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.
22 *
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/atomicAccess.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 return current->lock_stack().contains(object());
56 } else {
57 return has_owner(current);
58 }
59 return false;
60 }
61
62 inline uintptr_t ObjectMonitor::metadata() const {
63 return AtomicAccess::load(&_metadata);
64 }
65
66 inline void ObjectMonitor::set_metadata(uintptr_t value) {
67 AtomicAccess::store(&_metadata, value);
68 }
69
70 inline volatile uintptr_t* ObjectMonitor::metadata_addr() {
71 STATIC_ASSERT(std::is_standard_layout<ObjectMonitor>::value);
72 STATIC_ASSERT(offsetof(ObjectMonitor, _metadata) == 0);
73 return &_metadata;
74 }
75
76 inline markWord ObjectMonitor::header() const {
77 assert(!UseObjectMonitorTable, "Lightweight locking with OM table does not use header");
78 return markWord(metadata());
79 }
80
81 inline void ObjectMonitor::set_header(markWord hdr) {
82 assert(!UseObjectMonitorTable, "Lightweight locking with OM table does not use header");
83 set_metadata(hdr.value());
84 }
85
86 inline intptr_t ObjectMonitor::hash() const {
87 assert(UseObjectMonitorTable, "Only used by lightweight locking with OM table");
88 return metadata();
89 }
90
91 inline void ObjectMonitor::set_hash(intptr_t hash) {
92 assert(UseObjectMonitorTable, "Only used by lightweight locking with OM table");
93 set_metadata(hash);
94 }
95
96 inline int ObjectMonitor::waiters() const {
97 return _waiters;
98 }
99
100 inline bool ObjectMonitor::has_owner() const {
101 int64_t owner = owner_raw();
102 return owner != NO_OWNER && owner != DEFLATER_MARKER;
103 }
104
105 // Returns NO_OWNER if DEFLATER_MARKER is observed.
106 inline int64_t ObjectMonitor::owner() const {
107 int64_t owner = owner_raw();
108 return owner != DEFLATER_MARKER ? owner : NO_OWNER;
109 }
110
111 inline int64_t ObjectMonitor::owner_raw() const {
112 return AtomicAccess::load(&_owner);
113 }
114
115 // Returns true if owner field == DEFLATER_MARKER and false otherwise.
116 inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() const {
117 return owner_raw() == DEFLATER_MARKER;
118 }
119
120 // Returns true if 'this' is being async deflated and false otherwise.
121 inline bool ObjectMonitor::is_being_async_deflated() {
122 return contentions() < 0;
123 }
124
125 // Return number of threads contending for this monitor.
126 inline int ObjectMonitor::contentions() const {
127 return AtomicAccess::load(&_contentions);
128 }
129
130 // Add value to the contentions field.
131 inline void ObjectMonitor::add_to_contentions(int value) {
132 AtomicAccess::add(&_contentions, value);
133 }
134
135 inline void ObjectMonitor::inc_unmounted_vthreads() {
136 assert(_unmounted_vthreads >= 0, "");
137 AtomicAccess::inc(&_unmounted_vthreads, memory_order_relaxed);
138 }
139
140 inline void ObjectMonitor::dec_unmounted_vthreads() {
141 assert(_unmounted_vthreads > 0, "");
142 AtomicAccess::dec(&_unmounted_vthreads, memory_order_relaxed);
143 }
144
145 inline bool ObjectMonitor::has_unmounted_vthreads() const {
146 assert(_unmounted_vthreads >= 0, "");
147 return AtomicAccess::load(&_unmounted_vthreads) > 0;
148 }
149
150 inline void ObjectMonitor::set_recursions(size_t recursions) {
151 assert(_recursions == 0, "must be");
152 assert(has_owner(), "must be owned");
153 _recursions = checked_cast<intx>(recursions);
154 }
155
156 inline void ObjectMonitor::increment_recursions(JavaThread* current) {
157 assert(has_owner(current), "must be the owner");
158 _recursions++;
159 }
160
161 // Clear _owner field; current value must match old_value.
162 inline void ObjectMonitor::release_clear_owner(JavaThread* old_owner) {
163 int64_t old_value = owner_id_from(old_owner);
164 #ifdef ASSERT
165 int64_t prev = AtomicAccess::load(&_owner);
166 assert(prev == old_value, "unexpected prev owner=" INT64_FORMAT
167 ", expected=" INT64_FORMAT, prev, old_value);
168 #endif
169 AtomicAccess::release_store(&_owner, NO_OWNER);
170 log_trace(monitorinflation, owner)("release_clear_owner(): mid="
171 INTPTR_FORMAT ", old_value=" INT64_FORMAT,
172 p2i(this), old_value);
173 }
174
175 // Simply set _owner field to new_value; current value must match old_value.
176 // (Simple means no memory sync needed.)
