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.serializer; |
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20 | |
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21 | import java.io.IOException; |
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22 | import java.util.Comparator; |
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23 | |
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24 | import org.apache.hadoop.io.InputBuffer; |
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25 | import org.apache.hadoop.io.RawComparator; |
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26 | |
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27 | /** |
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28 | * <p> |
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29 | * A {@link RawComparator} that uses a {@link Deserializer} to deserialize |
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30 | * the objects to be compared so that the standard {@link Comparator} can |
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31 | * be used to compare them. |
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32 | * </p> |
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33 | * <p> |
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34 | * One may optimize compare-intensive operations by using a custom |
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35 | * implementation of {@link RawComparator} that operates directly |
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36 | * on byte representations. |
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37 | * </p> |
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38 | * @param <T> |
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39 | */ |
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40 | public abstract class DeserializerComparator<T> implements RawComparator<T> { |
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41 | |
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42 | private InputBuffer buffer = new InputBuffer(); |
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43 | private Deserializer<T> deserializer; |
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44 | |
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45 | private T key1; |
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46 | private T key2; |
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47 | |
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48 | protected DeserializerComparator(Deserializer<T> deserializer) |
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49 | throws IOException { |
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50 | |
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51 | this.deserializer = deserializer; |
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52 | this.deserializer.open(buffer); |
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53 | } |
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54 | |
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55 | public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) { |
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56 | try { |
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57 | |
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58 | buffer.reset(b1, s1, l1); |
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59 | key1 = deserializer.deserialize(key1); |
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60 | |
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61 | buffer.reset(b2, s2, l2); |
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62 | key2 = deserializer.deserialize(key2); |
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63 | |
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64 | } catch (IOException e) { |
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65 | throw new RuntimeException(e); |
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66 | } |
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67 | return compare(key1, key2); |
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68 | } |
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69 | |
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70 | } |
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