1 /*
2 * Copyright (c) 1998, 2019, 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(hdr, &_header);
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 OrderAccess::load_acquire(&_owner) == DEFLATER_MARKER;
66 }
67
68 inline void ObjectMonitor::clear() {
69 assert(Atomic::load(&_header).value() != 0, "must be non-zero");
70 assert(_owner == NULL, "must be NULL: owner=" INTPTR_FORMAT, p2i(_owner));
71 assert(ref_count() == 0, "must be 0: ref_count=%d", ref_count());
72
73 Atomic::store(markWord::zero(), &_header);
74
75 clear_using_JT();
76 }
77
78 inline void ObjectMonitor::clear_using_JT() {
79 // Unlike other *_using_JT() functions, we cannot assert
80 // AsyncDeflateIdleMonitors or Thread::current()->is_Java_thread()
81 // because clear() calls this function for the rest of its checks.
82
83 if (AsyncDeflateIdleMonitors) {
84 // Async deflation protocol uses the header, owner and ref_count
85 // fields. While the ObjectMonitor being deflated is on the global free
86 // list, we leave those three fields alone; owner == DEFLATER_MARKER
87 // and ref_count < 0 will force any racing threads to retry. The
88 // header field is used by install_displaced_markword_in_object()
89 // in the last part of the deflation protocol so we cannot check
90 // its value here.
91 guarantee(_owner == NULL || _owner == DEFLATER_MARKER,
92 "must be NULL or DEFLATER_MARKER: owner=" INTPTR_FORMAT,
93 p2i(_owner));
94 guarantee(ref_count() <= 0, "must be <= 0: ref_count=%d", ref_count());
95 }
96 assert(_contentions == 0, "must be 0: contentions=%d", _contentions);
97 assert(_waiters == 0, "must be 0: waiters=%d", _waiters);
98 assert(_recursions == 0, "must be 0: recursions=" INTX_FORMAT, _recursions);
99 assert(_object != NULL, "must be non-NULL");
100
101 set_allocation_state(Free);
102 _object = NULL;
103 }
104
105 inline void* ObjectMonitor::object() const {
106 return _object;
107 }
108
109 inline void* ObjectMonitor::object_addr() {
110 return (void *)(&_object);
111 }
112
113 inline void ObjectMonitor::set_object(void* obj) {
114 _object = obj;
115 }
116
117 // return number of threads contending for this monitor
118 inline jint ObjectMonitor::contentions() const {
119 return _contentions;
120 }
121
122 // Set _owner field to new_value; current value must match old_value.
123 inline void ObjectMonitor::set_owner_from(void* new_value, void* old_value) {
124 void* prev = Atomic::cmpxchg(new_value, &_owner, old_value);
125 ADIM_guarantee(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
126 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
127 log_trace(monitorinflation, owner)("mid=" INTPTR_FORMAT ", prev="
128 INTPTR_FORMAT ", new=" INTPTR_FORMAT,
129 p2i(this), p2i(prev), p2i(new_value));
130 }
131
132 // Set _owner field to new_value; current value must match old_value1 or old_value2.
133 inline void ObjectMonitor::set_owner_from(void* new_value, void* old_value1, void* old_value2) {
134 void* prev = Atomic::cmpxchg(new_value, &_owner, old_value1);
135 if (prev != old_value1) {
136 prev = Atomic::cmpxchg(new_value, &_owner, old_value2);
137 }
138 ADIM_guarantee(prev == old_value1 || prev == old_value2,
139 "unexpected prev owner=" INTPTR_FORMAT ", expected1="
140 INTPTR_FORMAT " or expected2=" INTPTR_FORMAT, p2i(prev),
141 p2i(old_value1), p2i(old_value2));
142 log_trace(monitorinflation, owner)("mid=" INTPTR_FORMAT ", prev="
143 INTPTR_FORMAT ", new=" INTPTR_FORMAT,
144 p2i(this), p2i(prev), p2i(new_value));
145 }
146
147 // Set _owner field to self; current value must match basic_lock_p.
148 inline void ObjectMonitor::set_owner_from_BasicLock(Thread* self, void* basic_lock_p) {
149 assert(self->is_lock_owned((address)basic_lock_p), "self=" INTPTR_FORMAT
150 " must own basic_lock_p=" INTPTR_FORMAT, p2i(self), p2i(basic_lock_p));
151 void* prev = _owner;
152 ADIM_guarantee(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
153 ", expected=" INTPTR_FORMAT, p2i(prev), p2i(basic_lock_p));
154 // Non-null owner field to non-null owner field is safe without
155 // cmpxchg() as long as all readers can tolerate either flavor.
156 _owner = self;
157 log_trace(monitorinflation, owner)("mid=" INTPTR_FORMAT ", prev="
158 INTPTR_FORMAT ", new=" INTPTR_FORMAT,
159 p2i(this), p2i(prev), p2i(self));
160 }
161
162 // Try to set _owner field to new_value if the current value matches
163 // old_value. Otherwise, does not change the _owner field.
164 inline void* ObjectMonitor::try_set_owner_from(void* new_value, void* old_value) {
165 void* prev = Atomic::cmpxchg(new_value, &_owner, old_value);
166 if (prev == old_value) {
167 log_trace(monitorinflation, owner)("mid=" INTPTR_FORMAT ", prev="
168 INTPTR_FORMAT ", new=" INTPTR_FORMAT,
169 p2i(this), p2i(prev), p2i(new_value));
170 }
171 return prev;
172 }
173
174 inline void ObjectMonitor::set_allocation_state(ObjectMonitor::AllocationState s) {
175 _allocation_state = s;
176 }
177
178 inline ObjectMonitor::AllocationState ObjectMonitor::allocation_state() const {
179 return _allocation_state;
180 }
181
182 inline bool ObjectMonitor::is_free() const {
183 return _allocation_state == Free;
184 }
185
186 inline bool ObjectMonitor::is_active() const {
187 return !is_free();
188 }
189
190 inline bool ObjectMonitor::is_old() const {
191 return _allocation_state == Old;
192 }
193
194 inline bool ObjectMonitor::is_new() const {
195 return _allocation_state == New;
196 }
197
198 inline void ObjectMonitor::dec_ref_count() {
199 // The decrement only needs to be MO_ACQ_REL since the reference
200 // counter is volatile.
201 Atomic::dec(&_ref_count);
202 // Can be negative as part of async deflation protocol.
203 ADIM_guarantee(AsyncDeflateIdleMonitors || ref_count() >= 0,
204 "sanity check: ref_count=%d", ref_count());
205 }
206
207 inline void ObjectMonitor::inc_ref_count() {
208 // The increment needs to be MO_SEQ_CST so that the reference
209 // counter update is seen as soon as possible in a race with the
210 // async deflation protocol.
211 Atomic::inc(&_ref_count);
212 // Can be negative as part of async deflation protocol.
213 ADIM_guarantee(AsyncDeflateIdleMonitors || ref_count() > 0,
214 "sanity check: ref_count=%d", ref_count());
215 }
216
217 inline jint ObjectMonitor::ref_count() const {
218 return OrderAccess::load_acquire(&_ref_count);
219 }
220
221 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP