org.apache.cassandra.dht

Class RandomPartitioner

java.lang.Object

org.apache.cassandra.dht.RandomPartitioner

All Implemented Interfaces:

IPartitioner

public class RandomPartitioner
extends java.lang.Object
implements IPartitioner

This class generates a BigIntegerToken using MD5 hash.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RandomPartitioner.BigIntegerToken

Field Summary

Fields

Modifier and Type	Field and Description
static RandomPartitioner	instance
static java.math.BigInteger	MAXIMUM
static RandomPartitioner.BigIntegerToken	MINIMUM
static AbstractType<?>	partitionOrdering
static java.math.BigInteger	ZERO

Constructor Summary

Constructors

Constructor and Description
RandomPartitioner()

Method Summary

Modifier and Type	Method and Description
DecoratedKey	decorateKey(java.nio.ByteBuffer key) Transform key to object representation of the on-disk format.
java.util.Map<Token,java.lang.Float>	describeOwnership(java.util.List<Token> sortedTokens) Calculate the deltas between tokens in the ring in order to compare relative sizes.
RandomPartitioner.BigIntegerToken	getMinimumToken()
RandomPartitioner.BigIntegerToken	getRandomToken()
RandomPartitioner.BigIntegerToken	getToken(java.nio.ByteBuffer key)
Token.TokenFactory	getTokenFactory()
AbstractType<?>	getTokenValidator()
Token	midpoint(Token ltoken, Token rtoken) Calculate a Token representing the approximate "middle" of the given range.
AbstractType<?>	partitionOrdering() Abstract type that orders the same way as DecoratedKeys provided by this partitioner.
boolean	preservesOrder()

Methods inherited from class java.lang.Object

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

Field Detail

ZERO

public static final java.math.BigInteger ZERO

MINIMUM

public static final RandomPartitioner.BigIntegerToken MINIMUM

MAXIMUM

public static final java.math.BigInteger MAXIMUM

instance

public static final RandomPartitioner instance

partitionOrdering

public static final AbstractType<?> partitionOrdering

Constructor Detail

RandomPartitioner

public RandomPartitioner()

Method Detail

decorateKey

public DecoratedKey decorateKey(java.nio.ByteBuffer key)

Description copied from interface: IPartitioner

Transform key to object representation of the on-disk format.

Specified by:

decorateKey in interface IPartitioner

Parameters:

key - the raw, client-facing key

Returns:

decorated version of key

midpoint

public Token midpoint(Token ltoken,
                      Token rtoken)

Description copied from interface: IPartitioner

Calculate a Token representing the approximate "middle" of the given range.

Specified by:

midpoint in interface IPartitioner

Returns:

The approximate midpoint between left and right.

getMinimumToken

public RandomPartitioner.BigIntegerToken getMinimumToken()

Specified by:

getMinimumToken in interface IPartitioner

Returns:

A Token smaller than all others in the range that is being partitioned. Not legal to assign to a node or key. (But legal to use in range scans.)

getRandomToken

public RandomPartitioner.BigIntegerToken getRandomToken()

Specified by:

getRandomToken in interface IPartitioner

Returns:

a randomly generated token

getTokenFactory

public Token.TokenFactory getTokenFactory()

Specified by:

getTokenFactory in interface IPartitioner

preservesOrder

public boolean preservesOrder()

Specified by:

preservesOrder in interface IPartitioner

Returns:

True if the implementing class preserves key order in the Tokens it generates.

getToken

public RandomPartitioner.BigIntegerToken getToken(java.nio.ByteBuffer key)

Specified by:

getToken in interface IPartitioner

Returns:

a Token that can be used to route a given key (This is NOT a method to create a Token from its string representation; for that, use TokenFactory.fromString.)

describeOwnership

public java.util.Map<Token,java.lang.Float> describeOwnership(java.util.List<Token> sortedTokens)

Description copied from interface: IPartitioner

Calculate the deltas between tokens in the ring in order to compare relative sizes.

Specified by:

describeOwnership in interface IPartitioner

Parameters:

sortedTokens - a sorted List of Tokens

Returns:

the mapping from 'token' to 'percentage of the ring owned by that token'.

getTokenValidator

public AbstractType<?> getTokenValidator()

Specified by:

getTokenValidator in interface IPartitioner

partitionOrdering

public AbstractType<?> partitionOrdering()

Description copied from interface: IPartitioner

Abstract type that orders the same way as DecoratedKeys provided by this partitioner. Used by secondary indices.

Specified by:

partitionOrdering in interface IPartitioner