hadoop FixedLengthInputFormat 源码

haddop FixedLengthInputFormat 代码

文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/FixedLengthInputFormat.java

/**
 * 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.mapred;

import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.CompressionCodecFactory;

/**
 * FixedLengthInputFormat is an input format used to read input files
 * which contain fixed length records.  The content of a record need not be
 * text.  It can be arbitrary binary data.  Users must configure the record
 * length property by calling:
 * FixedLengthInputFormat.setRecordLength(conf, recordLength);<br><br> or
 * conf.setInt(FixedLengthInputFormat.FIXED_RECORD_LENGTH, recordLength);
 * <br><br>
 * @see FixedLengthRecordReader
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class FixedLengthInputFormat
    extends FileInputFormat<LongWritable, BytesWritable>
    implements JobConfigurable {

  private CompressionCodecFactory compressionCodecs = null;
  
  public static final String FIXED_RECORD_LENGTH =
      "fixedlengthinputformat.record.length"; 

  /**
   * Set the length of each record
   * @param conf configuration
   * @param recordLength the length of a record
   */
  public static void setRecordLength(Configuration conf, int recordLength) {
    conf.setInt(FIXED_RECORD_LENGTH, recordLength);
  }

  /**
   * Get record length value
   * @param conf configuration
   * @return the record length, zero means none was set
   */
  public static int getRecordLength(Configuration conf) {
    return conf.getInt(FIXED_RECORD_LENGTH, 0);
  }

  @Override
  public void configure(JobConf conf) {
    compressionCodecs = new CompressionCodecFactory(conf);
  }

  @Override
  public RecordReader<LongWritable, BytesWritable>
      getRecordReader(InputSplit genericSplit, JobConf job, Reporter reporter)
      throws IOException {
    reporter.setStatus(genericSplit.toString());
    int recordLength = getRecordLength(job);
    if (recordLength <= 0) {
      throw new IOException("Fixed record length " + recordLength
          + " is invalid.  It should be set to a value greater than zero");
    }
    return new FixedLengthRecordReader(job, (FileSplit)genericSplit,
                                       recordLength);
  }

  @Override
  protected boolean isSplitable(FileSystem fs, Path file) {
    final CompressionCodec codec = compressionCodecs.getCodec(file);
    return(null == codec);
  }

}

相关信息

hadoop 源码目录

相关文章

hadoop AMFeedback 源码

hadoop BackupStore 源码

hadoop BasicTypeSorterBase 源码

hadoop BufferSorter 源码

hadoop CleanupQueue 源码

hadoop Clock 源码

hadoop ClusterStatus 源码

hadoop Counters 源码

hadoop CumulativePeriodicStats 源码

hadoop DeprecatedQueueConfigurationParser 源码