com.aliyun.fs.oss.common.OssRecordReader.java Source code

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Here is the source code for com.aliyun.fs.oss.common.OssRecordReader.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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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 com.aliyun.fs.oss.common;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.Seekable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.compress.CodecPool;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.CompressionCodecFactory;
import org.apache.hadoop.io.compress.Decompressor;
import org.apache.hadoop.io.compress.SplitCompressionInputStream;
import org.apache.hadoop.io.compress.SplittableCompressionCodec;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.LineRecordReader.LineReader;
import org.apache.hadoop.mapred.RecordReader;

import java.io.IOException;

public class OssRecordReader implements RecordReader<LongWritable, Text> {

    private static final Log LOG = LogFactory.getLog(OssRecordReader.class.getName());
    private final Seekable filePosition;
    int maxLineLength;
    private CompressionCodecFactory compressionCodecs = null;
    private long start;
    private long pos;
    private long end;
    private LineReader in;
    private FSDataInputStream fileIn;
    private CompressionCodec codec;
    private Decompressor decompressor;

    public OssRecordReader(Configuration job, FileSplit split, FileSystem fs, byte[] recordDelimiter)
            throws IOException {
        this.maxLineLength = job.getInt(org.apache.hadoop.mapreduce.lib.input.LineRecordReader.MAX_LINE_LENGTH,
                Integer.MAX_VALUE);
        start = split.getStart();
        end = start + split.getLength();
        final Path file = split.getPath();
        compressionCodecs = new CompressionCodecFactory(job);
        codec = compressionCodecs.getCodec(file);

        // open the file and seek to the start of the split
        fileIn = fs.open(file);
        if (isCompressedInput()) {
            decompressor = CodecPool.getDecompressor(codec);
            if (codec instanceof SplittableCompressionCodec) {
                final SplitCompressionInputStream cIn = ((SplittableCompressionCodec) codec).createInputStream(
                        fileIn, decompressor, start, end, SplittableCompressionCodec.READ_MODE.BYBLOCK);
                in = new LineReader(cIn, job, recordDelimiter);
                start = cIn.getAdjustedStart();
                end = cIn.getAdjustedEnd();
                filePosition = cIn; // take pos from compressed stream
            } else {
                in = new LineReader(codec.createInputStream(fileIn, decompressor), job, recordDelimiter);
                filePosition = fileIn;
            }
        } else {
            fileIn.seek(start);
            in = new LineReader(fileIn, job, recordDelimiter);
            filePosition = fileIn;
        }
        // If this is not the first split, we always throw away first record
        // because we always (except the last split) read one extra line in
        // next() method.
        if (start != 0) {
            start += in.readLine(new Text(), 0, maxBytesToConsume(start));
        }
        this.pos = start;
    }

    private boolean isCompressedInput() {
        return (codec != null);
    }

    private int maxBytesToConsume(long pos) {
        return isCompressedInput() ? Integer.MAX_VALUE : (int) Math.min(Integer.MAX_VALUE, end - pos);
    }

    private long getFilePosition() throws IOException {
        long retVal;
        if (isCompressedInput() && null != filePosition) {
            retVal = filePosition.getPos();
        } else {
            retVal = pos;
        }
        return retVal;
    }

    public boolean next(LongWritable key, Text value) throws IOException {
        // We always read one extra line, which lies outside the upper
        // split limit i.e. (end - 1)
        while (getFilePosition() <= end) {
            key.set(pos);

            int newSize = in.readLine(value, maxLineLength, Math.max(maxBytesToConsume(pos), maxLineLength));
            if (newSize == 0) {
                return false;
            }
            pos += newSize;
            if (newSize < maxLineLength) {
                return true;
            }

            // line too long. try again
            LOG.info("Skipped line of size " + newSize + " at pos " + (pos - newSize));
        }

        return false;
    }

    public LongWritable createKey() {
        return new LongWritable();
    }

    public Text createValue() {
        return new Text();
    }

    public long getPos() throws IOException {
        return pos;
    }

    public void close() throws IOException {
        try {
            if (in != null) {
                in.close();
            }
        } finally {
            if (decompressor != null) {
                CodecPool.returnDecompressor(decompressor);
            }
        }
    }

    public float getProgress() throws IOException {
        if (start == end) {
            return 0.0f;
        } else {
            return Math.min(1.0f, (getFilePosition() - start) / (float) (end - start));
        }
    }
}