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Massive On-line Analysis is an environment for massive data mining. MOA provides a framework for data stream mining and includes tools for evaluation and a collection of machine learning algorithms. Related to the WEKA project, also written in Java, while scaling to more demanding problems.

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/*
 *    MainTask.java
 *    Copyright (C) 2007 University of Waikato, Hamilton, New Zealand
 *    @author Richard Kirkby ([email protected])
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program. If not, see .
 *    
 */
package moa.tasks;

import java.io.File;
import java.io.IOException;
import java.io.Serializable;

import moa.core.ObjectRepository;
import moa.core.SerializeUtils;
import com.github.javacliparser.FileOption;

/**
 * Abstract Main Task. All tasks that want to write their result 
 * to a file must extend this class.
 *
 * @author Richard Kirkby ([email protected])
 * @version $Revision: 7 $
 */
public abstract class MainTask extends AbstractTask {

    private static final long serialVersionUID = 1L;

    /** The number of instances between monitor updates. */
    protected static final int INSTANCES_BETWEEN_MONITOR_UPDATES = 10;

    /** File option to save the final result of the task to. */
    public FileOption outputFileOption = new FileOption("taskResultFile", 'O',
            "File to save the final result of the task to.", null, "moa", true);

    @Override
    protected Object doTaskImpl(TaskMonitor monitor, ObjectRepository repository) {
        Object result = doMainTask(monitor, repository);
        if (monitor.taskShouldAbort()) {
            return null;
        }
        File outputFile = this.outputFileOption.getFile();
        if (outputFile != null) {
            if (result instanceof Serializable) {
                monitor.setCurrentActivity("Saving result of task "
                        + getTaskName() + " to file " + outputFile + "...",
                        -1.0);
                try {
                    SerializeUtils.writeToFile(outputFile,
                            (Serializable) result);
                } catch (IOException ioe) {
                    throw new RuntimeException("Failed writing result of task "
                            + getTaskName() + " to file " + outputFile, ioe);
                }
            } else {
                throw new RuntimeException("Result of task " + getTaskName()
                        + " is not serializable, so cannot be written to file "
                        + outputFile);
            }
        }
        return result;
    }

    /**
     * This method performs this task.
     * AbstractTask implements doTask,
     * that uses doTaskImpl.
     * MainTask implements doTaskImpl using
     * doMainTask so its extensions only need to implement
     * doMainTask.
     *
     * @param monitor the TaskMonitor to use
     * @param repository  the ObjectRepository to use
     * @return an object with the result of this task
     */
    protected abstract Object doMainTask(TaskMonitor monitor,
            ObjectRepository repository);
}