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/lockStack.inline.hpp"
 34 #include "runtime/synchronizer.hpp"
 35 
 36 inline bool ObjectMonitor::is_entered(JavaThread* current) const {
 37   if (LockingMode == LM_LIGHTWEIGHT) {
 38     if (is_owner_anonymous()) {
 39       return current->lock_stack().contains(object());
 40     } else {
 41       return current == owner_raw();
 42     }
 43   } else {
 44     void* owner = owner_raw();
 45     if (current == owner || current->is_lock_owned((address)owner)) {
 46       return true;
 47     }
 48   }
 49   return false;
 50 }
 51 
 52 inline markWord ObjectMonitor::header() const {
 53   return Atomic::load(&_header);
 54 }
 55 
 56 inline volatile markWord* ObjectMonitor::header_addr() {
 57   return &_header;
 58 }
 59 
 60 inline void ObjectMonitor::set_header(markWord hdr) {
 61   Atomic::store(&_header, hdr);
 62 }
 63 
 64 inline int ObjectMonitor::waiters() const {
 65   return _waiters;
 66 }
 67 
 68 inline bool ObjectMonitor::has_owner() const {
 69   void* owner = owner_raw();
 70   return owner != nullptr && owner != DEFLATER_MARKER;
 71 }
 72 
 73 // Returns null if DEFLATER_MARKER is observed.
 74 inline void* ObjectMonitor::owner() const {
 75   void* owner = owner_raw();
 76   return owner != DEFLATER_MARKER ? owner : nullptr;
 77 }
 78 
 79 inline void* ObjectMonitor::owner_raw() const {
 80   return Atomic::load(&_owner);
 81 }
 82 
 83 // Returns true if owner field == DEFLATER_MARKER and false otherwise.
 84 // This accessor is called when we really need to know if the owner
 85 // field == DEFLATER_MARKER and any non-null value won't do the trick.
 86 inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() const {
 87   return owner_raw() == DEFLATER_MARKER;
 88 }
 89 
 90 // Returns true if 'this' is being async deflated and false otherwise.
 91 inline bool ObjectMonitor::is_being_async_deflated() {
 92   return contentions() < 0;
 93 }
 94 
 95 // Return number of threads contending for this monitor.
 96 inline int ObjectMonitor::contentions() const {
 97   return Atomic::load(&_contentions);
 98 }
 99 
100 // Add value to the contentions field.
101 inline void ObjectMonitor::add_to_contentions(int value) {
102   Atomic::add(&_contentions, value);
103 }
104 
105 // Clear _owner field; current value must match old_value.
106 inline void ObjectMonitor::release_clear_owner(void* old_value) {
107 #ifdef ASSERT
108   void* prev = Atomic::load(&_owner);
109   assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
110          ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
111 #endif
112   Atomic::release_store(&_owner, (void*)nullptr);
113   log_trace(monitorinflation, owner)("release_clear_owner(): mid="
114                                      INTPTR_FORMAT ", old_value=" INTPTR_FORMAT,
115                                      p2i(this), p2i(old_value));
116 }
117 
118 // Simply set _owner field to new_value; current value must match old_value.
119 // (Simple means no memory sync needed.)
120 inline void ObjectMonitor::set_owner_from(void* old_value, void* new_value) {
121 #ifdef ASSERT
122   void* prev = Atomic::load(&_owner);
123   assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
124          ", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
125 #endif
126   Atomic::store(&_owner, new_value);
127   log_trace(monitorinflation, owner)("set_owner_from(): mid="
128                                      INTPTR_FORMAT ", old_value=" INTPTR_FORMAT
129                                      ", new_value=" INTPTR_FORMAT, p2i(this),
130                                      p2i(old_value), p2i(new_value));
131 }
132 
133 // Simply set _owner field to self; current value must match basic_lock_p.
134 inline void ObjectMonitor::set_owner_from_BasicLock(void* basic_lock_p, JavaThread* current) {
135 #ifdef ASSERT
136   void* prev = Atomic::load(&_owner);
137   assert(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
138          ", expected=" INTPTR_FORMAT, p2i(prev), p2i(basic_lock_p));
139 #endif
140   // Non-null owner field to non-null owner field is safe without
141   // cmpxchg() as long as all readers can tolerate either flavor.
142   Atomic::store(&_owner, current);
143   log_trace(monitorinflation, owner)("set_owner_from_BasicLock(): mid="
144                                      INTPTR_FORMAT ", basic_lock_p="
145                                      INTPTR_FORMAT ", new_value=" INTPTR_FORMAT,
146                                      p2i(this), p2i(basic_lock_p), p2i(current));
147 }
148 
149 // Try to set _owner field to new_value if the current value matches
150 // old_value. Otherwise, does not change the _owner field. Returns
151 // the prior value of the _owner field.
152 inline void* ObjectMonitor::try_set_owner_from(void* old_value, void* new_value) {
153   void* prev = Atomic::cmpxchg(&_owner, old_value, new_value);
154   if (prev == old_value) {
155     log_trace(monitorinflation, owner)("try_set_owner_from(): mid="
156                                        INTPTR_FORMAT ", prev=" INTPTR_FORMAT
157                                        ", new=" INTPTR_FORMAT, p2i(this),
158                                        p2i(prev), p2i(new_value));
159   }
160   return prev;
161 }
162 
163 // The _next_om field can be concurrently read and modified so we
164 // use Atomic operations to disable compiler optimizations that
165 // might try to elide loading and/or storing this field.
166 
167 // Simply get _next_om field.
168 inline ObjectMonitor* ObjectMonitor::next_om() const {
169   return Atomic::load(&_next_om);
170 }
171 
172 // Simply set _next_om field to new_value.
173 inline void ObjectMonitor::set_next_om(ObjectMonitor* new_value) {
174   Atomic::store(&_next_om, new_value);
175 }
176 
177 #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP