1 /*
2 * Copyright (c) 1998, 2020, 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 "logging/log.hpp"
29 #include "runtime/atomic.hpp"
30
31 inline intptr_t ObjectMonitor::is_entered(TRAPS) const {
32 if (THREAD == _owner || THREAD->is_lock_owned((address) _owner)) {
33 return 1;
34 }
35 return 0;
36 }
37
38 inline markWord ObjectMonitor::header() const {
39 return Atomic::load(&_header);
40 }
41
42 inline volatile markWord* ObjectMonitor::header_addr() {
43 assert((intptr_t)this == (intptr_t)&_header, "sync code expects this");
44 return &_header;
45 }
46
47 inline void ObjectMonitor::set_header(markWord hdr) {
48 Atomic::store(&_header, hdr);
49 }
50
51 inline jint ObjectMonitor::waiters() const {
52 return _waiters;
53 }
54
55 // Returns NULL if DEFLATER_MARKER is observed.
56 inline void* ObjectMonitor::owner() const {
57 void* owner = _owner;
58 return owner != DEFLATER_MARKER ? owner : NULL;
59 }
60
61 // Returns true if owner field == DEFLATER_MARKER and false otherwise.
62 // This accessor is called when we really need to know if the owner
63 // field == DEFLATER_MARKER and any non-NULL value won't do the trick.
64 inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() {
65 return _owner == DEFLATER_MARKER;
66 }
67
68 // Returns true if 'this' is being async deflated and false otherwise.
69 inline bool ObjectMonitor::is_being_async_deflated() {
70 return owner_is_DEFLATER_MARKER() && contentions() < 0;
71 }
72
73 inline void ObjectMonitor::clear() {
74 assert(Atomic::load(&_header).value() != 0, "must be non-zero");
75 assert(_owner == NULL, "must be NULL: owner=" INTPTR_FORMAT, p2i(_owner));
76
77 Atomic::store(&_header, markWord::zero());
78
79 clear_using_JT();
80 }
81
82 inline void ObjectMonitor::clear_using_JT() {
83 // Unlike other *_using_JT() functions, we cannot assert
84 // AsyncDeflateIdleMonitors or Thread::current()->is_Java_thread()
85 // because clear() calls this function for the rest of its checks.
86
87 if (AsyncDeflateIdleMonitors) {
88 // Async deflation protocol uses the header, owner and contentions
89 // fields. While the ObjectMonitor being deflated is on the global free
90 // list, we leave those three fields alone; owner == DEFLATER_MARKER
91 // and contentions < 0 will force any racing threads to retry. The
92 // header field is used by install_displaced_markword_in_object()
93 // to restore the object's header so we cannot check its value here.
94 guarantee(_owner == NULL || _owner == DEFLATER_MARKER,
95 "must be NULL or DEFLATER_MARKER: owner=" INTPTR_FORMAT,
96 p2i(_owner));
97 }
98 assert(contentions() <= 0, "must not be positive: contentions=%d", contentions());
99 assert(_waiters == 0, "must be 0: waiters=%d", _waiters);
100 assert(_recursions == 0, "must be 0: recursions=" INTX_FORMAT, _recursions);
101 assert(_object != NULL, "must be non-NULL");
102
103 set_allocation_state(Free);
104 _object = NULL;
105 }
106
107 inline void* ObjectMonitor::object() const {
108 return _object;
109 }
110
111 inline void* ObjectMonitor::object_addr() {
112 return (void *)(&_object);
113 }
114
115 inline void ObjectMonitor::set_object(void* obj) {
116 _object = obj;
117 }
118
119 // Return number of threads contending for this monitor.
120 inline jint ObjectMonitor::contentions() const {
121 return Atomic::load(&_contentions);
122 }
123
124 // Clear _owner field; current value must match old_value.
125 inline void ObjectMonitor::release_clear_owner(void* old_value) {
126 void* prev = Atomic::load(&_owner);
127 ADIM_guarantee(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
128 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
129 Atomic::release_store(&_owner, (void*)NULL);
130 log_trace(monitorinflation, owner)("release_clear_owner(): mid="
131 INTPTR_FORMAT ", old_value=" INTPTR_FORMAT,
132 p2i(this), p2i(old_value));
133 }
134
135 // Simply set _owner field to new_value; current value must match old_value.
