[120] | 1 | /** |
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one |
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| 3 | * or more contributor license agreements. See the NOTICE file |
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| 4 | * distributed with this work for additional information |
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| 5 | * regarding copyright ownership. The ASF licenses this file |
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| 6 | * to you under the Apache License, Version 2.0 (the |
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| 7 | * "License"); you may not use this file except in compliance |
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| 8 | * with the License. You may obtain a copy of the License at |
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| 9 | * |
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| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 11 | * |
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| 12 | * Unless required by applicable law or agreed to in writing, software |
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| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 15 | * See the License for the specific language governing permissions and |
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| 16 | * limitations under the License. |
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| 17 | */ |
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| 18 | |
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| 19 | package org.apache.hadoop.io; |
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| 20 | |
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| 21 | import java.io.*; |
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| 22 | |
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| 23 | import org.apache.commons.logging.Log; |
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| 24 | import org.apache.commons.logging.LogFactory; |
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| 25 | import org.apache.hadoop.fs.*; |
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| 26 | import org.apache.hadoop.conf.*; |
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| 27 | import org.apache.hadoop.util.Progressable; |
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| 28 | import org.apache.hadoop.util.ReflectionUtils; |
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| 29 | import org.apache.hadoop.io.SequenceFile.CompressionType; |
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| 30 | import org.apache.hadoop.io.compress.CompressionCodec; |
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| 31 | import org.apache.hadoop.io.compress.DefaultCodec; |
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| 32 | |
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| 33 | /** A file-based map from keys to values. |
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| 34 | * |
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| 35 | * <p>A map is a directory containing two files, the <code>data</code> file, |
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| 36 | * containing all keys and values in the map, and a smaller <code>index</code> |
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| 37 | * file, containing a fraction of the keys. The fraction is determined by |
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| 38 | * {@link Writer#getIndexInterval()}. |
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| 39 | * |
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| 40 | * <p>The index file is read entirely into memory. Thus key implementations |
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| 41 | * should try to keep themselves small. |
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| 42 | * |
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| 43 | * <p>Map files are created by adding entries in-order. To maintain a large |
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| 44 | * database, perform updates by copying the previous version of a database and |
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| 45 | * merging in a sorted change list, to create a new version of the database in |
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| 46 | * a new file. Sorting large change lists can be done with {@link |
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| 47 | * SequenceFile.Sorter}. |
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| 48 | */ |
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| 49 | public class MapFile { |
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| 50 | private static final Log LOG = LogFactory.getLog(MapFile.class); |
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| 51 | |
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| 52 | /** The name of the index file. */ |
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| 53 | public static final String INDEX_FILE_NAME = "index"; |
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| 54 | |
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| 55 | /** The name of the data file. */ |
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| 56 | public static final String DATA_FILE_NAME = "data"; |
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| 57 | |
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| 58 | protected MapFile() {} // no public ctor |
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| 59 | |
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| 60 | /** Writes a new map. */ |
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| 61 | public static class Writer implements java.io.Closeable { |
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| 62 | private SequenceFile.Writer data; |
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| 63 | private SequenceFile.Writer index; |
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| 64 | |
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| 65 | final private static String INDEX_INTERVAL = "io.map.index.interval"; |
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| 66 | private int indexInterval = 128; |
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| 67 | |
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| 68 | private long size; |
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| 69 | private LongWritable position = new LongWritable(); |
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| 70 | |
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| 71 | // the following fields are used only for checking key order |
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| 72 | private WritableComparator comparator; |
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| 73 | private DataInputBuffer inBuf = new DataInputBuffer(); |
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| 74 | private DataOutputBuffer outBuf = new DataOutputBuffer(); |
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| 75 | private WritableComparable lastKey; |
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| 76 | |
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| 77 | |
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| 78 | /** Create the named map for keys of the named class. */ |
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| 79 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 80 | Class<? extends WritableComparable> keyClass, Class valClass) |
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| 81 | throws IOException { |
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| 82 | this(conf, fs, dirName, |
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| 83 | WritableComparator.get(keyClass), valClass, |
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| 84 | SequenceFile.getCompressionType(conf)); |
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| 85 | } |
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| 86 | |
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| 87 | /** Create the named map for keys of the named class. */ |
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| 88 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 89 | Class<? extends WritableComparable> keyClass, Class valClass, |
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| 90 | CompressionType compress, Progressable progress) |
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| 91 | throws IOException { |
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| 92 | this(conf, fs, dirName, WritableComparator.get(keyClass), valClass, |
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| 93 | compress, progress); |
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| 94 | } |
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| 95 | |
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| 96 | /** Create the named map for keys of the named class. */ |
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| 97 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 98 | Class<? extends WritableComparable> keyClass, Class valClass, |
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| 99 | CompressionType compress, CompressionCodec codec, |
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| 100 | Progressable progress) |
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| 101 | throws IOException { |
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| 102 | this(conf, fs, dirName, WritableComparator.get(keyClass), valClass, |
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| 103 | compress, codec, progress); |
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| 104 | } |
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| 105 | |
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| 106 | /** Create the named map for keys of the named class. */ |
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| 107 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 108 | Class<? extends WritableComparable> keyClass, Class valClass, |
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| 109 | CompressionType compress) |
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| 110 | throws IOException { |
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| 111 | this(conf, fs, dirName, WritableComparator.get(keyClass), valClass, compress); |
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| 112 | } |
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| 113 | |
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| 114 | /** Create the named map using the named key comparator. */ |
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| 115 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 116 | WritableComparator comparator, Class valClass) |
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| 117 | throws IOException { |
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| 118 | this(conf, fs, dirName, comparator, valClass, |
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| 119 | SequenceFile.getCompressionType(conf)); |
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| 120 | } |
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| 121 | /** Create the named map using the named key comparator. */ |
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| 122 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 123 | WritableComparator comparator, Class valClass, |
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| 124 | SequenceFile.CompressionType compress) |
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| 125 | throws IOException { |
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| 126 | this(conf, fs, dirName, comparator, valClass, compress, null); |
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| 127 | } |
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| 128 | /** Create the named map using the named key comparator. */ |
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| 129 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 130 | WritableComparator comparator, Class valClass, |
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| 131 | SequenceFile.CompressionType compress, |
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| 132 | Progressable progress) |
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| 133 | throws IOException { |
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| 134 | this(conf, fs, dirName, comparator, valClass, |
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| 135 | compress, new DefaultCodec(), progress); |
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| 136 | } |
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| 137 | /** Create the named map using the named key comparator. */ |
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| 138 | public Writer(Configuration conf, FileSystem fs, String dirName, |
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| 139 | WritableComparator comparator, Class valClass, |
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| 140 | SequenceFile.CompressionType compress, CompressionCodec codec, |
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| 141 | Progressable progress) |
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| 142 | throws IOException { |
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| 143 | |
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| 144 | this.indexInterval = conf.getInt(INDEX_INTERVAL, this.indexInterval); |
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| 145 | |
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| 146 | this.comparator = comparator; |
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| 147 | this.lastKey = comparator.newKey(); |
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| 148 | |
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| 149 | Path dir = new Path(dirName); |
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| 150 | if (!fs.mkdirs(dir)) { |
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| 151 | throw new IOException("Mkdirs failed to create directory " + dir.toString()); |
