1 /*
2 * Copyright (c) 1997, 2015, 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
33 package jdk.test.lib.hprof.model;
34
35 import java.util.Enumeration;
36 import java.util.HashMap;
37 import java.util.Map;
38 import jdk.test.lib.hprof.util.Misc;
39
40
41 /**
42 *
43 * @author Bill Foote
44 */
45
46 /**
47 * Represents an object that's allocated out of the Java heap. It occupies
48 * memory in the VM, and is the sort of thing that in a JDK 1.1 VM had
49 * a handle. It can be a
50 * JavaClass, a JavaObjectArray, a JavaValueArray or a JavaObject.
51 */
52
53 public abstract class JavaHeapObject extends JavaThing {
54
55 //
56 // Who we refer to. This is heavily optimized for space, because it's
57 // well worth trading a bit of speed for less swapping.
58 // referers and referersLen go through two phases: Building and
59 // resolved. When building, referers might have duplicates, but can
60 // be appended to. When resolved, referers has no duplicates or
61 // empty slots.
62 //
63 private JavaThing[] referers = null;
64 private int referersLen = 0; // -1 when resolved
65
66 public abstract JavaClass getClazz();
67 public abstract int getSize();
68 public abstract long getId();
69
70 /**
71 * Do any initialization this thing needs after its data is read in.
72 * Subclasses that override this should call super.resolve().
73 */
74 public void resolve(Snapshot snapshot) {
75 StackTrace trace = snapshot.getSiteTrace(this);
76 if (trace != null) {
77 trace.resolve(snapshot);
78 }
79 }
80
81 //
82 // Eliminate duplicates from referers, and size the array exactly.
83 // This sets us up to answer queries. See the comments around the
84 // referers data member for details.
85 //
86 void setupReferers() {
87 if (referersLen > 1) {
88 // Copy referers to map, screening out duplicates
89 Map<JavaThing, JavaThing> map = new HashMap<JavaThing, JavaThing>();
90 for (int i = 0; i < referersLen; i++) {
91 if (map.get(referers[i]) == null) {
92 map.put(referers[i], referers[i]);
93 }
94 }
95
96 // Now copy into the array
97 referers = new JavaThing[map.size()];
98 map.keySet().toArray(referers);
99 }
100 referersLen = -1;
101 }
102
103
104 /**
105 * @return the id of this thing as hex string
106 */
107 public String getIdString() {
108 return Misc.toHex(getId());
109 }
110
111 public String toString() {
112 return getClazz().getName() + "@" + getIdString();
113 }
114
115 /**
116 * @return the StackTrace of the point of allocation of this object,
117 * or null if unknown
118 */
119 public StackTrace getAllocatedFrom() {
120 return getClazz().getSiteTrace(this);
121 }
122
123 public boolean isNew() {
124 return getClazz().isNew(this);
125 }
126
127 void setNew(boolean flag) {
128 getClazz().setNew(this, flag);
129 }
130
131 /**
132 * Tell the visitor about all of the objects we refer to
133 */
134 public void visitReferencedObjects(JavaHeapObjectVisitor v) {
135 v.visit(getClazz());
136 }
137
138 void addReferenceFrom(JavaHeapObject other) {
139 if (referersLen == 0) {
140 referers = new JavaThing[1]; // It was null
141 } else if (referersLen == referers.length) {
142 JavaThing[] copy = new JavaThing[(3 * (referersLen + 1)) / 2];
143 System.arraycopy(referers, 0, copy, 0, referersLen);
144 referers = copy;
145 }
146 referers[referersLen++] = other;
147 // We just append to referers here. Measurements have shown that
148 // around 10% to 30% are duplicates, so it's better to just append
149 // blindly and screen out all the duplicates at once.
150 }
151
152 void addReferenceFromRoot(Root r) {
153 getClazz().addReferenceFromRoot(r, this);
154 }
155
156 /**
157 * If the rootset includes this object, return a Root describing one
158 * of the reasons why.
159 */
160 public Root getRoot() {
161 return getClazz().getRoot(this);
162 }
163
164 /**
165 * Tell who refers to us.
166 *
167 * @return an Enumeration of JavaHeapObject instances
168 */
169 public Enumeration<JavaThing> getReferers() {
170 if (referersLen != -1) {
171 throw new RuntimeException("not resolved: " + getIdString());
172 }
173 return new Enumeration<JavaThing>() {
174
175 private int num = 0;
176
177 public boolean hasMoreElements() {
178 return referers != null && num < referers.length;
179 }
180
181 public JavaThing nextElement() {
182 return referers[num++];
183 }
184 };
185 }
186
187 /**
188 * Given other, which the caller promises is in referers, determines if
189 * the reference is only a weak reference.
190 */
191 public boolean refersOnlyWeaklyTo(Snapshot ss, JavaThing other) {
192 return false;
193 }
194
195 /**
196 * Describe the reference that this thing has to target. This will only
197 * be called if target is in the array returned by getChildrenForRootset.
198 */
199 public String describeReferenceTo(JavaThing target, Snapshot ss) {
200 return "??";
201 }
202
203 public boolean isHeapAllocated() {
204 return true;
205 }
206
207 }