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

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 2000-2001 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.runtime;
26
27 import java.util.*;
28 import sun.jvm.hotspot.debugger.*;
29 import sun.jvm.hotspot.runtime.*;
30 import sun.jvm.hotspot.types.*;
31 import sun.jvm.hotspot.utilities.*;
32
33 /** */
34 public class JNIHandleBlock extends VMObject {
35 private static Field handlesField;
36 private static CIntegerField topField;
37 private static AddressField nextField;
38
39 private static int blockSizeInOops;
40
41 static {
42 VM.registerVMInitializedObserver(new Observer() {
43 public void update(Observable o, Object data) {
44 initialize(VM.getVM().getTypeDataBase());
45 }
46 });
47 }
48
49 private static synchronized void initialize(TypeDataBase db) {
50 Type type = db.lookupType("JNIHandleBlock");
51
52 handlesField = type.getField("_handles");
53 topField = type.getCIntegerField("_top");
54 nextField = type.getAddressField("_next");
55
56 blockSizeInOops = db.lookupIntConstant("JNIHandleBlock::block_size_in_oops").intValue();
57 }
58
59 public JNIHandleBlock(Address addr) {
60 super(addr);
61 }
62
63 public JNIHandleBlock next() {
64 Address handleAddr = nextField.getValue(addr);
65 if (handleAddr == null) {
66 return null;
67 }
68
69 /* the next handle block is valid only if the current block is full */
70 if (top() < blockSizeInOops) {
71 return null;
72 }
73 return new JNIHandleBlock(handleAddr);
74 }
75
76 public int top() {
77 return (int) topField.getValue(addr);
78 }
79
80 public void oopsDo(AddressVisitor visitor) {
81 // Visit handles in this block
82 for (int i = 0; i < top(); i++) {
83 Address cur = getOopHandleAddress(i);
84 if (cur != null) {
85 visitor.visitAddress(cur);
86 }
87 }
88
89 // Visit handles in subsequent blocks if necessary
90 JNIHandleBlock n = next();
91 if (n != null) {
92 n.oopsDo(visitor);
93 }
94 }
95
96 public OopHandle getOopHandle(int x) {
97 Address oopAddr = getOopHandleAddress(x);
98 if (oopAddr != null) {
99 return oopAddr.getOopHandleAt(0);
100 }
101 return null;
102 }
103
104 /** Debugging routine only. Returns non-null JNIHandleBlock
105 containing the JNI handle or null if this handle block and its
106 successors did not contain it (or if the handle was deleted). */
107 public JNIHandleBlock blockContainingHandle(Address jniHandle) {
108 JNIHandleBlock cur = this;
109 while (cur != null) {
110 if (indexOfHandle(jniHandle) >= 0) {
111 return cur;
112 }
113 cur = cur.next();
114 }
115 return null;
116 }
117
118 /** Debugging routine: returns the index (0..top() - 1) of the
119 handle in this block, or -1 if the handle was not contained in
120 this block. Does not search successor blocks. */
121 public int indexOfHandle(Address jniHandle) {
122 for (int i = 0; i < top(); i++) {
123 Address addr = getOopHandleAddress(i);
124 if (addr != null) {
125 if (addr.equals(jniHandle)) {
126 return i;
127 }
128 }
129 }
130 return -1;
131 }
132
133 public String toString() {
134 Address handleBase = addr.addOffsetTo(handlesField.getOffset());
135 Address handleEnd = addr.addOffsetTo(handlesField.getOffset() + top() * VM.getVM().getOopSize());
136 return "JNIHandleBlock [" + handleBase + ", " + handleEnd + ")";
137 }
138
139 /** Only returns addresses of valid OopHandles */
140 private Address getOopHandleAddress(int x) {
141 if (Assert.ASSERTS_ENABLED) {
142 Assert.that(x < top(), "out of bounds");
143 }
144
145 Address oopAddr = addr.addOffsetTo(handlesField.getOffset() + x * VM.getVM().getOopSize());
146 OopHandle handle = oopAddr.getOopHandleAt(0);
147 if (VM.getVM().getUniverse().isInReserved(handle) && !VM.getVM().getJNIHandles().isDeletedHandle(handle)) {
148 /* the oop handle is valid only if it is not freed (i.e. reserved in heap) and is not a deleted oop */
149 return oopAddr;
150 } else {
151 return null;
152 }
153 }
154 }