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| 152 | } |
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| 153 | Path dataFile = new Path(dir, DATA_FILE_NAME); |
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| 154 | Path indexFile = new Path(dir, INDEX_FILE_NAME); |
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| 155 | |
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| 156 | Class keyClass = comparator.getKeyClass(); |
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| 157 | this.data = |
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| 158 | SequenceFile.createWriter |
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| 159 | (fs, conf, dataFile, keyClass, valClass, compress, codec, progress); |
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| 160 | this.index = |
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| 161 | SequenceFile.createWriter |
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| 162 | (fs, conf, indexFile, keyClass, LongWritable.class, |
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| 163 | CompressionType.BLOCK, progress); |
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| 164 | } |
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| 165 | |
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| 166 | /** The number of entries that are added before an index entry is added.*/ |
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| 167 | public int getIndexInterval() { return indexInterval; } |
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| 168 | |
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| 169 | /** Sets the index interval. |
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| 170 | * @see #getIndexInterval() |
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| 171 | */ |
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| 172 | public void setIndexInterval(int interval) { indexInterval = interval; } |
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| 173 | |
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| 174 | /** Sets the index interval and stores it in conf |
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| 175 | * @see #getIndexInterval() |
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| 176 | */ |
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| 177 | public static void setIndexInterval(Configuration conf, int interval) { |
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| 178 | conf.setInt(INDEX_INTERVAL, interval); |
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| 179 | } |
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| 180 | |
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| 181 | /** Close the map. */ |
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| 182 | public synchronized void close() throws IOException { |
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| 183 | data.close(); |
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| 184 | index.close(); |
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| 185 | } |
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| 186 | |
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| 187 | /** Append a key/value pair to the map. The key must be greater or equal |
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| 188 | * to the previous key added to the map. */ |
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| 189 | public synchronized void append(WritableComparable key, Writable val) |
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| 190 | throws IOException { |
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| 191 | |
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| 192 | checkKey(key); |
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| 193 | |
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| 194 | if (size % indexInterval == 0) { // add an index entry |
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| 195 | position.set(data.getLength()); // point to current eof |
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| 196 | index.append(key, position); |
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| 197 | } |
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| 198 | |
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| 199 | data.append(key, val); // append key/value to data |
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| 200 | size++; |
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| 201 | } |
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| 202 | |
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| 203 | private void checkKey(WritableComparable key) throws IOException { |
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| 204 | // check that keys are well-ordered |
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| 205 | if (size != 0 && comparator.compare(lastKey, key) > 0) |
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| 206 | throw new IOException("key out of order: "+key+" after "+lastKey); |
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| 207 | |
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| 208 | // update lastKey with a copy of key by writing and reading |
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| 209 | outBuf.reset(); |
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| 210 | key.write(outBuf); // write new key |
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| 211 | |
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| 212 | inBuf.reset(outBuf.getData(), outBuf.getLength()); |
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| 213 | lastKey.readFields(inBuf); // read into lastKey |
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| 214 | } |
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| 215 | |
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| 216 | } |
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| 217 | |
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| 218 | /** Provide access to an existing map. */ |
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| 219 | public static class Reader implements java.io.Closeable { |
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| 220 | |
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| 221 | /** Number of index entries to skip between each entry. Zero by default. |
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| 222 | * Setting this to values larger than zero can facilitate opening large map |
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| 223 | * files using less memory. */ |
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| 224 | private int INDEX_SKIP = 0; |
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| 225 | |
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| 226 | private WritableComparator comparator; |
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| 227 | |
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| 228 | private WritableComparable nextKey; |
