hadoop CombineFileRecordReaderWrapper 源码
haddop CombineFileRecordReaderWrapper 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/lib/CombineFileRecordReaderWrapper.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.lib;
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.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;
/**
* A wrapper class for a record reader that handles a single file split. It
* delegates most of the methods to the wrapped instance. A concrete subclass
* needs to provide a constructor that calls this parent constructor with the
* appropriate input format. The subclass constructor must satisfy the specific
* constructor signature that is required by
* <code>CombineFileRecordReader</code>.
*
* Subclassing is needed to get a concrete record reader wrapper because of the
* constructor requirement.
*
* @see CombineFileRecordReader
* @see CombineFileInputFormat
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class CombineFileRecordReaderWrapper<K,V>
implements RecordReader<K,V> {
private final RecordReader<K,V> delegate;
protected CombineFileRecordReaderWrapper(FileInputFormat<K,V> inputFormat,
CombineFileSplit split, Configuration conf, Reporter reporter, Integer idx)
throws IOException {
FileSplit fileSplit = new FileSplit(split.getPath(idx),
split.getOffset(idx),
split.getLength(idx),
split.getLocations());
delegate = inputFormat.getRecordReader(fileSplit, (JobConf)conf, reporter);
}
public boolean next(K key, V value) throws IOException {
return delegate.next(key, value);
}
public K createKey() {
return delegate.createKey();
}
public V createValue() {
return delegate.createValue();
}
public long getPos() throws IOException {
return delegate.getPos();
}
public void close() throws IOException {
delegate.close();
}
public float getProgress() throws IOException {
return delegate.getProgress();
}
}
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