001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.mapred;
020
021import java.io.IOException;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025import org.apache.hadoop.io.Writable;
026
027/**
028 * <code>InputSplit</code> represents the data to be processed by an 
029 * individual {@link Mapper}. 
030 *
031 * <p>Typically, it presents a byte-oriented view on the input and is the 
032 * responsibility of {@link RecordReader} of the job to process this and present
033 * a record-oriented view.
034 * 
035 * @see InputFormat
036 * @see RecordReader
037 */
038@InterfaceAudience.Public
039@InterfaceStability.Stable
040public interface InputSplit extends Writable {
041
042  /**
043   * Get the total number of bytes in the data of the <code>InputSplit</code>.
044   * 
045   * @return the number of bytes in the input split.
046   * @throws IOException
047   */
048  long getLength() throws IOException;
049  
050  /**
051   * Get the list of hostnames where the input split is located.
052   * 
053   * @return list of hostnames where data of the <code>InputSplit</code> is
054   *         located as an array of <code>String</code>s.
055   * @throws IOException
056   */
057  String[] getLocations() throws IOException;
058}