| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.util; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configurable; |
| |
| /** |
| * A tool interface that supports handling of generic command-line options. |
| * |
| * <p><code>Tool</code>, is the standard for any Map-Reduce tool/application. |
| * The tool/application should delegate the handling of |
| * <a href="{@docRoot}/../hadoop-project-dist/hadoop-common/CommandsManual.html#Generic_Options"> |
| * standard command-line options</a> to {@link ToolRunner#run(Tool, String[])} |
| * and only handle its custom arguments.</p> |
| * |
| * <p>Here is how a typical <code>Tool</code> is implemented:</p> |
| * <p><blockquote><pre> |
| * public class MyApp extends Configured implements Tool { |
| * |
| * public int run(String[] args) throws Exception { |
| * // <code>Configuration</code> processed by <code>ToolRunner</code> |
| * Configuration conf = getConf(); |
| * |
| * // Create a JobConf using the processed <code>conf</code> |
| * JobConf job = new JobConf(conf, MyApp.class); |
| * |
| * // Process custom command-line options |
| * Path in = new Path(args[1]); |
| * Path out = new Path(args[2]); |
| * |
| * // Specify various job-specific parameters |
| * job.setJobName("my-app"); |
| * job.setInputPath(in); |
| * job.setOutputPath(out); |
| * job.setMapperClass(MyMapper.class); |
| * job.setReducerClass(MyReducer.class); |
| * |
| * // Submit the job, then poll for progress until the job is complete |
| * RunningJob runningJob = JobClient.runJob(job); |
| * if (runningJob.isSuccessful()) { |
| * return 0; |
| * } else { |
| * return 1; |
| * } |
| * } |
| * |
| * public static void main(String[] args) throws Exception { |
| * // Let <code>ToolRunner</code> handle generic command-line options |
| * int res = ToolRunner.run(new Configuration(), new MyApp(), args); |
| * |
| * System.exit(res); |
| * } |
| * } |
| * </pre></blockquote></p> |
| * |
| * @see GenericOptionsParser |
| * @see ToolRunner |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public interface Tool extends Configurable { |
| /** |
| * Execute the command with the given arguments. |
| * |
| * @param args command specific arguments. |
| * @return exit code. |
| * @throws Exception |
| */ |
| int run(String [] args) throws Exception; |
| } |