| /** |
| * |
| * 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: |
| * - Redistributions of source code must retain the above copyright |
| * 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 |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
| * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| * POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** |
| * 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.util.bloom; |
| |
| import java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.List; |
| import java.util.Random; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * Implements a <i>retouched Bloom filter</i>, as defined in the CoNEXT 2006 paper. |
| * <p> |
| * It allows the removal of selected false positives at the cost of introducing |
| * random false negatives, and with the benefit of eliminating some random false |
| * positives at the same time. |
| * |
| * <p> |
| * Originally created by |
| * <a href="http://www.one-lab.org">European Commission One-Lab Project 034819</a>. |
| * |
| * @see Filter The general behavior of a filter |
| * @see BloomFilter A Bloom filter |
| * @see RemoveScheme The different selective clearing algorithms |
| * |
| * @see <a href="http://www-rp.lip6.fr/site_npa/site_rp/_publications/740-rbf_cameraready.pdf">Retouched Bloom Filters: Allowing Networked Applications to Trade Off Selected False Positives Against False Negatives</a> |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public final class RetouchedBloomFilter extends BloomFilter |
| implements RemoveScheme { |
| /** |
| * KeyList vector (or ElementList Vector, as defined in the paper) of false positives. |
| */ |
| List<Key>[] fpVector; |
| |
| /** |
| * KeyList vector of keys recorded in the filter. |
| */ |
| List<Key>[] keyVector; |
| |
| /** |
| * Ratio vector. |
| */ |
| double[] ratio; |
| |
| private Random rand; |
| |
| /** Default constructor - use with readFields */ |
| public RetouchedBloomFilter() {} |
| |
| /** |
| * Constructor |
| * @param vectorSize The vector size of <i>this</i> filter. |
| * @param nbHash The number of hash function to consider. |
| * @param hashType type of the hashing function (see |
| * {@link org.apache.hadoop.util.hash.Hash}). |
| */ |
| public RetouchedBloomFilter(int vectorSize, int nbHash, int hashType) { |
| super(vectorSize, nbHash, hashType); |
| |
| this.rand = null; |
| createVector(); |
| } |
| |
| @Override |
| public void add(Key key) { |
| if (key == null) { |
| throw new NullPointerException("key can not be null"); |
| } |
| |
| int[] h = hash.hash(key); |
| hash.clear(); |
| |
| for (int i = 0; i < nbHash; i++) { |
| bits.set(h[i]); |
| keyVector[h[i]].add(key); |
| } |
| } |
| |
| /** |
| * Adds a false positive information to <i>this</i> retouched Bloom filter. |
| * <p> |
| * <b>Invariant</b>: if the false positive is <code>null</code>, nothing happens. |
| * @param key The false positive key to add. |
| */ |
| public void addFalsePositive(Key key) { |
| if (key == null) { |
| throw new NullPointerException("key can not be null"); |
| } |
| |
| int[] h = hash.hash(key); |
| hash.clear(); |
| |
| for (int i = 0; i < nbHash; i++) { |
| fpVector[h[i]].add(key); |
| } |
| } |
| |
| /** |
| * Adds a collection of false positive information to <i>this</i> retouched Bloom filter. |
| * @param coll The collection of false positive. |
| */ |
| public void addFalsePositive(Collection<Key> coll) { |
| if (coll == null) { |
| throw new NullPointerException("Collection<Key> can not be null"); |
| } |
| |
| for (Key k : coll) { |
| addFalsePositive(k); |
| } |