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| 229 | private long seekPosition = -1; |
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| 230 | private int seekIndex = -1; |
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| 231 | private long firstPosition; |
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| 232 | |
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| 233 | // the data, on disk |
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| 234 | private SequenceFile.Reader data; |
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| 235 | private SequenceFile.Reader index; |
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| 236 | |
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| 237 | // whether the index Reader was closed |
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| 238 | private boolean indexClosed = false; |
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| 239 | |
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| 240 | // the index, in memory |
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| 241 | private int count = -1; |
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| 242 | private WritableComparable[] keys; |
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| 243 | private long[] positions; |
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| 244 | |
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| 245 | /** Returns the class of keys in this file. */ |
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| 246 | public Class<?> getKeyClass() { return data.getKeyClass(); } |
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| 247 | |
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| 248 | /** Returns the class of values in this file. */ |
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| 249 | public Class<?> getValueClass() { return data.getValueClass(); } |
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| 250 | |
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| 251 | /** Construct a map reader for the named map.*/ |
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| 252 | public Reader(FileSystem fs, String dirName, Configuration conf) throws IOException { |
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| 253 | this(fs, dirName, null, conf); |
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| 254 | INDEX_SKIP = conf.getInt("io.map.index.skip", 0); |
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| 255 | } |
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| 256 | |
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| 257 | /** Construct a map reader for the named map using the named comparator.*/ |
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| 258 | public Reader(FileSystem fs, String dirName, WritableComparator comparator, Configuration conf) |
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| 259 | throws IOException { |
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| 260 | this(fs, dirName, comparator, conf, true); |
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| 261 | } |
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| 262 | |
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| 263 | /** |
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| 264 | * Hook to allow subclasses to defer opening streams until further |
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| 265 | * initialization is complete. |
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| 266 | * @see #createDataFileReader(FileSystem, Path, Configuration) |
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| 267 | */ |
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| 268 | protected Reader(FileSystem fs, String dirName, |
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| 269 | WritableComparator comparator, Configuration conf, boolean open) |
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| 270 | throws IOException { |
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| 271 | |
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| 272 | if (open) { |
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| 273 | open(fs, dirName, comparator, conf); |
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| 274 | } |
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| 275 | } |
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| 276 | |
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| 277 | protected synchronized void open(FileSystem fs, String dirName, |
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| 278 | WritableComparator comparator, Configuration conf) throws IOException { |
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| 279 | Path dir = new Path(dirName); |
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| 280 | Path dataFile = new Path(dir, DATA_FILE_NAME); |
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| 281 | Path indexFile = new Path(dir, INDEX_FILE_NAME); |
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| 282 | |
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| 283 | // open the data |
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| 284 | this.data = createDataFileReader(fs, dataFile, conf); |
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| 285 | this.firstPosition = data.getPosition(); |
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| 286 | |
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| 287 | if (comparator == null) |
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| 288 | this.comparator = WritableComparator.get(data.getKeyClass().asSubclass(WritableComparable.class)); |
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| 289 | else |
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| 290 | this.comparator = comparator; |
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| 291 | |
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| 292 | // open the index |
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| 293 | this.index = new SequenceFile.Reader(fs, indexFile, conf); |
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| 294 | } |
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| 295 | |
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| 296 | /** |
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| 297 | * Override this method to specialize the type of |
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| 298 | * {@link SequenceFile.Reader} returned. |
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| 299 | */ |
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| 300 | protected SequenceFile.Reader createDataFileReader(FileSystem fs, |
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| 301 | Path dataFile, Configuration conf) throws IOException { |
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| 302 | return new SequenceFile.Reader(fs, dataFile, conf); |
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| 303 | } |
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| 304 | |
