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/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::set_recursions(size_t recursions) {
136 assert(_recursions == 0, "must be");
137 assert(has_owner(), "must be owned");
138 _recursions = checked_cast<intx>(recursions);
139 }
140
141 inline void ObjectMonitor::increment_recursions(JavaThread* current) {
142 assert(has_owner(current), "must be the owner");
143 _recursions++;
144 }
145
146 // Clear _owner field; current value must match old_value.
147 inline void ObjectMonitor::release_clear_owner(JavaThread* old_owner) {
148 int64_t old_value = owner_id_from(old_owner);
149 #ifdef ASSERT
150 int64_t prev = AtomicAccess::load(&_owner);
151 assert(prev == old_value, "unexpected prev owner=" INT64_FORMAT
152 ", expected=" INT64_FORMAT, prev, old_value);
153 #endif
154 AtomicAccess::release_store(&_owner, NO_OWNER);
155 log_trace(monitorinflation, owner)("release_clear_owner(): mid="
156 INTPTR_FORMAT ", old_value=" INT64_FORMAT,
157 p2i(this), old_value);
158 }
159
160 // Simply set _owner field to new_value; current value must match old_value.
161 // (Simple means no memory sync needed.)
162 inline void ObjectMonitor::set_owner_from_raw(int64_t old_value, int64_t new_value) {
163 #ifdef ASSERT
164 int64_t prev = AtomicAccess::load(&_owner);
165 assert((int64_t)prev < ThreadIdentifier::current(), "must be reasonable");
166 assert(prev == old_value, "unexpected prev owner=" INT64_FORMAT
167 ", expected=" INT64_FORMAT, prev, old_value);
168 #endif
169 AtomicAccess::store(&_owner, new_value);
170 log_trace(monitorinflation, owner)("set_owner_from(): mid="
171 INTPTR_FORMAT ", old_value=" INT64_FORMAT
172 ", new_value=" INT64_FORMAT, p2i(this),
173 old_value, new_value);
174 }
175
176 inline void ObjectMonitor::set_owner_from(int64_t old_value, JavaThread* current) {
177 set_owner_from_raw(old_value, owner_id_from(current));
178 }
179
180 // Try to set _owner field to new_value if the current value matches
181 // old_value. Otherwise, does not change the _owner field. Returns
182 // the prior value of the _owner field.
183 inline int64_t ObjectMonitor::try_set_owner_from_raw(int64_t old_value, int64_t new_value) {
184 assert((int64_t)new_value < ThreadIdentifier::current(), "must be reasonable");
185 int64_t prev = AtomicAccess::cmpxchg(&_owner, old_value, new_value);
186 if (prev == old_value) {
187 log_trace(monitorinflation, owner)("try_set_owner_from(): mid="
188 INTPTR_FORMAT ", prev=" INT64_FORMAT
189 ", new=" INT64_FORMAT, p2i(this),
190 prev, new_value);
191 }
192 return prev;
193 }
194
195 inline int64_t ObjectMonitor::try_set_owner_from(int64_t old_value, JavaThread* current) {
196 return try_set_owner_from_raw(old_value, owner_id_from(current));
197 }
198
199 inline bool ObjectMonitor::has_successor() const {
200 return AtomicAccess::load(&_succ) != NO_OWNER;
201 }
202
203 inline bool ObjectMonitor::has_successor(JavaThread* thread) const {
204 return owner_id_from(thread) == AtomicAccess::load(&_succ);
205 }
206
207 inline void ObjectMonitor::set_successor(JavaThread* thread) {
208 AtomicAccess::store(&_succ, owner_id_from(thread));
209 }
210
211 inline void ObjectMonitor::set_successor(oop vthread) {
212 AtomicAccess::store(&_succ, java_lang_Thread::thread_id(vthread));
213 }
214
215 inline void ObjectMonitor::clear_successor() {
216 AtomicAccess::store(&_succ, NO_OWNER);
217 }
218
219 inline int64_t ObjectMonitor::successor() const {
220 return AtomicAccess::load(&_succ);
221 }
222
223 // The _next_om field can be concurrently read and modified so we
224 // use Atomic operations to disable compiler optimizations that
225 // might try to elide loading and/or storing this field.
226
227 // Simply get _next_om field.
228 inline ObjectMonitor* ObjectMonitor::next_om() const {
229 return AtomicAccess::load(&_next_om);
230 }
231
232 // Simply set _next_om field to new_value.
233 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
234 AtomicAccess::store(&_next_om, new_value);
235 }
236
237 // Block out deflation.
238 inline ObjectMonitorContentionMark::ObjectMonitorContentionMark(ObjectMonitor* monitor)
239 : _monitor(monitor), _extended(false) {
240 // Contentions is incremented to a positive value as part of the
241 // contended enter protocol, which prevents the deflater thread from
242 // winning the last part of the 2-part async deflation
243 // protocol. See: ObjectMonitor::deflate_monitor() and
244 // ObjectMonitor::try_lock_with_contention_mark().
245 _monitor->add_to_contentions(1);
246 }
247
248 inline ObjectMonitorContentionMark::~ObjectMonitorContentionMark() {
249 // Decrement contentions when the contention mark goes out of
250 // scope. This opens up for deflation, if the contention mark
251 // hasn't been extended.
252 _monitor->add_to_contentions(-1);
253 }
254
255 inline void ObjectMonitorContentionMark::extend() {
256 // Used by ObjectMonitor::try_lock_with_contention_mark() to "extend the
257 // lifetime" of the contention mark.
258 assert(!_extended, "extending twice is probably a bad design");
259 _monitor->add_to_contentions(1);
260 _extended = true;
261 }
262
263 inline oop ObjectMonitor::object_peek() const {
264 if (_object.is_null()) {
265 return nullptr;
266 }
267 return _object.peek();
268 }
269
270 inline bool ObjectMonitor::object_is_dead() const {
271 return object_peek() == nullptr;
272 }
273
274 inline bool ObjectMonitor::object_refers_to(oop obj) const {
275 if (_object.is_null()) {
276 return false;
277 }
278 return _object.peek() == obj;
279 }
280
281 inline bool ObjectMonitor::is_jfr_excluded(const Klass* monitor_klass) {
282 assert(monitor_klass != nullptr, "invariant");
283 NOT_JFR_RETURN_(false);
284 JFR_ONLY(return vmSymbols::jdk_jfr_internal_management_HiddenWait() == monitor_klass->name();)
285 }
286
287 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP