com.datasalt.pangool.tuplemr.mapred.lib.input.TupleFileRecordReader.java Source code

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Here is the source code for com.datasalt.pangool.tuplemr.mapred.lib.input.TupleFileRecordReader.java

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package com.datasalt.pangool.tuplemr.mapred.lib.input;

/**
 * Copyright [2012] [Datasalt Systems S.L.]
 *
 * Licensed 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.
 */

import com.datasalt.pangool.io.ITuple;
import com.datasalt.pangool.io.Tuple;
import com.datasalt.pangool.io.TupleFile;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.io.IOException;

/**
 * An {@link org.apache.hadoop.mapreduce.RecordReader} for {@link com.datasalt.pangool.io.TupleFile}s.
 */
public class TupleFileRecordReader extends RecordReader<ITuple, NullWritable> {
    private TupleFile.Reader in;
    private long start;
    private long end;
    private boolean more = true;
    private ITuple tuple = null;
    private NullWritable value = NullWritable.get();
    protected Configuration conf;

    @Override
    public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
        org.apache.hadoop.mapreduce.lib.input.FileSplit fileSplit = (org.apache.hadoop.mapreduce.lib.input.FileSplit) split;
        conf = context.getConfiguration();
        Path path = fileSplit.getPath();
        FileSystem fs = path.getFileSystem(conf);
        this.in = new TupleFile.Reader(fs, conf, path);
        this.end = fileSplit.getStart() + fileSplit.getLength();

        if (fileSplit.getStart() > in.getPosition()) {
            in.sync(fileSplit.getStart());
        }

        this.start = in.getPosition();
        more = start < end;

        tuple = new Tuple(in.getSchema());
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        if (!more) {
            return false;
        }
        long pos = in.getPosition();
        boolean hasNext = in.next(tuple);
        if (!hasNext || (pos >= end && in.syncSeen())) {
            more = false;
            tuple = null;
            value = null;
        }
        return more;
    }

    @Override
    public ITuple getCurrentKey() {
        return tuple;
    }

    @Override
    public NullWritable getCurrentValue() {
        return value;
    }

    /**
     * Return the progress within the input split
     *
     * @return 0.0 to 1.0 of the input byte range
     */
    public float getProgress() throws IOException {
        if (end == start) {
            return 0.0f;
        } else {
            return Math.min(1.0f, (in.getPosition() - start) / (float) (end - start));
        }
    }

    public synchronized void close() throws IOException {
        in.close();
    }
}