org.infinispan.distribution.ch.impl

Class DefaultConsistentHashFactory

java.lang.Object

org.infinispan.distribution.ch.impl.DefaultConsistentHashFactory

All Implemented Interfaces:

ConsistentHashFactory<DefaultConsistentHash>

Direct Known Subclasses:

DefaultConsistentHashFactory, TopologyAwareConsistentHashFactory

public class DefaultConsistentHashFactory
extends Object
implements ConsistentHashFactory<DefaultConsistentHash>

Default implementation of ConsistentHashFactory. All methods except union(DefaultConsistentHash, DefaultConsistentHash) return a consistent hash with floor(numOwners*numSegments/numNodes) <= segments per owner <= ceil(numOwners*numSegments/numNodes).

Since:

5.2

Author:

Dan Berindei, anistor@redhat.com

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	DefaultConsistentHashFactory.Builder
static class	DefaultConsistentHashFactory.Externalizer

Constructor Summary

Constructors

Constructor and Description
DefaultConsistentHashFactory()

Method Summary

Modifier and Type	Method and Description
protected void	addBackupOwners(DefaultConsistentHashFactory.Builder builder)
protected void	addPrimaryOwners(DefaultConsistentHashFactory.Builder builder)
DefaultConsistentHash	create(Hash hashFunction, int numOwners, int numSegments, List<Address> members, Map<Address,Float> capacityFactors) Create a new consistent hash instance.
protected void	doAddBackupOwners(DefaultConsistentHashFactory.Builder builder)
boolean	equals(Object other)
protected Address	findNewBackupOwner(DefaultConsistentHashFactory.Builder builder, Collection<Address> excludes, Address owner)
protected Address	findNewPrimaryOwner(DefaultConsistentHashFactory.Builder builder, Collection<Address> candidates, Address primaryOwner)
DefaultConsistentHash	fromPersistentState(ScopedPersistentState state) Recreates a ConsistentHash from a previously stored persistent state
int	hashCode()
DefaultConsistentHash	rebalance(DefaultConsistentHash baseCH) Create a new consistent hash instance, based on an existing instance, but "balanced" according to the implementation's rules.
protected void	rebalanceBuilder(DefaultConsistentHashFactory.Builder builder)
protected void	removeExtraBackupOwners(DefaultConsistentHashFactory.Builder builder)
protected void	replaceBackupOwners(DefaultConsistentHashFactory.Builder builder)
protected void	replacePrimaryOwners(DefaultConsistentHashFactory.Builder builder, int maxOwners)
protected void	swapPrimaryOwnersWithBackups(DefaultConsistentHashFactory.Builder builder)
DefaultConsistentHash	union(DefaultConsistentHash dch1, DefaultConsistentHash dch2) Merges two consistent hash objects that have the same number of segments, numOwners and hash function.
DefaultConsistentHash	updateMembers(DefaultConsistentHash baseCH, List<Address> actualMembers, Map<Address,Float> actualCapacityFactors) Leavers are removed and segments without owners are assigned new owners.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultConsistentHashFactory

public DefaultConsistentHashFactory()

Method Detail

create

public DefaultConsistentHash create(Hash hashFunction,
                                    int numOwners,
                                    int numSegments,
                                    List<Address> members,
                                    Map<Address,Float> capacityFactors)

Description copied from interface: ConsistentHashFactory

Create a new consistent hash instance.

Specified by:

create in interface ConsistentHashFactory<DefaultConsistentHash>

Parameters:

hashFunction - The hash function to use on top of the keys' own hashCode() implementation.

numOwners - The ideal number of owners for each key. The created consistent hash can have more or less owners, but each key will have at least one owner.

numSegments - Number of hash-space segments. The implementation may round up the number of segments for performance, or may ignore the parameter altogether.

members - A list of addresses representing the new cache members.

capacityFactors - The capacity factor of each member. Determines the relative capacity of each node compared to the others. The implementation may ignore this parameter. If null, all the members are assumed to have a capacity factor of 1.

fromPersistentState

public DefaultConsistentHash fromPersistentState(ScopedPersistentState state)

Description copied from interface: ConsistentHashFactory

Recreates a ConsistentHash from a previously stored persistent state

Specified by:

fromPersistentState in interface ConsistentHashFactory<DefaultConsistentHash>

updateMembers

public DefaultConsistentHash updateMembers(DefaultConsistentHash baseCH,
                                           List<Address> actualMembers,
                                           Map<Address,Float> actualCapacityFactors)

Leavers are removed and segments without owners are assigned new owners. Joiners might get some of the un-owned segments but otherwise they are not taken into account (that should happen during a rebalance).

Specified by:

updateMembers in interface ConsistentHashFactory<DefaultConsistentHash>

Parameters:

baseCH - An existing consistent hash instance, should not be null

actualMembers - A list of addresses representing the new cache members.

actualCapacityFactors - The capacity factor of each member. Determines the relative capacity of each node compared to the others. The implementation may ignore this parameter. If null, all the members are assumed to have a capacity factor of 1.

Returns:

rebalance

public DefaultConsistentHash rebalance(DefaultConsistentHash baseCH)

Description copied from interface: ConsistentHashFactory

Create a new consistent hash instance, based on an existing instance, but "balanced" according to the implementation's rules.

It must be possible to switch from the "intermediary" consistent hash that includes the old owners to the new consistent hash without any state transfer.

rebalance(rebalance(ch)) must be equivalent to rebalance(ch).

Specified by:

rebalance in interface ConsistentHashFactory<DefaultConsistentHash>

Parameters:

baseCH - An existing consistent hash instance, should not be null

Returns:

A new ConsistentHash instance, or baseCH if the existing instance does not need any changes.

union

public DefaultConsistentHash union(DefaultConsistentHash dch1,
                                   DefaultConsistentHash dch2)

Merges two consistent hash objects that have the same number of segments, numOwners and hash function. For each segment, the primary owner of the first CH has priority, the other primary owners become backups.

Specified by:

union in interface ConsistentHashFactory<DefaultConsistentHash>

rebalanceBuilder

protected void rebalanceBuilder(DefaultConsistentHashFactory.Builder builder)

addPrimaryOwners

protected void addPrimaryOwners(DefaultConsistentHashFactory.Builder builder)

replacePrimaryOwners

protected void replacePrimaryOwners(DefaultConsistentHashFactory.Builder builder,
                                    int maxOwners)

swapPrimaryOwnersWithBackups

protected void swapPrimaryOwnersWithBackups(DefaultConsistentHashFactory.Builder builder)

addBackupOwners

protected void addBackupOwners(DefaultConsistentHashFactory.Builder builder)

removeExtraBackupOwners

protected void removeExtraBackupOwners(DefaultConsistentHashFactory.Builder builder)

doAddBackupOwners

protected void doAddBackupOwners(DefaultConsistentHashFactory.Builder builder)

replaceBackupOwners

protected void replaceBackupOwners(DefaultConsistentHashFactory.Builder builder)

findNewBackupOwner

protected Address findNewBackupOwner(DefaultConsistentHashFactory.Builder builder,
                                     Collection<Address> excludes,
                                     Address owner)

Returns:

The member with the worst owned segments/capacity ratio that is also not in the excludes list.

findNewPrimaryOwner

protected Address findNewPrimaryOwner(DefaultConsistentHashFactory.Builder builder,
                                      Collection<Address> candidates,
                                      Address primaryOwner)

Returns:

The candidate with the worst primary-owned segments/capacity ratio that is also not in the excludes list.

equals

public boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object