org.apache.hadoop.mapred.lib.CombineFileInputFormat Maven / Gradle / Ivy
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* 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.lib;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.CompressionCodecFactory;
import org.apache.hadoop.io.compress.SplittableCompressionCodec;
import org.apache.hadoop.mapred.InputFormat;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
/**
* An abstract {@link org.apache.hadoop.mapred.InputFormat} that returns {@link CombineFileSplit}'s
* in {@link org.apache.hadoop.mapred.InputFormat#getSplits(JobConf, int)} method.
* Splits are constructed from the files under the input paths.
* A split cannot have files from different pools.
* Each split returned may contain blocks from different files.
* If a maxSplitSize is specified, then blocks on the same node are
* combined to form a single split. Blocks that are left over are
* then combined with other blocks in the same rack.
* If maxSplitSize is not specified, then blocks from the same rack
* are combined in a single split; no attempt is made to create
* node-local splits.
* If the maxSplitSize is equal to the block size, then this class
* is similar to the default spliting behaviour in Hadoop: each
* block is a locally processed split.
* Subclasses implement {@link org.apache.hadoop.mapred.InputFormat#getRecordReader(InputSplit, JobConf, Reporter)}
* to construct RecordReader's for CombineFileSplit's.
* @see CombineFileSplit
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class CombineFileInputFormat
extends org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat
implements InputFormat{
/**
* default constructor
*/
public CombineFileInputFormat() {
}
public InputSplit[] getSplits(JobConf job, int numSplits)
throws IOException {
List newStyleSplits =
super.getSplits(Job.getInstance(job));
InputSplit[] ret = new InputSplit[newStyleSplits.size()];
for(int pos = 0; pos < newStyleSplits.size(); ++pos) {
org.apache.hadoop.mapreduce.lib.input.CombineFileSplit newStyleSplit =
(org.apache.hadoop.mapreduce.lib.input.CombineFileSplit) newStyleSplits.get(pos);
ret[pos] = new CombineFileSplit(job, newStyleSplit.getPaths(),
newStyleSplit.getStartOffsets(), newStyleSplit.getLengths(),
newStyleSplit.getLocations());
}
return ret;
}
/**
* Create a new pool and add the filters to it.
* A split cannot have files from different pools.
* @deprecated Use {@link #createPool(List)}.
*/
@Deprecated
protected void createPool(JobConf conf, List filters) {
createPool(filters);
}
/**
* Create a new pool and add the filters to it.
* A pathname can satisfy any one of the specified filters.
* A split cannot have files from different pools.
* @deprecated Use {@link #createPool(PathFilter...)}.
*/
@Deprecated
protected void createPool(JobConf conf, PathFilter... filters) {
createPool(filters);
}
/**
* This is not implemented yet.
*/
public abstract RecordReader getRecordReader(InputSplit split,
JobConf job, Reporter reporter)
throws IOException;
// abstract method from super class implemented to return null
public org.apache.hadoop.mapreduce.RecordReader createRecordReader(
org.apache.hadoop.mapreduce.InputSplit split,
TaskAttemptContext context) throws IOException {
return null;
}
/** List input directories.
* Subclasses may override to, e.g., select only files matching a regular
* expression.
*
* @param job the job to list input paths for
* @return array of FileStatus objects
* @throws IOException if zero items.
*/
protected FileStatus[] listStatus(JobConf job) throws IOException {
List result = super.listStatus(Job.getInstance(job));
return result.toArray(new FileStatus[result.size()]);
}
/**
* Subclasses should avoid overriding this method and should instead only
* override {@link #isSplitable(FileSystem, Path)}. The implementation of
* this method simply calls the other method to preserve compatibility.
* @see
* MAPREDUCE-5530
*
* @param context the job context
* @param file the file name to check
* @return is this file splitable?
*/
@InterfaceAudience.Private
@Override
protected boolean isSplitable(JobContext context, Path file) {
try {
return isSplitable(FileSystem.get(context.getConfiguration()), file);
}
catch (IOException ioe) {
throw new RuntimeException(ioe);
}
}
protected boolean isSplitable(FileSystem fs, Path file) {
final CompressionCodec codec =
new CompressionCodecFactory(fs.getConf()).getCodec(file);
if (null == codec) {
return true;
}
return codec instanceof SplittableCompressionCodec;
}
}