org.apache.mina.filter.executor.DefaultIoEventSizeEstimator Maven / Gradle / Ivy
/**
* Copyright 2007-2015, Kaazing Corporation. All rights reserved.
*
* 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 org.apache.mina.filter.executor;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoEvent;
import org.apache.mina.core.write.WriteRequest;
/**
* A default {@link IoEventSizeEstimator} implementation.
*
* Martin's Java Notes
* was used for estimation. For unknown types, it inspects declaring fields of the
* class of the specified event and the parameter of the event. The size of unknown
* declaring fields are approximated to the specified averageSizePerField
* (default: 64).
*
* All the estimated sizes of classes are cached for performance improvement.
*
* @author Apache MINA Project
*/
public class DefaultIoEventSizeEstimator implements IoEventSizeEstimator {
/** A map containing the estimated size of each Java objects we know for */
private final ConcurrentMap, Integer> class2size = new ConcurrentHashMap, Integer>();
/**
* Create a new instance of this class, injecting the known size of
* basic java types.
*/
public DefaultIoEventSizeEstimator() {
class2size.put(boolean.class, 4); // Probably an integer.
class2size.put(byte.class, 1);
class2size.put(char.class, 2);
class2size.put(int.class, 4);
class2size.put(short.class, 2);
class2size.put(long.class, 8);
class2size.put(float.class, 4);
class2size.put(double.class, 8);
class2size.put(void.class, 0);
}
/**
* {@inheritDoc}
*/
public int estimateSize(IoEvent event) {
return estimateSize((Object) event) + estimateSize(event.getParameter());
}
/**
* Estimate the size of an Objecr in number of bytes
* @param message The object to estimate
* @return The estimated size of the object
*/
public int estimateSize(Object message) {
if (message == null) {
return 8;
}
int answer = 8 + estimateSize(message.getClass(), null);
if (message instanceof IoBuffer) {
answer += ((IoBuffer) message).remaining();
} else if (message instanceof WriteRequest) {
answer += estimateSize(((WriteRequest) message).getMessage());
} else if (message instanceof CharSequence) {
answer += ((CharSequence) message).length() << 1;
} else if (message instanceof Iterable) {
for (Object m: (Iterable) message) {
answer += estimateSize(m);
}
}
return align(answer);
}
private int estimateSize(Class clazz, Set> visitedClasses) {
Integer objectSize = class2size.get(clazz);
if (objectSize != null) {
return objectSize;
}
if (visitedClasses != null) {
if (visitedClasses.contains(clazz)) {
return 0;
}
} else {
visitedClasses = new HashSet>();
}
visitedClasses.add(clazz);
int answer = 8; // Basic overhead.
for (Class c = clazz; c != null; c = c.getSuperclass()) {
Field[] fields = c.getDeclaredFields();
for (Field f: fields) {
if ((f.getModifiers() & Modifier.STATIC) != 0) {
// Ignore static fields.
continue;
}
answer += estimateSize(f.getType(), visitedClasses);
}
}
visitedClasses.remove(clazz);
// Some alignment.
answer = align(answer);
// Put the final answer.
class2size.putIfAbsent(clazz, answer);
return answer;
}
private static int align(int size) {
if (size % 8 != 0) {
size /= 8;
size ++;
size *= 8;
}
return size;
}
}