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 | package org.apache.hadoop.io.compress; |
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19 | |
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20 | import java.util.ArrayList; |
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21 | import java.util.HashMap; |
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22 | import java.util.List; |
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23 | import java.util.Map; |
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24 | |
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25 | import org.apache.commons.logging.Log; |
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26 | import org.apache.commons.logging.LogFactory; |
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27 | import org.apache.hadoop.util.ReflectionUtils; |
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28 | |
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29 | /** |
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30 | * A global compressor/decompressor pool used to save and reuse |
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31 | * (possibly native) compression/decompression codecs. |
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32 | */ |
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33 | public class CodecPool { |
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34 | private static final Log LOG = LogFactory.getLog(CodecPool.class); |
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35 | |
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36 | /** |
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37 | * A global compressor pool used to save the expensive |
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38 | * construction/destruction of (possibly native) decompression codecs. |
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39 | */ |
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40 | private static final Map<Class<Compressor>, List<Compressor>> compressorPool = |
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41 | new HashMap<Class<Compressor>, List<Compressor>>(); |
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42 | |
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43 | /** |
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44 | * A global decompressor pool used to save the expensive |
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45 | * construction/destruction of (possibly native) decompression codecs. |
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46 | */ |
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47 | private static final Map<Class<Decompressor>, List<Decompressor>> decompressorPool = |
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48 | new HashMap<Class<Decompressor>, List<Decompressor>>(); |
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49 | |
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50 | private static <T> T borrow(Map<Class<T>, List<T>> pool, |
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51 | Class<? extends T> codecClass) { |
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52 | T codec = null; |
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53 | |
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54 | // Check if an appropriate codec is available |
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55 | synchronized (pool) { |
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56 | if (pool.containsKey(codecClass)) { |
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57 | List<T> codecList = pool.get(codecClass); |
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58 | |
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59 | if (codecList != null) { |
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60 | synchronized (codecList) { |
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61 | if (!codecList.isEmpty()) { |
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62 | codec = codecList.remove(codecList.size()-1); |
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63 | } |
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64 | } |
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65 | } |
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66 | } |
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67 | } |
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68 | |
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69 | return codec; |
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70 | } |
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71 | |
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72 | private static <T> void payback(Map<Class<T>, List<T>> pool, T codec) { |
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73 | if (codec != null) { |
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74 | Class<T> codecClass = ReflectionUtils.getClass(codec); |
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75 | synchronized (pool) { |
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76 | if (!pool.containsKey(codecClass)) { |
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77 | pool.put(codecClass, new ArrayList<T>()); |
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78 | } |
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79 | |
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80 | List<T> codecList = pool.get(codecClass); |
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81 | synchronized (codecList) { |
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82 | codecList.add(codec); |
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83 | } |
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84 | } |
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85 | } |
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86 | } |
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87 | |
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88 | /** |
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89 | * Get a {@link Compressor} for the given {@link CompressionCodec} from the |
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90 | * pool or a new one. |
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91 | * |
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92 | * @param codec the <code>CompressionCodec</code> for which to get the |
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93 | * <code>Compressor</code> |
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94 | * @return <code>Compressor</code> for the given |
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95 | * <code>CompressionCodec</code> from the pool or a new one |
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96 | */ |
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97 | public static Compressor getCompressor(CompressionCodec codec) { |
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98 | Compressor compressor = borrow(compressorPool, codec.getCompressorType()); |
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99 | if (compressor == null) { |
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100 | compressor = codec.createCompressor(); |
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101 | LOG.info("Got brand-new compressor"); |
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102 | } else { |
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103 | LOG.debug("Got recycled compressor"); |
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104 | } |
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105 | return compressor; |
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106 | } |
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107 | |
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108 | /** |
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109 | * Get a {@link Decompressor} for the given {@link CompressionCodec} from the |
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110 | * pool or a new one. |
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111 | * |
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112 | * @param codec the <code>CompressionCodec</code> for which to get the |
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113 | * <code>Decompressor</code> |
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114 | * @return <code>Decompressor</code> for the given |
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115 | * <code>CompressionCodec</code> the pool or a new one |
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116 | */ |
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117 | public static Decompressor getDecompressor(CompressionCodec codec) { |
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118 | Decompressor decompressor = borrow(decompressorPool, codec.getDecompressorType()); |
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119 | if (decompressor == null) { |
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120 | decompressor = codec.createDecompressor(); |
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121 | LOG.info("Got brand-new decompressor"); |
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122 | } else { |
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123 | LOG.debug("Got recycled decompressor"); |
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124 | } |
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125 | return decompressor; |
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126 | } |
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127 | |
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128 | /** |
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129 | * Return the {@link Compressor} to the pool. |
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130 | * |
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131 | * @param compressor the <code>Compressor</code> to be returned to the pool |
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132 | */ |
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133 | public static void returnCompressor(Compressor compressor) { |
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134 | if (compressor == null) { |
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135 | return; |
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136 | } |
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137 | compressor.reset(); |
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138 | payback(compressorPool, compressor); |
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139 | } |
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140 | |
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141 | /** |
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142 | * Return the {@link Decompressor} to the pool. |
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143 | * |
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144 | * @param decompressor the <code>Decompressor</code> to be returned to the |
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145 | * pool |
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146 | */ |
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147 | public static void returnDecompressor(Decompressor decompressor) { |
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148 | if (decompressor == null) { |
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149 | return; |
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150 | } |
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151 | decompressor.reset(); |
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152 | payback(decompressorPool, decompressor); |
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153 | } |
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154 | } |
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