1 /*
2 * Copyright (c) 1998, 2024, 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 "logging/log.hpp"
31 #include "oops/access.inline.hpp"
32 #include "oops/markWord.hpp"
33 #include "runtime/atomic.hpp"
34 #include "runtime/globals.hpp"
35 #include "runtime/lockStack.inline.hpp"
36 #include "runtime/synchronizer.hpp"
37 #include "utilities/checkedCast.hpp"
38 #include "utilities/globalDefinitions.hpp"
39
40 inline bool ObjectMonitor::is_entered(JavaThread* current) const {
41 if (LockingMode == LM_LIGHTWEIGHT) {
42 if (is_owner_anonymous()) {
43 return current->lock_stack().contains(object());
44 } else {
45 return current == owner_raw();
46 }
47 } else {
48 void* owner = owner_raw();
49 if (current == owner || current->is_lock_owned((address)owner)) {
50 return true;
51 }
52 }
53 return false;
54 }
55
56 inline uintptr_t ObjectMonitor::metadata() const {
57 return Atomic::load(&_metadata);
58 }
59
60 inline void ObjectMonitor::set_metadata(uintptr_t value) {
61 Atomic::store(&_metadata, value);
62 }
63
64 inline volatile uintptr_t* ObjectMonitor::metadata_addr() {
65 STATIC_ASSERT(std::is_standard_layout<ObjectMonitor>::value);
66 STATIC_ASSERT(offsetof(ObjectMonitor, _metadata) == 0);
67 return &_metadata;
68 }
69
70 inline markWord ObjectMonitor::header() const {
71 assert(LockingMode != LM_LIGHTWEIGHT, "Lightweight locking does not use header");
72 return markWord(metadata());
73 }
74
75 inline void ObjectMonitor::set_header(markWord hdr) {
76 assert(LockingMode != LM_LIGHTWEIGHT, "Lightweight locking does not use header");
77 set_metadata(hdr.value());
78 }
79
80 inline intptr_t ObjectMonitor::hash() const {
81 assert(LockingMode == LM_LIGHTWEIGHT, "Only used by lightweight locking");
82 return metadata();
83 }
84
85 inline void ObjectMonitor::set_hash(intptr_t hash) {
86 assert(LockingMode == LM_LIGHTWEIGHT, "Only used by lightweight locking");
87 set_metadata(hash);
88 }
89
90 inline int ObjectMonitor::waiters() const {
91 return _waiters;
92 }
93
94 inline bool ObjectMonitor::has_owner() const {
95 void* owner = owner_raw();
96 return owner != nullptr && owner != DEFLATER_MARKER;
97 }
98
99 // Returns null if DEFLATER_MARKER is observed.
100 inline void* ObjectMonitor::owner() const {
101 void* owner = owner_raw();
102 return owner != DEFLATER_MARKER ? owner : nullptr;
103 }
104
105 inline void* ObjectMonitor::owner_raw() const {
106 return Atomic::load(&_owner);
107 }
108
109 // Returns true if owner field == DEFLATER_MARKER and false otherwise.
110 // This accessor is called when we really need to know if the owner
111 // field == DEFLATER_MARKER and any non-null value won't do the trick.
112 inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() const {
113 return owner_raw() == DEFLATER_MARKER;
114 }
115
116 // Returns true if 'this' is being async deflated and false otherwise.
117 inline bool ObjectMonitor::is_being_async_deflated() {
118 return contentions() < 0;
119 }
120
121 // Return number of threads contending for this monitor.
122 inline int ObjectMonitor::contentions() const {
123 return Atomic::load(&_contentions);
124 }
125
126 // Add value to the contentions field.
127 inline void ObjectMonitor::add_to_contentions(int value) {
128 Atomic::add(&_contentions, value);
129 }
130
131 inline void ObjectMonitor::set_recursions(size_t recursions) {
132 assert(_recursions == 0, "must be");
133 assert(has_owner(), "must be owned");
134 _recursions = checked_cast<intx>(recursions);
135 }
136
137 // Clear _owner field; current value must match old_value.
