org.apache.hadoop.mapreduce.lib.input.CombineFileSplit.java Source code

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Here is the source code for org.apache.hadoop.mapreduce.lib.input.CombineFileSplit.java

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/**
 * 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.mapreduce.lib.input;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;

/**
 * A sub-collection of input files. 
 * 
 * Unlike {@link FileSplit}, CombineFileSplit class does not represent 
 * a split of a file, but a split of input files into smaller sets. 
 * A split may contain blocks from different file but all 
 * the blocks in the same split are probably local to some rack <br> 
 * CombineFileSplit can be used to implement {@link RecordReader}'s, 
 * with reading one record per file.
 * 
 * @see FileSplit
 * @see CombineFileInputFormat 
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class CombineFileSplit extends InputSplit implements Writable {

    private Path[] paths;
    private long[] startoffset;
    private long[] lengths;
    private String[] locations;
    private long totLength;

    /**
     * default constructor
     */
    public CombineFileSplit() {
    }

    public CombineFileSplit(Path[] files, long[] start, long[] lengths, String[] locations) {
        initSplit(files, start, lengths, locations);
    }

    public CombineFileSplit(Path[] files, long[] lengths) {
        long[] startoffset = new long[files.length];
        for (int i = 0; i < startoffset.length; i++) {
            startoffset[i] = 0;
        }
        String[] locations = new String[files.length];
        for (int i = 0; i < locations.length; i++) {
            locations[i] = "";
        }
        initSplit(files, startoffset, lengths, locations);
    }

    private void initSplit(Path[] files, long[] start, long[] lengths, String[] locations) {
        this.startoffset = start;
        this.lengths = lengths;
        this.paths = files;
        this.totLength = 0;
        this.locations = locations;
        for (long length : lengths) {
            totLength += length;
        }
    }

    /**
     * Copy constructor
     */
    public CombineFileSplit(CombineFileSplit old) throws IOException {
        this(old.getPaths(), old.getStartOffsets(), old.getLengths(), old.getLocations());
    }

    public long getLength() {
        return totLength;
    }

    /** Returns an array containing the start offsets of the files in the split*/
    public long[] getStartOffsets() {
        return startoffset;
    }

    /** Returns an array containing the lengths of the files in the split*/
    public long[] getLengths() {
        return lengths;
    }

    /** Returns the start offset of the i<sup>th</sup> Path */
    public long getOffset(int i) {
        return startoffset[i];
    }

    /** Returns the length of the i<sup>th</sup> Path */
    public long getLength(int i) {
        return lengths[i];
    }

    /** Returns the number of Paths in the split */
    public int getNumPaths() {
        return paths.length;
    }

    /** Returns the i<sup>th</sup> Path */
    public Path getPath(int i) {
        return paths[i];
    }

    /** Returns all the Paths in the split */
    public Path[] getPaths() {
        return paths;
    }

    /** Returns all the Paths where this input-split resides */
    public String[] getLocations() throws IOException {
        return locations;
    }

    public void readFields(DataInput in) throws IOException {
        totLength = in.readLong();
        int arrLength = in.readInt();
        lengths = new long[arrLength];
        for (int i = 0; i < arrLength; i++) {
            lengths[i] = in.readLong();
        }
        int filesLength = in.readInt();
        paths = new Path[filesLength];
        for (int i = 0; i < filesLength; i++) {
            paths[i] = new Path(Text.readString(in));
        }
        arrLength = in.readInt();
        startoffset = new long[arrLength];
        for (int i = 0; i < arrLength; i++) {
            startoffset[i] = in.readLong();
        }
    }

    public void write(DataOutput out) throws IOException {
        out.writeLong(totLength);
        out.writeInt(lengths.length);
        for (long length : lengths) {
            out.writeLong(length);
        }
        out.writeInt(paths.length);
        for (Path p : paths) {
            Text.writeString(out, p.toString());
        }
        out.writeInt(startoffset.length);
        for (long length : startoffset) {
            out.writeLong(length);
        }
    }

    @Override
    public String toString() {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < paths.length; i++) {
            if (i == 0) {
                sb.append("Paths:");
            }
            sb.append(paths[i].toUri().getPath() + ":" + startoffset[i] + "+" + lengths[i]);
            if (i < paths.length - 1) {
                sb.append(",");
            }
        }
        if (locations != null) {
            String locs = "";
            StringBuffer locsb = new StringBuffer();
            for (int i = 0; i < locations.length; i++) {
                locsb.append(locations[i] + ":");
            }
            locs = locsb.toString();
            sb.append(" Locations:" + locs + "; ");
        }
        return sb.toString();
    }
}