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comparison agent/src/share/classes/sun/jvm/hotspot/utilities/BasicHashtableEntry.java @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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children c18cbe5936b8
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 2003-2004 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 package sun.jvm.hotspot.utilities;
26
27 import java.util.*;
28 import sun.jvm.hotspot.debugger.*;
29 import sun.jvm.hotspot.oops.Oop;
30 import sun.jvm.hotspot.oops.ObjectHeap;
31 import sun.jvm.hotspot.types.*;
32 import sun.jvm.hotspot.runtime.*;
33
34 public class BasicHashtableEntry extends VMObject {
35 static {
36 VM.registerVMInitializedObserver(new Observer() {
37 public void update(Observable o, Object data) {
38 initialize(VM.getVM().getTypeDataBase());
39 }
40 });
41 }
42
43 private static synchronized void initialize(TypeDataBase db) {
44 Type type = db.lookupType("BasicHashtableEntry");
45 hashField = type.getCIntegerField("_hash");
46 nextField = type.getAddressField("_next");
47 }
48
49 // Fields
50 private static CIntegerField hashField;
51 private static AddressField nextField;
52
53 // Accessors
54 public long hash() {
55 return hashField.getValue(addr) & 0xFFFFFFFFL;
56 }
57
58 private long nextAddressValue() {
59 Debugger dbg = VM.getVM().getDebugger();
60 Address nextValue = nextField.getValue(addr);
61 return (nextValue != null) ? dbg.getAddressValue(nextValue) : 0L;
62 }
63
64 public boolean isShared() {
65 return (nextAddressValue() & 1L) != 0;
66 }
67
68 public BasicHashtableEntry next() {
69 Address nextValue = nextField.getValue(addr);
70 Address next = (nextValue != null)? nextValue.andWithMask(-2L) : null;
71 // using this.getClass so that return type will be as expected in
72 // subclass context. But, because we can't use covariant return type
73 // caller has to use this next and cast the result to correct type.
74 return (BasicHashtableEntry) VMObjectFactory.newObject(this.getClass(), next);
75 }
76
77 public BasicHashtableEntry(Address addr) {
78 super(addr);
79 }
80 }