org.apache.cassandra.dht
Class OrderPreservingPartitioner

java.lang.Object
  org.apache.cassandra.dht.AbstractPartitioner<StringToken>
      org.apache.cassandra.dht.OrderPreservingPartitioner

All Implemented Interfaces:

IPartitioner<StringToken>

public class OrderPreservingPartitioner
extends AbstractPartitioner<StringToken>

Field Summary

static java.math.BigInteger	CHAR_MASK
static StringToken	MINIMUM

Constructor Summary

OrderPreservingPartitioner()

Method Summary

DecoratedKey	convertFromDiskFormat(java.nio.ByteBuffer key)
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.
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 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

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 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

convertFromDiskFormat

public DecoratedKey convertFromDiskFormat(java.nio.ByteBuffer key)

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.

Returns:

The approximate midpoint between left and right.

getMinimumToken

public StringToken getMinimumToken()

Returns:

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

getRandomToken

public StringToken getRandomToken()

Returns:

a randomly generated token

getTokenFactory

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

preservesOrder

public boolean preservesOrder()

Returns:

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

getToken

public StringToken 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'.