1 /*
2 * Copyright (c) 1998, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #ifndef SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP
26 #define SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP
27
28 #include "runtime/objectMonitor.hpp"
29
30 #include "classfile/vmSymbols.hpp"
31 #include "logging/log.hpp"
32 #include "oops/access.inline.hpp"
33 #include "oops/markWord.hpp"
34 #include "runtime/atomic.hpp"
35 #include "runtime/globals.hpp"
36 #include "runtime/javaThread.inline.hpp"
37 #include "runtime/lockStack.inline.hpp"
38 #include "runtime/synchronizer.hpp"
39 #include "runtime/threadIdentifier.hpp"
40 #include "utilities/checkedCast.hpp"
41 #include "utilities/globalDefinitions.hpp"
42
43 inline int64_t ObjectMonitor::owner_id_from(JavaThread* thread) {
44 return thread->monitor_owner_id();
45 }
46
47 inline int64_t ObjectMonitor::owner_id_from(oop vthread) {
48 int64_t id = java_lang_Thread::thread_id(vthread);
49 ThreadIdentifier::verify_id(id);
50 return id;
51 }
52
53 inline bool ObjectMonitor::is_entered(JavaThread* current) const {
54 if (has_anonymous_owner()) {
55 if (LockingMode == LM_LIGHTWEIGHT) {
56 return current->lock_stack().contains(object());
57 } else {
58 return current->is_lock_owned((address)stack_locker());
59 }
60 } else {
61 return has_owner(current);
62 }
63 return false;
64 }
65
66 inline uintptr_t ObjectMonitor::metadata() const {
67 return Atomic::load(&_metadata);
68 }
69
70 inline void ObjectMonitor::set_metadata(uintptr_t value) {
71 Atomic::store(&_metadata, value);
72 }
73
74 inline volatile uintptr_t* ObjectMonitor::metadata_addr() {
75 STATIC_ASSERT(std::is_standard_layout<ObjectMonitor>::value);
76 STATIC_ASSERT(offsetof(ObjectMonitor, _metadata) == 0);
77 return &_metadata;
78 }
79
80 inline markWord ObjectMonitor::header() const {
81 assert(!UseObjectMonitorTable, "Lightweight locking with OM table does not use header");
82 return markWord(metadata());
83 }
84
85 inline void ObjectMonitor::set_header(markWord hdr) {
86 assert(!UseObjectMonitorTable, "Lightweight locking with OM table does not use header");
87 set_metadata(hdr.value());
88 }
89
90 inline intptr_t ObjectMonitor::hash() const {
91 assert(UseObjectMonitorTable, "Only used by lightweight locking with OM table");
92 return metadata();
93 }
94
95 inline void ObjectMonitor::set_hash(intptr_t hash) {
96 assert(UseObjectMonitorTable, "Only used by lightweight locking with OM table");
97 set_metadata(hash);
98 }
99
100 inline int ObjectMonitor::waiters() const {
101 return _waiters;
102 }
103
104 inline bool ObjectMonitor::has_owner() const {
105 int64_t owner = owner_raw();
106 return owner != NO_OWNER && owner != DEFLATER_MARKER;
107 }
108
109 // Returns NO_OWNER if DEFLATER_MARKER is observed.
110 inline int64_t ObjectMonitor::owner() const {
111 int64_t owner = owner_raw();
112 return owner != DEFLATER_MARKER ? owner : NO_OWNER;
113 }
114
115 inline int64_t ObjectMonitor::owner_raw() const {
116 return Atomic::load(&_owner);
117 }
118
119 inline BasicLock* ObjectMonitor::stack_locker() const {
120 return Atomic::load(&_stack_locker);
121 }
122
123 inline void ObjectMonitor::set_stack_locker(BasicLock* locker) {
124 Atomic::store(&_stack_locker, locker);
125 }
126
127 // Returns true if owner field == DEFLATER_MARKER and false otherwise.
128 inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() const {
129 return owner_raw() == DEFLATER_MARKER;
130 }
131
132 // Returns true if 'this' is being async deflated and false otherwise.
133 inline bool ObjectMonitor::is_being_async_deflated() {
134 return contentions() < 0;
135 }
136
137 // Return number of threads contending for this monitor.
138 inline int ObjectMonitor::contentions() const {
139 return Atomic::load(&_contentions);
140 }
141
142 // Add value to the contentions field.
143 inline void ObjectMonitor::add_to_contentions(int value) {
144 Atomic::add(&_contentions, value);
145 }
146
147 inline void ObjectMonitor::set_recursions(size_t recursions) {
148 assert(_recursions == 0, "must be");
149 assert(has_owner(), "must be owned");
150 _recursions = checked_cast<intx>(recursions);
151 }
152
153 inline void ObjectMonitor::increment_recursions(JavaThread* current) {
154 assert(has_owner(current), "must be the owner");
155 _recursions++;
156 }
157
158 // Clear _owner field; current value must match old_value.
159 inline void ObjectMonitor::release_clear_owner(JavaThread* old_owner) {
160 int64_t old_value = owner_id_from(old_owner);
161 #ifdef ASSERT
162 int64_t prev = Atomic::load(&_owner);
163 assert(prev == old_value, "unexpected prev owner=" INT64_FORMAT
164 ", expected=" INT64_FORMAT, prev, old_value);
165 #endif
166 Atomic::release_store(&_owner, NO_OWNER);
167 log_trace(monitorinflation, owner)("release_clear_owner(): mid="
168 INTPTR_FORMAT ", old_value=" INT64_FORMAT,
169 p2i(this), old_value);
170 }
171
172 // Simply set _owner field to new_value; current value must match old_value.
