/*
* Copyright © 2016 Cask Data, Inc.
*
* Licensed 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 co.cask.cdap.internal.app.runtime.batch.dataset.input;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.util.ReflectionUtils;
import java.io.IOException;
/**
* This is a delegating RecordReader, which delegates the functionality to the
* underlying record reader in {@link TaggedInputSplit}
*
* @param <K> Type of key
* @param <V> Type of value
*/
public class DelegatingRecordReader<K, V> extends RecordReader<K, V> {
private final RecordReader<K, V> originalRR;
/**
* Constructs the DelegatingRecordReader.
*
* @param taggedInputSplit TaggedInputSplit object
* @param context TaskAttemptContext object
*
* @throws IOException
* @throws InterruptedException
*/
@SuppressWarnings("unchecked")
public DelegatingRecordReader(TaggedInputSplit taggedInputSplit,
TaskAttemptContext context) throws IOException, InterruptedException {
// Find the InputFormat and then the RecordReader from the TaggedInputSplit.
InputFormat<K, V> inputFormat = (InputFormat<K, V>) ReflectionUtils.newInstance(
taggedInputSplit.getInputFormatClass(), context.getConfiguration());
InputSplit inputSplit = taggedInputSplit.getInputSplit();
originalRR = inputFormat.createRecordReader(inputSplit, context);
}
@Override
public void close() throws IOException {
originalRR.close();
}
@Override
public K getCurrentKey() throws IOException, InterruptedException {
return originalRR.getCurrentKey();
}
@Override
public V getCurrentValue() throws IOException, InterruptedException {
return originalRR.getCurrentValue();
}
@Override
public float getProgress() throws IOException, InterruptedException {
return originalRR.getProgress();
}
@Override
public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
InputSplit inputSplit = ((TaggedInputSplit) split).getInputSplit();
originalRR.initialize(inputSplit, context);
}
@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
return originalRR.nextKeyValue();
}
}