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.mapreduce; |
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20 | |
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21 | import java.io.IOException; |
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22 | |
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23 | import org.apache.hadoop.conf.Configuration; |
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24 | import org.apache.hadoop.util.Progressable; |
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25 | |
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26 | /** |
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27 | * A context object that allows input and output from the task. It is only |
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28 | * supplied to the {@link Mapper} or {@link Reducer}. |
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29 | * @param <KEYIN> the input key type for the task |
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30 | * @param <VALUEIN> the input value type for the task |
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31 | * @param <KEYOUT> the output key type for the task |
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32 | * @param <VALUEOUT> the output value type for the task |
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33 | */ |
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34 | public abstract class TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT> |
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35 | extends TaskAttemptContext implements Progressable { |
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36 | private RecordWriter<KEYOUT,VALUEOUT> output; |
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37 | private StatusReporter reporter; |
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38 | private OutputCommitter committer; |
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39 | |
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40 | public TaskInputOutputContext(Configuration conf, TaskAttemptID taskid, |
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41 | RecordWriter<KEYOUT,VALUEOUT> output, |
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42 | OutputCommitter committer, |
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43 | StatusReporter reporter) { |
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44 | super(conf, taskid); |
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45 | this.output = output; |
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46 | this.reporter = reporter; |
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47 | this.committer = committer; |
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48 | } |
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49 | |
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50 | /** |
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51 | * Advance to the next key, value pair, returning null if at end. |
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52 | * @return the key object that was read into, or null if no more |
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53 | */ |
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54 | public abstract |
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55 | boolean nextKeyValue() throws IOException, InterruptedException; |
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56 | |
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57 | /** |
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58 | * Get the current key. |
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59 | * @return the current key object or null if there isn't one |
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60 | * @throws IOException |
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61 | * @throws InterruptedException |
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62 | */ |
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63 | public abstract |
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64 | KEYIN getCurrentKey() throws IOException, InterruptedException; |
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65 | |
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66 | /** |
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67 | * Get the current value. |
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68 | * @return the value object that was read into |
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69 | * @throws IOException |
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70 | * @throws InterruptedException |
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71 | */ |
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72 | public abstract VALUEIN getCurrentValue() throws IOException, |
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73 | InterruptedException; |
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74 | |
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75 | /** |
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76 | * Generate an output key/value pair. |
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77 | */ |
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78 | public void write(KEYOUT key, VALUEOUT value |
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79 | ) throws IOException, InterruptedException { |
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80 | output.write(key, value); |
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81 | } |
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82 | |
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83 | public Counter getCounter(Enum<?> counterName) { |
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84 | return reporter.getCounter(counterName); |
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85 | } |
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86 | |
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87 | public Counter getCounter(String groupName, String counterName) { |
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88 | return reporter.getCounter(groupName, counterName); |
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89 | } |
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90 | |
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91 | @Override |
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92 | public void progress() { |
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93 | reporter.progress(); |
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94 | } |
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95 | |
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96 | @Override |
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97 | public void setStatus(String status) { |
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98 | reporter.setStatus(status); |
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99 | } |
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100 | |
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101 | public OutputCommitter getOutputCommitter() { |
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102 | return committer; |
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103 | } |
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104 | } |
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