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| 305 | private void readIndex() throws IOException { |
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| 306 | // read the index entirely into memory |
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| 307 | if (this.keys != null) |
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| 308 | return; |
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| 309 | this.count = 0; |
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| 310 | this.keys = new WritableComparable[1024]; |
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| 311 | this.positions = new long[1024]; |
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| 312 | try { |
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| 313 | int skip = INDEX_SKIP; |
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| 314 | LongWritable position = new LongWritable(); |
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| 315 | WritableComparable lastKey = null; |
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| 316 | while (true) { |
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| 317 | WritableComparable k = comparator.newKey(); |
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| 318 | |
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| 319 | if (!index.next(k, position)) |
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| 320 | break; |
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| 321 | |
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| 322 | // check order to make sure comparator is compatible |
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| 323 | if (lastKey != null && comparator.compare(lastKey, k) > 0) |
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| 324 | throw new IOException("key out of order: "+k+" after "+lastKey); |
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| 325 | lastKey = k; |
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| 326 | |
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| 327 | if (skip > 0) { |
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| 328 | skip--; |
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| 329 | continue; // skip this entry |
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| 330 | } else { |
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| 331 | skip = INDEX_SKIP; // reset skip |
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| 332 | } |
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| 333 | |
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| 334 | if (count == keys.length) { // time to grow arrays |
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| 335 | int newLength = (keys.length*3)/2; |
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| 336 | WritableComparable[] newKeys = new WritableComparable[newLength]; |
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| 337 | long[] newPositions = new long[newLength]; |
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| 338 | System.arraycopy(keys, 0, newKeys, 0, count); |
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| 339 | System.arraycopy(positions, 0, newPositions, 0, count); |
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| 340 | keys = newKeys; |
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| 341 | positions = newPositions; |
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| 342 | } |
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| 343 | |
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| 344 | keys[count] = k; |
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| 345 | positions[count] = position.get(); |
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| 346 | count++; |
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| 347 | } |
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| 348 | } catch (EOFException e) { |
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| 349 | LOG.warn("Unexpected EOF reading " + index + |
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| 350 | " at entry #" + count + ". Ignoring."); |
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| 351 | } finally { |
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| 352 | indexClosed = true; |
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| 353 | index.close(); |
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| 354 | } |
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| 355 | } |
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| 356 | |
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| 357 | /** Re-positions the reader before its first key. */ |
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| 358 | public synchronized void reset() throws IOException { |
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| 359 | data.seek(firstPosition); |
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| 360 | } |
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| 361 | |
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| 362 | /** Get the key at approximately the middle of the file. |
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| 363 | * |
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| 364 | * @throws IOException |
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| 365 | */ |
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| 366 | public synchronized WritableComparable midKey() throws IOException { |
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| 367 | |
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| 368 | readIndex(); |
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| 369 | int pos = ((count - 1) / 2); // middle of the index |
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| 370 | if (pos < 0) { |
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| 371 | throw new IOException("MapFile empty"); |
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| 372 | } |
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| 373 | |
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| 374 | return keys[pos]; |
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| 375 | } |
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| 376 | |
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| 377 | /** Reads the final key from the file. |
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| 378 | * |
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| 379 | * @param key key to read into |
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| 380 | */ |
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| 381 | public synchronized void finalKey(WritableComparable key) |
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| 382 | throws IOException { |
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| 383 | |
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| 384 | long originalPosition = data.getPosition(); // save position |
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| 385 | try { |
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| 386 | readIndex(); // make sure index is valid |