177 inline void ObjectMonitor::set_owner_from_raw(int64_t old_value, int64_t new_value) {
178 #ifdef ASSERT
179 int64_t prev = AtomicAccess::load(&_owner);
180 assert((int64_t)prev < ThreadIdentifier::current(), "must be reasonable");
181 assert(prev == old_value, "unexpected prev owner=" INT64_FORMAT
182 ", expected=" INT64_FORMAT, prev, old_value);
183 #endif
184 AtomicAccess::store(&_owner, new_value);
185 log_trace(monitorinflation, owner)("set_owner_from(): mid="
186 INTPTR_FORMAT ", old_value=" INT64_FORMAT
187 ", new_value=" INT64_FORMAT, p2i(this),
188 old_value, new_value);
189 }
190
191 inline void ObjectMonitor::set_owner_from(int64_t old_value, JavaThread* current) {
192 set_owner_from_raw(old_value, owner_id_from(current));
193 }
194
195 // Try to set _owner field to new_value if the current value matches
196 // old_value. Otherwise, does not change the _owner field. Returns
197 // the prior value of the _owner field.
198 inline int64_t ObjectMonitor::try_set_owner_from_raw(int64_t old_value, int64_t new_value) {
199 assert((int64_t)new_value < ThreadIdentifier::current(), "must be reasonable");
200 int64_t prev = AtomicAccess::cmpxchg(&_owner, old_value, new_value);
201 if (prev == old_value) {
202 log_trace(monitorinflation, owner)("try_set_owner_from(): mid="
203 INTPTR_FORMAT ", prev=" INT64_FORMAT
204 ", new=" INT64_FORMAT, p2i(this),
205 prev, new_value);
206 }
207 return prev;
208 }
209
210 inline int64_t ObjectMonitor::try_set_owner_from(int64_t old_value, JavaThread* current) {
211 return try_set_owner_from_raw(old_value, owner_id_from(current));
212 }
213
214 inline bool ObjectMonitor::has_successor() const {
215 return AtomicAccess::load(&_succ) != NO_OWNER;
216 }
217
218 inline bool ObjectMonitor::has_successor(JavaThread* thread) const {
219 return owner_id_from(thread) == AtomicAccess::load(&_succ);
220 }
221
222 inline void ObjectMonitor::set_successor(JavaThread* thread) {
223 AtomicAccess::store(&_succ, owner_id_from(thread));
224 }
225
226 inline void ObjectMonitor::set_successor(oop vthread) {
227 AtomicAccess::store(&_succ, java_lang_Thread::thread_id(vthread));
228 }
229
230 inline void ObjectMonitor::clear_successor() {
231 AtomicAccess::store(&_succ, NO_OWNER);
232 }
233
234 inline int64_t ObjectMonitor::successor() const {
235 return AtomicAccess::load(&_succ);
236 }
237
238 // The _next_om field can be concurrently read and modified so we
239 // use Atomic operations to disable compiler optimizations that
240 // might try to elide loading and/or storing this field.
241
242 // Simply get _next_om field.
243 inline ObjectMonitor* ObjectMonitor::next_om() const {
244 return AtomicAccess::load(&_next_om);
245 }
246
247 // Simply set _next_om field to new_value.
248 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
249 AtomicAccess::store(&_next_om, new_value);
250 }
251
252 // Block out deflation.
253 inline ObjectMonitorContentionMark::ObjectMonitorContentionMark(ObjectMonitor* monitor)
254 : _monitor(monitor), _extended(false) {
255 // Contentions is incremented to a positive value as part of the
256 // contended enter protocol, which prevents the deflater thread from
257 // winning the last part of the 2-part async deflation
258 // protocol. See: ObjectMonitor::deflate_monitor() and
259 // ObjectMonitor::try_lock_with_contention_mark().
260 _monitor->add_to_contentions(1);
261 }
262
263 inline ObjectMonitorContentionMark::~ObjectMonitorContentionMark() {
264 // Decrement contentions when the contention mark goes out of
265 // scope. This opens up for deflation, if the contention mark
266 // hasn't been extended.
267 _monitor->add_to_contentions(-1);
268 }
269
270 inline void ObjectMonitorContentionMark::extend() {
271 // Used by ObjectMonitor::try_lock_with_contention_mark() to "extend the
272 // lifetime" of the contention mark.
273 assert(!_extended, "extending twice is probably a bad design");
274 _monitor->add_to_contentions(1);
275 _extended = true;
276 }
277
278 inline oop ObjectMonitor::object_peek() const {
279 if (_object.is_null()) {
280 return nullptr;
281 }
282 return _object.peek();
283 }
284
285 inline bool ObjectMonitor::object_is_dead() const {
286 return object_peek() == nullptr;
287 }
288
289 inline bool ObjectMonitor::object_refers_to(oop obj) const {
290 if (_object.is_null()) {
291 return false;
292 }
293 return _object.peek() == obj;
294 }
295
296 inline bool ObjectMonitor::is_jfr_excluded(const Klass* monitor_klass) {
297 assert(monitor_klass != nullptr, "invariant");
298 NOT_JFR_RETURN_(false);
299 JFR_ONLY(return vmSymbols::jdk_jfr_internal_management_HiddenWait() == monitor_klass->name();)
300 }
301
302 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP