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1 /*
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2 * Copyright 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.runtime;
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26
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27 import java.util.*;
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28 import sun.jvm.hotspot.debugger.*;
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29 import sun.jvm.hotspot.runtime.*;
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30 import sun.jvm.hotspot.types.*;
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31 import sun.jvm.hotspot.utilities.*;
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32
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33 /** */
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34 public class JNIHandleBlock extends VMObject {
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35 private static Field handlesField;
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36 private static CIntegerField topField;
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37 private static AddressField nextField;
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38
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39 private static int blockSizeInOops;
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40
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41 static {
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42 VM.registerVMInitializedObserver(new Observer() {
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43 public void update(Observable o, Object data) {
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44 initialize(VM.getVM().getTypeDataBase());
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45 }
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46 });
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47 }
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48
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49 private static synchronized void initialize(TypeDataBase db) {
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50 Type type = db.lookupType("JNIHandleBlock");
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51
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52 handlesField = type.getField("_handles");
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53 topField = type.getCIntegerField("_top");
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54 nextField = type.getAddressField("_next");
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55
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56 blockSizeInOops = db.lookupIntConstant("JNIHandleBlock::block_size_in_oops").intValue();
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57 }
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58
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59 public JNIHandleBlock(Address addr) {
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60 super(addr);
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61 }
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62
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63 public JNIHandleBlock next() {
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64 Address handleAddr = nextField.getValue(addr);
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65 if (handleAddr == null) {
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66 return null;
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67 }
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68
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69 /* the next handle block is valid only if the current block is full */
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70 if (top() < blockSizeInOops) {
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71 return null;
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72 }
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73 return new JNIHandleBlock(handleAddr);
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74 }
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75
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76 public int top() {
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77 return (int) topField.getValue(addr);
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78 }
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79
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80 public void oopsDo(AddressVisitor visitor) {
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81 // Visit handles in this block
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82 for (int i = 0; i < top(); i++) {
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83 Address cur = getOopHandleAddress(i);
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84 if (cur != null) {
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85 visitor.visitAddress(cur);
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86 }
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87 }
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88
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89 // Visit handles in subsequent blocks if necessary
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90 JNIHandleBlock n = next();
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91 if (n != null) {
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92 n.oopsDo(visitor);
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93 }
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94 }
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95
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96 public OopHandle getOopHandle(int x) {
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97 Address oopAddr = getOopHandleAddress(x);
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98 if (oopAddr != null) {
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99 return oopAddr.getOopHandleAt(0);
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100 }
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101 return null;
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102 }
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103
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104 /** Debugging routine only. Returns non-null JNIHandleBlock
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105 containing the JNI handle or null if this handle block and its
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106 successors did not contain it (or if the handle was deleted). */
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107 public JNIHandleBlock blockContainingHandle(Address jniHandle) {
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108 JNIHandleBlock cur = this;
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109 while (cur != null) {
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110 if (indexOfHandle(jniHandle) >= 0) {
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111 return cur;
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112 }
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113 cur = cur.next();
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114 }
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115 return null;
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116 }
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117
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118 /** Debugging routine: returns the index (0..top() - 1) of the
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119 handle in this block, or -1 if the handle was not contained in
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120 this block. Does not search successor blocks. */
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121 public int indexOfHandle(Address jniHandle) {
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122 for (int i = 0; i < top(); i++) {
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123 Address addr = getOopHandleAddress(i);
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124 if (addr != null) {
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125 if (addr.equals(jniHandle)) {
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126 return i;
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127 }
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128 }
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129 }
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130 return -1;
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131 }
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132
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133 public String toString() {
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134 Address handleBase = addr.addOffsetTo(handlesField.getOffset());
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135 Address handleEnd = addr.addOffsetTo(handlesField.getOffset() + top() * VM.getVM().getOopSize());
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136 return "JNIHandleBlock [" + handleBase + ", " + handleEnd + ")";
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137 }
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138
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139 /** Only returns addresses of valid OopHandles */
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140 private Address getOopHandleAddress(int x) {
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141 if (Assert.ASSERTS_ENABLED) {
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142 Assert.that(x < top(), "out of bounds");
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143 }
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144
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145 Address oopAddr = addr.addOffsetTo(handlesField.getOffset() + x * VM.getVM().getOopSize());
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146 OopHandle handle = oopAddr.getOopHandleAt(0);
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147 if (VM.getVM().getUniverse().isInReserved(handle) && !VM.getVM().getJNIHandles().isDeletedHandle(handle)) {
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148 /* the oop handle is valid only if it is not freed (i.e. reserved in heap) and is not a deleted oop */
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149 return oopAddr;
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150 } else {
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151 return null;
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152 }
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153 }
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154 }
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