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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.db.marshal;
import java.nio.ByteBuffer;
import java.util.UUID;
import java.util.regex.Pattern;
import com.google.common.primitives.UnsignedLongs;
import org.apache.cassandra.cql3.CQL3Type;
import org.apache.cassandra.cql3.Constants;
import org.apache.cassandra.cql3.Term;
import org.apache.cassandra.cql3.functions.ArgumentDeserializer;
import org.apache.cassandra.serializers.TypeSerializer;
import org.apache.cassandra.serializers.MarshalException;
import org.apache.cassandra.serializers.UUIDSerializer;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.bytecomparable.ByteComparable;
import org.apache.cassandra.utils.bytecomparable.ByteSource;
import org.apache.cassandra.utils.bytecomparable.ByteSourceInverse;
import org.apache.cassandra.utils.UUIDGen;
/**
* Compares UUIDs using the following criteria:
* - if count of supplied bytes is less than 16, compare counts
* - compare UUID version fields
* - nil UUID is always lesser
* - compare timestamps if both are time-based
* - compare lexically, unsigned msb-to-lsb comparison
*
* @see "com.fasterxml.uuid.UUIDComparator"
*/
public class UUIDType extends AbstractType
{
public static final UUIDType instance = new UUIDType();
private static final ArgumentDeserializer ARGUMENT_DESERIALIZER = new DefaultArgumentDeserializer(instance);
private static final ByteBuffer MASKED_VALUE = instance.decompose(UUID.fromString("00000000-0000-0000-0000-000000000000"));
UUIDType()
{
super(ComparisonType.CUSTOM);
}
@Override
public boolean allowsEmpty()
{
return true;
}
@Override
public boolean isEmptyValueMeaningless()
{
return true;
}
public int compareCustom(VL left, ValueAccessor accessorL, VR right, ValueAccessor accessorR)
{
// Compare for length
boolean p1 = accessorL.size(left) == 16, p2 = accessorR.size(right) == 16;
if (!(p1 & p2))
{
// should we assert exactly 16 bytes (or 0)? seems prudent
assert p1 || accessorL.isEmpty(left);
assert p2 || accessorR.isEmpty(right);
return p1 ? 1 : p2 ? -1 : 0;
}
// Compare versions
long msb1 = accessorL.getLong(left, 0);
long msb2 = accessorR.getLong(right, 0);
int version1 = (int) ((msb1 >>> 12) & 0xf);
int version2 = (int) ((msb2 >>> 12) & 0xf);
if (version1 != version2)
return version1 - version2;
// bytes: version is top 4 bits of byte 6
// then: [6.5-8), [4-6), [0-4)
if (version1 == 1)
{
long reorder1 = TimeUUIDType.reorderTimestampBytes(msb1);
long reorder2 = TimeUUIDType.reorderTimestampBytes(msb2);
// we know this is >= 0, since the top 3 bits will be 0
int c = Long.compare(reorder1, reorder2);
if (c != 0)
return c;
}
else
{
int c = UnsignedLongs.compare(msb1, msb2);
if (c != 0)
return c;
}
// Amusingly (or not so much), although UUIDType freely takes time UUIDs (UUIDs with version 1), it compares
// them differently than TimeUUIDType. This is evident in the least significant bytes comparison (the code
// below for UUIDType), where UUIDType treats them as unsigned bytes, while TimeUUIDType compares the bytes
// signed. See CASSANDRA-8730 for details around this discrepancy.
