001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.hadoop.mapreduce;
031
032import org.apache.hadoop.conf.Configured;
033import org.apache.hadoop.fs.Path;
034import org.apache.hadoop.mapreduce.Job;
035import org.apache.hadoop.util.Tool;
036import org.apache.hadoop.util.ToolRunner;
037import org.openimaj.hadoop.mapreduce.stage.Stage;
038
039/**
040 * A StageRunner provides the various components to run an individual stage.
041 * StageRunners get given the the arguments of tools and must provide the inputs of jobs,
042 * the job output location and the actual stage which will provide the job.
043 * 
044 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
045 *
046 */
047public abstract class StageRunner extends Configured implements Tool{
048        @Override
049        public int run(String[] args) throws Exception {
050                args(args);
051                Stage<?, ?, ?, ?, ?, ?, ?, ?> thestage = stage();
052                Job job = thestage.stage(inputs(), output(),this.getConf());
053                if(shouldWait()){
054                        job.waitForCompletion(true);
055                        thestage.finished(job);
056                }
057                else{
058                        job.submit();
059                }
060                return 0;
061        }
062        
063        /**
064         * @return Whether this stage runner should wait for the stage to complete
065         */
066        public boolean shouldWait() {
067                return true;
068        }
069
070        /**
071         * @return the stage which should be ran 
072         */
073        public abstract Stage<?,?,?,?,?,?,?,?> stage();
074        
075        /**
076         * @return the output fed to the stage
077         */
078        public abstract Path output() ;
079
080        /**
081         * @return the inputs fed to the stage
082         * @throws Exception 
083         */
084        public abstract Path[] inputs() throws Exception;
085
086        /**
087         * @param args arguments handed to the {@link Tool#run(String[])}. Given before
088         * outputs, inputs or stages are asked for.
089         * @throws Exception
090         */
091        public abstract void args(String[] args) throws Exception;
092        
093        /**
094         * @param args should be used as a direct proxy for a main method
095         * @throws Exception 
096         */
097        public void runMain(String args[]) throws Exception{
098                ToolRunner.run(this, args);
099        }
100        
101}