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Ehcache is an open source, standards-based cache used to boost performance,
offload the database and simplify scalability. Ehcache is robust, proven and full-featured and
this has made it the most widely-used Java-based cache.
/**
* Copyright Terracotta, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.sf.ehcache.pool.sizeof;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Stack;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import net.sf.ehcache.pool.sizeof.filter.PassThroughFilter;
import net.sf.ehcache.pool.sizeof.filter.SizeOfFilter;
import static net.sf.ehcache.pool.sizeof.JvmInformation.CURRENT_JVM_INFORMATION;
/**
* SizeOf that uses reflection to measure on heap size of object graphs
*
* @author Alex Snaps
* @author Chris Dennis
*/
public class ReflectionSizeOf extends SizeOf {
private static final Logger LOGGER = LoggerFactory.getLogger(ReflectionSizeOf.class);
/**
* Builds a new SizeOf that will not filter fields and will cache reflected fields
* @see #ReflectionSizeOf(net.sf.ehcache.pool.sizeof.filter.SizeOfFilter, boolean)
*/
public ReflectionSizeOf() {
this(new PassThroughFilter());
}
/**
* Builds a new SizeOf that will filter fields and will cache reflected fields
* @param fieldFilter The filter to apply
* @see #ReflectionSizeOf(net.sf.ehcache.pool.sizeof.filter.SizeOfFilter, boolean)
* @see SizeOfFilter
*/
public ReflectionSizeOf(SizeOfFilter fieldFilter) {
this(fieldFilter, true);
}
/**
* Builds a new SizeOf that will filter fields
* @param fieldFilter The filter to apply
* @param caching Whether to cache reflected fields
* @see SizeOfFilter
*/
public ReflectionSizeOf(SizeOfFilter fieldFilter, boolean caching) {
super(fieldFilter, caching);
if (!CURRENT_JVM_INFORMATION.supportsReflectionSizeOf()) {
LOGGER.warn("ReflectionSizeOf is not always accurate on the JVM (" + CURRENT_JVM_INFORMATION.getJvmDescription() +
"). Please consider enabling AgentSizeOf.");
}
}
/**
* {@inheritDoc}
*/
@Override
public long sizeOf(Object obj) {
if (obj == null) {
return 0;
}
Class aClass = obj.getClass();
if (aClass.isArray()) {
return guessArraySize(obj);
} else {
long size = CURRENT_JVM_INFORMATION.getObjectHeaderSize();
Stack> classStack = new Stack>();
for (Class klazz = aClass; klazz != null; klazz = klazz.getSuperclass()) {
classStack.push(klazz);
}
while (!classStack.isEmpty()) {
Class klazz = classStack.pop();
//assuming default class layout
int oops = 0;
int doubles = 0;
int words = 0;
int shorts = 0;
int bytes = 0;
for (Field f : klazz.getDeclaredFields()) {
if (Modifier.isStatic(f.getModifiers())) {
continue;
}
if (f.getType().isPrimitive()) {
switch (PrimitiveType.forType(f.getType())) {
case BOOLEAN:
case BYTE:
bytes++;
break;
case SHORT:
case CHAR:
shorts++;
break;
case INT:
case FLOAT:
words++;
break;
case DOUBLE:
case LONG:
doubles++;
break;
default:
throw new AssertionError();
}
} else {
oops++;
}
}
if (doubles > 0 && (size % PrimitiveType.LONG.getSize()) != 0) {
long length = PrimitiveType.LONG.getSize() - (size % PrimitiveType.LONG.getSize());
size += PrimitiveType.LONG.getSize() - (size % PrimitiveType.LONG.getSize());
while (length >= PrimitiveType.INT.getSize() && words > 0) {
length -= PrimitiveType.INT.getSize();
words--;
}
while (length >= PrimitiveType.SHORT.getSize() && shorts > 0) {
length -= PrimitiveType.SHORT.getSize();
shorts--;
}
while (length >= PrimitiveType.BYTE.getSize() && bytes > 0) {
length -= PrimitiveType.BYTE.getSize();
bytes--;
}
while (length >= PrimitiveType.getReferenceSize() && oops > 0) {
length -= PrimitiveType.getReferenceSize();
oops--;
}
}
size += PrimitiveType.DOUBLE.getSize() * doubles;
size += PrimitiveType.INT.getSize() * words;
size += PrimitiveType.SHORT.getSize() * shorts;
size += PrimitiveType.BYTE.getSize() * bytes;
if (oops > 0) {
if ((size % PrimitiveType.getReferenceSize()) != 0) {
size += PrimitiveType.getReferenceSize() - (size % PrimitiveType.getReferenceSize());
}
size += oops * PrimitiveType.getReferenceSize();
}
if ((doubles + words + shorts + bytes + oops) > 0 && (size % CURRENT_JVM_INFORMATION.getPointerSize()) != 0) {
size += CURRENT_JVM_INFORMATION.getPointerSize() - (size % CURRENT_JVM_INFORMATION.getPointerSize());
}
}
if ((size % CURRENT_JVM_INFORMATION.getObjectAlignment()) != 0) {
size += CURRENT_JVM_INFORMATION.getObjectAlignment() - (size % CURRENT_JVM_INFORMATION.getObjectAlignment());
}
return Math.max(size, CURRENT_JVM_INFORMATION.getMinimumObjectSize());
}
}
private long guessArraySize(Object obj) {
long size = PrimitiveType.getArraySize();
int length = Array.getLength(obj);
if (length != 0) {
Class arrayElementClazz = obj.getClass().getComponentType();
if (arrayElementClazz.isPrimitive()) {
size += length * PrimitiveType.forType(arrayElementClazz).getSize();
} else {
size += length * PrimitiveType.getReferenceSize();
}
}
if ((size % CURRENT_JVM_INFORMATION.getObjectAlignment()) != 0) {
size += CURRENT_JVM_INFORMATION.getObjectAlignment() - (size % CURRENT_JVM_INFORMATION.getObjectAlignment());
}
return Math.max(size, CURRENT_JVM_INFORMATION.getMinimumObjectSize());
}
}