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Gobblin Ingestion Framework
There is a newer version: 0.8.0
/*
 * Copyright (C) 2014-2016 LinkedIn Corp. All rights reserved.
 *
 * 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.
 */

package gobblin.writer;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.Arrays;

import org.apache.commons.lang3.ArrayUtils;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.primitives.Longs;

import gobblin.configuration.ConfigurationKeys;
import gobblin.configuration.State;


/**
 * An implementation of {@link DataWriter} that writes bytes directly to HDFS.
 *
 * This class accepts two new configuration parameters:
 * 
 * {@link ConfigurationKeys#SIMPLE_WRITER_PREPEND_SIZE} is a boolean configuration option. If true, for each record,
 * it will write out a big endian long representing the record size and then write the record. i.e. the file format
 * will be the following:
 * r := >long<>record<
 * file := empty | r file
 * 
{@link ConfigurationKeys#SIMPLE_WRITER_DELIMITER} accepts a byte value. If specified, this byte will be used
 * as a separator between records. If unspecified, no delimiter will be used between records.
 * 
 * @author [email protected]
 */
public class SimpleDataWriter extends FsDataWriter {

  private final Optional recordDelimiter; // optional byte to place between each record write
  private final boolean prependSize;

  private int recordsWritten;
  private int bytesWritten;

  private final OutputStream stagingFileOutputStream;

  public SimpleDataWriter(SimpleDataWriterBuilder builder, State properties) throws IOException {
    super(builder, properties);
    String delim;
    if ((delim = properties.getProp(ConfigurationKeys.SIMPLE_WRITER_DELIMITER, null)) == null || delim.length() == 0) {
      this.recordDelimiter = Optional.absent();
    } else {
      this.recordDelimiter = Optional.of(delim.getBytes(ConfigurationKeys.DEFAULT_CHARSET_ENCODING)[0]);
    }

    this.prependSize = properties.getPropAsBoolean(ConfigurationKeys.SIMPLE_WRITER_PREPEND_SIZE, false);
    this.recordsWritten = 0;
    this.bytesWritten = 0;
    this.stagingFileOutputStream = createStagingFileOutputStream();

    setStagingFileGroup();
  }

  /**
   * Write a source record to the staging file
   *
   * @param record data record to write
   * @throws java.io.IOException if there is anything wrong writing the record
   */
  @Override
  public void write(byte[] record) throws IOException {
    Preconditions.checkNotNull(record);

    byte[] toWrite = record;
    if (this.recordDelimiter.isPresent()) {
      toWrite = Arrays.copyOf(record, record.length + 1);
      toWrite[toWrite.length - 1] = this.recordDelimiter.get();
    }
    if (this.prependSize) {
      long recordSize = toWrite.length;
      ByteBuffer buf = ByteBuffer.allocate(Longs.BYTES);
      buf.putLong(recordSize);
      toWrite = ArrayUtils.addAll(buf.array(), toWrite);
    }
    this.stagingFileOutputStream.write(toWrite);
    this.bytesWritten += toWrite.length;
    this.recordsWritten++;
  }

  /**
   * Get the number of records written.
   *
   * @return number of records written
   */
  @Override
  public long recordsWritten() {
    return this.recordsWritten;
  }

  /**
   * Get the number of bytes written.
   *
   * @return number of bytes written
   */
  @Override
  public long bytesWritten() throws IOException {
    return this.bytesWritten;
  }
}