1 /*
2 * Copyright (c) 2001, 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 package sun.jvm.hotspot.runtime;
26
27 import java.util.*;
28
29 import sun.jvm.hotspot.oops.*;
30 import sun.jvm.hotspot.utilities.*;
31 import sun.jvm.hotspot.debugger.*;
32 import sun.jvm.hotspot.types.*;
33 import sun.jvm.hotspot.utilities.Observable;
34 import sun.jvm.hotspot.utilities.Observer;
35
36 public class ObjectSynchronizer {
37 static {
38 VM.registerVMInitializedObserver(new Observer() {
39 public void update(Observable o, Object data) {
40 initialize(VM.getVM().getTypeDataBase());
41 }
42 });
43 }
44
45 private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
46 Type objectSynchronizerType = db.lookupType("ObjectSynchronizer");
47 Type monitorListType = db.lookupType("MonitorList");
48 Address monitorListAddr = objectSynchronizerType.getField("_in_use_list").getStaticFieldAddress();
49 inUseListHead = monitorListType.getAddressField("_head").getAddress(monitorListAddr);
50 }
51
52 public long identityHashValueFor(Oop obj) {
53 Mark mark = obj.getMark();
54 if (mark.isUnlocked()) {
55 // FIXME: can not generate marks in debugging system
56 return mark.hash();
57 } else if (mark.hasMonitor()) {
58 if (VM.getVM().getCommandLineFlag("LockingMode").getInt() == LockingMode.getLightweight()) {
59 return mark.hash();
60 }
61 ObjectMonitor monitor = mark.monitor();
62 Mark temp = monitor.header();
63 return temp.hash();
64 } else {
65 if (Assert.ASSERTS_ENABLED) {
66 Assert.that(VM.getVM().isDebugging(), "Can not access displaced header otherwise");
67 }
68 if (mark.hasDisplacedMarkHelper()) {
69 Mark temp = mark.displacedMarkHelper();
70 return temp.hash();
71 }
72 // FIXME: can not do anything else here in debugging system
73 return 0;
74 }
75 }
76
77 public static Iterator objectMonitorIterator() {
78 return new ObjectMonitorIterator();
79 }
80
81 private static class ObjectMonitorIterator implements Iterator {
82
83 // JVMTI raw monitors are not included in _in_use_list and
84 // are not returned by this Iterator.
85
86 ObjectMonitorIterator() {
87 mon = inUseListHead == null ? null : new ObjectMonitor(inUseListHead);
88 }
89
90 public boolean hasNext() {
91 return (mon != null);
92 }
93
94 public Object next() {
95 ObjectMonitor ret = mon;
96 if (ret == null) {
97 throw new NoSuchElementException();
98 }
99 // advance to next entry
100 Address nextMon = mon.nextOM();
101 mon = nextMon == null ? null : new ObjectMonitor(nextMon);
102
103 return ret;
104 }
105
106 public void remove() {
107 throw new UnsupportedOperationException();
108 }
109
110 private ObjectMonitor mon;
111 }
112
113 private static Address inUseListHead;
114
115 }