/*
* 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.geode.internal.cache.lru;
/**
* An interface that allows an object to define its own size.<br>
*
* <b>Sample Implementation</b><br>
* <code>public int getSizeInBytes(){</code><br>
* // The sizes of the primitive as well as object instance variables are calculated:<br>
*
* <code>int size = 0;</code><br>
*
* // Add overhead for this instance.<br>
* <code>size += Sizeable.PER_OBJECT_OVERHEAD;</code><br>
*
* // Add object references (implements Sizeable)<br>
* // value reference = 4 bytes <br>
*
* <code>size += 4;</code><br>
*
* // Add primitive instance variable size<br>
* // byte bytePr = 1 byte<br>
* // boolean flag = 1 byte<br>
*
* <code>size += 2;</code><br>
*
* // Add individual object size<br>
* <code>size += (value.getSizeInBytes());</code><br>
*
* <code>return size;</code><br>
* }<br>
*
*
* @since GemFire 3.2
*/
public interface Sizeable {
/** The overhead of an object in the VM in bytes */
public static final int PER_OBJECT_OVERHEAD = 8; // TODO for a 64bit jvm with small oops this is
// 12; for other 64bit jvms it is 16
/**
* Returns the size (in bytes) of this object including the {@link #PER_OBJECT_OVERHEAD}.
*/
public int getSizeInBytes();
}