JavaLazyReadObject.java revision 2779:56d1e05e0def 
1/*
2 * Copyright (c) 1997, 2017, 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    @Override
51    public final long getSize() {
52        return getValueLength() + getClazz().getMinimumObjectSize();
53    }
54
55    protected final long getOffset() {
56        return offset;
57    }
58
59    protected ReadBuffer buf() {
60        return getClazz().getReadBuffer();
61    }
62
63    protected int idSize() {
64        return getClazz().getIdentifierSize();
65    }
66
67    // return the length of the data for this object
68    protected final long getValueLength() {
69        try {
70            return readValueLength();
71        } catch (IOException exp) {
72            System.err.println("lazy read failed at offset " + offset);
73            exp.printStackTrace();
74            return 0;
75        }
76    }
77
78    // get this object's content as byte array
79    protected final JavaThing[] getValue() {
80        try {
81            return readValue();
82        } catch (IOException exp) {
83            System.err.println("lazy read failed at offset " + offset);
84            exp.printStackTrace();
85            return Snapshot.EMPTY_JAVATHING_ARRAY;
86        }
87    }
88
89    // get ID of this object
90    public final long getId() {
91        try {
92        if (idSize() == 4) {
93                return ((long)buf().getInt(offset)) & Snapshot.SMALL_ID_MASK;
94            } else {
95                return buf().getLong(offset);
96            }
97        } catch (IOException exp) {
98            System.err.println("lazy read failed at offset " + offset);
99            exp.printStackTrace();
100            return -1;
101        }
102    }
103
104    protected abstract long readValueLength() throws IOException;
105    protected abstract JavaThing[] readValue() throws IOException;
106
107    // make Integer or Long for given object ID
108    protected static Number makeId(long id) {
109        if ((id & ~Snapshot.SMALL_ID_MASK) == 0) {
110            return (int)id;
111        } else {
112            return id;
113        }
114    }
115
116    // get ID as long value from Number
117    protected static long getIdValue(Number num) {
118        long id = num.longValue();
119        if (num instanceof Integer) {
120            id &= Snapshot.SMALL_ID_MASK;
121        }
122        return id;
123    }
124
125    // read object ID from given index from given byte array
126    protected final long objectIdAt(long offset) throws IOException {
127        if (idSize() == 4) {
128            return ((long)intAt(offset)) & Snapshot.SMALL_ID_MASK;
129        } else {
130            return longAt(offset);
131        }
132    }
133
134    // utility methods to read primitive types from byte array
135    protected byte byteAt(long offset) throws IOException {
136        return buf().getByte(offset);
137    }
138
139    protected boolean booleanAt(long offset) throws IOException {
140        return byteAt(offset) == 0 ? false : true;
141    }
142
143    protected char charAt(long offset) throws IOException {
144        return buf().getChar(offset);
145    }
146
147    protected short shortAt(long offset) throws IOException {
148        return buf().getShort(offset);
149    }
150
151    protected int intAt(long offset) throws IOException {
152        return buf().getInt(offset);
153    }
154
155    protected long longAt(long offset) throws IOException {
156        return buf().getLong(offset);
157    }
158
159    protected float floatAt(long offset) throws IOException {
160        int val = intAt(offset);
161        return Float.intBitsToFloat(val);
162    }
163
164    protected double doubleAt(long offset) throws IOException {
165        long val = longAt(offset);
166        return Double.longBitsToDouble(val);
167    }
168}
169