org.apache.hadoop.hive.ql.exec.tez.tools.KeyValuesInputMerger.java Source code

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Here is the source code for org.apache.hadoop.hive.ql.exec.tez.tools.KeyValuesInputMerger.java

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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.hive.ql.exec.tez.tools;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.PriorityQueue;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.BinaryComparable;
import org.apache.tez.runtime.api.Input;
import org.apache.tez.runtime.library.api.KeyValuesReader;

/**
 * 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.
 */
public class KeyValuesInputMerger extends KeyValuesReader {

    private class KeyValuesIterable implements Iterable<Object> {

        KeyValuesIterator currentIterator = null;

        KeyValuesIterable(int size) {
            currentIterator = new KeyValuesIterator(size);
        }

        @Override
        public Iterator<Object> iterator() {
            return currentIterator;
        }

        public void init(List<KeyValuesReader> readerList) {
            currentIterator.init(readerList);
        }
    }

    private class KeyValuesIterator implements Iterator<Object> {
        KeyValuesReader[] readerArray = null;
        Iterator<Object> currentIterator = null;
        int currentIndex = 0;
        int loadedSize = 0;

        KeyValuesIterator(int size) {
            readerArray = new KeyValuesReader[size];
        }

        public void init(List<KeyValuesReader> readerList) {
            for (int i = 0; i < readerList.size(); i++) {
                readerArray[i] = null;
            }
            loadedSize = 0;
            for (KeyValuesReader kvsReader : readerList) {
                readerArray[loadedSize] = kvsReader;
                loadedSize++;
            }
            currentIterator = null;
            currentIndex = 0;
        }

        @Override
        public boolean hasNext() {
            if ((currentIterator == null) || (currentIterator.hasNext() == false)) {
                if (currentIndex == loadedSize) {
                    return false;
                }

                try {
                    if (readerArray[currentIndex] == null) {
                        return false;
                    }
                    currentIterator = readerArray[currentIndex].getCurrentValues().iterator();
                    currentIndex++;
                    return currentIterator.hasNext();
                } catch (IOException e) {
                    return false;
                }
            }

            return true;
        }

        @Override
        public Object next() {
            l4j.info("next called on " + currentIterator);
            return currentIterator.next();
        }

        @Override
        public void remove() {
            // nothing to do
        }
    }

    public static final Log l4j = LogFactory.getLog(KeyValuesInputMerger.class);
    private PriorityQueue<KeyValuesReader> pQueue = null;
    private final List<KeyValuesReader> nextKVReaders = new ArrayList<KeyValuesReader>();
    KeyValuesIterable kvsIterable = null;

    public KeyValuesInputMerger(List<? extends Input> shuffleInputs) throws Exception {
        //get KeyValuesReaders from the LogicalInput and add them to priority queue
        int initialCapacity = shuffleInputs.size();
        kvsIterable = new KeyValuesIterable(initialCapacity);
        pQueue = new PriorityQueue<KeyValuesReader>(initialCapacity, new KVReaderComparator());
        for (Input input : shuffleInputs) {
            addToQueue((KeyValuesReader) input.getReader());
        }
    }

    /**
     * Add KeyValuesReader to queue if it has more key-values
     * @param kvsReadr
     * @throws IOException
     */
    private void addToQueue(KeyValuesReader kvsReadr) throws IOException {
        if (kvsReadr.next()) {
            pQueue.add(kvsReadr);
        }
    }

    /**
     * @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 (!nextKVReaders.isEmpty()) {
            for (KeyValuesReader kvReader : nextKVReaders) {
                addToQueue(kvReader);
            }
            nextKVReaders.clear();
        }

        KeyValuesReader nextKVReader = null;
        //get the new nextKVReader with lowest key
        nextKVReader = pQueue.poll();
        if (nextKVReader != null) {
            nextKVReaders.add(nextKVReader);
        }

        while (pQueue.peek() != null) {
            KeyValuesReader equalValueKVReader = pQueue.poll();
            if (pQueue.comparator().compare(nextKVReader, equalValueKVReader) == 0) {
                nextKVReaders.add(equalValueKVReader);
            } else {
                pQueue.add(equalValueKVReader);
                break;
            }
        }
        return !(nextKVReaders.isEmpty());
    }

    @Override
    public Object getCurrentKey() throws IOException {
        // return key from any of the readers
        return nextKVReaders.get(0).getCurrentKey();
    }

    @Override
    public Iterable<Object> getCurrentValues() throws IOException {
        kvsIterable.init(nextKVReaders);
        return kvsIterable;
    }

    /**
     * Comparator that compares KeyValuesReader on their current key
     */
    class KVReaderComparator implements Comparator<KeyValuesReader> {

        @Override
        public int compare(KeyValuesReader kvReadr1, KeyValuesReader kvReadr2) {
            try {
                BinaryComparable key1 = (BinaryComparable) kvReadr1.getCurrentKey();
                BinaryComparable key2 = (BinaryComparable) kvReadr2.getCurrentKey();
                return key1.compareTo(key2);
            } catch (IOException e) {
                l4j.error("Caught exception while reading shuffle input", e);
                //die!
                throw new RuntimeException(e);
            }
        }
    }

}