173 // (Simple means no memory sync needed.)
174 inline void ObjectMonitor::set_owner_from_raw(int64_t old_value, int64_t new_value) {
175 #ifdef ASSERT
176 int64_t prev = Atomic::load(&_owner);
177 assert((int64_t)prev < ThreadIdentifier::current(), "must be reasonable");
178 assert(prev == old_value, "unexpected prev owner=" INT64_FORMAT
179 ", expected=" INT64_FORMAT, prev, old_value);
180 #endif
181 Atomic::store(&_owner, new_value);
182 log_trace(monitorinflation, owner)("set_owner_from(): mid="
183 INTPTR_FORMAT ", old_value=" INT64_FORMAT
184 ", new_value=" INT64_FORMAT, p2i(this),
185 old_value, new_value);
186 }
187
188 inline void ObjectMonitor::set_owner_from(int64_t old_value, JavaThread* current) {
189 set_owner_from_raw(old_value, owner_id_from(current));
190 }
191
192 // Try to set _owner field to new_value if the current value matches
193 // old_value. Otherwise, does not change the _owner field. Returns
194 // the prior value of the _owner field.
195 inline int64_t ObjectMonitor::try_set_owner_from_raw(int64_t old_value, int64_t new_value) {
196 assert((int64_t)new_value < ThreadIdentifier::current(), "must be reasonable");
197 int64_t prev = Atomic::cmpxchg(&_owner, old_value, new_value);
198 if (prev == old_value) {
199 log_trace(monitorinflation, owner)("try_set_owner_from(): mid="
200 INTPTR_FORMAT ", prev=" INT64_FORMAT
201 ", new=" INT64_FORMAT, p2i(this),
202 prev, new_value);
203 }
204 return prev;
205 }
206
207 inline int64_t ObjectMonitor::try_set_owner_from(int64_t old_value, JavaThread* current) {
208 return try_set_owner_from_raw(old_value, owner_id_from(current));
209 }
210
211 inline bool ObjectMonitor::has_successor() const {
212 return Atomic::load(&_succ) != NO_OWNER;
213 }
214
215 inline bool ObjectMonitor::has_successor(JavaThread* thread) const {
216 return owner_id_from(thread) == Atomic::load(&_succ);
217 }
218
219 inline void ObjectMonitor::set_successor(JavaThread* thread) {
220 Atomic::store(&_succ, owner_id_from(thread));
221 }
222
223 inline void ObjectMonitor::set_successor(oop vthread) {
224 Atomic::store(&_succ, java_lang_Thread::thread_id(vthread));
225 }
226
227 inline void ObjectMonitor::clear_successor() {
228 Atomic::store(&_succ, NO_OWNER);
229 }
230
231 inline int64_t ObjectMonitor::successor() const {
232 return Atomic::load(&_succ);
233 }
234
235 // The _next_om field can be concurrently read and modified so we
236 // use Atomic operations to disable compiler optimizations that
237 // might try to elide loading and/or storing this field.
238
239 // Simply get _next_om field.
240 inline ObjectMonitor* ObjectMonitor::next_om() const {
241 return Atomic::load(&_next_om);
242 }
243
244 // Simply set _next_om field to new_value.
245 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
246 Atomic::store(&_next_om, new_value);
247 }
248
249 // Block out deflation.
250 inline ObjectMonitorContentionMark::ObjectMonitorContentionMark(ObjectMonitor* monitor)
251 : _monitor(monitor), _extended(false) {
252 // Contentions is incremented to a positive value as part of the
253 // contended enter protocol, which prevents the deflater thread from
254 // winning the last part of the 2-part async deflation
255 // protocol. See: ObjectMonitor::deflate_monitor() and
256 // ObjectMonitor::try_lock_with_contention_mark().
257 _monitor->add_to_contentions(1);
258 }
259
260 inline ObjectMonitorContentionMark::~ObjectMonitorContentionMark() {
261 // Decrement contentions when the contention mark goes out of
262 // scope. This opens up for deflation, if the contention mark
263 // hasn't been extended.
264 _monitor->add_to_contentions(-1);
265 }
266
267 inline void ObjectMonitorContentionMark::extend() {
268 // Used by ObjectMonitor::try_lock_with_contention_mark() to "extend the
269 // lifetime" of the contention mark.
270 assert(!_extended, "extending twice is probably a bad design");
271 _monitor->add_to_contentions(1);
272 _extended = true;
273 }
274
275 inline oop ObjectMonitor::object_peek() const {
276 if (_object.is_null()) {
277 return nullptr;
278 }
279 return _object.peek();
280 }
281
282 inline bool ObjectMonitor::object_is_dead() const {
283 return object_peek() == nullptr;
284 }
285
286 inline bool ObjectMonitor::object_refers_to(oop obj) const {
287 if (_object.is_null()) {
288 return false;
289 }
290 return _object.peek() == obj;
291 }
292
293 inline bool ObjectMonitor::is_jfr_excluded(const Klass* monitor_klass) {
294 assert(monitor_klass != nullptr, "invariant");
295 NOT_JFR_RETURN_(false);
296 JFR_ONLY(return vmSymbols::jdk_jfr_internal_management_HiddenWait() == monitor_klass->name();)
297 }
298
299 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP