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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.io.util;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Supplier;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.primitives.Ints;
import org.apache.cassandra.io.compress.BufferType;
import org.apache.cassandra.io.compress.CompressionMetadata;
import org.apache.cassandra.io.compress.CorruptBlockException;
import org.apache.cassandra.io.sstable.CorruptSSTableException;
import org.apache.cassandra.utils.ChecksumType;
public abstract class CompressedChunkReader extends AbstractReaderFileProxy implements ChunkReader
{
final CompressionMetadata metadata;
final int maxCompressedLength;
final Supplier crcCheckChanceSupplier;
protected CompressedChunkReader(ChannelProxy channel, CompressionMetadata metadata, Supplier crcCheckChanceSupplier)
{
super(channel, metadata.dataLength);
this.metadata = metadata;
this.maxCompressedLength = metadata.maxCompressedLength();
this.crcCheckChanceSupplier = crcCheckChanceSupplier;
assert Integer.bitCount(metadata.chunkLength()) == 1; //must be a power of two
}
@VisibleForTesting
public double getCrcCheckChance()
{
return crcCheckChanceSupplier.get();
}
boolean shouldCheckCrc()
{
double checkChance = getCrcCheckChance();
return checkChance >= 1d || (checkChance > 0d && checkChance > ThreadLocalRandom.current().nextDouble());
}
@Override
public String toString()
{
return String.format("CompressedChunkReader.%s(%s - %s, chunk length %d, data length %d)",
getClass().getSimpleName(),
channel.filePath(),
metadata.compressor().getClass().getSimpleName(),
metadata.chunkLength(),
metadata.dataLength);
}
@Override
public int chunkSize()
{
return metadata.chunkLength();
}
@Override
public BufferType preferredBufferType()
{
return metadata.compressor().preferredBufferType();
}
@Override
public Rebufferer instantiateRebufferer()
{
return new BufferManagingRebufferer.Aligned(this);
}
public static class Standard extends CompressedChunkReader
{
// we read the raw compressed bytes into this buffer, then uncompressed them into the provided one.
private final ThreadLocalByteBufferHolder bufferHolder;
public Standard(ChannelProxy channel, CompressionMetadata metadata, Supplier crcCheckChanceSupplier)
{
super(channel, metadata, crcCheckChanceSupplier);
bufferHolder = new ThreadLocalByteBufferHolder(metadata.compressor().preferredBufferType());
}
@Override
public void readChunk(long position, ByteBuffer uncompressed)
{
try
{
// accesses must always be aligned
assert (position & -uncompressed.capacity()) == position;
assert position <= fileLength;
CompressionMetadata.Chunk chunk = metadata.chunkFor(position);
boolean shouldCheckCrc = shouldCheckCrc();
int length = shouldCheckCrc ? chunk.length + Integer.BYTES // compressed length + checksum length
: chunk.length;
if (chunk.length < maxCompressedLength)
{
ByteBuffer compressed = bufferHolder.getBuffer(length);
if (channel.read(compressed, chunk.offset) != length)
throw new CorruptBlockException(channel.filePath(), chunk);
compressed.flip();
compressed.limit(chunk.length);
uncompressed.clear();
if (shouldCheckCrc)
{
int checksum = (int) ChecksumType.CRC32.of(compressed);
compressed.limit(length);
if (compressed.getInt() != checksum)
throw new CorruptBlockException(channel.filePath(), chunk);
compressed.position(0).limit(chunk.length);
}
try
{
metadata.compressor().uncompress(compressed, uncompressed);
}
catch (IOException e)
{
throw new CorruptBlockException(channel.filePath(), chunk, e);
}
}
else
{
uncompressed.position(0).limit(chunk.length);
if (channel.read(uncompressed, chunk.offset) != chunk.length)
throw new CorruptBlockException(channel.filePath(), chunk);
if (shouldCheckCrc)
{
uncompressed.flip();
int checksum = (int) ChecksumType.CRC32.of(uncompressed);
ByteBuffer scratch = bufferHolder.getBuffer(Integer.BYTES);
if (channel.read(scratch, chunk.offset + chunk.length) != Integer.BYTES
|| scratch.getInt(0) != checksum)
throw new CorruptBlockException(channel.filePath(), chunk);
}
}
uncompressed.flip();
}
catch (CorruptBlockException e)
{
// Make sure reader does not see stale data.
uncompressed.position(0).limit(0);
throw new CorruptSSTableException(e, channel.filePath());
}
}
}
public static class Mmap extends CompressedChunkReader
{
protected final MmappedRegions regions;
public Mmap(ChannelProxy channel, CompressionMetadata metadata, MmappedRegions regions, Supplier crcCheckChanceSupplier)
{
super(channel, metadata, crcCheckChanceSupplier);
this.regions = regions;
}
@Override
public void readChunk(long position, ByteBuffer uncompressed)
{
try
{
// accesses must always be aligned
assert (position & -uncompressed.capacity()) == position;
assert position <= fileLength;
CompressionMetadata.Chunk chunk = metadata.chunkFor(position);
MmappedRegions.Region region = regions.floor(chunk.offset);
long segmentOffset = region.offset();
int chunkOffset = Ints.checkedCast(chunk.offset - segmentOffset);
ByteBuffer compressedChunk = region.buffer();
compressedChunk.position(chunkOffset).limit(chunkOffset + chunk.length);
uncompressed.clear();
try
{
if (shouldCheckCrc())
{
int checksum = (int) ChecksumType.CRC32.of(compressedChunk);
compressedChunk.limit(compressedChunk.capacity());
if (compressedChunk.getInt() != checksum)
throw new CorruptBlockException(channel.filePath(), chunk);
compressedChunk.position(chunkOffset).limit(chunkOffset + chunk.length);
}
if (chunk.length < maxCompressedLength)
metadata.compressor().uncompress(compressedChunk, uncompressed);
else
uncompressed.put(compressedChunk);
}
catch (IOException e)
{
throw new CorruptBlockException(channel.filePath(), chunk, e);
}
uncompressed.flip();
}
catch (CorruptBlockException e)
{
// Make sure reader does not see stale data.
uncompressed.position(0).limit(0);
throw new CorruptSSTableException(e, channel.filePath());
}
}
public void close()
{
regions.closeQuietly();
super.close();
}
}
}