parquet.hadoop.ParquetRecordReader.java Source code

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Here is the source code for parquet.hadoop.ParquetRecordReader.java

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/**
 * Copyright 2012 Twitter, Inc.
 *
 * 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 parquet.hadoop;

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;
import parquet.Log;
import parquet.filter.UnboundRecordFilter;
import parquet.hadoop.api.ReadSupport;
import parquet.hadoop.util.counters.BenchmarkCounter;
import parquet.hadoop.util.ContextUtil;
import parquet.schema.MessageTypeParser;

/**
 * Reads the records from a block of a Parquet file
 *
 * @see ParquetInputFormat
 *
 * @author Julien Le Dem
 *
 * @param <T> type of the materialized records
 */
public class ParquetRecordReader<T> extends RecordReader<Void, T> {

    private static final Log LOG = Log.getLog(ParquetRecordReader.class);
    private InternalParquetRecordReader<T> internalReader;

    /**
     * @param readSupport Object which helps reads files of the given type, e.g. Thrift, Avro.
     */
    public ParquetRecordReader(ReadSupport<T> readSupport) {
        this(readSupport, null);
    }

    /**
     * @param readSupport Object which helps reads files of the given type, e.g. Thrift, Avro.
     * @param filter Optional filter for only returning matching records.
     */
    public ParquetRecordReader(ReadSupport<T> readSupport, UnboundRecordFilter filter) {
        internalReader = new InternalParquetRecordReader<T>(readSupport, filter);
    }

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

    /**
     * always returns null
     */
    @Override
    public Void getCurrentKey() throws IOException, InterruptedException {
        return null;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public T getCurrentValue() throws IOException, InterruptedException {
        return internalReader.getCurrentValue();
    }

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

    /**
     * {@inheritDoc}
     */
    @Override
    public void initialize(InputSplit inputSplit, TaskAttemptContext context)
            throws IOException, InterruptedException {
        if (context instanceof TaskInputOutputContext<?, ?, ?, ?>) {
            BenchmarkCounter.initCounterFromContext((TaskInputOutputContext<?, ?, ?, ?>) context);
        } else {
            LOG.error(
                    "Can not initialize counter due to context is not a instance of TaskInputOutputContext, but is "
                            + context.getClass().getCanonicalName());
        }

        initializeInternalReader((ParquetInputSplit) inputSplit, ContextUtil.getConfiguration(context));
    }

    public void initialize(InputSplit inputSplit, Configuration configuration, Reporter reporter)
            throws IOException, InterruptedException {
        BenchmarkCounter.initCounterFromReporter(reporter, configuration);
        initializeInternalReader((ParquetInputSplit) inputSplit, configuration);
    }

    private void initializeInternalReader(ParquetInputSplit split, Configuration configuration) throws IOException {

        internalReader.initialize(MessageTypeParser.parseMessageType(split.getRequestedSchema()),
                MessageTypeParser.parseMessageType(split.getFileSchema()), split.getExtraMetadata(),
                split.getReadSupportMetadata(), split.getPath(), split.getBlocks(), configuration);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        return internalReader.nextKeyValue();
    }
}