| } |
| |
| /** |
| * Adds a list of false positive information to <i>this</i> retouched Bloom filter. |
| * @param keys The list of false positive. |
| */ |
| public void addFalsePositive(List<Key> keys) { |
| if (keys == null) { |
| throw new NullPointerException("ArrayList<Key> can not be null"); |
| } |
| |
| for (Key k : keys) { |
| addFalsePositive(k); |
| } |
| } |
| |
| /** |
| * Adds an array of false positive information to <i>this</i> retouched Bloom filter. |
| * @param keys The array of false positive. |
| */ |
| public void addFalsePositive(Key[] keys) { |
| if (keys == null) { |
| throw new NullPointerException("Key[] can not be null"); |
| } |
| |
| for (int i = 0; i < keys.length; i++) { |
| addFalsePositive(keys[i]); |
| } |
| } |
| |
| /** |
| * Performs the selective clearing for a given key. |
| * @param k The false positive key to remove from <i>this</i> retouched Bloom filter. |
| * @param scheme The selective clearing scheme to apply. |
| */ |
| public void selectiveClearing(Key k, short scheme) { |
| if (k == null) { |
| throw new NullPointerException("Key can not be null"); |
| } |
| |
| if (!membershipTest(k)) { |
| throw new IllegalArgumentException("Key is not a member"); |
| } |
| |
| int index = 0; |
| int[] h = hash.hash(k); |
| |
| switch(scheme) { |
| |
| case RANDOM: |
| index = randomRemove(); |
| break; |
| |
| case MINIMUM_FN: |
| index = minimumFnRemove(h); |
| break; |
| |
| case MAXIMUM_FP: |
| index = maximumFpRemove(h); |
| break; |
| |
| case RATIO: |
| index = ratioRemove(h); |
| break; |
| |
| default: |
| throw new AssertionError("Undefined selective clearing scheme"); |
| |
| } |
| |
| clearBit(index); |
| } |
| |
| private int randomRemove() { |
| if (rand == null) { |
| rand = new Random(); |
| } |
| |
| return rand.nextInt(nbHash); |
| } |
| |
| /** |
| * Chooses the bit position that minimizes the number of false negative generated. |
| * @param h The different bit positions. |
| * @return The position that minimizes the number of false negative generated. |
| */ |
| private int minimumFnRemove(int[] h) { |
| int minIndex = Integer.MAX_VALUE; |
| double minValue = Double.MAX_VALUE; |
| |
| for (int i = 0; i < nbHash; i++) { |
| double keyWeight = getWeight(keyVector[h[i]]); |
| |
| if (keyWeight < minValue) { |
| minIndex = h[i]; |
| minValue = keyWeight; |
| } |
| |
| } |
| |
| return minIndex; |
| } |
| |
| /** |
| * Chooses the bit position that maximizes the number of false positive removed. |
| * @param h The different bit positions. |
| * @return The position that maximizes the number of false positive removed. |
| */ |
| private int maximumFpRemove(int[] h) { |
| int maxIndex = Integer.MIN_VALUE; |
| double maxValue = Double.MIN_VALUE; |
| |
| for (int i = 0; i < nbHash; i++) { |
| double fpWeight = getWeight(fpVector[h[i]]); |
| |
| if (fpWeight > maxValue) { |
| maxValue = fpWeight; |
| maxIndex = h[i]; |
| } |
| } |
| |
| return maxIndex; |
| } |
| |
| /** |
| * Chooses the bit position that minimizes the number of false negative generated while maximizing. |
| * the number of false positive removed. |
| * @param h The different bit positions. |
| * @return The position that minimizes the number of false negative generated while maximizing. |
| */ |
| private int ratioRemove(int[] h) { |
| computeRatio(); |
| int minIndex = Integer.MAX_VALUE; |
| double minValue = Double.MAX_VALUE; |
| |
| for (int i = 0; i < nbHash; i++) { |
| if (ratio[h[i]] < minValue) { |
| minValue = ratio[h[i]]; |
| minIndex = h[i]; |
| } |
| } |
| |
| return minIndex; |
| } |
| |
| /** |
