/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.wicket.util.instrument;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.lang.instrument.Instrumentation;
import org.apache.wicket.core.util.lang.WicketObjects.IObjectSizeOfStrategy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Object size of strategy that is based on instrumentation.
*
* @author eelcohillenius
*/
public class InstrumentationObjectSizeOfStrategy implements IObjectSizeOfStrategy
{
private static final Logger LOG = LoggerFactory.getLogger(InstrumentationObjectSizeOfStrategy.class);
/**
* Records the size of an object and it's dependents as if they were serialized but using the
* instrumentation API to calculate.
*/
private final class SizeRecodingOutputStream extends ObjectOutputStream
{
private long totalSize = 0;
/**
* Construct.
*
* @throws IOException
*/
public SizeRecodingOutputStream() throws IOException
{
super(new OutputStream()
{
@Override
public void write(int b) throws IOException
{
}
});
enableReplaceObject(true);
}
/**
* Gets the calculated size.
*
* @return
*/
public long getTotalSize()
{
return totalSize;
}
@Override
protected Object replaceObject(Object obj) throws IOException
{
if (obj != null)
{
totalSize += instrumentation.getObjectSize(obj);
}
return obj;
}
}
/**
* Instrumentation instance.
*/
private final Instrumentation instrumentation;
/**
* Construct.
*
* @param instrumentation
*/
public InstrumentationObjectSizeOfStrategy(Instrumentation instrumentation)
{
this.instrumentation = instrumentation;
}
/**
* Calculates full size of object iterating over its hierarchy graph.
*
* @param obj
* object to calculate size of
* @return object size
*
* @see org.apache.wicket.core.util.lang.WicketObjects.IObjectSizeOfStrategy#sizeOf(java.io.Serializable)
*/
@Override
public long sizeOf(Serializable obj)
{
if (obj == null)
{
return 0;
}
try
{
SizeRecodingOutputStream recorder = new SizeRecodingOutputStream();
recorder.writeObject(obj);
return recorder.getTotalSize();
}
catch (IOException e)
{
LOG.error("An error occurred while calculating the size of object: " + obj, e);
return -1;
}
}
}