org.apache.trevni.avro.mapreduce.AvroTrevniRecordReaderBase.java Source code

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Here is the source code for org.apache.trevni.avro.mapreduce.AvroTrevniRecordReaderBase.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.trevni.avro.mapreduce;

import java.io.IOException;

import org.apache.avro.mapreduce.AvroJob;
import org.apache.avro.reflect.ReflectData;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.trevni.avro.AvroColumnReader;
import org.apache.trevni.avro.HadoopInput;

/**
 * Abstract base class for <code>RecordReader</code>s that read Trevni container files.
 *
 * @param <K> The type of key the record reader should generate.
 * @param <V> The type of value the record reader should generate.
 * @param <T> The type of the entries within the Trevni container file being read.
 */
public abstract class AvroTrevniRecordReaderBase<K, V, T> extends RecordReader<K, V> {

    /** The Trevni file reader */
    private AvroColumnReader<T> reader;

    /** Number of rows in the Trevni file */
    private float rows;

    /** The current row number being read in */
    private long row;

    /** A reusable object to hold records of the Avro container file. */
    private T mCurrentRecord;

    /** {@inheritDoc} */
    @Override
    public void initialize(InputSplit inputSplit, TaskAttemptContext context)
            throws IOException, InterruptedException {
        final FileSplit file = (FileSplit) inputSplit;
        context.setStatus(file.toString());

        final AvroColumnReader.Params params = new AvroColumnReader.Params(
                new HadoopInput(file.getPath(), context.getConfiguration()));
        params.setModel(ReflectData.get());

        if (AvroJob.getInputKeySchema(context.getConfiguration()) != null) {
            params.setSchema(AvroJob.getInputKeySchema(context.getConfiguration()));
        }

        reader = new AvroColumnReader<T>(params);
        rows = reader.getRowCount();
    }

    /** {@inheritDoc} */
    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        if (!reader.hasNext())
            return false;
        mCurrentRecord = reader.next();
        row++;
        return true;
    }

    /**
     * Gets the current record read from the Trevni container file.
     *
     * <p>Calling <code>nextKeyValue()</code> moves this to the next record.</p>
     *
     * @return The current Trevni record (may be null if no record has been read).
     */
    protected T getCurrentRecord() {
        return mCurrentRecord;
    }

    /** {@inheritDoc} */
    @Override
    public void close() throws IOException {
        reader.close();
    }

    /** {@inheritDoc} */
    @Override
    public float getProgress() throws IOException, InterruptedException {
        return row / rows;
    }
}