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
019 package org.apache.hadoop.mapred.lib;
020
021 import java.io.IOException;
022 import java.util.List;
023
024 import org.apache.hadoop.classification.InterfaceAudience;
025 import org.apache.hadoop.classification.InterfaceStability;
026 import org.apache.hadoop.fs.FileStatus;
027 import org.apache.hadoop.fs.FileSystem;
028 import org.apache.hadoop.fs.Path;
029 import org.apache.hadoop.fs.PathFilter;
030 import org.apache.hadoop.io.compress.CompressionCodec;
031 import org.apache.hadoop.io.compress.CompressionCodecFactory;
032 import org.apache.hadoop.io.compress.SplittableCompressionCodec;
033 import org.apache.hadoop.mapred.InputFormat;
034 import org.apache.hadoop.mapred.InputSplit;
035 import org.apache.hadoop.mapred.JobConf;
036 import org.apache.hadoop.mapred.RecordReader;
037 import org.apache.hadoop.mapred.Reporter;
038 import org.apache.hadoop.mapreduce.Job;
039 import org.apache.hadoop.mapreduce.JobContext;
040 import org.apache.hadoop.mapreduce.TaskAttemptContext;
041
042 /**
043 * An abstract {@link org.apache.hadoop.mapred.InputFormat} that returns {@link CombineFileSplit}'s
044 * in {@link org.apache.hadoop.mapred.InputFormat#getSplits(JobConf, int)} method.
045 * Splits are constructed from the files under the input paths.
046 * A split cannot have files from different pools.
047 * Each split returned may contain blocks from different files.
048 * If a maxSplitSize is specified, then blocks on the same node are
049 * combined to form a single split. Blocks that are left over are
050 * then combined with other blocks in the same rack.
051 * If maxSplitSize is not specified, then blocks from the same rack
052 * are combined in a single split; no attempt is made to create
053 * node-local splits.
054 * If the maxSplitSize is equal to the block size, then this class
055 * is similar to the default spliting behaviour in Hadoop: each
056 * block is a locally processed split.
057 * Subclasses implement {@link org.apache.hadoop.mapred.InputFormat#getRecordReader(InputSplit, JobConf, Reporter)}
058 * to construct <code>RecordReader</code>'s for <code>CombineFileSplit</code>'s.
059 * @see CombineFileSplit
060 */
061 @InterfaceAudience.Public
062 @InterfaceStability.Stable
063 public abstract class CombineFileInputFormat<K, V>
064 extends org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat<K, V>
065 implements InputFormat<K, V>{
066
067 /**
068 * default constructor
069 */
070 public CombineFileInputFormat() {
071 }
072
073 public InputSplit[] getSplits(JobConf job, int numSplits)
074 throws IOException {
075 List<org.apache.hadoop.mapreduce.InputSplit> newStyleSplits =
076 super.getSplits(new Job(job));
077 InputSplit[] ret = new InputSplit[newStyleSplits.size()];
078 for(int pos = 0; pos < newStyleSplits.size(); ++pos) {
079 org.apache.hadoop.mapreduce.lib.input.CombineFileSplit newStyleSplit =
080 (org.apache.hadoop.mapreduce.lib.input.CombineFileSplit) newStyleSplits.get(pos);
081 ret[pos] = new CombineFileSplit(job, newStyleSplit.getPaths(),
082 newStyleSplit.getStartOffsets(), newStyleSplit.getLengths(),
083 newStyleSplit.getLocations());
084 }
085 return ret;
086 }
087
088 /**
089 * Create a new pool and add the filters to it.
090 * A split cannot have files from different pools.
091 * @deprecated Use {@link #createPool(List)}.
092 */
093 @Deprecated
094 protected void createPool(JobConf conf, List<PathFilter> filters) {
095 createPool(filters);
096 }
097
098 /**
099 * Create a new pool and add the filters to it.
100 * A pathname can satisfy any one of the specified filters.
101 * A split cannot have files from different pools.
102 * @deprecated Use {@link #createPool(PathFilter...)}.
103 */
104 @Deprecated
105 protected void createPool(JobConf conf, PathFilter... filters) {
106 createPool(filters);
107 }
108
109 /**
110 * This is not implemented yet.
111 */
112 public abstract RecordReader<K, V> getRecordReader(InputSplit split,
113 JobConf job, Reporter reporter)
114 throws IOException;
115
116 // abstract method from super class implemented to return null
117 public org.apache.hadoop.mapreduce.RecordReader<K, V> createRecordReader(
118 org.apache.hadoop.mapreduce.InputSplit split,
119 TaskAttemptContext context) throws IOException {
120 return null;
121 }
122
123 /** List input directories.
124 * Subclasses may override to, e.g., select only files matching a regular
125 * expression.
126 *
127 * @param job the job to list input paths for
128 * @return array of FileStatus objects
129 * @throws IOException if zero items.
130 */
131 protected FileStatus[] listStatus(JobConf job) throws IOException {
132 List<FileStatus> result = super.listStatus(new Job(job));
133 return result.toArray(new FileStatus[result.size()]);
134 }
135
136 /**
137 * Subclasses should avoid overriding this method and should instead only
138 * override {@link #isSplitable(FileSystem, Path)}. The implementation of
139 * this method simply calls the other method to preserve compatibility.
140 * @see <a href="https://issues.apache.org/jira/browse/MAPREDUCE-5530">
141 * MAPREDUCE-5530</a>
142 *
143 * @param context the job context
144 * @param file the file name to check
145 * @return is this file splitable?
146 */
147 @InterfaceAudience.Private
148 @Override
149 protected boolean isSplitable(JobContext context, Path file) {
150 try {
151 return isSplitable(FileSystem.get(context.getConfiguration()), file);
152 }
153 catch (IOException ioe) {
154 throw new RuntimeException(ioe);
155 }
156 }
157
158 protected boolean isSplitable(FileSystem fs, Path file) {
159 final CompressionCodec codec =
160 new CompressionCodecFactory(fs.getConf()).getCodec(file);
161 if (null == codec) {
162 return true;
163 }
164 return codec instanceof SplittableCompressionCodec;
165 }
166 }