Package org.apache.cassandra.dht

Class Token

java.lang.Object

org.apache.cassandra.dht.Token

All Implemented Interfaces:

java.io.Serializable, java.lang.Comparable<Token>, RingPosition<Token>

Direct Known Subclasses:

ByteOrderedPartitioner.BytesToken, LocalPartitioner.LocalToken, Murmur3Partitioner.LongToken, OrderPreservingPartitioner.StringToken, RandomPartitioner.BigIntegerToken

public abstract class Token
extends java.lang.Object
implements RingPosition<Token>, java.io.Serializable

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Token.KeyBound
static class	Token.TokenFactory
static class	Token.TokenSerializer

Field Summary

Fields

Modifier and Type	Field	Description
static Token.TokenSerializer	serializer

Constructor Summary

Constructors

Constructor	Description
Token()

Method Summary

Modifier and Type	Method	Description
abstract ByteSource	asComparableBytes(ByteComparable.Version version)	Produce a weakly prefix-free byte-comparable representation of the token, i.e.
abstract long	getHeapSize()
long	getLongValue()	This method exists so that callers can access the primitive long value for this Token, if one exits.
abstract IPartitioner	getPartitioner()
Token	getToken()
abstract java.lang.Object	getTokenValue()
boolean	isMinimum()
Token.KeyBound	maxKeyBound()
Token.KeyBound	minKeyBound()
Token	minValue()
abstract Token	nextValidToken()	Returns the next possible token in the token space, one that compares greater than this and such that there is no other token that sits between this token and it in the token order.
abstract double	size(Token next)	Returns a measure for the token space covered between this token and next.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Comparable

compareTo

Field Detail

serializer

public static final Token.TokenSerializer serializer

Constructor Detail

Token

public Token()

Method Detail

getPartitioner

public abstract IPartitioner getPartitioner()

Specified by:

getPartitioner in interface RingPosition<Token>

getHeapSize

public abstract long getHeapSize()

getTokenValue

public abstract java.lang.Object getTokenValue()

getLongValue

public long getLongValue()

This method exists so that callers can access the primitive long value for this Token, if one exits. It is especially useful when the auto-boxing induced by a call to getTokenValue() would be unacceptable for reasons of performance.

Returns:

the primitive long value of this token, if one exists

Throws:

java.lang.UnsupportedOperationException - if this Token is not backed by a primitive long value

asComparableBytes

public abstract ByteSource asComparableBytes(ByteComparable.Version version)

Produce a weakly prefix-free byte-comparable representation of the token, i.e. such a sequence of bytes that any pair x, y of valid tokens of this type and any bytes b1, b2 between 0x10 and 0xEF, (+ stands for concatenation) compare(x, y) == compareLexicographicallyUnsigned(asByteComparable(x)+b1, asByteComparable(y)+b2) (i.e. the values compare like the original type, and an added 0x10-0xEF byte at the end does not change that) and: asByteComparable(x)+b1 is not a prefix of asByteComparable(y) (weakly prefix free) (i.e. a valid representation of a value may be a prefix of another valid representation of a value only if the following byte in the latter is smaller than 0x10 or larger than 0xEF). These properties are trivially true if the encoding compares correctly and is prefix free, but also permits a little more freedom that enables somewhat more efficient encoding of arbitrary-length byte-comparable blobs.

size

public abstract double size(Token next)

Returns a measure for the token space covered between this token and next. Used by the token allocation algorithm (see CASSANDRA-7032).

nextValidToken

public abstract Token nextValidToken()

Returns the next possible token in the token space, one that compares greater than this and such that there is no other token that sits between this token and it in the token order. This is not possible for all token types, esp. for comparison-based tokens such as the LocalPartioner used for classic secondary indexes. Used to avoid clashes between nodes in separate datacentres trying to use the same token via the token allocation algorithm, as well as in constructing token ranges for sstables.

getToken

public Token getToken()

Specified by:

getToken in interface RingPosition<Token>

minValue

public Token minValue()

Specified by:

minValue in interface RingPosition<Token>

isMinimum

public boolean isMinimum()

Specified by:

isMinimum in interface RingPosition<Token>

minKeyBound

public Token.KeyBound minKeyBound()

maxKeyBound

public Token.KeyBound maxKeyBound()