com.metamx.druid.index.v1.CompressedObjectStrategy.java Source code

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Here is the source code for com.metamx.druid.index.v1.CompressedObjectStrategy.java

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/*
 * Druid - a distributed column store.
 * Copyright (C) 2012  Metamarkets Group Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package com.metamx.druid.index.v1;

import com.google.common.base.Throwables;
import com.google.common.io.Closeables;
import com.metamx.druid.collect.ResourceHolder;
import com.metamx.druid.kv.ObjectStrategy;
import com.ning.compress.lzf.ChunkEncoder;
import com.ning.compress.lzf.LZFChunk;
import com.ning.compress.lzf.LZFDecoder;

import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
*/
public class CompressedObjectStrategy<T extends Buffer> implements ObjectStrategy<ResourceHolder<T>> {
    private final ByteOrder order;
    private final BufferConverter<T> converter;

    protected CompressedObjectStrategy(final ByteOrder order, final BufferConverter<T> converter) {
        this.order = order;
        this.converter = converter;
    }

    @Override
    @SuppressWarnings("unchecked")
    public Class<? extends ResourceHolder<T>> getClazz() {
        return (Class) ResourceHolder.class;
    }

    @Override
    public ResourceHolder<T> fromByteBuffer(ByteBuffer buffer, int numBytes) {
        byte[] bytes = new byte[numBytes];
        buffer.get(bytes);

        final ResourceHolder<ByteBuffer> bufHolder = CompressedPools.getByteBuf(order);
        final ByteBuffer buf = bufHolder.get();
        buf.position(0);
        buf.limit(buf.capacity());

        try {
            final ResourceHolder<byte[]> outputBytesHolder = CompressedPools.getOutputBytes();

            byte[] outputBytes = outputBytesHolder.get();
            int numDecompressedBytes = LZFDecoder.decode(bytes, outputBytes);
            buf.put(outputBytes, 0, numDecompressedBytes);
            buf.flip();

            Closeables.closeQuietly(outputBytesHolder);

            return new ResourceHolder<T>() {
                @Override
                public T get() {
                    return converter.convert(buf);
                }

                @Override
                public void close() throws IOException {
                    bufHolder.close();
                }
            };
        } catch (IOException e) {
            throw Throwables.propagate(e);
        }
    }

    @Override
    public byte[] toBytes(ResourceHolder<T> holder) {
        T val = holder.get();
        ByteBuffer buf = ByteBuffer.allocate(converter.sizeOf(val.remaining())).order(order);
        converter.combine(buf, val);

        final ResourceHolder<ChunkEncoder> encoder = CompressedPools.getChunkEncoder();
        LZFChunk chunk = encoder.get().encodeChunk(buf.array(), 0, buf.array().length);
        Closeables.closeQuietly(encoder);

        return chunk.getData();
    }

    @Override
    public int compare(ResourceHolder<T> o1, ResourceHolder<T> o2) {
        return converter.compare(o1.get(), o2.get());
    }

    public static interface BufferConverter<T> {
        public T convert(ByteBuffer buf);

        public int compare(T lhs, T rhs);

        public int sizeOf(int count);

        public T combine(ByteBuffer into, T from);
    }
}