return UnsignedLongs.compare(accessorL.getLong(left, 8), accessorR.getLong(right, 8));
}
@Override
public ByteSource asComparableBytes(ValueAccessor accessor, V data, ByteComparable.Version v)
{
if (accessor.isEmpty(data))
return null;
long msb = accessor.getLong(data, 0);
long version = ((msb >>> 12) & 0xf);
ByteBuffer swizzled = ByteBuffer.allocate(16);
if (version == 1)
swizzled.putLong(0, TimeUUIDType.reorderTimestampBytes(msb));
else
swizzled.putLong(0, (version << 60) | ((msb >>> 4) & 0x0FFFFFFFFFFFF000L) | (msb & 0xFFFL));
swizzled.putLong(8, accessor.getLong(data, 8));
// fixed-length thus prefix-free
return ByteSource.fixedLength(swizzled);
}
@Override
public V fromComparableBytes(ValueAccessor accessor, ByteSource.Peekable comparableBytes, ByteComparable.Version version)
{
// Optional-style encoding of empty values as null sources
if (comparableBytes == null)
return accessor.empty();
// The UUID bits are stored as an unsigned fixed-length 128-bit integer.
long hiBits = ByteSourceInverse.getUnsignedFixedLengthAsLong(comparableBytes, 8);
long loBits = ByteSourceInverse.getUnsignedFixedLengthAsLong(comparableBytes, 8);
long uuidVersion = hiBits >>> 60 & 0xF;
if (uuidVersion == 1)
{
// If the version bits are set to 1, this is a time-based UUID, and its high bits are significantly more
// shuffled than in other UUIDs. Revert the shuffle.
hiBits = TimeUUIDType.reorderBackTimestampBytes(hiBits);
}
else
{
// For non-time UUIDs, the only thing that's needed is to put the version bits back where they were originally.
hiBits = hiBits << 4 & 0xFFFFFFFFFFFF0000L
| uuidVersion << 12
| hiBits & 0x0000000000000FFFL;
}
return makeUuidBytes(accessor, hiBits, loBits);
}
static V makeUuidBytes(ValueAccessor accessor, long high, long low)
{
V buffer = accessor.allocate(16);
accessor.putLong(buffer, 0, high);
accessor.putLong(buffer, 8, low);
return buffer;
}
@Override
public boolean isValueCompatibleWithInternal(AbstractType otherType)
{
return otherType instanceof UUIDType || otherType instanceof TimeUUIDType;
}
@Override
public ByteBuffer fromString(String source) throws MarshalException
{
// Return an empty ByteBuffer for an empty string.
ByteBuffer parsed = parse(source);
if (parsed != null)
return parsed;
throw new MarshalException(String.format("Unable to make UUID from '%s'", source));
}
@Override
public CQL3Type asCQL3Type()
{
return CQL3Type.Native.UUID;
}
@Override
public TypeSerializer getSerializer()
{
return UUIDSerializer.instance;
}
@Override
public ArgumentDeserializer getArgumentDeserializer()
{
return ARGUMENT_DESERIALIZER;
}
static final Pattern regexPattern = Pattern.compile("[A-Fa-f0-9]{8}\\-[A-Fa-f0-9]{4}\\-[A-Fa-f0-9]{4}\\-[A-Fa-f0-9]{4}\\-[A-Fa-f0-9]{12}");
static ByteBuffer parse(String source)
{
if (source.isEmpty())
return ByteBufferUtil.EMPTY_BYTE_BUFFER;
if (regexPattern.matcher(source).matches())
{
try
{
return UUIDGen.toByteBuffer(UUID.fromString(source));
}
catch (IllegalArgumentException e)
{
throw new MarshalException(String.format("Unable to make UUID from '%s'", source), e);
}
}
return null;
}
@Override
public Term fromJSONObject(Object parsed) throws MarshalException
{
try
{
return new Constants.Value(fromString((String) parsed));
}
catch (ClassCastException exc)
{
throw new MarshalException(String.format(
"Expected a string representation of a uuid, but got a %s: %s", parsed.getClass().getSimpleName(), parsed));
}
}
static int version(ByteBuffer uuid)
{
return (uuid.get(6) & 0xf0) >> 4;
}
@Override
public int valueLengthIfFixed()
{
return 16;
}
@Override
public ByteBuffer getMaskedValue()
{
return MASKED_VALUE;
}
}