001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.wicket.util.instrument; 018 019import java.io.IOException; 020import java.io.ObjectOutputStream; 021import java.io.OutputStream; 022import java.io.Serializable; 023import java.lang.instrument.Instrumentation; 024 025import org.apache.wicket.core.util.lang.WicketObjects.IObjectSizeOfStrategy; 026import org.slf4j.Logger; 027import org.slf4j.LoggerFactory; 028 029/** 030 * Object size of strategy that is based on instrumentation. 031 * 032 * @author eelcohillenius 033 */ 034public class InstrumentationObjectSizeOfStrategy implements IObjectSizeOfStrategy 035{ 036 037 private static final Logger LOG = LoggerFactory.getLogger(InstrumentationObjectSizeOfStrategy.class); 038 039 /** 040 * Records the size of an object and it's dependents as if they were serialized but using the 041 * instrumentation API to calculate. 042 */ 043 private final class SizeRecodingOutputStream extends ObjectOutputStream 044 { 045 046 private long totalSize = 0; 047 048 /** 049 * Construct. 050 * 051 * @throws IOException 052 */ 053 public SizeRecodingOutputStream() throws IOException 054 { 055 super(new OutputStream() 056 { 057 058 @Override 059 public void write(int b) throws IOException 060 { 061 } 062 }); 063 enableReplaceObject(true); 064 } 065 066 /** 067 * Gets the calculated size. 068 * 069 * @return 070 */ 071 public long getTotalSize() 072 { 073 return totalSize; 074 } 075 076 @Override 077 protected Object replaceObject(Object obj) throws IOException 078 { 079 080 if (obj != null) 081 { 082 totalSize += instrumentation.getObjectSize(obj); 083 } 084 085 return obj; 086 } 087 } 088 089 /** 090 * Instrumentation instance. 091 */ 092 private final Instrumentation instrumentation; 093 094 /** 095 * Construct. 096 * 097 * @param instrumentation 098 */ 099 public InstrumentationObjectSizeOfStrategy(Instrumentation instrumentation) 100 { 101 this.instrumentation = instrumentation; 102 } 103 104 /** 105 * Calculates full size of object iterating over its hierarchy graph. 106 * 107 * @param obj 108 * object to calculate size of 109 * @return object size 110 * 111 * @see org.apache.wicket.core.util.lang.WicketObjects.IObjectSizeOfStrategy#sizeOf(java.io.Serializable) 112 */ 113 @Override 114 public long sizeOf(Serializable obj) 115 { 116 if (obj == null) 117 { 118 return 0; 119 } 120 try 121 { 122 SizeRecodingOutputStream recorder = new SizeRecodingOutputStream(); 123 recorder.writeObject(obj); 124 return recorder.getTotalSize(); 125 } 126 catch (IOException e) 127 { 128 LOG.error("An error occurred while calculating the size of object: " + obj, e); 129 return -1; 130 } 131 132 } 133}