org.apache.cassandra.dht
Class LocalPartitioner

java.lang.Object
  org.apache.cassandra.dht.AbstractPartitioner<LocalToken>
      org.apache.cassandra.dht.LocalPartitioner

All Implemented Interfaces:

IPartitioner<LocalToken>

public class LocalPartitioner
extends AbstractPartitioner<LocalToken>

Constructor Summary

LocalPartitioner(AbstractType<?> comparator)

Method Summary

DecoratedKey<LocalToken>	convertFromDiskFormat(java.nio.ByteBuffer key)
DecoratedKey<LocalToken>	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.
LocalToken	getMinimumToken()
LocalToken	getRandomToken()
LocalToken	getToken(java.nio.ByteBuffer key)
Token.TokenFactory	getTokenFactory()
Token	midpoint(Token left, Token right) 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

Constructor Detail

LocalPartitioner

public LocalPartitioner(AbstractType<?> comparator)

Method Detail

convertFromDiskFormat

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

Parameters:

key - On disk representation

Returns:

DecoratedKey object

decorateKey

public DecoratedKey<LocalToken> 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 left,
                      Token right)

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 LocalToken getMinimumToken()

Returns:

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

getToken

public LocalToken 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.)

getRandomToken

public LocalToken getRandomToken()

Returns:

a randomly generated token

getTokenFactory

public Token.TokenFactory getTokenFactory()

preservesOrder

public boolean preservesOrder()

Returns:

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

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'.