1 /*
2 * Copyright (c) 1998, 2023, 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 "logging/log.hpp"
31 #include "oops/access.inline.hpp"
32 #include "runtime/atomic.hpp"
33 #include "runtime/synchronizer.hpp"
34
35 inline intptr_t ObjectMonitor::is_entered(JavaThread* current) const {
36 void* owner = owner_raw();
37 if (current == owner || current->is_lock_owned((address)owner)) {
38 return 1;
39 }
40 return 0;
41 }
42
43 inline markWord ObjectMonitor::header() const {
44 return Atomic::load(&_header);
45 }
46
47 inline volatile markWord* ObjectMonitor::header_addr() {
48 return &_header;
49 }
50
51 inline void ObjectMonitor::set_header(markWord hdr) {
52 Atomic::store(&_header, hdr);
53 }
54
55 inline int ObjectMonitor::waiters() const {
56 return _waiters;
57 }
58
59 inline bool ObjectMonitor::has_owner() const {
60 void* owner = owner_raw();
61 return owner != nullptr && owner != DEFLATER_MARKER;
62 }
63
64 // Returns null if DEFLATER_MARKER is observed.
65 inline void* ObjectMonitor::owner() const {
66 void* owner = owner_raw();
67 return owner != DEFLATER_MARKER ? owner : nullptr;
68 }
69
70 inline void* ObjectMonitor::owner_raw() const {
71 return Atomic::load(&_owner);
72 }
73
74 // Returns true if owner field == DEFLATER_MARKER and false otherwise.
75 // This accessor is called when we really need to know if the owner
76 // field == DEFLATER_MARKER and any non-null value won't do the trick.
77 inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() const {
78 return owner_raw() == DEFLATER_MARKER;
79 }
80
81 // Returns true if 'this' is being async deflated and false otherwise.
82 inline bool ObjectMonitor::is_being_async_deflated() {
83 return contentions() < 0;
84 }
85
86 // Return number of threads contending for this monitor.
87 inline int ObjectMonitor::contentions() const {
88 return Atomic::load(&_contentions);
89 }
90
91 // Add value to the contentions field.
92 inline void ObjectMonitor::add_to_contentions(int value) {
93 Atomic::add(&_contentions, value);
94 }
95
96 // Clear _owner field; current value must match old_value.
97 inline void ObjectMonitor::release_clear_owner(void* old_value) {
98 #ifdef ASSERT
99 void* prev = Atomic::load(&_owner);
100 assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
101 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
102 #endif
103 Atomic::release_store(&_owner, (void*)nullptr);
104 log_trace(monitorinflation, owner)("release_clear_owner(): mid="
105 INTPTR_FORMAT ", old_value=" INTPTR_FORMAT,
106 p2i(this), p2i(old_value));
107 }
108
109 // Simply set _owner field to new_value; current value must match old_value.
110 // (Simple means no memory sync needed.)
111 inline void ObjectMonitor::set_owner_from(void* old_value, void* new_value) {
112 #ifdef ASSERT
113 void* prev = Atomic::load(&_owner);
114 assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
115 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
116 #endif
117 Atomic::store(&_owner, new_value);
118 log_trace(monitorinflation, owner)("set_owner_from(): mid="
119 INTPTR_FORMAT ", old_value=" INTPTR_FORMAT
120 ", new_value=" INTPTR_FORMAT, p2i(this),
121 p2i(old_value), p2i(new_value));
122 }
123
124 // Simply set _owner field to self; current value must match basic_lock_p.
125 inline void ObjectMonitor::set_owner_from_BasicLock(void* basic_lock_p, JavaThread* current) {
126 #ifdef ASSERT
127 void* prev = Atomic::load(&_owner);
128 assert(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
129 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(basic_lock_p));
130 #endif
131 // Non-null owner field to non-null owner field is safe without
132 // cmpxchg() as long as all readers can tolerate either flavor.
133 Atomic::store(&_owner, current);
134 log_trace(monitorinflation, owner)("set_owner_from_BasicLock(): mid="
135 INTPTR_FORMAT ", basic_lock_p="
136 INTPTR_FORMAT ", new_value=" INTPTR_FORMAT,
137 p2i(this), p2i(basic_lock_p), p2i(current));
138 }
139
140 // Try to set _owner field to new_value if the current value matches
141 // old_value. Otherwise, does not change the _owner field. Returns
142 // the prior value of the _owner field.
143 inline void* ObjectMonitor::try_set_owner_from(void* old_value, void* new_value) {
144 void* prev = Atomic::cmpxchg(&_owner, old_value, new_value);
145 if (prev == old_value) {
146 log_trace(monitorinflation, owner)("try_set_owner_from(): mid="
147 INTPTR_FORMAT ", prev=" INTPTR_FORMAT
148 ", new=" INTPTR_FORMAT, p2i(this),
149 p2i(prev), p2i(new_value));
150 }
151 return prev;
152 }
153
154 // The _next_om field can be concurrently read and modified so we
155 // use Atomic operations to disable compiler optimizations that
156 // might try to elide loading and/or storing this field.
157
158 // Simply get _next_om field.
159 inline ObjectMonitor* ObjectMonitor::next_om() const {
160 return Atomic::load(&_next_om);
161 }
162
163 // Simply set _next_om field to new_value.
164 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
165 Atomic::store(&_next_om, new_value);
166 }
167
168 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP