org.apache.ignite.cache.affinity.rendezvous

Class RendezvousAffinityFunction

java.lang.Object

org.apache.ignite.cache.affinity.rendezvous.RendezvousAffinityFunction

All Implemented Interfaces:

Serializable, AffinityFunction

public class RendezvousAffinityFunction
extends Object
implements AffinityFunction, Serializable

Affinity function for partitioned cache based on Highest Random Weight algorithm. This function supports the following configuration:

• partitions - Number of partitions to spread across nodes.
• excludeNeighbors - If set to true, will exclude same-host-neighbors from being backups of each other. This flag can be ignored in cases when topology has no enough nodes for assign backups. Note that backupFilter is ignored if excludeNeighbors is set to true.
• backupFilter - Optional filter for back up nodes. If provided, then only nodes that pass this filter will be selected as backup nodes. If not provided, then primary and backup nodes will be selected out of all nodes available for this cache.

Cache affinity can be configured for individual caches via CacheConfiguration.getAffinity() method.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	DFLT_PARTITION_COUNT Default number of partitions.

Constructor Summary

Constructors

Constructor and Description
RendezvousAffinityFunction() Empty constructor with all defaults.
RendezvousAffinityFunction(boolean exclNeighbors) Initializes affinity with flag to exclude same-host-neighbors from being backups of each other and specified number of backups.
RendezvousAffinityFunction(boolean exclNeighbors, int parts) Initializes affinity with flag to exclude same-host-neighbors from being backups of each other, and specified number of backups and partitions.
RendezvousAffinityFunction(int parts, @Nullable IgniteBiPredicate<ClusterNode,ClusterNode> backupFilter) Initializes optional counts for replicas and backups.

Method Summary

Modifier and Type	Method and Description
List<ClusterNode>	assignPartition(int part, List<ClusterNode> nodes, int backups, @Nullable Map<UUID,Collection<ClusterNode>> neighborhoodCache) Returns collection of nodes (primary first) for specified partition.
List<List<ClusterNode>>	assignPartitions(AffinityFunctionContext affCtx) Gets affinity nodes for a partition.
static int	calculateMask(int parts) Helper method to calculates mask.
static int	calculatePartition(Object key, int mask, int parts) Helper method to calculate partition.
@Nullable IgniteBiPredicate<ClusterNode,List<ClusterNode>>	getAffinityBackupFilter() Gets optional backup filter.
@Nullable IgniteBiPredicate<ClusterNode,ClusterNode>	getBackupFilter() Gets optional backup filter.
int	getPartitions() Gets total number of key partitions.
boolean	isExcludeNeighbors() Checks flag to exclude same-host-neighbors from being backups of each other (default is false).
int	partition(Object key) Gets partition number for a given key starting from 0.
int	partitions() Gets total number of partitions available.
void	removeNode(UUID nodeId) Removes node from affinity.
void	reset() Resets cache affinity to its initial state.
Object	resolveNodeHash(ClusterNode node) Resolves node hash.
RendezvousAffinityFunction	setAffinityBackupFilter(@Nullable IgniteBiPredicate<ClusterNode,List<ClusterNode>> affinityBackupFilter) Sets optional backup filter.
RendezvousAffinityFunction	setBackupFilter(@Nullable IgniteBiPredicate<ClusterNode,ClusterNode> backupFilter) Deprecated. Use affinityBackupFilter instead.
RendezvousAffinityFunction	setExcludeNeighbors(boolean exclNeighbors) Sets flag to exclude same-host-neighbors from being backups of each other (default is false).
RendezvousAffinityFunction	setPartitions(int parts) Sets total number of partitions.If the number of partitions is a power of two, the PowerOfTwo hashing method will be used.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

DFLT_PARTITION_COUNT

public static final int DFLT_PARTITION_COUNT

Default number of partitions.

See Also:

Constant Field Values

Constructor Detail

RendezvousAffinityFunction

public RendezvousAffinityFunction()

Empty constructor with all defaults.

RendezvousAffinityFunction

public RendezvousAffinityFunction(boolean exclNeighbors)

Initializes affinity with flag to exclude same-host-neighbors from being backups of each other and specified number of backups.

Note that backupFilter is ignored if excludeNeighbors is set to true.

Parameters:

exclNeighbors - True if nodes residing on the same host may not act as backups of each other.

RendezvousAffinityFunction

public RendezvousAffinityFunction(boolean exclNeighbors,
                                  int parts)

Initializes affinity with flag to exclude same-host-neighbors from being backups of each other, and specified number of backups and partitions.

Note that backupFilter is ignored if excludeNeighbors is set to true.

Parameters:

exclNeighbors - True if nodes residing on the same host may not act as backups of each other.

parts - Total number of partitions.

RendezvousAffinityFunction

public RendezvousAffinityFunction(int parts,
                                  @Nullable
                                  @Nullable IgniteBiPredicate<ClusterNode,ClusterNode> backupFilter)

Initializes optional counts for replicas and backups.

Note that backupFilter is ignored if excludeNeighbors is set to true.

Parameters:

parts - Total number of partitions.

backupFilter - Optional back up filter for nodes. If provided, backups will be selected from all nodes that pass this filter. First argument for this filter is primary node, and second argument is node being tested.

Note that backupFilter is ignored if excludeNeighbors is set to true.

Method Detail

calculateMask

public static int calculateMask(int parts)

Helper method to calculates mask.

Parameters:

parts - Number of partitions.

Returns:

Mask to use in calculation when partitions count is power of 2.

calculatePartition

public static int calculatePartition(Object key,
                                     int mask,
                                     int parts)

Helper method to calculate partition.

Parameters:

key - – Key to get partition for.

mask - Mask to use in calculation when partitions count is power of 2.

parts - Number of partitions.

Returns:

Partition number for a given key.

getPartitions

public int getPartitions()

Gets total number of key partitions. To ensure that all partitions are equally distributed across all nodes, please make sure that this number is significantly larger than a number of nodes. Also, partition size should be relatively small. Try to avoid having partitions with more than quarter million keys.

For fully replicated caches this method works the same way as a partitioned cache.

Returns:

Total partition count.

setPartitions

public RendezvousAffinityFunction setPartitions(int parts)

Sets total number of partitions.If the number of partitions is a power of two, the PowerOfTwo hashing method will be used. Otherwise the Standard hashing method will be applied.

Parameters:

parts - Total number of partitions.

Returns:

this for chaining.

getBackupFilter

@Nullable
public @Nullable IgniteBiPredicate<ClusterNode,ClusterNode> getBackupFilter()

Gets optional backup filter. If not null, backups will be selected from all nodes that pass this filter. First node passed to this filter is primary node, and second node is a node being tested.

Note that backupFilter is ignored if excludeNeighbors is set to true.

Returns:

Optional backup filter.

setBackupFilter

@Deprecated
public RendezvousAffinityFunction setBackupFilter(@Nullable
                                                              @Nullable IgniteBiPredicate<ClusterNode,ClusterNode> backupFilter)

Deprecated. Use affinityBackupFilter instead.

Sets optional backup filter. If provided, then backups will be selected from all nodes that pass this filter. First node being passed to this filter is primary node, and second node is a node being tested.

Note that backupFilter is ignored if excludeNeighbors is set to true.

Parameters:

backupFilter - Optional backup filter.

Returns:

this for chaining.

getAffinityBackupFilter

@Nullable
public @Nullable IgniteBiPredicate<ClusterNode,List<ClusterNode>> getAffinityBackupFilter()

Gets optional backup filter. If not null, backups will be selected from all nodes that pass this filter. First node passed to this filter is a node being tested, and the second parameter is a list of nodes that are already assigned for a given partition (primary node is the first in the list).

Note that affinityBackupFilter is ignored if excludeNeighbors is set to true.

Returns:

Optional backup filter.

setAffinityBackupFilter

public RendezvousAffinityFunction setAffinityBackupFilter(@Nullable
                                                          @Nullable IgniteBiPredicate<ClusterNode,List<ClusterNode>> affinityBackupFilter)

Sets optional backup filter. If provided, then backups will be selected from all nodes that pass this filter. First node being passed to this filter is a node being tested, and the second parameter is a list of nodes that are already assigned for a given partition (primary node is the first in the list).

Note that affinityBackupFilter is ignored if excludeNeighbors is set to true.

For an example filter, see ClusterNodeAttributeAffinityBackupFilter.

Parameters:

affinityBackupFilter - Optional backup filter.

Returns:

this for chaining.

isExcludeNeighbors

public boolean isExcludeNeighbors()

Checks flag to exclude same-host-neighbors from being backups of each other (default is false).

Note that backupFilter is ignored if excludeNeighbors is set to true.

Returns:

True if nodes residing on the same host may not act as backups of each other.

setExcludeNeighbors

public RendezvousAffinityFunction setExcludeNeighbors(boolean exclNeighbors)

Sets flag to exclude same-host-neighbors from being backups of each other (default is false).

Note that backupFilter is ignored if excludeNeighbors is set to true.

Parameters:

exclNeighbors - True if nodes residing on the same host may not act as backups of each other.

Returns:

this for chaining.

resolveNodeHash

public Object resolveNodeHash(ClusterNode node)

Resolves node hash.

Parameters:

node - Cluster node;

Returns:

Node hash.

assignPartition

public List<ClusterNode> assignPartition(int part,
                                         List<ClusterNode> nodes,
                                         int backups,
                                         @Nullable
                                         @Nullable Map<UUID,Collection<ClusterNode>> neighborhoodCache)

Returns collection of nodes (primary first) for specified partition.

Parameters:

part - Partition.

nodes - Nodes.

backups - Number of backups.

neighborhoodCache - Neighborhood.

Returns:

Assignment.

reset

public void reset()

Resets cache affinity to its initial state. This method will be called by the system any time the affinity has been sent to remote node where it has to be reinitialized. If your implementation of affinity function has no initialization logic, leave this method empty.

Specified by:

reset in interface AffinityFunction

partitions

public int partitions()

Gets total number of partitions available. All caches should always provide correct partition count which should be the same on all participating nodes. Note that partitions should always be numbered from 0 inclusively to N exclusively without any gaps.

Specified by:

partitions in interface AffinityFunction

Returns:

Total partition count.

partition

public int partition(Object key)

Gets partition number for a given key starting from 0. Partitioned caches should make sure that keys are about evenly distributed across all partitions from 0 to partition count for best performance.

Note that for fully replicated caches it is possible to segment key sets among different grid node groups. In that case each node group should return a unique partition number. However, unlike partitioned cache, mappings of keys to nodes in replicated caches are constant and a node cannot migrate from one partition to another.

Specified by:

partition in interface AffinityFunction

Parameters:

key - Key to get partition for.

Returns:

Partition number for a given key.

assignPartitions

public List<List<ClusterNode>> assignPartitions(AffinityFunctionContext affCtx)

Gets affinity nodes for a partition. In case of replicated cache, all returned nodes are updated in the same manner. In case of partitioned cache, the returned list should contain only the primary and back up nodes with primary node being always first.

Note that partitioned affinity must obey the following contract: given that node N is primary for some key K, if any other node(s) leave grid and no node joins grid, node N will remain primary for key K.

Specified by:

assignPartitions in interface AffinityFunction

Parameters:

affCtx - Affinity function context. Will provide all required information to calculate new partition assignments.

Returns:

Unmodifiable list indexed by partition number. Each element of array is a collection in which first node is a primary node and other nodes are backup nodes.

removeNode

public void removeNode(UUID nodeId)

Removes node from affinity. This method is called when it is safe to remove left node from affinity mapping.

Specified by:

removeNode in interface AffinityFunction

Parameters:

nodeId - ID of node to remove.

toString

public String toString()

Overrides:

toString in class Object