data.intelligence.platform.yarn.etl.io.CodecPool.java Source code

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Here is the source code for data.intelligence.platform.yarn.etl.io.CodecPool.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 data.intelligence.platform.yarn.etl.io;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.Compressor;
import org.apache.hadoop.io.compress.Decompressor;

/**
 * A global compressor/decompressor pool used to save and reuse (possibly
 * native) compression/decompression codecs.
 */
public final class CodecPool {
    private static final Log LOG = LogFactory.getLog(CodecPool.class);

    /**
     * A global compressor pool used to save the expensive
     * construction/destruction of (possibly native) decompression codecs.
     */
    private static final Map<Class<Compressor>, List<Compressor>> COMPRESSOR_POOL = new HashMap<Class<Compressor>, List<Compressor>>();

    /**
     * A global decompressor pool used to save the expensive
     * construction/destruction of (possibly native) decompression codecs.
     */
    private static final Map<Class<Decompressor>, List<Decompressor>> DECOMPRESSOR_POOL = new HashMap<Class<Decompressor>, List<Decompressor>>();

    private static <T> T borrow(Map<Class<T>, List<T>> pool, Class<? extends T> codecClass) {
        T codec = null;

        // Check if an appropriate codec is available
        synchronized (pool) {
            if (pool.containsKey(codecClass)) {
                List<T> codecList = pool.get(codecClass);

                if (codecList != null) {
                    synchronized (codecList) {
                        if (!codecList.isEmpty()) {
                            codec = codecList.remove(codecList.size() - 1);
                        }
                    }
                }
            }
        }

        return codec;
    }

    @SuppressWarnings("unchecked")
    private static <T> void payback(Map<Class<T>, List<T>> pool, T codec) {
        if (codec != null) {
            Class<T> codecClass = (Class<T>) codec.getClass();
            synchronized (pool) {
                if (!pool.containsKey(codecClass)) {
                    pool.put(codecClass, new ArrayList<T>());
                }

                List<T> codecList = pool.get(codecClass);
                synchronized (codecList) {
                    codecList.add(codec);
                }
            }
        }
    }

    /**
     * Get a {@link Compressor} for the given {@link CompressionCodec} from the
     * pool or a new one.
     * 
     * @param codec
     *            the <code>CompressionCodec</code> for which to get the
     *            <code>Compressor</code>
     * @return <code>Compressor</code> for the given
     *         <code>CompressionCodec</code> from the pool or a new one
     */
    public static Compressor getCompressor(CompressionCodec codec) {
        Compressor compressor = borrow(COMPRESSOR_POOL, codec.getCompressorType());
        if (compressor == null) {
            compressor = codec.createCompressor();
            LOG.info("Got brand-new compressor");
        } else {
            LOG.debug("Got recycled compressor");
        }
        return compressor;
    }

    /**
     * Get a {@link Decompressor} for the given {@link CompressionCodec} from
     * the pool or a new one.
     * 
     * @param codec
     *            the <code>CompressionCodec</code> for which to get the
     *            <code>Decompressor</code>
     * @return <code>Decompressor</code> for the given
     *         <code>CompressionCodec</code> the pool or a new one
     */
    public static Decompressor getDecompressor(CompressionCodec codec) {
        Decompressor decompressor = borrow(DECOMPRESSOR_POOL, codec.getDecompressorType());
        if (decompressor == null) {
            decompressor = codec.createDecompressor();
            LOG.info("Got brand-new decompressor");
        } else {
            LOG.debug("Got recycled decompressor");
        }
        return decompressor;
    }

    /**
     * Return the {@link Compressor} to the pool.
     * 
     * @param compressor
     *            the <code>Compressor</code> to be returned to the pool
     */
    public static void returnCompressor(Compressor compressor) {
        if (compressor == null) {
            return;
        }
        compressor.reset();
        payback(COMPRESSOR_POOL, compressor);
    }

    /**
     * Return the {@link Decompressor} to the pool.
     * 
     * @param decompressor
     *            the <code>Decompressor</code> to be returned to the pool
     */
    public static void returnDecompressor(Decompressor decompressor) {
        if (decompressor == null) {
            return;
        }
        decompressor.reset();
        payback(DECOMPRESSOR_POOL, decompressor);
    }

    private CodecPool() {
        // prevent instantiation
    }
}