[120] | 1 | /** |
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| 2 | * |
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| 3 | * Copyright (c) 2005, European Commission project OneLab under contract 034819 |
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| 4 | * (http://www.one-lab.org) |
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| 5 | * |
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| 6 | * All rights reserved. |
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| 7 | * Redistribution and use in source and binary forms, with or |
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| 8 | * without modification, are permitted provided that the following |
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| 9 | * conditions are met: |
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| 10 | * - Redistributions of source code must retain the above copyright |
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| 11 | * notice, this list of conditions and the following disclaimer. |
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| 12 | * - Redistributions in binary form must reproduce the above copyright |
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| 13 | * notice, this list of conditions and the following disclaimer in |
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| 14 | * the documentation and/or other materials provided with the distribution. |
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| 15 | * - Neither the name of the University Catholique de Louvain - UCL |
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| 16 | * nor the names of its contributors may be used to endorse or |
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| 17 | * promote products derived from this software without specific prior |
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| 18 | * written permission. |
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| 19 | * |
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| 20 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| 21 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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| 22 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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| 23 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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| 24 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 25 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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| 26 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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| 27 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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| 28 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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| 30 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 31 | * POSSIBILITY OF SUCH DAMAGE. |
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| 32 | */ |
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| 33 | |
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| 34 | /** |
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| 35 | * Licensed to the Apache Software Foundation (ASF) under one |
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| 36 | * or more contributor license agreements. See the NOTICE file |
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| 37 | * distributed with this work for additional information |
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| 38 | * regarding copyright ownership. The ASF licenses this file |
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| 39 | * to you under the Apache License, Version 2.0 (the |
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| 40 | * "License"); you may not use this file except in compliance |
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| 41 | * with the License. You may obtain a copy of the License at |
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| 42 | * |
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| 43 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 44 | * |
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| 45 | * Unless required by applicable law or agreed to in writing, software |
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| 46 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 47 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 48 | * See the License for the specific language governing permissions and |
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| 49 | * limitations under the License. |
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| 50 | */ |
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| 51 | package org.apache.hadoop.util.bloom; |
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| 52 | |
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| 53 | import java.io.DataInput; |
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| 54 | import java.io.DataOutput; |
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| 55 | import java.io.IOException; |
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| 56 | import java.util.Collection; |
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| 57 | import java.util.List; |
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| 58 | |
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| 59 | import org.apache.hadoop.io.Writable; |
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| 60 | import org.apache.hadoop.util.hash.Hash; |
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| 61 | |
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| 62 | /** |
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| 63 | * Defines the general behavior of a filter. |
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| 64 | * <p> |
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| 65 | * A filter is a data structure which aims at offering a lossy summary of a set <code>A</code>. The |
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| 66 | * key idea is to map entries of <code>A</code> (also called <i>keys</i>) into several positions |
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| 67 | * in a vector through the use of several hash functions. |
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| 68 | * <p> |
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| 69 | * Typically, a filter will be implemented as a Bloom filter (or a Bloom filter extension). |
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| 70 | * <p> |
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| 71 | * It must be extended in order to define the real behavior. |
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| 72 | * |
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| 73 | * @see Key The general behavior of a key |
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| 74 | * @see HashFunction A hash function |
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| 75 | */ |
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| 76 | public abstract class Filter implements Writable { |
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| 77 | private static final int VERSION = -1; // negative to accommodate for old format |
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| 78 | /** The vector size of <i>this</i> filter. */ |
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| 79 | protected int vectorSize; |
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| 80 | |
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| 81 | /** The hash function used to map a key to several positions in the vector. */ |
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| 82 | protected HashFunction hash; |
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| 83 | |
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| 84 | /** The number of hash function to consider. */ |
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| 85 | protected int nbHash; |
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| 86 | |
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| 87 | /** Type of hashing function to use. */ |
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| 88 | protected int hashType; |
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| 89 | |
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| 90 | protected Filter() {} |
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| 91 | |
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| 92 | /** |
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| 93 | * Constructor. |
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| 94 | * @param vectorSize The vector size of <i>this</i> filter. |
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| 95 | * @param nbHash The number of hash functions to consider. |
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| 96 | * @param hashType type of the hashing function (see {@link Hash}). |
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| 97 | */ |
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| 98 | protected Filter(int vectorSize, int nbHash, int hashType) { |
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| 99 | this.vectorSize = vectorSize; |
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| 100 | this.nbHash = nbHash; |
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| 101 | this.hashType = hashType; |
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| 102 | this.hash = new HashFunction(this.vectorSize, this.nbHash, this.hashType); |
