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.lib; 020 021import java.io.IOException; 022import java.util.List; 023 024import org.apache.hadoop.classification.InterfaceAudience; 025import org.apache.hadoop.classification.InterfaceStability; 026import org.apache.hadoop.fs.FileStatus; 027import org.apache.hadoop.fs.PathFilter; 028import org.apache.hadoop.mapred.InputFormat; 029import org.apache.hadoop.mapred.InputSplit; 030import org.apache.hadoop.mapred.JobConf; 031import org.apache.hadoop.mapred.RecordReader; 032import org.apache.hadoop.mapred.Reporter; 033import org.apache.hadoop.mapreduce.Job; 034import org.apache.hadoop.mapreduce.TaskAttemptContext; 035 036/** 037 * An abstract {@link org.apache.hadoop.mapred.InputFormat} that returns {@link CombineFileSplit}'s 038 * in {@link org.apache.hadoop.mapred.InputFormat#getSplits(JobConf, int)} method. 039 * Splits are constructed from the files under the input paths. 040 * A split cannot have files from different pools. 041 * Each split returned may contain blocks from different files. 042 * If a maxSplitSize is specified, then blocks on the same node are 043 * combined to form a single split. Blocks that are left over are 044 * then combined with other blocks in the same rack. 045 * If maxSplitSize is not specified, then blocks from the same rack 046 * are combined in a single split; no attempt is made to create 047 * node-local splits. 048 * If the maxSplitSize is equal to the block size, then this class 049 * is similar to the default spliting behaviour in Hadoop: each 050 * block is a locally processed split. 051 * Subclasses implement {@link org.apache.hadoop.mapred.InputFormat#getRecordReader(InputSplit, JobConf, Reporter)} 052 * to construct <code>RecordReader</code>'s for <code>CombineFileSplit</code>'s. 053 * @see CombineFileSplit 054 */ 055@InterfaceAudience.Public 056@InterfaceStability.Stable 057public abstract class CombineFileInputFormat<K, V> 058 extends org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat<K, V> 059 implements InputFormat<K, V>{ 060 061 /** 062 * default constructor 063 */ 064 public CombineFileInputFormat() { 065 } 066 067 public InputSplit[] getSplits(JobConf job, int numSplits) 068 throws IOException { 069 List<org.apache.hadoop.mapreduce.InputSplit> newStyleSplits = 070 super.getSplits(new Job(job)); 071 InputSplit[] ret = new InputSplit[newStyleSplits.size()]; 072 for(int pos = 0; pos < newStyleSplits.size(); ++pos) { 073 org.apache.hadoop.mapreduce.lib.input.CombineFileSplit newStyleSplit = 074 (org.apache.hadoop.mapreduce.lib.input.CombineFileSplit) newStyleSplits.get(pos); 075 ret[pos] = new CombineFileSplit(job, newStyleSplit.getPaths(), 076 newStyleSplit.getStartOffsets(), newStyleSplit.getLengths(), 077 newStyleSplit.getLocations()); 078 } 079 return ret; 080 } 081 082 /** 083 * Create a new pool and add the filters to it. 084 * A split cannot have files from different pools. 085 * @deprecated Use {@link #createPool(List)}. 086 */ 087 @Deprecated 088 protected void createPool(JobConf conf, List<PathFilter> filters) { 089 createPool(filters); 090 } 091 092 /** 093 * Create a new pool and add the filters to it. 094 * A pathname can satisfy any one of the specified filters. 095 * A split cannot have files from different pools. 096 * @deprecated Use {@link #createPool(PathFilter...)}. 097 */ 098 @Deprecated 099 protected void createPool(JobConf conf, PathFilter... filters) { 100 createPool(filters); 101 } 102 103 /** 104 * This is not implemented yet. 105 */ 106 public abstract RecordReader<K, V> getRecordReader(InputSplit split, 107 JobConf job, Reporter reporter) 108 throws IOException; 109 110 // abstract method from super class implemented to return null 111 public org.apache.hadoop.mapreduce.RecordReader<K, V> createRecordReader( 112 org.apache.hadoop.mapreduce.InputSplit split, 113 TaskAttemptContext context) throws IOException { 114 return null; 115 } 116 117 /** List input directories. 118 * Subclasses may override to, e.g., select only files matching a regular 119 * expression. 120 * 121 * @param job the job to list input paths for 122 * @return array of FileStatus objects 123 * @throws IOException if zero items. 124 */ 125 protected FileStatus[] listStatus(JobConf job) throws IOException { 126 List<FileStatus> result = super.listStatus(new Job(job)); 127 return result.toArray(new FileStatus[result.size()]); 128 } 129 130}