hbase-it/src/test/java/org/apache/hadoop/hbase/test/util/warc/WARCInputFormat.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
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 * 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.
 */
/*
 * The MIT License (MIT)
 * Copyright (c) 2014 Martin Kleppmann
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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package org.apache.hadoop.hbase.test.util.warc;

import java.io.EOFException;
import java.io.IOException;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

/**
 * Hadoop InputFormat for mapreduce jobs ('new' API) that want to process data in WARC files.
 *
 * Usage:
 *
 * ```java
 * Job job = new Job(getConf());
 * job.setInputFormatClass(WARCInputFormat.class);
 * ```
 *
 * Mappers should use a key of {@link org.apache.hadoop.io.LongWritable} (which is
 * 1 for the first record in a file, 2 for the second record, etc.) and a value of
 * {@link WARCWritable}.
 */
public class WARCInputFormat extends FileInputFormat<LongWritable, WARCWritable> {

  /**
   * Opens a WARC file (possibly compressed) for reading, and returns a RecordReader for
   * accessing it.
   */
  @Override
  public RecordReader<LongWritable, WARCWritable> createRecordReader(InputSplit split,
      TaskAttemptContext context)
          throws IOException, InterruptedException {
    return new WARCReader();
  }

  /**
   * Always returns false, as WARC files cannot be split.
   */
  @Override
  protected boolean isSplitable(JobContext context, Path filename) {
    return false;
  }

  private static class WARCReader extends RecordReader<LongWritable, WARCWritable> {
    private final LongWritable key = new LongWritable();
    private final WARCWritable value = new WARCWritable();
    private WARCFileReader reader;

    @Override
    public void initialize(InputSplit split, TaskAttemptContext context)
        throws IOException, InterruptedException {
      reader = new WARCFileReader(context.getConfiguration(), ((FileSplit) split).getPath());
    }

    @Override
    public boolean nextKeyValue() throws IOException {
      try {
        WARCRecord record = reader.read();
        key.set(reader.getRecordsRead());
        value.setRecord(record);
        return true;
      } catch (EOFException eof) {
        return false;
      }
    }

    @Override
    public void close() throws IOException {
      reader.close();
    }

    @Override
    public float getProgress() throws IOException {
      return reader.getProgress();
    }

    @Override
    public LongWritable getCurrentKey() throws IOException, InterruptedException {
      return key;
    }

    @Override
    public WARCWritable getCurrentValue() throws IOException, InterruptedException {
      return value;
    }
  }

}