branch-2.0.4-alpha/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/bloom/RemoveScheme.java

/**
 *
 * Copyright (c) 2005, European Commission project OneLab under contract 034819
 * (http://www.one-lab.org)
 * 
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
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 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in 
 *    the documentation and/or other materials provided with the distribution.
 *  - Neither the name of the University Catholique de Louvain - UCL
 *    nor the names of its contributors may be used to endorse or 
 *    promote products derived from this software without specific prior 
 *    written permission.
 *    
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
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/**
 * 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
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 *
 *     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,
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package org.apache.hadoop.util.bloom;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * Defines the different remove scheme for retouched Bloom filters.
 * <p>
 * Originally created by
 * <a href="http://www.one-lab.org">European Commission One-Lab Project 034819</a>.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public interface RemoveScheme {
  /**
   * Random selection.
   * <p>
   * The idea is to randomly select a bit to reset.
   */
  public final static short RANDOM = 0;

  /**
   * MinimumFN Selection.
   * <p>
   * The idea is to select the bit to reset that will generate the minimum
   * number of false negative.
   */
  public final static short MINIMUM_FN = 1;

  /**
   * MaximumFP Selection.
   * <p>
   * The idea is to select the bit to reset that will remove the maximum number
   * of false positive.
   */
  public final static short MAXIMUM_FP = 2;

  /**
   * Ratio Selection.
   * <p>
   * The idea is to select the bit to reset that will, at the same time, remove
   * the maximum number of false positve while minimizing the amount of false
   * negative generated.
   */
  public final static short RATIO = 3;
}