com.uber.hoodie.hadoop.RecordReaderValueIterator.java Source code

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Here is the source code for com.uber.hoodie.hadoop.RecordReaderValueIterator.java

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/*
 *  Copyright (c) 2017 Uber Technologies, Inc. (hoodie-dev-group@uber.com)
 *
 *  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 com.uber.hoodie.hadoop;

import com.uber.hoodie.exception.HoodieException;
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.mapred.RecordReader;

/**
 * Provides Iterator Interface to iterate value entries read from record reader
 *
 * @param <K> Key Type
 * @param <V> Value Type
 */
public class RecordReaderValueIterator<K, V> implements Iterator<V> {

    public static final Log LOG = LogFactory.getLog(RecordReaderValueIterator.class);

    private final RecordReader<K, V> reader;
    private V nextVal = null;

    /**
     * Construct RecordReaderValueIterator
     *
     * @param reader reader
     */
    public RecordReaderValueIterator(RecordReader<K, V> reader) {
        this.reader = reader;
    }

    @Override
    public boolean hasNext() {
        if (nextVal == null) {
            K key = reader.createKey();
            V val = reader.createValue();
            try {
                boolean notDone = reader.next(key, val);
                if (!notDone) {
                    return false;
                }
                this.nextVal = val;
            } catch (IOException e) {
                LOG.error("Got error reading next record from record reader");
                throw new HoodieException(e);
            }
        }
        return true;
    }

    @Override
    public V next() {
        if (!hasNext()) {
            throw new NoSuchElementException("Make sure you are following iterator contract.");
        }
        V retVal = this.nextVal;
        this.nextVal = null;
        return retVal;
    }

    public void close() throws IOException {
        this.reader.close();
    }
}