org.apache.parquet.hadoop.util.HadoopStreams.java Source code

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Here is the source code for org.apache.parquet.hadoop.util.HadoopStreams.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.parquet.hadoop.util;

import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.parquet.io.ParquetDecodingException;
import org.apache.parquet.io.SeekableInputStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

/**
 * Convenience methods to get Parquet abstractions for Hadoop data streams.
 */
public class HadoopStreams {

    private static final Logger LOG = LoggerFactory.getLogger(HadoopStreams.class);

    private static final Class<?> byteBufferReadableClass = getReadableClass();
    static final Constructor<SeekableInputStream> h2SeekableConstructor = getH2SeekableConstructor();

    /**
     * Wraps a {@link FSDataInputStream} in a {@link SeekableInputStream}
     * implementation for Parquet readers.
     *
     * @param stream a Hadoop FSDataInputStream
     * @return a SeekableInputStream
     */
    public static SeekableInputStream wrap(FSDataInputStream stream) {
        if (byteBufferReadableClass != null && h2SeekableConstructor != null
                && byteBufferReadableClass.isInstance(stream.getWrappedStream())) {
            try {
                return h2SeekableConstructor.newInstance(stream);
            } catch (InstantiationException e) {
                LOG.warn("Could not instantiate H2SeekableInputStream, falling back to byte array reads", e);
                return new H1SeekableInputStream(stream);
            } catch (IllegalAccessException e) {
                LOG.warn("Could not instantiate H2SeekableInputStream, falling back to byte array reads", e);
                return new H1SeekableInputStream(stream);
            } catch (InvocationTargetException e) {
                throw new ParquetDecodingException("Could not instantiate H2SeekableInputStream",
                        e.getTargetException());
            }
        } else {
            return new H1SeekableInputStream(stream);
        }
    }

    private static Class<?> getReadableClass() {
        try {
            return Class.forName("org.apache.hadoop.fs.ByteBufferReadable");
        } catch (ClassNotFoundException e) {
            return null;
        } catch (NoClassDefFoundError e) {
            return null;
        }
    }

    @SuppressWarnings("unchecked")
    private static Class<SeekableInputStream> getH2SeekableClass() {
        try {
            return (Class<SeekableInputStream>) Class
                    .forName("org.apache.parquet.hadoop.util.H2SeekableInputStream");
        } catch (ClassNotFoundException e) {
            return null;
        } catch (NoClassDefFoundError e) {
            return null;
        }
    }

    private static Constructor<SeekableInputStream> getH2SeekableConstructor() {
        Class<SeekableInputStream> h2SeekableClass = getH2SeekableClass();
        if (h2SeekableClass != null) {
            try {
                return h2SeekableClass.getConstructor(FSDataInputStream.class);
            } catch (NoSuchMethodException e) {
                return null;
            }
        }
        return null;
    }

}