Package io.hekate.partition

Class RendezvousHashMapper

java.lang.Object

io.hekate.partition.PartitionMapperBase

io.hekate.partition.RendezvousHashMapper

All Implemented Interfaces:

PartitionMapper

public final class RendezvousHashMapper
extends PartitionMapperBase

Implementation of PartitionMapper that uses Rendezvous (aka Highest Random Weight) hashing algorithm for partition mapping.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	RendezvousHashMapper.Builder	Builder for RendezvousHashMapper.

Field Summary

Fields

Modifier and Type	Field	Description
static int	DEFAULT_PARTITIONS	Default value (=256) for RendezvousHashMapper.Builder.withPartitions(int).

Method Summary

Modifier and Type	Method	Description
RendezvousHashMapper	copy(ClusterTopologySupport cluster)	Returns a copy of this mapper that will use the specified cluster topology and will inherit the mapping logic and all the configuration options from this instance.
boolean	isSnapshot()	Returns true if this instance is a snapshot.
Partition	map(Object key)	Maps the specified key to a Partition.
Partition	mapInt(int key)	Maps the specified key of Integer type to a Partition.
static RendezvousHashMapper.Builder	of(ClusterTopologySupport cluster)	Constructs a new builder that can be used to configure RendezvousHashMapper.
static RendezvousHashMapper	of(ClusterTopologySupport cluster, int partitions, int backupNodes)	Constructs a new mapper.
Partition	partition(int id)	Returns a partition for the specified Partition.id().
PartitionMapper	snapshot()	Creates a point in time snapshot of this mapper.
ClusterTopology	topology()	Returns the cluster topology as it is visible to this mapper.
String	toString()

Methods inherited from class io.hekate.partition.PartitionMapperBase

backupNodes, partitions

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PARTITIONS

public static final int DEFAULT_PARTITIONS

Default value (=256) for RendezvousHashMapper.Builder.withPartitions(int).

See Also:

Constant Field Values

Method Detail

of

public static RendezvousHashMapper.Builder of(ClusterTopologySupport cluster)

Constructs a new builder that can be used to configure RendezvousHashMapper.

Parameters:

cluster - Cluster topology that should be used for partitions mapping.

Returns:

Builder.

See Also:

RendezvousHashMapper.Builder.build()

of

public static RendezvousHashMapper of(ClusterTopologySupport cluster,
                                      int partitions,
                                      int backupNodes)

Constructs a new mapper.

Parameters:

cluster - Cluster topology that should be used for partitions mapping.

partitions - See RendezvousHashMapper.Builder.withPartitions(int)

backupNodes - See RendezvousHashMapper.Builder.withBackupNodes(int)

Returns:

New mapper.

copy

public RendezvousHashMapper copy(ClusterTopologySupport cluster)

Description copied from interface: PartitionMapper

Returns a copy of this mapper that will use the specified cluster topology and will inherit the mapping logic and all the configuration options from this instance.

Note that copying is not supported on snapshots (see PartitionMapper.isSnapshot()).

Parameters:

cluster - Cluster topology.

Returns:

New mapper.

map

public Partition map(Object key)

Description copied from interface: PartitionMapper

Maps the specified key to a Partition.

Note that the returned Partition instances are immutable and will not reflect changes in the cluster topology. Consider calling this method with the same key in order to obtain the Partition instance with the latest cluster topology mapping.

Specified by:

map in interface PartitionMapper

Overrides:

map in class PartitionMapperBase

Parameters:

key - Data key.

Returns:

Partition.

See Also:

Partition.primaryNode(), Partition.backupNodes()

mapInt

public Partition mapInt(int key)

Description copied from interface: PartitionMapper

Maps the specified key of Integer type to a Partition.

Note that the returned Partition instances are immutable and will not reflect changes in the cluster topology. Consider calling this method with the same key in order to obtain the Partition instance with the latest cluster topology mapping.

Specified by:

mapInt in interface PartitionMapper

Overrides:

mapInt in class PartitionMapperBase

Parameters:

key - Data key.

Returns:

Partition.

See Also:

Partition.primaryNode(), Partition.backupNodes()

partition

public Partition partition(int id)

Description copied from interface: PartitionMapper

Returns a partition for the specified Partition.id().

Parameters:

id - See Partition.id().

Returns:

Partition.

topology

public ClusterTopology topology()

Description copied from interface: PartitionMapper

Returns the cluster topology as it is visible to this mapper.

If mapper is a snapshot then this method will always return the same topology at the time when the snapshot was created. If mapper is a live mapper then it will always return the latest cluster topology.

Returns:

Cluster topology.

snapshot

public PartitionMapper snapshot()

Description copied from interface: PartitionMapper

Creates a point in time snapshot of this mapper. The returned snapshot is immutable and will not change its partitions mapping even if cluster topology changes.

Returns:

New snapshot or the same instance if this instance is already a snapshot.

See Also:

PartitionMapper.isSnapshot()

isSnapshot

public boolean isSnapshot()

Description copied from interface: PartitionMapper

Returns true if this instance is a snapshot.

Returns:

true if this instance is a snapshot.

See Also:

PartitionMapper.snapshot()

toString

public String toString()

Overrides:

toString in class Object