138 inline void ObjectMonitor::release_clear_owner(void* old_value) {
139 #ifdef ASSERT
140 void* prev = Atomic::load(&_owner);
141 assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
142 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
143 #endif
144 Atomic::release_store(&_owner, (void*)nullptr);
145 log_trace(monitorinflation, owner)("release_clear_owner(): mid="
146 INTPTR_FORMAT ", old_value=" INTPTR_FORMAT,
147 p2i(this), p2i(old_value));
148 }
149
150 // Simply set _owner field to new_value; current value must match old_value.
151 // (Simple means no memory sync needed.)
152 inline void ObjectMonitor::set_owner_from(void* old_value, void* new_value) {
153 #ifdef ASSERT
154 void* prev = Atomic::load(&_owner);
155 assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
156 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
157 #endif
158 Atomic::store(&_owner, new_value);
159 log_trace(monitorinflation, owner)("set_owner_from(): mid="
160 INTPTR_FORMAT ", old_value=" INTPTR_FORMAT
161 ", new_value=" INTPTR_FORMAT, p2i(this),
162 p2i(old_value), p2i(new_value));
163 }
164
165 // Simply set _owner field to self; current value must match basic_lock_p.
166 inline void ObjectMonitor::set_owner_from_BasicLock(void* basic_lock_p, JavaThread* current) {
167 #ifdef ASSERT
168 void* prev = Atomic::load(&_owner);
169 assert(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
170 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(basic_lock_p));
171 #endif
172 // Non-null owner field to non-null owner field is safe without
173 // cmpxchg() as long as all readers can tolerate either flavor.
174 Atomic::store(&_owner, current);
175 log_trace(monitorinflation, owner)("set_owner_from_BasicLock(): mid="
176 INTPTR_FORMAT ", basic_lock_p="
177 INTPTR_FORMAT ", new_value=" INTPTR_FORMAT,
178 p2i(this), p2i(basic_lock_p), p2i(current));
179 }
180
181 // Try to set _owner field to new_value if the current value matches
182 // old_value. Otherwise, does not change the _owner field. Returns
183 // the prior value of the _owner field.
184 inline void* ObjectMonitor::try_set_owner_from(void* old_value, void* new_value) {
185 void* prev = Atomic::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=" INTPTR_FORMAT
189 ", new=" INTPTR_FORMAT, p2i(this),
190 p2i(prev), p2i(new_value));
191 }
192 return prev;
193 }
194
195 // The _next_om field can be concurrently read and modified so we
196 // use Atomic operations to disable compiler optimizations that
197 // might try to elide loading and/or storing this field.
198
199 // Simply get _next_om field.
200 inline ObjectMonitor* ObjectMonitor::next_om() const {
201 return Atomic::load(&_next_om);
202 }
203
204 // Simply set _next_om field to new_value.
205 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
206 Atomic::store(&_next_om, new_value);
207 }
208
209 inline ObjectMonitorContentionMark::ObjectMonitorContentionMark(ObjectMonitor* monitor)
210 : _monitor(monitor) {
211 _monitor->add_to_contentions(1);
212 }
213
214 inline ObjectMonitorContentionMark::~ObjectMonitorContentionMark() {
215 _monitor->add_to_contentions(-1);
216 }
217
218 inline oop ObjectMonitor::object_peek() const {
219 if (_object.is_null()) {
220 return nullptr;
221 }
222 return _object.peek();
223 }
224
225 inline bool ObjectMonitor::object_is_dead() const {
226 return object_peek() == nullptr;
227 }
228
229 inline bool ObjectMonitor::object_is_cleared() const {
230 return _object.is_null();
231 }
232
233 inline bool ObjectMonitor::object_refers_to(oop obj) const {
234 if (_object.is_null()) {
235 return false;
236 }
237 return _object.peek() == obj;
238 }
239
240 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP