JavaLazyReadObject.java revision 2224:2a8815d86b93 
1/*
2 * Copyright (c) 1997, 2016, 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26
27/*
28 * The Original Code is HAT. The Initial Developer of the
29 * Original Code is Bill Foote, with contributions from others
30 * at JavaSoft/Sun.
31 */
32
33package jdk.test.lib.hprof.model;
34
35import java.io.IOException;
36import jdk.test.lib.hprof.parser.ReadBuffer;
37
38/*
39 * Base class for lazily read Java heap objects.
40 */
41public abstract class JavaLazyReadObject extends JavaHeapObject {
42
43    // file offset from which this object data starts
44    private final long offset;
45
46    protected JavaLazyReadObject(long offset) {
47        this.offset = offset;
48    }
49
50    public final int getSize() {
51        return getValueLength() + getClazz().getMinimumObjectSize();
52    }
53
54    protected final long getOffset() {
55        return offset;
56    }
57
58    // return the length of the data for this object
59    protected final int getValueLength() {
60        try {
61            return readValueLength();
62        } catch (IOException exp) {
63            System.err.println("lazy read failed at offset " + offset);
64            exp.printStackTrace();
65            return 0;
66        }
67    }
68
69    // get this object's content as byte array
70    protected final byte[] getValue() {
71        try {
72            return readValue();
73        } catch (IOException exp) {
74            System.err.println("lazy read failed at offset " + offset);
75            exp.printStackTrace();
76            return Snapshot.EMPTY_BYTE_ARRAY;
77        }
78    }
79
80    // get ID of this object
81    public final long getId() {
82        try {
83            ReadBuffer buf = getClazz().getReadBuffer();
84            int idSize = getClazz().getIdentifierSize();
85            if (idSize == 4) {
86                return ((long)buf.getInt(offset)) & Snapshot.SMALL_ID_MASK;
87            } else {
88                return buf.getLong(offset);
89            }
90        } catch (IOException exp) {
91            System.err.println("lazy read failed at offset " + offset);
92            exp.printStackTrace();
93            return -1;
94        }
95    }
96
97    protected abstract int readValueLength() throws IOException;
98    protected abstract byte[] readValue() throws IOException;
99
100    // make Integer or Long for given object ID
101    protected static Number makeId(long id) {
102        if ((id & ~Snapshot.SMALL_ID_MASK) == 0) {
103            return (int)id;
104        } else {
105            return id;
106        }
107    }
108
109    // get ID as long value from Number
110    protected static long getIdValue(Number num) {
111        long id = num.longValue();
112        if (num instanceof Integer) {
113            id &= Snapshot.SMALL_ID_MASK;
114        }
115        return id;
116    }
117
118    // read object ID from given index from given byte array
119    protected final long objectIdAt(int index, byte[] data) {
120        int idSize = getClazz().getIdentifierSize();
121        if (idSize == 4) {
122            return ((long)intAt(index, data)) & Snapshot.SMALL_ID_MASK;
123        } else {
124            return longAt(index, data);
125        }
126    }
127
128    // utility methods to read primitive types from byte array
129    protected static byte byteAt(int index, byte[] value) {
130        return value[index];
131    }
132
133    protected static boolean booleanAt(int index, byte[] value) {
134        return (value[index] & 0xff) == 0? false: true;
135    }
136
137    protected static char charAt(int index, byte[] value) {
138        int b1 = ((int) value[index++] & 0xff);
139        int b2 = ((int) value[index++] & 0xff);
140        return (char) ((b1 << 8) + b2);
141    }
142
143    protected static short shortAt(int index, byte[] value) {
144        int b1 = ((int) value[index++] & 0xff);
145        int b2 = ((int) value[index++] & 0xff);
146        return (short) ((b1 << 8) + b2);
147    }
148
149    protected static int intAt(int index, byte[] value) {
150        int b1 = ((int) value[index++] & 0xff);
151        int b2 = ((int) value[index++] & 0xff);
152        int b3 = ((int) value[index++] & 0xff);
153        int b4 = ((int) value[index++] & 0xff);
154        return ((b1 << 24) + (b2 << 16) + (b3 << 8) + b4);
155    }
156
157    protected static long longAt(int index, byte[] value) {
158        long val = 0;
159        for (int j = 0; j < 8; j++) {
160            val = val << 8;
161            int b = ((int)value[index++]) & 0xff;
162            val |= b;
163        }
164        return val;
165    }
166
167    protected static float floatAt(int index, byte[] value) {
168        int val = intAt(index, value);
169        return Float.intBitsToFloat(val);
170    }
171
172    protected static double doubleAt(int index, byte[] value) {
173        long val = longAt(index, value);
174        return Double.longBitsToDouble(val);
175    }
176}
177