org.apache.cassandra.dht

Class OrderPreservingPartitioner

java.lang.Object

org.apache.cassandra.dht.OrderPreservingPartitioner

All Implemented Interfaces:

IPartitioner

public class OrderPreservingPartitioner
extends java.lang.Object

Field Summary

Fields

Modifier and Type	Field and Description
static java.math.BigInteger	CHAR_MASK
static StringToken	MINIMUM

Constructor Summary

Constructors

Constructor and Description
OrderPreservingPartitioner()

Method Summary

Modifier and Type	Method and Description
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.
long	getHeapSizeOf(Token token)
StringToken	getMinimumToken()
StringToken	getRandomToken()
StringToken	getToken(java.nio.ByteBuffer key)
Token.TokenFactory	getTokenFactory()
AbstractType<?>	getTokenValidator()
StringToken	midpoint(Token ltoken, Token rtoken) Calculate a Token representing the approximate "middle" of the given range.
<R extends RingPosition<R>> R	minValue(java.lang.Class<R> klass)
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 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 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:

A Token smaller than all others in the range that is being partitioned. Not legal to assign to a node or key. (But legal to use in range scans.)

getRandomToken

public StringToken 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.

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.)

getHeapSizeOf

public long getHeapSizeOf(Token token)

Returns:

the on-heap memory used by the provided token

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'.

getTokenValidator

public AbstractType<?> getTokenValidator()

minValue

public <R extends RingPosition<R>> R minValue(java.lang.Class<R> klass)

Specified by:

minValue in interface IPartitioner