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| 387 | if (count > 0) { |
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| 388 | data.seek(positions[count-1]); // skip to last indexed entry |
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| 389 | } else { |
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| 390 | reset(); // start at the beginning |
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| 391 | } |
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| 392 | while (data.next(key)) {} // scan to eof |
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| 393 | |
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| 394 | } finally { |
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| 395 | data.seek(originalPosition); // restore position |
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| 396 | } |
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| 397 | } |
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| 398 | |
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| 399 | /** Positions the reader at the named key, or if none such exists, at the |
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| 400 | * first entry after the named key. Returns true iff the named key exists |
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| 401 | * in this map. |
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| 402 | */ |
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| 403 | public synchronized boolean seek(WritableComparable key) throws IOException { |
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| 404 | return seekInternal(key) == 0; |
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| 405 | } |
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| 406 | |
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| 407 | /** |
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| 408 | * Positions the reader at the named key, or if none such exists, at the |
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| 409 | * first entry after the named key. |
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| 410 | * |
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| 411 | * @return 0 - exact match found |
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| 412 | * < 0 - positioned at next record |
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| 413 | * 1 - no more records in file |
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| 414 | */ |
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| 415 | private synchronized int seekInternal(WritableComparable key) |
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| 416 | throws IOException { |
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| 417 | return seekInternal(key, false); |
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| 418 | } |
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| 419 | |
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| 420 | /** |
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| 421 | * Positions the reader at the named key, or if none such exists, at the |
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| 422 | * key that falls just before or just after dependent on how the |
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| 423 | * <code>before</code> parameter is set. |
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| 424 | * |
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| 425 | * @param before - IF true, and <code>key</code> does not exist, position |
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| 426 | * file at entry that falls just before <code>key</code>. Otherwise, |
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| 427 | * position file at record that sorts just after. |
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| 428 | * @return 0 - exact match found |
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| 429 | * < 0 - positioned at next record |
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| 430 | * 1 - no more records in file |
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| 431 | */ |
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| 432 | private synchronized int seekInternal(WritableComparable key, |
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| 433 | final boolean before) |
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| 434 | throws IOException { |
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| 435 | readIndex(); // make sure index is read |
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| 436 | |
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| 437 | if (seekIndex != -1 // seeked before |
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| 438 | && seekIndex+1 < count |
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| 439 | && comparator.compare(key, keys[seekIndex+1])<0 // before next indexed |
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| 440 | && comparator.compare(key, nextKey) |
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| 441 | >= 0) { // but after last seeked |
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| 442 | // do nothing |
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| 443 | } else { |
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| 444 | seekIndex = binarySearch(key); |
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| 445 | if (seekIndex < 0) // decode insertion point |
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| 446 | seekIndex = -seekIndex-2; |
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| 447 | |
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| 448 | if (seekIndex == -1) // belongs before first entry |
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| 449 | seekPosition = firstPosition; // use beginning of file |
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| 450 | else |
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| 451 | seekPosition = positions[seekIndex]; // else use index |
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| 452 | } |
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| 453 | data.seek(seekPosition); |
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| 454 | |
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| 455 | if (nextKey == null) |
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| 456 | nextKey = comparator.newKey(); |
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| 457 | |
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| 458 | // If we're looking for the key before, we need to keep track |
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| 459 | // of the position we got the current key as well as the position |
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| 460 | // of the key before it. |
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| 461 | long prevPosition = -1; |
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| 462 | long curPosition = seekPosition; |
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| 463 | |
