code
153   //   and small values encode much better
154   // - We test for anonymous owner by testing for the lowest bit, therefore
155   //   DEFLATER_MARKER must *not* have that bit set.
156   #define DEFLATER_MARKER reinterpret_cast<void*>(2)
157   #define ANONYMOUS_OWNER reinterpret_cast<void*>(1)
158   void* volatile _owner;            // pointer to owning thread OR BasicLock
159   volatile jlong _previous_owner_tid;  // thread id of the previous owner of the monitor
160   // Separate _owner and _next_om on different cache lines since
161   // both can have busy multi-threaded access. _previous_owner_tid is only
162   // changed by ObjectMonitor::exit() so it is a good choice to share the
163   // cache line with _owner.
164   DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
165                         sizeof(volatile jlong));
166   ObjectMonitor* _next_om;          // Next ObjectMonitor* linkage
167   volatile intx _recursions;        // recursion count, 0 for first entry
168   ObjectWaiter* volatile _EntryList;  // Threads blocked on entry or reentry.
169                                       // The list is actually composed of WaitNodes,
170                                       // acting as proxies for Threads.
171 
172   ObjectWaiter* volatile _cxq;      // LL of recently-arrived threads blocked on entry.
173   JavaThread* volatile _succ;       // Heir presumptive thread - used for futile wakeup throttling
174   JavaThread* volatile _Responsible;
175 
176   volatile int _Spinner;            // for exit->spinner handoff optimization
177   volatile int _SpinDuration;

237 
238   markWord           header() const;
239   volatile markWord* header_addr();
240   void               set_header(markWord hdr);
241 
242   bool is_busy() const {
243     // TODO-FIXME: assert _owner == null implies _recursions = 0
244     intptr_t ret_code = _waiters | intptr_t(_cxq) | intptr_t(_EntryList);
245     if (contentions() > 0) {
246       ret_code |= contentions();
247     }
248     if (!owner_is_DEFLATER_MARKER()) {
249       ret_code |= intptr_t(owner_raw());
250     }
251     return ret_code != 0;
252   }
253   const char* is_busy_to_string(stringStream* ss);
254 
255   intptr_t  is_entered(JavaThread* current) const;
256 
257   bool      has_owner() const;
258   void*     owner() const;  // Returns NULL if DEFLATER_MARKER is observed.
259   void*     owner_raw() const;
260   // Returns true if owner field == DEFLATER_MARKER and false otherwise.
261   bool      owner_is_DEFLATER_MARKER() const;
262   // Returns true if 'this' is being async deflated and false otherwise.
263   bool      is_being_async_deflated();
264   // Clear _owner field; current value must match old_value.
265   void      release_clear_owner(void* old_value);
266   // Simply set _owner field to new_value; current value must match old_value.
267   void      set_owner_from(void* old_value, void* new_value);
268   // Simply set _owner field to current; current value must match basic_lock_p.
269   void      set_owner_from_BasicLock(void* basic_lock_p, JavaThread* current);
270   // Try to set _owner field to new_value if the current value matches
271   // old_value, using Atomic::cmpxchg(). Otherwise, does not change the
272   // _owner field. Returns the prior value of the _owner field.
273   void*     try_set_owner_from(void* old_value, void* new_value);
274 
275   void set_owner_anonymous() {
276     set_owner_from(NULL, ANONYMOUS_OWNER);
277   }
278 
279   bool is_owner_anonymous() const {
280     return owner_raw() == ANONYMOUS_OWNER;
281   }
282 
283   void set_owner_from_anonymous(Thread* owner) {
284     set_owner_from(ANONYMOUS_OWNER, owner);
285   }
286 
287   // Simply get _next_om field.
288   ObjectMonitor* next_om() const;
289   // Get _next_om field with acquire semantics.
290   ObjectMonitor* next_om_acquire() const;
291   // Simply set _next_om field to new_value.
292   void set_next_om(ObjectMonitor* new_value);
293   // Set _next_om field to new_value with release semantics.
294   void release_set_next_om(ObjectMonitor* new_value);
295   // Try to set _next_om field to new_value if the current value matches
296   // old_value, using Atomic::cmpxchg(). Otherwise, does not change the
297   // _next_om field. Returns the prior value of the _next_om field.
298   ObjectMonitor* try_set_next_om(ObjectMonitor* old_value, ObjectMonitor* new_value);
299 
300   jint      waiters() const;
301 
302   jint      contentions() const;
303   void      add_to_contentions(jint value);
304   intx      recursions() const                                         { return _recursions; }
305 
306   // JVM/TI GetObjectMonitorUsage() needs this:

335     ClearSuccOnSuspend(ObjectMonitor* om) : _om(om)  {}
336     void operator()(JavaThread* current);
337   };
338  public:
339   bool      enter(JavaThread* current);
340   void      exit(JavaThread* current, bool not_suspended = true);
341   void      wait(jlong millis, bool interruptible, TRAPS);
342   void      notify(TRAPS);
343   void      notifyAll(TRAPS);
344 
345   void      print() const;
346 #ifdef ASSERT
347   void      print_debug_style_on(outputStream* st) const;
348 #endif
349   void      print_on(outputStream* st) const;
350 
351   // Use the following at your own risk
352   intx      complete_exit(JavaThread* current);
353   bool      reenter(intx recursions, JavaThread* current);
354 
355   static void maybe_deflate_dead(oop* p);
356 
357  private:
358   void      AddWaiter(ObjectWaiter* waiter);
359   void      INotify(JavaThread* current);
360   ObjectWaiter* DequeueWaiter();
361   void      DequeueSpecificWaiter(ObjectWaiter* waiter);
362   void      EnterI(JavaThread* current);
363   void      ReenterI(JavaThread* current, ObjectWaiter* current_node);
364   void      UnlinkAfterAcquire(JavaThread* current, ObjectWaiter* current_node);
365   int       TryLock(JavaThread* current);
366   int       NotRunnable(JavaThread* current, JavaThread* Owner);
367   int       TrySpin(JavaThread* current);
368   void      ExitEpilog(JavaThread* current, ObjectWaiter* Wakee);
369 
370   // Deflation support
371   bool      deflate_monitor();
372   void      install_displaced_markword_in_object(const oop obj);
373 };
374 
375 #endif // SHARE_RUNTIME_OBJECTMONITOR_HPP
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