/**
* 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.tez.runtime.library.input;
import java.io.IOException;
import java.util.List;
import org.apache.tez.dag.api.GroupInputEdge;
import org.apache.tez.dag.api.TezUncheckedException;
import org.apache.tez.runtime.api.Input;
import org.apache.tez.runtime.api.MergedLogicalInput;
import org.apache.tez.runtime.api.Reader;
import org.apache.tez.runtime.api.MergedInputContext;
import org.apache.tez.runtime.library.api.KeyValueReader;
/**
* Implements a {@link MergedLogicalInput} that merges the incoming inputs
* (e.g. from a {@link GroupInputEdge} and provide a unified view of the
* input. It concatenates all the inputs to provide a unified view
*/
public class ConcatenatedMergedKeyValueInput extends MergedLogicalInput {
public ConcatenatedMergedKeyValueInput(MergedInputContext context,
List<Input> inputs) {
super(context, inputs);
}
public class ConcatenatedMergedKeyValueReader extends KeyValueReader {
private int currentReaderIndex = 0;
private KeyValueReader currentReader;
@Override
public boolean next() throws IOException {
while ((currentReader == null) || !currentReader.next()) {
if (currentReaderIndex == getInputs().size()) {
return false;
}
try {
Reader reader = getInputs().get(currentReaderIndex).getReader();
if (!(reader instanceof KeyValueReader)) {
throw new TezUncheckedException("Expected KeyValueReader. "
+ "Got: " + reader.getClass().getName());
}
currentReader = (KeyValueReader) reader;
currentReaderIndex++;
} catch (Exception e) {
throw new IOException(e);
}
}
return true;
}
@Override
public Object getCurrentKey() throws IOException {
return currentReader.getCurrentKey();
}
@Override
public Object getCurrentValue() throws IOException {
return currentReader.getCurrentValue();
}
}
/**
* Provides a {@link KeyValueReader} that iterates over the
* concatenated input data
*/
@Override
public KeyValueReader getReader() throws Exception {
return new ConcatenatedMergedKeyValueReader();
}
@Override
public void setConstituentInputIsReady(Input input) {
informInputReady();
}
}