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| 103 | } |
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| 104 | |
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| 105 | /** |
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| 106 | * Adds a key to <i>this</i> filter. |
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| 107 | * @param key The key to add. |
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| 108 | */ |
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| 109 | public abstract void add(Key key); |
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| 110 | |
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| 111 | /** |
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| 112 | * Determines wether a specified key belongs to <i>this</i> filter. |
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| 113 | * @param key The key to test. |
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| 114 | * @return boolean True if the specified key belongs to <i>this</i> filter. |
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| 115 | * False otherwise. |
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| 116 | */ |
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| 117 | public abstract boolean membershipTest(Key key); |
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| 118 | |
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| 119 | /** |
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| 120 | * Peforms a logical AND between <i>this</i> filter and a specified filter. |
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| 121 | * <p> |
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| 122 | * <b>Invariant</b>: The result is assigned to <i>this</i> filter. |
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| 123 | * @param filter The filter to AND with. |
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| 124 | */ |
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| 125 | public abstract void and(Filter filter); |
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| 126 | |
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| 127 | /** |
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| 128 | * Peforms a logical OR between <i>this</i> filter and a specified filter. |
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| 129 | * <p> |
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| 130 | * <b>Invariant</b>: The result is assigned to <i>this</i> filter. |
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| 131 | * @param filter The filter to OR with. |
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| 132 | */ |
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| 133 | public abstract void or(Filter filter); |
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| 134 | |
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| 135 | /** |
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| 136 | * Peforms a logical XOR between <i>this</i> filter and a specified filter. |
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| 137 | * <p> |
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| 138 | * <b>Invariant</b>: The result is assigned to <i>this</i> filter. |
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| 139 | * @param filter The filter to XOR with. |
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| 140 | */ |
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| 141 | public abstract void xor(Filter filter); |
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| 142 | |
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| 143 | /** |
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| 144 | * Performs a logical NOT on <i>this</i> filter. |
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| 145 | * <p> |
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| 146 | * The result is assigned to <i>this</i> filter. |
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| 147 | */ |
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| 148 | public abstract void not(); |
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| 149 | |
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| 150 | /** |
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| 151 | * Adds a list of keys to <i>this</i> filter. |
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| 152 | * @param keys The list of keys. |
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| 153 | */ |
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| 154 | public void add(List<Key> keys){ |
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| 155 | if(keys == null) { |
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| 156 | throw new IllegalArgumentException("ArrayList<Key> may not be null"); |
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| 157 | } |
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| 158 | |
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| 159 | for(Key key: keys) { |
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| 160 | add(key); |
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| 161 | } |
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| 162 | }//end add() |
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| 163 | |
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| 164 | /** |
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| 165 | * Adds a collection of keys to <i>this</i> filter. |
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| 166 | * @param keys The collection of keys. |
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| 167 | */ |
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| 168 | public void add(Collection<Key> keys){ |
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| 169 | if(keys == null) { |
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| 170 | throw new IllegalArgumentException("Collection<Key> may not be null"); |
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| 171 | } |
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| 172 | for(Key key: keys) { |
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| 173 | add(key); |
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| 174 | } |
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| 175 | }//end add() |
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| 176 | |
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| 177 | /** |
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| 178 | * Adds an array of keys to <i>this</i> filter. |
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| 179 | * @param keys The array of keys. |
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| 180 | */ |
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| 181 | public void add(Key[] keys){ |
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| 182 | if(keys == null) { |
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| 183 | throw new IllegalArgumentException("Key[] may not be null"); |
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| 184 | } |
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| 185 | for(int i = 0; i < keys.length; i++) { |
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| 186 | add(keys[i]); |
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| 187 | } |
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| 188 | }//end add() |
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| 189 | |
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| 190 | // Writable interface |
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| 191 | |
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| 192 | public void write(DataOutput out) throws IOException { |
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| 193 | out.writeInt(VERSION); |
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| 194 | out.writeInt(this.nbHash); |
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| 195 | out.writeByte(this.hashType); |
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| 196 | out.writeInt(this.vectorSize); |
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| 197 | } |
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| 198 | |
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| 199 | public void readFields(DataInput in) throws IOException { |
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| 200 | int ver = in.readInt(); |
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| 201 | if (ver > 0) { // old unversioned format |
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| 202 | this.nbHash = ver; |
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| 203 | this.hashType = Hash.JENKINS_HASH; |
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| 204 | } else if (ver == VERSION) { |
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| 205 | this.nbHash = in.readInt(); |
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| 206 | this.hashType = in.readByte(); |
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| 207 | } else { |
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| 208 | throw new IOException("Unsupported version: " + ver); |
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| 209 | } |
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| 210 | this.vectorSize = in.readInt(); |
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| 211 | this.hash = new HashFunction(this.vectorSize, this.nbHash, this.hashType); |
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| 212 | } |
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| 213 | }//end class |
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