org.apache.cassandra.dht
Class OrderPreservingPartitioner

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

All Implemented Interfaces:

IPartitioner<StringToken>

public class OrderPreservingPartitioner
extends java.lang.Object
implements IPartitioner<StringToken>

Field Summary

static java.math.BigInteger	CHAR_MASK
static StringToken	MINIMUM

Constructor Summary

OrderPreservingPartitioner()

Method Summary

DecoratedKey<StringToken>	convertFromDiskFormat(java.nio.ByteBuffer key)
DecoratedKey<StringToken>	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.
StringToken	getMinimumToken()
StringToken	getRandomToken()
StringToken	getToken(java.nio.ByteBuffer key)
Token.TokenFactory<java.lang.String>	getTokenFactory()
StringToken	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

MINIMUM

public static final StringToken MINIMUM

CHAR_MASK

public static final java.math.BigInteger CHAR_MASK

Constructor Detail

OrderPreservingPartitioner

public OrderPreservingPartitioner()

Method Detail

decorateKey

public DecoratedKey<StringToken> 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<StringToken>

Parameters:

key - the raw, client-facing key

Returns:

decorated version of key

convertFromDiskFormat

public DecoratedKey<StringToken> convertFromDiskFormat(java.nio.ByteBuffer key)

Specified by:

convertFromDiskFormat in interface IPartitioner<StringToken>

Parameters:

key - On disk representation

Returns:

DecoratedKey object

midpoint

public StringToken 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<StringToken>

Returns:

The approximate midpoint between left and right.

getMinimumToken

public StringToken getMinimumToken()

Specified by:

getMinimumToken in interface IPartitioner<StringToken>

Returns:

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

getRandomToken

public StringToken getRandomToken()

Specified by:

getRandomToken in interface IPartitioner<StringToken>

Returns:

a randomly generated token

getTokenFactory

public Token.TokenFactory<java.lang.String> getTokenFactory()

Specified by:

getTokenFactory in interface IPartitioner<StringToken>

preservesOrder

public boolean preservesOrder()

Specified by:

preservesOrder in interface IPartitioner<StringToken>

Returns:

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

getToken

public StringToken getToken(java.nio.ByteBuffer key)

Specified by:

getToken in interface IPartitioner<StringToken>

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<StringToken>

Parameters:

sortedTokens - a sorted List of Tokens

Returns:

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