Package org.apache.cassandra.dht

Class OrderPreservingPartitioner

java.lang.Object

org.apache.cassandra.dht.OrderPreservingPartitioner

All Implemented Interfaces:

IPartitioner

public class OrderPreservingPartitioner
extends Object
implements IPartitioner

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	OrderPreservingPartitioner.StringToken

Field Summary

Fields

Modifier and Type	Field	Description
static final BigInteger	CHAR_MASK
static final OrderPreservingPartitioner	instance
static final OrderPreservingPartitioner.StringToken	MINIMUM

Constructor Summary

Constructors

Constructor	Description
OrderPreservingPartitioner()

Method Summary

Modifier and Type	Method	Description
DecoratedKey	decorateKey(ByteBuffer key)	Transform key to object representation of the on-disk format.
Map<Token,Float>	describeOwnership(List<Token> sortedTokens)	Calculate the deltas between tokens in the ring in order to compare relative sizes.
OrderPreservingPartitioner.StringToken	getMinimumToken()
OrderPreservingPartitioner.StringToken	getRandomToken()
OrderPreservingPartitioner.StringToken	getRandomToken(Random random)
OrderPreservingPartitioner.StringToken	getToken(ByteBuffer key)
Token.TokenFactory	getTokenFactory()
AbstractType<?>	getTokenValidator()
OrderPreservingPartitioner.StringToken	midpoint(Token ltoken, Token rtoken)	Calculate a Token representing the approximate "middle" of the given range.
AbstractType<?>	partitionOrdering()
boolean	preservesOrder()
Token	split(Token left, Token right, double ratioToLeft)	Calculate a Token which take approximate 0 <= ratioToLeft <= 1 ownership of the given range.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.cassandra.dht.IPartitioner

getMaximumToken, getMaxTokenSize, partitionOrdering, splitter

Field Details

MINIMUM

public static final OrderPreservingPartitioner.StringToken MINIMUM

CHAR_MASK

public static final BigInteger CHAR_MASK

instance

public static final OrderPreservingPartitioner instance

Constructor Details

OrderPreservingPartitioner

public OrderPreservingPartitioner()

Method Details

decorateKey

public DecoratedKey decorateKey(ByteBuffer key)

Description copied from interface: IPartitioner

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

Specified by:

decorateKey in interface IPartitioner

Parameters:

key - the raw, client-facing key

Returns:

decorated version of key

midpoint

public OrderPreservingPartitioner.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

Returns:

The approximate midpoint between left and right.

split

public Token split(Token left,
 Token right,
 double ratioToLeft)

Description copied from interface: IPartitioner

Calculate a Token which take approximate 0 <= ratioToLeft <= 1 ownership of the given range.

Specified by:

split in interface IPartitioner

getMinimumToken

public OrderPreservingPartitioner.StringToken getMinimumToken()

Specified by:

getMinimumToken in interface IPartitioner

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 OrderPreservingPartitioner.StringToken getRandomToken()

Specified by:

getRandomToken in interface IPartitioner

Returns:

a randomly generated token

getRandomToken

public OrderPreservingPartitioner.StringToken getRandomToken(Random random)

Specified by:

getRandomToken in interface IPartitioner

Parameters:

random - instance of Random to use when generating the token

Returns:

a randomly generated token

getTokenFactory

public Token.TokenFactory getTokenFactory()

Specified by:

getTokenFactory in interface IPartitioner

preservesOrder

public boolean preservesOrder()

Specified by:

preservesOrder in interface IPartitioner

Returns:

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

getToken

public OrderPreservingPartitioner.StringToken getToken(ByteBuffer key)

Specified by:

getToken in interface IPartitioner

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 Map<Token,Float> describeOwnership(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

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()

Specified by:

getTokenValidator in interface IPartitioner

partitionOrdering

public AbstractType<?> partitionOrdering()

Specified by:

partitionOrdering in interface IPartitioner