136 // (Simple means no memory sync needed.)
137 inline void ObjectMonitor::set_owner_from(void* old_value, void* new_value) {
138 void* prev = Atomic::load(&_owner);
139 ADIM_guarantee(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
140 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
141 Atomic::store(&_owner, new_value);
142 log_trace(monitorinflation, owner)("set_owner_from(): mid="
143 INTPTR_FORMAT ", old_value=" INTPTR_FORMAT
144 ", new_value=" INTPTR_FORMAT, p2i(this),
145 p2i(old_value), p2i(new_value));
146 }
147
148 // Simply set _owner field to new_value; current value must match old_value1 or old_value2.
149 // (Simple means no memory sync needed.)
150 inline void ObjectMonitor::set_owner_from(void* old_value1, void* old_value2, void* new_value) {
151 void* prev = Atomic::load(&_owner);
152 ADIM_guarantee(prev == old_value1 || prev == old_value2,
153 "unexpected prev owner=" INTPTR_FORMAT ", expected1="
154 INTPTR_FORMAT " or expected2=" INTPTR_FORMAT, p2i(prev),
155 p2i(old_value1), p2i(old_value2));
156 _owner = new_value;
157 log_trace(monitorinflation, owner)("set_owner_from(old1=" INTPTR_FORMAT
158 ", old2=" INTPTR_FORMAT "): mid="
159 INTPTR_FORMAT ", prev=" INTPTR_FORMAT
160 ", new=" INTPTR_FORMAT, p2i(old_value1),
161 p2i(old_value2), p2i(this), p2i(prev),
162 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, Thread* self) {
167 void* prev = Atomic::load(&_owner);
168 ADIM_guarantee(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
169 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(basic_lock_p));
170 // Non-null owner field to non-null owner field is safe without
171 // cmpxchg() as long as all readers can tolerate either flavor.
172 Atomic::store(&_owner, self);
173 log_trace(monitorinflation, owner)("set_owner_from_BasicLock(): mid="
174 INTPTR_FORMAT ", basic_lock_p="
175 INTPTR_FORMAT ", new_value=" INTPTR_FORMAT,
176 p2i(this), p2i(basic_lock_p), p2i(self));
177 }
178
179 // Try to set _owner field to new_value if the current value matches
180 // old_value. Otherwise, does not change the _owner field. Returns
181 // the prior value of the _owner field.
182 inline void* ObjectMonitor::try_set_owner_from(void* old_value, void* new_value) {
183 void* prev = Atomic::cmpxchg(&_owner, old_value, new_value);
184 if (prev == old_value) {
185 log_trace(monitorinflation, owner)("try_set_owner_from(): mid="
186 INTPTR_FORMAT ", prev=" INTPTR_FORMAT
187 ", new=" INTPTR_FORMAT, p2i(this),
188 p2i(prev), p2i(new_value));
189 }
190 return prev;
191 }
192
193 inline void ObjectMonitor::set_allocation_state(ObjectMonitor::AllocationState s) {
194 _allocation_state = s;
195 }
196
197 inline ObjectMonitor::AllocationState ObjectMonitor::allocation_state() const {
198 return _allocation_state;
199 }
200
201 inline bool ObjectMonitor::is_free() const {
202 return _allocation_state == Free;
203 }
204
205 inline bool ObjectMonitor::is_old() const {
206 return _allocation_state == Old;
207 }
208
209 inline bool ObjectMonitor::is_new() const {
210 return _allocation_state == New;
211 }
212
213 // The _next_om field can be concurrently read and modified so we
214 // use Atomic operations to disable compiler optimizations that
215 // might try to elide loading and/or storing this field.
216
217 inline ObjectMonitor* ObjectMonitor::next_om() const {
218 return Atomic::load(&_next_om);
219 }
220
221 // Simply set _next_om field to new_value.
222 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
223 Atomic::store(&_next_om, new_value);
224 }
225
226 // Try to set _next_om field to new_value if the current value matches
227 // old_value. Otherwise, does not change the _next_om field. Returns
228 // the prior value of the _next_om field.
229 inline ObjectMonitor* ObjectMonitor::try_set_next_om(ObjectMonitor* old_value, ObjectMonitor* new_value) {
230 return Atomic::cmpxchg(&_next_om, old_value, new_value);
231 }
232
233 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP