/**
* Copyright The Apache Software Foundation
*
* 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.hadoop.hbase.io;
import org.apache.hadoop.classification.InterfaceAudience;
/**
* Implementations can be asked for an estimate of their size in bytes.
* <p>
* Useful for sizing caches. Its a given that implementation approximations
* do not account for 32 vs 64 bit nor for different VM implementations.
* <p>
* An Object's size is determined by the non-static data members in it,
* as well as the fixed {@link Object} overhead.
* <p>
* For example:
* <pre>
* public class SampleObject implements HeapSize {
*
* int [] numbers;
* int x;
* }
* </pre>
*/
@InterfaceAudience.Private
public interface HeapSize {
/**
* @return Approximate 'exclusive deep size' of implementing object. Includes
* count of payload and hosting object sizings.
*/
public long heapSize();
}