org.apache.cassandra.dht
Class RandomPartitioner

java.lang.Object
  org.apache.cassandra.dht.RandomPartitioner

All Implemented Interfaces:

IPartitioner<BigIntegerToken>

public class RandomPartitioner
extends java.lang.Object
implements IPartitioner<BigIntegerToken>

This class generates a BigIntegerToken using MD5 hash.

Field Summary

static java.math.BigInteger	MAXIMUM
static BigIntegerToken	MINIMUM
static java.math.BigInteger	ZERO

Constructor Summary

RandomPartitioner()

Method Summary

DecoratedKey<BigIntegerToken>	convertFromDiskFormat(java.nio.ByteBuffer fromdisk)
DecoratedKey<BigIntegerToken>	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()
Token	midpoint(Token ltoken, Token rtoken) Calculate a Token representing the approximate "middle" of the given range.
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 BigIntegerToken MINIMUM

MAXIMUM

public static final java.math.BigInteger MAXIMUM

Constructor Detail

RandomPartitioner

public RandomPartitioner()

Method Detail

decorateKey

public DecoratedKey<BigIntegerToken> 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<BigIntegerToken>

Parameters:

key - the raw, client-facing key

Returns:

decorated version of key

convertFromDiskFormat

public DecoratedKey<BigIntegerToken> convertFromDiskFormat(java.nio.ByteBuffer fromdisk)

Specified by:

convertFromDiskFormat in interface IPartitioner<BigIntegerToken>

Parameters:

fromdisk - On disk representation

Returns:

DecoratedKey object

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<BigIntegerToken>

Returns:

The approximate midpoint between left and right.

getMinimumToken

public BigIntegerToken getMinimumToken()

Specified by:

getMinimumToken in interface IPartitioner<BigIntegerToken>

Returns:

The minimum possible Token in the range that is being partitioned.

getRandomToken

public BigIntegerToken getRandomToken()

Specified by:

getRandomToken in interface IPartitioner<BigIntegerToken>

Returns:

a randomly generated token

getTokenFactory

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

Specified by:

getTokenFactory in interface IPartitioner<BigIntegerToken>

preservesOrder

public boolean preservesOrder()

Specified by:

preservesOrder in interface IPartitioner<BigIntegerToken>

Returns:

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

getToken

public BigIntegerToken getToken(java.nio.ByteBuffer key)

Specified by:

getToken in interface IPartitioner<BigIntegerToken>

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<BigIntegerToken>

Parameters:

sortedTokens - a sorted List of Tokens

Returns:

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