org.apache.cassandra.dht

Class RandomPartitioner

java.lang.Object

org.apache.cassandra.dht.AbstractPartitioner<BigIntegerToken>

org.apache.cassandra.dht.RandomPartitioner

All Implemented Interfaces:

IPartitioner<BigIntegerToken>

public class RandomPartitioner
extends AbstractPartitioner<BigIntegerToken>

This class generates a BigIntegerToken using MD5 hash.

Field Summary

Fields

Modifier and Type	Field and Description
static java.math.BigInteger	MAXIMUM
static BigIntegerToken	MINIMUM
static java.math.BigInteger	ZERO

Constructor Summary

Constructors

Constructor and Description
RandomPartitioner()

Method Summary

Methods

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.
BigIntegerToken	getMinimumToken()
BigIntegerToken	getRandomToken()
BigIntegerToken	getToken(java.nio.ByteBuffer key)
Token.TokenFactory<java.math.BigInteger>	getTokenFactory()
AbstractType<?>	getTokenValidator()
Token	midpoint(Token ltoken, Token rtoken) Calculate a Token representing the approximate "middle" of the given range.
boolean	preservesOrder()

Methods inherited from class org.apache.cassandra.dht.AbstractPartitioner

minValue

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 BigIntegerToken MINIMUM

MAXIMUM

public static final java.math.BigInteger MAXIMUM

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.

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.

Returns:

The approximate midpoint between left and right.

getMinimumToken

public BigIntegerToken getMinimumToken()

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 BigIntegerToken getRandomToken()

Returns:

a randomly generated token

getTokenFactory

public Token.TokenFactory<java.math.BigInteger> getTokenFactory()

preservesOrder

public boolean preservesOrder()

Returns:

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

getToken

public BigIntegerToken getToken(java.nio.ByteBuffer key)

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.

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()