org.apache.cassandra.dht
Interface IPartitioner<T extends Token>

All Known Implementing Classes:

AbstractByteOrderedPartitioner, ByteOrderedPartitioner, CollatingOrderPreservingPartitioner, LocalPartitioner, OrderPreservingPartitioner, RandomPartitioner

public interface IPartitioner<T extends Token>

Method Summary

DecoratedKey<T>	convertFromDiskFormat(java.nio.ByteBuffer key) Deprecated. Used by SSTables before version 'e'. Convert the on disk representation to a DecoratedKey object
DecoratedKey<T>	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.
T	getMinimumToken()
T	getRandomToken()
T	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()

Method Detail

convertFromDiskFormat

DecoratedKey<T> convertFromDiskFormat(java.nio.ByteBuffer key)

Deprecated. Used by SSTables before version 'e'. Convert the on disk representation to a DecoratedKey object

Parameters:

key - On disk representation

Returns:

DecoratedKey object

decorateKey

DecoratedKey<T> decorateKey(java.nio.ByteBuffer key)

Transform key to object representation of the on-disk format.

Parameters:

key - the raw, client-facing key

Returns:

decorated version of key

midpoint

Token midpoint(Token left,
               Token right)

Calculate a Token representing the approximate "middle" of the given range.

Returns:

The approximate midpoint between left and right.

getMinimumToken

T getMinimumToken()

Returns:

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

getToken

T 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

T getRandomToken()

Returns:

a randomly generated token

getTokenFactory

Token.TokenFactory getTokenFactory()

preservesOrder

boolean preservesOrder()

Returns:

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

describeOwnership

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.

Parameters:

sortedTokens - a sorted List of Tokens

Returns:

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