Package org.apache.cassandra.db

Class DecoratedKey

java.lang.Object

org.apache.cassandra.db.DecoratedKey

All Implemented Interfaces:

Comparable<PartitionPosition>, PartitionPosition, RingPosition<PartitionPosition>, ByteComparable, IFilter.FilterKey

Direct Known Subclasses:

BufferDecoratedKey, NativeDecoratedKey

public abstract class DecoratedKey
extends Object
implements PartitionPosition, IFilter.FilterKey

Represents a decorated key, handy for certain operations where just working with strings gets slow. We do a lot of sorting of DecoratedKeys, so for speed, we assume that tokens correspond one-to-one with keys. This is not quite correct in the case of RandomPartitioner (which uses MD5 to hash keys to tokens); if this matters, you can subclass RP to use a stronger hash, or use a non-lossy tokenization scheme (as in the OrderPreservingPartitioner classes).

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.cassandra.utils.bytecomparable.ByteComparable

ByteComparable.Version

Nested classes/interfaces inherited from interface org.apache.cassandra.db.PartitionPosition

PartitionPosition.ForKey, PartitionPosition.Kind, PartitionPosition.RowPositionSerializer

Field Summary

Fields

Modifier and Type	Field	Description
static final Comparator<DecoratedKey>	comparator

Fields inherited from interface org.apache.cassandra.utils.bytecomparable.ByteComparable

EMPTY

Fields inherited from interface org.apache.cassandra.db.PartitionPosition

serializer

Constructor Summary

Constructors

Constructor	Description
DecoratedKey(Token token)

Method Summary

Modifier and Type	Method	Description
ByteComparable	asComparableBound(boolean before)	Produce a byte-comparable representation for the position before or after the key.
ByteSource	asComparableBytes(ByteComparable.Version version)	Produce a prefix-free byte-comparable representation of the key, i.e.
int	compareTo(PartitionPosition pos)
static int	compareTo(IPartitioner partitioner, ByteBuffer key, PartitionPosition position)
boolean	equals(Object obj)
void	filterHash(long[] dest)	Places the murmur3 hash of the key in the given long array of size at least two.
abstract ByteBuffer	getKey()
abstract int	getKeyLength()
IPartitioner	getPartitioner()
Token	getToken()
int	hashCode()
boolean	isMinimum()
protected ByteSource	keyComparableBytes(ByteComparable.Version version)
static byte[]	keyFromByteSource(ByteSource.Peekable peekableByteSource, ByteComparable.Version version, IPartitioner partitioner)
PartitionPosition.Kind	kind()
Token.KeyBound	minValue()
DecoratedKey	retainable()	If this key occupies only part of a larger buffer, allocate a new buffer that is only as large as necessary.
String	toCQLString(TableMetadata metadata)	Returns a CQL representation of this key.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.cassandra.utils.bytecomparable.ByteComparable

byteComparableAsString

Methods inherited from interface org.apache.cassandra.utils.IFilter.FilterKey

filterHashLowerBits

Field Details

comparator

public static final Comparator<DecoratedKey> comparator

Constructor Details

DecoratedKey

public DecoratedKey(Token token)

Method Details

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

compareTo

public int compareTo(PartitionPosition pos)

Specified by:

compareTo in interface Comparable<PartitionPosition>

compareTo

public static int compareTo(IPartitioner partitioner,
 ByteBuffer key,
 PartitionPosition position)

asComparableBytes

public ByteSource asComparableBytes(ByteComparable.Version version)

Description copied from interface: PartitionPosition

Produce a prefix-free byte-comparable representation of the key, i.e. such a sequence of bytes that any pair x, y of valid positions (with the same key column types and partitioner), x.compareTo(y) == compareLexicographicallyUnsigned(x.asComparableBytes(), y.asComparableBytes()) and x.asComparableBytes() is not a prefix of y.asComparableBytes() We use a two-component tuple for decorated keys, and a one-component tuple for key bounds, where the terminator byte is chosen to yield the correct comparison result. No decorated key can be a prefix of another (per the tuple encoding), and no key bound can be a prefix of one because it uses a terminator byte that is different from the tuple separator.

Specified by:

asComparableBytes in interface ByteComparable

Specified by:

asComparableBytes in interface PartitionPosition

asComparableBound

public ByteComparable asComparableBound(boolean before)

Description copied from interface: PartitionPosition

Produce a byte-comparable representation for the position before or after the key. This does nothing for token boundaries (which are already at a position between valid keys), and changes the terminator byte for keys.

Specified by:

asComparableBound in interface PartitionPosition

keyComparableBytes

protected ByteSource keyComparableBytes(ByteComparable.Version version)

getPartitioner

public IPartitioner getPartitioner()

Specified by:

getPartitioner in interface RingPosition<PartitionPosition>

minValue

public Token.KeyBound minValue()

Specified by:

minValue in interface RingPosition<PartitionPosition>

isMinimum

public boolean isMinimum()

Specified by:

isMinimum in interface PartitionPosition

Specified by:

isMinimum in interface RingPosition<PartitionPosition>

kind

public PartitionPosition.Kind kind()

Specified by:

kind in interface PartitionPosition

toString

public String toString()

Overrides:

toString in class Object

toCQLString

public String toCQLString(TableMetadata metadata)

Returns a CQL representation of this key.

Parameters:

metadata - the metadata of the table that this key belogs to

Returns:

a CQL representation of this key

getToken

public Token getToken()

Specified by:

getToken in interface RingPosition<PartitionPosition>

getKey

public abstract ByteBuffer getKey()

getKeyLength

public abstract int getKeyLength()

retainable

public DecoratedKey retainable()

If this key occupies only part of a larger buffer, allocate a new buffer that is only as large as necessary. Otherwise, it returns this key.

filterHash

public void filterHash(long[] dest)

Description copied from interface: IFilter.FilterKey

Places the murmur3 hash of the key in the given long array of size at least two.

Specified by:

filterHash in interface IFilter.FilterKey

keyFromByteSource

public static byte[] keyFromByteSource(ByteSource.Peekable peekableByteSource,
 ByteComparable.Version version,
 IPartitioner partitioner)