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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
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* distributed with this work for additional information
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* 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,
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package org.apache.cassandra.db.marshal;
import java.nio.ByteBuffer;
import java.util.UUID;
import org.apache.cassandra.cql3.CQL3Type;
import org.apache.cassandra.cql3.Constants;
import org.apache.cassandra.cql3.Duration;
import org.apache.cassandra.cql3.Term;
import org.apache.cassandra.serializers.MarshalException;
import org.apache.cassandra.serializers.UUIDSerializer;
import org.apache.cassandra.utils.TimeUUID;
import org.apache.cassandra.utils.bytecomparable.ByteComparable;
import org.apache.cassandra.utils.bytecomparable.ByteSource;
import org.apache.cassandra.utils.bytecomparable.ByteSourceInverse;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.apache.cassandra.utils.TimeUUID.Generator.nextTimeUUIDAsBytes;
// Fully compatible with UUID, and indeed is interpreted as UUID for UDF
public abstract class AbstractTimeUUIDType extends TemporalType
{
AbstractTimeUUIDType()
{
super(ComparisonType.CUSTOM);
} // singleton
@Override
public boolean allowsEmpty()
{
return true;
}
@Override
public boolean isEmptyValueMeaningless()
{
return true;
}
@Override
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;
}
long msb1 = accessorL.getLong(left, 0);
long msb2 = accessorR.getLong(right, 0);
verifyVersion(msb1);
verifyVersion(msb2);
msb1 = reorderTimestampBytes(msb1);
msb2 = reorderTimestampBytes(msb2);
int c = Long.compare(msb1, msb2);
if (c != 0)
return c;
// this has to be a signed per-byte comparison for compatibility
// so we transform the bytes so that a simple long comparison is equivalent
long lsb1 = signedBytesToNativeLong(accessorL.getLong(left, 8));
long lsb2 = signedBytesToNativeLong(accessorR.getLong(right, 8));
return Long.compare(lsb1, lsb2);
}
@Override
public ByteSource asComparableBytes(ValueAccessor accessor, V data, ByteComparable.Version version)
{
if (accessor.isEmpty(data))
return null;
long hiBits = accessor.getLong(data, 0);
verifyVersion(hiBits);
ByteBuffer swizzled = ByteBuffer.allocate(16);
swizzled.putLong(0, TimeUUIDType.reorderTimestampBytes(hiBits));
swizzled.putLong(8, accessor.getLong(data, 8) ^ 0x8080808080808080L);
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 non-lexical UUID bits are stored as an unsigned fixed-length 128-bit integer.
long hiBits = ByteSourceInverse.getUnsignedFixedLengthAsLong(comparableBytes, 8);
long loBits = ByteSourceInverse.getUnsignedFixedLengthAsLong(comparableBytes, 8);
hiBits = reorderBackTimestampBytes(hiBits);
verifyVersion(hiBits);
// In addition, TimeUUIDType also touches the low bits of the UUID (see CASSANDRA-8730 and DB-1758).
loBits ^= 0x8080808080808080L;
return UUIDType.makeUuidBytes(accessor, hiBits, loBits);
}
// takes as input 8 signed bytes in native machine order
// returns the first byte unchanged, and the following 7 bytes converted to an unsigned representation
// which is the same as a 2's complement long in native format
public static long signedBytesToNativeLong(long signedBytes)
{
return signedBytes ^ 0x0080808080808080L;
}
private void verifyVersion(long hiBits)
{
long version = (hiBits >>> 12) & 0xF;
if (version != 1)
throw new MarshalException(String.format("Invalid UUID version %d for timeuuid",
version));
}
protected static long reorderTimestampBytes(long input)
{
return (input << 48)
| ((input << 16) & 0xFFFF00000000L)
| (input >>> 32);
}
protected static long reorderBackTimestampBytes(long input)
{
// In a time-based UUID the high bits are significantly more shuffled than in other UUIDs - if [X] represents a
// 16-bit tuple, [1][2][3][4] should become [3][4][2][1].
// See the UUID Javadoc (and more specifically the high bits layout of a Leach-Salz UUID) to understand the
// reasoning behind this bit twiddling in the first place (in the context of comparisons).
return (input << 32)
| ((input >>> 16) & 0xFFFF0000L)
| (input >>> 48);
}
public ByteBuffer fromString(String source) throws MarshalException
{
ByteBuffer parsed = UUIDType.parse(source);
if (parsed == null)
throw new MarshalException(String.format("Unknown timeuuid representation: %s", source));
if (parsed.remaining() == 16 && UUIDType.version(parsed) != 1)
throw new MarshalException("TimeUUID supports only version 1 UUIDs");
return parsed;
}
@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 timeuuid, but got a %s: %s", parsed.getClass().getSimpleName(), parsed));
}
}
public CQL3Type asCQL3Type()
{
return CQL3Type.Native.TIMEUUID;
}
@Override
public ByteBuffer decomposeUntyped(Object value)
{
if (value instanceof UUID)
return UUIDSerializer.instance.serialize((UUID) value);
if (value instanceof TimeUUID)
return TimeUUID.Serializer.instance.serialize((TimeUUID) value);
return super.decomposeUntyped(value);
}
@Override
public int valueLengthIfFixed()
{
return 16;
}
@Override
public long toTimeInMillis(ByteBuffer value)
{
return TimeUUID.deserialize(value).unix(MILLISECONDS);
}
@Override
public ByteBuffer addDuration(Number temporal, Duration duration)
{
throw new UnsupportedOperationException();
}
@Override
public ByteBuffer substractDuration(Number temporal, Duration duration)
{
throw new UnsupportedOperationException();
}
@Override
public ByteBuffer now()
{
return ByteBuffer.wrap(nextTimeUUIDAsBytes());
}
@Override
public boolean equals(Object obj)
{
return obj instanceof AbstractTimeUUIDType;
}
}