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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.transport;
import java.io.IOException;
import io.netty.buffer.ByteBuf;
import org.xerial.snappy.Snappy;
import org.xerial.snappy.SnappyError;
import net.jpountz.lz4.LZ4Factory;
import org.apache.cassandra.utils.JVMStabilityInspector;
public interface Compressor
{
public Envelope compress(Envelope uncompressed) throws IOException;
public Envelope decompress(Envelope compressed) throws IOException;
/*
* TODO: We can probably do more efficient, like by avoiding copy.
* Also, we don't reuse ICompressor because the API doesn't expose enough.
*/
public static class SnappyCompressor implements Compressor
{
public static final SnappyCompressor instance;
static
{
SnappyCompressor i;
try
{
i = new SnappyCompressor();
}
catch (Exception e)
{
JVMStabilityInspector.inspectThrowable(e);
i = null;
}
catch (NoClassDefFoundError | SnappyError | UnsatisfiedLinkError e)
{
i = null;
}
instance = i;
}
private SnappyCompressor()
{
// this would throw java.lang.NoClassDefFoundError if Snappy class
// wasn't found at runtime which should be processed by the calling method
Snappy.getNativeLibraryVersion();
}
public Envelope compress(Envelope uncompressed) throws IOException
{
byte[] input = CBUtil.readRawBytes(uncompressed.body);
ByteBuf output = CBUtil.allocator.heapBuffer(Snappy.maxCompressedLength(input.length));
try
{
int written = Snappy.compress(input, 0, input.length, output.array(), output.arrayOffset());
output.writerIndex(written);
}
catch (final Throwable e)
{
output.release();
throw e;
}
finally
{
uncompressed.release();
}
return uncompressed.with(output);
}
public Envelope decompress(Envelope compressed) throws IOException
{
byte[] input = CBUtil.readRawBytes(compressed.body);
if (!Snappy.isValidCompressedBuffer(input, 0, input.length))
throw new ProtocolException("Provided frame does not appear to be Snappy compressed");
ByteBuf output = CBUtil.allocator.heapBuffer(Snappy.uncompressedLength(input));
try
{
int size = Snappy.uncompress(input, 0, input.length, output.array(), output.arrayOffset());
output.writerIndex(size);
}
catch (final Throwable e)
{
output.release();
throw e;
}
finally
{
compressed.release();
}
return compressed.with(output);
}
}
/*
* This is very close to the ICompressor implementation, and in particular
* it also layout the uncompressed size at the beginning of the message to
* make uncompression faster, but contrarly to the ICompressor, that length
* is written in big-endian. The native protocol is entirely big-endian, so
* it feels like putting little-endian here would be a annoying trap for
* client writer.
*/
public static class LZ4Compressor implements Compressor
{
public static final LZ4Compressor instance = new LZ4Compressor();
private static final int INTEGER_BYTES = 4;
private final net.jpountz.lz4.LZ4Compressor compressor;
private final net.jpountz.lz4.LZ4Decompressor decompressor;
private LZ4Compressor()
{
final LZ4Factory lz4Factory = LZ4Factory.fastestInstance();
compressor = lz4Factory.fastCompressor();
decompressor = lz4Factory.decompressor();
}
public Envelope compress(Envelope uncompressed)
{
byte[] input = CBUtil.readRawBytes(uncompressed.body);
int maxCompressedLength = compressor.maxCompressedLength(input.length);
ByteBuf outputBuf = CBUtil.allocator.heapBuffer(INTEGER_BYTES + maxCompressedLength);
byte[] output = outputBuf.array();
int outputOffset = outputBuf.arrayOffset();
output[outputOffset ] = (byte) (input.length >>> 24);
output[outputOffset + 1] = (byte) (input.length >>> 16);
output[outputOffset + 2] = (byte) (input.length >>> 8);
output[outputOffset + 3] = (byte) (input.length);
try
{
int written = compressor.compress(input, 0, input.length, output, outputOffset + INTEGER_BYTES, maxCompressedLength);
outputBuf.writerIndex(INTEGER_BYTES + written);
return uncompressed.with(outputBuf);
}
catch (final Throwable e)
{
outputBuf.release();
throw e;
}
finally
{
uncompressed.release();
}
}
public Envelope decompress(Envelope compressed) throws IOException
{
byte[] input = CBUtil.readRawBytes(compressed.body);
int uncompressedLength = ((input[0] & 0xFF) << 24)
| ((input[1] & 0xFF) << 16)
| ((input[2] & 0xFF) << 8)
| ((input[3] & 0xFF));
ByteBuf output = CBUtil.allocator.heapBuffer(uncompressedLength);
try
{
int read = decompressor.decompress(input, INTEGER_BYTES, output.array(), output.arrayOffset(), uncompressedLength);
if (read != input.length - INTEGER_BYTES)
throw new IOException("Compressed lengths mismatch");
output.writerIndex(uncompressedLength);
return compressed.with(output);
}
catch (final Throwable e)
{
output.release();
throw e;
}
finally
{
//release the old message
compressed.release();
}
}
}
}