cascading.tap.hadoop.MultiInputSplit.java Source code

Introduction

Here is the source code for cascading.tap.hadoop.MultiInputSplit.java

Source

/*
 * Copyright (c) 2007-2010 Concurrent, Inc. All Rights Reserved.
 *
 * Project and contact information: http://www.cascading.org/
 *
 * This file is part of the Cascading project.
 *
 * Cascading 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.
 *
 * Cascading 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 Cascading.  If not, see <http://www.gnu.org/licenses/>.
 */

package cascading.tap.hadoop;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.JobConfigurable;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.log4j.Logger;

/** Class MultiInputSplit is used by MultiInputFormat */
public class MultiInputSplit implements InputSplit, JobConfigurable {
    private static final Logger LOG = Logger.getLogger(MultiInputSplit.class);

    /** Field jobConf */
    private transient JobConf jobConf;
    /** Field inputSplit */
    InputSplit inputSplit;
    /** Field config */
    Map<String, String> config;

    /**
     * Method getCurrentTapSourcePath finds and returns the current source Tap filename path, if any.
     * <p/>
     * Use this method inside an Operation to find the current file being processed.
     *
     * @param jobConf
     * @return a String
     */
    public static String getCurrentTapSourcePath(JobConf jobConf) {
        return jobConf.get("cascading.source.path");
    }

    public MultiInputSplit(InputSplit inputSplit, Map<String, String> config) {
        this.inputSplit = inputSplit;
        this.config = config;
    }

    public MultiInputSplit() {
    }

    public void configure(JobConf jobConf) {
        this.jobConf = jobConf;
    }

    public long getLength() throws IOException {
        return inputSplit.getLength();
    }

    public String[] getLocations() throws IOException {
        return inputSplit.getLocations();
    }

    public void write(DataOutput out) throws IOException {
        out.writeUTF(inputSplit.getClass().getName());

        String[] keys = config.keySet().toArray(new String[config.size()]);
        String[] values = new String[keys.length];

        for (int i = 0; i < keys.length; i++)
            values[i] = config.get(keys[i]);

        WritableUtils.writeStringArray(out, keys);
        WritableUtils.writeStringArray(out, values);

        inputSplit.write(out);
    }

    public void readFields(DataInput in) throws IOException {
        String splitType = in.readUTF();
        config = new HashMap<String, String>();

        String[] keys = WritableUtils.readStringArray(in);
        String[] values = WritableUtils.readStringArray(in);

        for (int i = 0; i < keys.length; i++)
            config.put(keys[i], values[i]);

        JobConf currentConf = MultiInputFormat.mergeConf(jobConf, config, false);

        try {
            inputSplit = (InputSplit) ReflectionUtils.newInstance(currentConf.getClassByName(splitType),
                    currentConf);
        } catch (ClassNotFoundException exp) {
            throw new IOException("split class " + splitType + " not found");
        }

        inputSplit.readFields(in);

        if (inputSplit instanceof FileSplit) {
            Path path = ((FileSplit) inputSplit).getPath();

            if (path != null) {
                jobConf.set("cascading.source.path", path.toString());

                if (LOG.isInfoEnabled())
                    LOG.info("current split input path: " + path.toString());
            }
        }
    }
}