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| 464 | while (data.next(nextKey)) { |
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| 465 | int c = comparator.compare(key, nextKey); |
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| 466 | if (c <= 0) { // at or beyond desired |
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| 467 | if (before && c != 0) { |
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| 468 | if (prevPosition == -1) { |
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| 469 | // We're on the first record of this index block |
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| 470 | // and we've already passed the search key. Therefore |
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| 471 | // we must be at the beginning of the file, so seek |
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| 472 | // to the beginning of this block and return c |
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| 473 | data.seek(curPosition); |
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| 474 | } else { |
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| 475 | // We have a previous record to back up to |
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| 476 | data.seek(prevPosition); |
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| 477 | data.next(nextKey); |
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| 478 | // now that we've rewound, the search key must be greater than this key |
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| 479 | return 1; |
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| 480 | } |
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| 481 | } |
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| 482 | return c; |
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| 483 | } |
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| 484 | if (before) { |
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| 485 | prevPosition = curPosition; |
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| 486 | curPosition = data.getPosition(); |
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| 487 | } |
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| 488 | } |
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| 489 | |
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| 490 | return 1; |
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| 491 | } |
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| 492 | |
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| 493 | private int binarySearch(WritableComparable key) { |
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| 494 | int low = 0; |
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| 495 | int high = count-1; |
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| 496 | |
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| 497 | while (low <= high) { |
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| 498 | int mid = (low + high) >>> 1; |
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| 499 | WritableComparable midVal = keys[mid]; |
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| 500 | int cmp = comparator.compare(midVal, key); |
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| 501 | |
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| 502 | if (cmp < 0) |
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| 503 | low = mid + 1; |
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| 504 | else if (cmp > 0) |
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| 505 | high = mid - 1; |
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| 506 | else |
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| 507 | return mid; // key found |
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| 508 | } |
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| 509 | return -(low + 1); // key not found. |
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| 510 | } |
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| 511 | |
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| 512 | /** Read the next key/value pair in the map into <code>key</code> and |
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| 513 | * <code>val</code>. Returns true if such a pair exists and false when at |
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| 514 | * the end of the map */ |
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| 515 | public synchronized boolean next(WritableComparable key, Writable val) |
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| 516 | throws IOException { |
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| 517 | return data.next(key, val); |
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| 518 | } |
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| 519 | |
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| 520 | /** Return the value for the named key, or null if none exists. */ |
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| 521 | public synchronized Writable get(WritableComparable key, Writable val) |
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| 522 | throws IOException { |
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| 523 | if (seek(key)) { |
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| 524 | data.getCurrentValue(val); |
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| 525 | return val; |
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| 526 | } else |
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| 527 | return null; |
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| 528 | } |
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| 529 | |
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| 530 | /** |
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| 531 | * Finds the record that is the closest match to the specified key. |
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| 532 | * Returns <code>key</code> or if it does not exist, at the first entry |
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| 533 | * after the named key. |
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| 534 | * |
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| 535 | - * @param key - key that we're trying to find |
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| 536 | - * @param val - data value if key is found |
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| 537 | - * @return - the key that was the closest match or null if eof. |
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| 538 | */ |
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| 539 | public synchronized WritableComparable getClosest(WritableComparable key, |
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| 540 | Writable val) |
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| 541 | throws IOException { |
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| 542 | return getClosest(key, val, false); |
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| 543 | } |
