org.apache.hadoop.hive.ql.exec.tez.tools.KeyValueInputMerger Maven / Gradle / Ivy
/**
* 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.hive.ql.exec.tez.tools;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.serde2.Deserializer;
import org.apache.hadoop.hive.serde2.SerDeException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.StructField;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.ObjectInspectorCopyOption;
import org.apache.hadoop.io.Writable;
import org.apache.tez.runtime.library.api.KeyValueReader;
/**
* A KeyValuesReader implementation that returns a sorted stream of key-values
* by doing a sorted merge of the key-value in LogicalInputs.
* Tags are in the last byte of the key, so no special handling for tags is required.
* Uses a priority queue to pick the KeyValuesReader of the input that is next in
* sort order.
*/
@SuppressWarnings("deprecation")
public class KeyValueInputMerger extends KeyValueReader {
public static final Log l4j = LogFactory.getLog(KeyValueInputMerger.class);
private PriorityQueue pQueue = null;
private KeyValueReader nextKVReader = null;
private ObjectInspector[] inputObjInspectors = null;
private Deserializer deserializer = null;
private List structFields = null;
private List fieldOIs = null;
private final Map> kvReaderStandardObjMap =
new HashMap>();
public KeyValueInputMerger(List multiMRInputs, Deserializer deserializer,
ObjectInspector[] inputObjInspectors, List sortCols) throws Exception {
//get KeyValuesReaders from the LogicalInput and add them to priority queue
int initialCapacity = multiMRInputs.size();
pQueue = new PriorityQueue(initialCapacity, new KVReaderComparator());
this.inputObjInspectors = inputObjInspectors;
this.deserializer = deserializer;
fieldOIs = new ArrayList();
structFields = new ArrayList();
StructObjectInspector structOI = (StructObjectInspector) inputObjInspectors[0];
for (String field : sortCols) {
StructField sf = structOI.getStructFieldRef(field);
structFields.add(sf);
ObjectInspector stdOI =
ObjectInspectorUtils.getStandardObjectInspector(sf.getFieldObjectInspector());
fieldOIs.add(stdOI);
}
l4j.info("Initialized the priority queue with multi mr inputs: " + multiMRInputs.size());
for (KeyValueReader input : multiMRInputs) {
addToQueue(input);
}
}
/**
* Add KeyValueReader to queue if it has more key-value
*
* @param kvReader
* @throws IOException
*/
private void addToQueue(KeyValueReader kvReader) throws IOException {
if (kvReader.next()) {
kvReaderStandardObjMap.remove(kvReader);
pQueue.add(kvReader);
}
}
/**
* @return true if there are more key-values and advances to next key-values
* @throws IOException
*/
@Override
public boolean next() throws IOException {
//add the previous nextKVReader back to queue
if(nextKVReader != null){
addToQueue(nextKVReader);
}
//get the new nextKVReader with lowest key
nextKVReader = pQueue.poll();
return nextKVReader != null;
}
@Override
public Object getCurrentKey() throws IOException {
return nextKVReader.getCurrentKey();
}
@Override
public Object getCurrentValue() throws IOException {
return nextKVReader.getCurrentValue();
}
/**
* Comparator that compares KeyValuesReader on their current key
*/
class KVReaderComparator implements Comparator {
@SuppressWarnings({ "unchecked" })
@Override
public int compare(KeyValueReader kvReadr1, KeyValueReader kvReadr2) {
try {
ObjectInspector oi = inputObjInspectors[0];
List