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.util; |
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19 | |
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20 | import java.io.PrintStream; |
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21 | |
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22 | import org.apache.hadoop.conf.Configuration; |
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23 | |
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24 | /** |
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25 | * A utility to help run {@link Tool}s. |
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26 | * |
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27 | * <p><code>ToolRunner</code> can be used to run classes implementing |
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28 | * <code>Tool</code> interface. It works in conjunction with |
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29 | * {@link GenericOptionsParser} to parse the |
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30 | * <a href="{@docRoot}/org/apache/hadoop/util/GenericOptionsParser.html#GenericOptions"> |
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31 | * generic hadoop command line arguments</a> and modifies the |
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32 | * <code>Configuration</code> of the <code>Tool</code>. The |
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33 | * application-specific options are passed along without being modified. |
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34 | * </p> |
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35 | * |
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36 | * @see Tool |
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37 | * @see GenericOptionsParser |
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38 | */ |
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39 | public class ToolRunner { |
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40 | |
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41 | /** |
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42 | * Runs the given <code>Tool</code> by {@link Tool#run(String[])}, after |
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43 | * parsing with the given generic arguments. Uses the given |
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44 | * <code>Configuration</code>, or builds one if null. |
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45 | * |
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46 | * Sets the <code>Tool</code>'s configuration with the possibly modified |
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47 | * version of the <code>conf</code>. |
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48 | * |
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49 | * @param conf <code>Configuration</code> for the <code>Tool</code>. |
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50 | * @param tool <code>Tool</code> to run. |
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51 | * @param args command-line arguments to the tool. |
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52 | * @return exit code of the {@link Tool#run(String[])} method. |
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53 | */ |
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54 | public static int run(Configuration conf, Tool tool, String[] args) |
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55 | throws Exception{ |
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56 | if(conf == null) { |
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57 | conf = new Configuration(); |
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58 | } |
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59 | GenericOptionsParser parser = new GenericOptionsParser(conf, args); |
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60 | //set the configuration back, so that Tool can configure itself |
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61 | tool.setConf(conf); |
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62 | |
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63 | //get the args w/o generic hadoop args |
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64 | String[] toolArgs = parser.getRemainingArgs(); |
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65 | return tool.run(toolArgs); |
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66 | } |
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67 | |
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68 | /** |
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69 | * Runs the <code>Tool</code> with its <code>Configuration</code>. |
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70 | * |
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71 | * Equivalent to <code>run(tool.getConf(), tool, args)</code>. |
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72 | * |
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73 | * @param tool <code>Tool</code> to run. |
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74 | * @param args command-line arguments to the tool. |
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75 | * @return exit code of the {@link Tool#run(String[])} method. |
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76 | */ |
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77 | public static int run(Tool tool, String[] args) |
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78 | throws Exception{ |
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79 | return run(tool.getConf(), tool, args); |
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80 | } |
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81 | |
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82 | /** |
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83 | * Prints generic command-line argurments and usage information. |
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84 | * |
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85 | * @param out stream to write usage information to. |
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86 | */ |
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87 | public static void printGenericCommandUsage(PrintStream out) { |
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88 | GenericOptionsParser.printGenericCommandUsage(out); |
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89 | } |
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90 | |
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91 | } |
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