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| 544 | |
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| 545 | /** |
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| 546 | * Finds the record that is the closest match to the specified key. |
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| 547 | * |
---|
| 548 | * @param key - key that we're trying to find |
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| 549 | * @param val - data value if key is found |
---|
| 550 | * @param before - IF true, and <code>key</code> does not exist, return |
---|
| 551 | * the first entry that falls just before the <code>key</code>. Otherwise, |
---|
| 552 | * return the record that sorts just after. |
---|
| 553 | * @return - the key that was the closest match or null if eof. |
---|
| 554 | */ |
---|
| 555 | public synchronized WritableComparable getClosest(WritableComparable key, |
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| 556 | Writable val, final boolean before) |
---|
| 557 | throws IOException { |
---|
| 558 | |
---|
| 559 | int c = seekInternal(key, before); |
---|
| 560 | |
---|
| 561 | // If we didn't get an exact match, and we ended up in the wrong |
---|
| 562 | // direction relative to the query key, return null since we |
---|
| 563 | // must be at the beginning or end of the file. |
---|
| 564 | if ((!before && c > 0) || |
---|
| 565 | (before && c < 0)) { |
---|
| 566 | return null; |
---|
| 567 | } |
---|
| 568 | |
---|
| 569 | data.getCurrentValue(val); |
---|
| 570 | return nextKey; |
---|
| 571 | } |
---|
| 572 | |
---|
| 573 | /** Close the map. */ |
---|
| 574 | public synchronized void close() throws IOException { |
---|
| 575 | if (!indexClosed) { |
---|
| 576 | index.close(); |
---|
| 577 | } |
---|
| 578 | data.close(); |
---|
| 579 | } |
---|
| 580 | |
---|
| 581 | } |
---|
| 582 | |
---|
| 583 | /** Renames an existing map directory. */ |
---|
| 584 | public static void rename(FileSystem fs, String oldName, String newName) |
---|
| 585 | throws IOException { |
---|
| 586 | Path oldDir = new Path(oldName); |
---|
| 587 | Path newDir = new Path(newName); |
---|
| 588 | if (!fs.rename(oldDir, newDir)) { |
---|
| 589 | throw new IOException("Could not rename " + oldDir + " to " + newDir); |
---|
| 590 | } |
---|
| 591 | } |
---|
| 592 | |
---|
| 593 | /** Deletes the named map file. */ |
---|
| 594 | public static void delete(FileSystem fs, String name) throws IOException { |
---|
| 595 | Path dir = new Path(name); |
---|
| 596 | Path data = new Path(dir, DATA_FILE_NAME); |
---|
| 597 | Path index = new Path(dir, INDEX_FILE_NAME); |
---|
| 598 | |
---|
| 599 | fs.delete(data, true); |
---|
| 600 | fs.delete(index, true); |
---|
| 601 | fs.delete(dir, true); |
---|
| 602 | } |
---|
| 603 | |
---|
| 604 | /** |
---|
| 605 | * This method attempts to fix a corrupt MapFile by re-creating its index. |
---|
| 606 | * @param fs filesystem |
---|
| 607 | * @param dir directory containing the MapFile data and index |
---|
| 608 | * @param keyClass key class (has to be a subclass of Writable) |
---|
| 609 | * @param valueClass value class (has to be a subclass of Writable) |
---|
| 610 | * @param dryrun do not perform any changes, just report what needs to be done |
---|
| 611 | * @return number of valid entries in this MapFile, or -1 if no fixing was needed |
---|
| 612 | * @throws Exception |
---|
| 613 | */ |
---|
| 614 | public static long fix(FileSystem fs, Path dir, |
---|
| 615 | Class<? extends Writable> keyClass, |
---|
| 616 | Class<? extends Writable> valueClass, boolean dryrun, |
---|
| 617 | Configuration conf) throws Exception { |
---|
| 618 | String dr = (dryrun ? "[DRY RUN ] " : ""); |
---|
| 619 | Path data = new Path(dir, DATA_FILE_NAME); |
---|
| 620 | Path index = new Path(dir, INDEX_FILE_NAME); |
---|
| 621 | int indexInterval = 128; |
---|
| 622 | if (!fs.exists(data)) { |
---|
| 623 | // there's nothing we can do to fix this! |
---|
| 624 | throw new Exception(dr + "Missing data file in " + dir + ", impossible to fix this."); |
---|
| 625 | } |
---|
| 626 | if (fs.exists(index)) { |
---|
| 627 | // no fixing needed |
---|
| 628 | return -1; |
---|
| 629 | } |
---|
| 630 | SequenceFile.Reader dataReader = new SequenceFile.Reader(fs, data, conf); |
---|
| 631 | if (!dataReader.getKeyClass().equals(keyClass)) { |
---|
| 632 | throw new Exception(dr + "Wrong key class in " + dir + ", expected" + keyClass.getName() + |
---|
| 633 | ", got " + dataReader.getKeyClass().getName()); |
---|
| 634 | } |
---|
| 635 | if (!dataReader.getValueClass().equals(valueClass)) { |
---|
| 636 | throw new Exception(dr + "Wrong value class in " + dir + ", expected" + valueClass.getName() + |
---|
| 637 | ", got " + dataReader.getValueClass().getName()); |
---|
| 638 | } |
---|
| 639 | long cnt = 0L; |
---|
| 640 | Writable key = ReflectionUtils.newInstance(keyClass, conf); |
---|
| 641 | Writable value = ReflectionUtils.newInstance(valueClass, conf); |
---|
| 642 | SequenceFile.Writer indexWriter = null; |
---|
| 643 | if (!dryrun) indexWriter = SequenceFile.createWriter(fs, conf, index, keyClass, LongWritable.class); |
---|
| 644 | try { |
---|
| 645 | long pos = 0L; |
---|
| 646 | LongWritable position = new LongWritable(); |
---|
| 647 | while(dataReader.next(key, value)) { |
---|
| 648 | cnt++; |
---|
| 649 | if (cnt % indexInterval == 0) { |
---|
| 650 | position.set(pos); |
---|
| 651 | if (!dryrun) indexWriter.append(key, position); |
---|
| 652 | } |
---|
| 653 | pos = dataReader.getPosition(); |
---|
| 654 | } |
---|
| 655 | } catch(Throwable t) { |
---|
| 656 | // truncated data file. swallow it. |
---|
| 657 | } |
---|
| 658 | dataReader.close(); |
---|
| 659 | if (!dryrun) indexWriter.close(); |
---|
| 660 | return cnt; |
---|
| 661 | } |
---|
| 662 | |
---|
| 663 | |
---|
| 664 | public static void main(String[] args) throws Exception { |
---|
| 665 | String usage = "Usage: MapFile inFile outFile"; |
---|
| 666 | |
---|
| 667 | if (args.length != 2) { |
---|
| 668 | System.err.println(usage); |
---|
| 669 | System.exit(-1); |
---|
| 670 | } |
---|
| 671 | |
---|
| 672 | String in = args[0]; |
---|
| 673 | String out = args[1]; |
---|
| 674 | |
---|
| 675 | Configuration conf = new Configuration(); |
---|
| 676 | FileSystem fs = FileSystem.getLocal(conf); |
---|
| 677 | MapFile.Reader reader = new MapFile.Reader(fs, in, conf); |
---|
| 678 | MapFile.Writer writer = |
---|
| 679 | new MapFile.Writer(conf, fs, out, |
---|
| 680 | reader.getKeyClass().asSubclass(WritableComparable.class), |
---|
| 681 | reader.getValueClass()); |
---|
| 682 | |
---|
| 683 | WritableComparable key = |
---|
| 684 | ReflectionUtils.newInstance(reader.getKeyClass().asSubclass(WritableComparable.class), conf); |
---|
| 685 | Writable value = |
---|
| 686 | ReflectionUtils.newInstance(reader.getValueClass().asSubclass(Writable.class), conf); |
---|
| 687 | |
---|
| 688 | while (reader.next(key, value)) // copy all entries |
---|
| 689 | writer.append(key, value); |
---|
| 690 | |
---|
| 691 | writer.close(); |
---|
| 692 | } |
---|
| 693 | |
---|
| 694 | } |
---|