org.pentaho.hadoop.shim.common.CommonSnappyShim.java Source code

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Here is the source code for org.pentaho.hadoop.shim.common.CommonSnappyShim.java

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/*******************************************************************************
 *
 * Pentaho Big Data
 *
 * Copyright (C) 2002-2017 by Hitachi Vantara : http://www.pentaho.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 org.pentaho.hadoop.shim.common;

import java.io.InputStream;
import java.io.OutputStream;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.compress.SnappyCodec;
import org.pentaho.hadoop.shim.ShimVersion;
import org.pentaho.hadoop.shim.spi.SnappyShim;

/**
 * Helper class for determining (via reflection) whether various Hadoop compression codecs (such as Snappy) are
 * available on the classpath and for returning Input/Output streams for reading/writing.
 *
 * @author Mark Hall (mhall{[at]}pentaho{[dot]}com)
 * @version $Revision: 16312 $
 */
public abstract class CommonSnappyShim implements SnappyShim {

    public static final String IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY = "io.compression.codec.snappy.buffersize";
    public static final int IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT = 256 * 1024;

    @Override
    public ShimVersion getVersion() {
        return new ShimVersion(1, 0);
    }

    /**
     * Gets a CompressionInputStream that uses the snappy codec and wraps the supplied base input stream.
     *
     * @param in the base input stream to wrap around
     * @return an InputStream that uses the Snappy codec
     * @throws Exception if snappy is not available or an error occurs during reflection
     */
    public InputStream getSnappyInputStream(InputStream in) throws Exception {
        return getSnappyInputStream(IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT, in);
    }

    /**
     * Gets an InputStream that uses the snappy codec and wraps the supplied base input stream.
     *
     * @param the buffer size for the codec to use (in bytes)
     * @param in  the base input stream to wrap around
     * @return an InputStream that uses the Snappy codec
     * @throws Exception if snappy is not available or an error occurs during reflection
     */
    public InputStream getSnappyInputStream(int bufferSize, InputStream in) throws Exception {
        if (!isHadoopSnappyAvailable()) {
            throw new Exception("Hadoop-snappy does not seem to be available");
        }

        ClassLoader cl = Thread.currentThread().getContextClassLoader();
        Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
        try {
            SnappyCodec c = new SnappyCodec();
            Configuration newConf = new Configuration();
            newConf.set(IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY, "" + bufferSize);
            c.setConf(newConf);
            return c.createInputStream(in);
        } finally {
            Thread.currentThread().setContextClassLoader(cl);
        }
    }

    /**
     * Gets an OutputStream that uses the snappy codec and wraps the supplied base output stream.
     *
     * @param the buffer size for the codec to use (in bytes)
     * @param out the base output stream to wrap around
     * @return a OutputStream that uses the Snappy codec
     * @throws Exception if snappy is not available or an error occurs during reflection
     */
    public OutputStream getSnappyOutputStream(OutputStream out) throws Exception {
        return getSnappyOutputStream(IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT, out);
    }

    /**
     * Gets an OutputStream that uses the snappy codec and wraps the supplied base output stream.
     *
     * @param the buffer size for the codec to use (in bytes)
     * @param out the base output stream to wrap around
     * @return a OutputStream that uses the Snappy codec
     * @throws Exception if snappy is not available or an error occurs during reflection
     */
    public OutputStream getSnappyOutputStream(int bufferSize, OutputStream out) throws Exception {
        if (!isHadoopSnappyAvailable()) {
            throw new Exception("Hadoop-snappy does not seem to be available");
        }

        ClassLoader cl = Thread.currentThread().getContextClassLoader();
        Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
        try {
            SnappyCodec c = new SnappyCodec();
            Configuration newConf = new Configuration();
            newConf.set(IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY, "" + bufferSize);
            c.setConf(newConf);
            return c.createOutputStream(out);
        } finally {
            Thread.currentThread().setContextClassLoader(cl);
        }
    }
}