1 /***
2 * Copyright 2003-2010 Terracotta, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.pool.sizeof;
18
19 import java.lang.reflect.Array;
20 import java.lang.reflect.Field;
21 import java.lang.reflect.Modifier;
22
23 import net.sf.ehcache.pool.sizeof.filter.PassThroughFilter;
24 import net.sf.ehcache.pool.sizeof.filter.SizeOfFilter;
25
26 import sun.misc.Unsafe;
27
28 import static net.sf.ehcache.pool.sizeof.JvmInformation.MINIMUM_OBJECT_SIZE;
29 import static net.sf.ehcache.pool.sizeof.JvmInformation.OBJECT_ALIGNMENT;
30
31 /***
32 * {@link sun.misc.Unsafe#theUnsafe} based sizeOf measurement
33 * All constructors will throw UnsupportedOperationException if theUnsafe isn't accessible on this platform
34 * @author Chris Dennis
35 */
36 @SuppressWarnings("restriction")
37 public class UnsafeSizeOf extends SizeOf {
38
39 private static final Unsafe UNSAFE;
40
41 static {
42 Unsafe unsafe;
43 try {
44 Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
45 unsafeField.setAccessible(true);
46 unsafe = (Unsafe)unsafeField.get(null);
47 } catch (Throwable t) {
48 unsafe = null;
49 }
50 UNSAFE = unsafe;
51 }
52
53 /***
54 * Builds a new SizeOf that will not filter fields and will cache reflected fields
55 *
56 * @throws UnsupportedOperationException If Unsafe isn't accessible
57 * @see #UnsafeSizeOf(net.sf.ehcache.pool.sizeof.filter.SizeOfFilter, boolean)
58 */
59 public UnsafeSizeOf() throws UnsupportedOperationException {
60 this(new PassThroughFilter());
61 }
62
63 /***
64 * Builds a new SizeOf that will filter fields according to the provided filter and will cache reflected fields
65 *
66 * @param filter The filter to apply
67 * @throws UnsupportedOperationException If Unsafe isn't accessible
68 * @see #UnsafeSizeOf(net.sf.ehcache.pool.sizeof.filter.SizeOfFilter, boolean)
69 * @see SizeOfFilter
70 */
71 public UnsafeSizeOf(SizeOfFilter filter) throws UnsupportedOperationException {
72 this(filter, true);
73 }
74
75 /***
76 * Builds a new SizeOf that will filter fields according to the provided filter
77 *
78 * @param filter The filter to apply
79 * @param caching whether to cache reflected fields
80 * @throws UnsupportedOperationException If Unsafe isn't accessible
81 * @see SizeOfFilter
82 */
83 public UnsafeSizeOf(SizeOfFilter filter, boolean caching) throws UnsupportedOperationException {
84 super(filter, caching);
85 if (UNSAFE == null) {
86 throw new UnsupportedOperationException("sun.misc.Unsafe instance not accessible");
87 }
88 }
89
90 /***
91 * {@inheritDoc}
92 */
93 @Override
94 protected long measureSizeOf(Object obj) {
95 if (obj.getClass().isArray()) {
96 Class<?> klazz = obj.getClass();
97 int base = UNSAFE.arrayBaseOffset(klazz);
98 int scale = UNSAFE.arrayIndexScale(klazz);
99 long size = base + (scale * Array.getLength(obj));
100 if ((size % OBJECT_ALIGNMENT) != 0) {
101 size += OBJECT_ALIGNMENT - (size % OBJECT_ALIGNMENT);
102 }
103 return Math.max(MINIMUM_OBJECT_SIZE, size);
104 } else {
105 for (Class<?> klazz = obj.getClass(); klazz != null; klazz = klazz.getSuperclass()) {
106 long lastFieldOffset = -1;
107 for (Field f : klazz.getDeclaredFields()) {
108 if (!Modifier.isStatic(f.getModifiers())) {
109 lastFieldOffset = Math.max(lastFieldOffset, UNSAFE.objectFieldOffset(f));
110 }
111 }
112 if (lastFieldOffset > 0) {
113 lastFieldOffset += 1;
114 if ((lastFieldOffset % OBJECT_ALIGNMENT) != 0) {
115 lastFieldOffset += OBJECT_ALIGNMENT - (lastFieldOffset % OBJECT_ALIGNMENT);
116 }
117 return Math.max(MINIMUM_OBJECT_SIZE, lastFieldOffset);
118 }
119 }
120
121 long size = PrimitiveType.CLASS.getSize();
122 if ((size % OBJECT_ALIGNMENT) != 0) {
123 size += OBJECT_ALIGNMENT - (size % OBJECT_ALIGNMENT);
124 }
125 return Math.max(MINIMUM_OBJECT_SIZE, size);
126 }
127 }
128
129 }