org.apache.hadoop.util.Tool Maven / Gradle / Ivy
/**
* 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.
*
* Tool, is the standard for any Map-Reduce tool/application.
* The tool/application should delegate the handling of
*
* standard command-line options to {@link ToolRunner#run(Tool, String[])}
* and only handle its custom arguments.
*
* Here is how a typical Tool is implemented:
*
* public class MyApp extends Configured implements Tool {
*
* public int run(String[] args) throws Exception {
* // Configuration processed by ToolRunner
* Configuration conf = getConf();
*
* // Create a JobConf using the processed conf
* 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 ToolRunner handle generic command-line options
* int res = ToolRunner.run(new Configuration(), new MyApp(), args);
*
* System.exit(res);
* }
* }
*
*
* @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;
}