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
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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
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