| * Clears a specified bit in the bit vector and keeps up-to-date the KeyList vectors. |
| * @param index The position of the bit to clear. |
| */ |
| private void clearBit(int index) { |
| if (index < 0 || index >= vectorSize) { |
| throw new ArrayIndexOutOfBoundsException(index); |
| } |
| |
| List<Key> kl = keyVector[index]; |
| List<Key> fpl = fpVector[index]; |
| |
| // update key list |
| int listSize = kl.size(); |
| for (int i = 0; i < listSize && !kl.isEmpty(); i++) { |
| removeKey(kl.get(0), keyVector); |
| } |
| |
| kl.clear(); |
| keyVector[index].clear(); |
| |
| //update false positive list |
| listSize = fpl.size(); |
| for (int i = 0; i < listSize && !fpl.isEmpty(); i++) { |
| removeKey(fpl.get(0), fpVector); |
| } |
| |
| fpl.clear(); |
| fpVector[index].clear(); |
| |
| //update ratio |
| ratio[index] = 0.0; |
| |
| //update bit vector |
| bits.clear(index); |
| } |
| |
| /** |
| * Removes a given key from <i>this</i> filer. |
| * @param k The key to remove. |
| * @param vector The counting vector associated to the key. |
| */ |
| private void removeKey(Key k, List<Key>[] vector) { |
| if (k == null) { |
| throw new NullPointerException("Key can not be null"); |
| } |
| if (vector == null) { |
| throw new NullPointerException("ArrayList<Key>[] can not be null"); |
| } |
| |
| int[] h = hash.hash(k); |
| hash.clear(); |
| |
| for (int i = 0; i < nbHash; i++) { |
| vector[h[i]].remove(k); |
| } |
| } |
| |
| /** |
| * Computes the ratio A/FP. |
| */ |
| private void computeRatio() { |
| for (int i = 0; i < vectorSize; i++) { |
| double keyWeight = getWeight(keyVector[i]); |
| double fpWeight = getWeight(fpVector[i]); |
| |
| if (keyWeight > 0 && fpWeight > 0) { |
| ratio[i] = keyWeight / fpWeight; |
| } |
| } |
| } |
| |
| private double getWeight(List<Key> keyList) { |
| double weight = 0.0; |
| for (Key k : keyList) { |
| weight += k.getWeight(); |
| } |
| return weight; |
| } |
| |
| /** |
| * Creates and initialises the various vectors. |
| */ |
| @SuppressWarnings("unchecked") |
| private void createVector() { |
| fpVector = new List[vectorSize]; |
| keyVector = new List[vectorSize]; |
| ratio = new double[vectorSize]; |
| |
| for (int i = 0; i < vectorSize; i++) { |
| fpVector[i] = Collections.synchronizedList(new ArrayList<Key>()); |
| keyVector[i] = Collections.synchronizedList(new ArrayList<Key>()); |
| ratio[i] = 0.0; |
| } |
| } |
| |
| // Writable |
| |
| @Override |
| public void write(DataOutput out) throws IOException { |
| super.write(out); |
| for (int i = 0; i < fpVector.length; i++) { |
| List<Key> list = fpVector[i]; |
| out.writeInt(list.size()); |
| for (Key k : list) { |
| k.write(out); |
| } |
| } |
| for (int i = 0; i < keyVector.length; i++) { |
| List<Key> list = keyVector[i]; |
| out.writeInt(list.size()); |
| for (Key k : list) { |
| k.write(out); |
| } |
| } |
| for (int i = 0; i < ratio.length; i++) { |
| out.writeDouble(ratio[i]); |
| } |
| } |
| |
| @Override |
| public void readFields(DataInput in) throws IOException { |
| super.readFields(in); |
| createVector(); |
| for (int i = 0; i < fpVector.length; i++) { |
| List<Key> list = fpVector[i]; |
| int size = in.readInt(); |
| for (int j = 0; j < size; j++) { |
| Key k = new Key(); |
| k.readFields(in); |
| list.add(k); |
| } |
| } |
| for (int i = 0; i < keyVector.length; i++) { |
| List<Key> list = keyVector[i]; |
| int size = in.readInt(); |
| for (int j = 0; j < size; j++) { |
| Key k = new Key(); |
| k.readFields(in); |
| list.add(k); |
| } |
| } |
| for (int i = 0; i < ratio.length; i++) { |
| ratio[i] = in.readDouble(); |
| } |
| } |
| } |