Package io.hekate.partition

Interface PartitionMapper

All Known Implementing Classes:

PartitionMapperBase, RendezvousHashMapper, UpdatablePartitionMapper

public interface PartitionMapper

Partition mapper.

This interface represents a data partition mapper that is responsible for mapping user-provided data to cluster partitions.

// Prepare mapper.
PartitionMapper mapper = RendezvousHashMapper.of(hekate.cluster())
    .withPartitions(128)
    .withBackupNodes(2)
    .build();

// Map some imaginary data key to a partition.
Partition partition = mapper.map("someDataKey1");

System.out.println("Primary node: " + partition.primaryNode());
System.out.println("Backup nodes: " + partition.backupNodes());

See Also:

RendezvousHashMapper

Method Summary

Modifier and Type	Method	Description
int	backupNodes()	Returns the amount of backup nodes that should be assigned to each partition.
PartitionMapper	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.
Partition	partition(int id)	Returns a partition for the specified Partition.id().
int	partitions()	Returns the total amount of partitions.
PartitionMapper	snapshot()	Creates a point in time snapshot of this mapper.
ClusterTopology	topology()	Returns the cluster topology as it is visible to this mapper.

Method Detail

map

Partition map(Object key)

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.

Parameters:

key - Data key.

Returns:

Partition.

See Also:

Partition.primaryNode(), Partition.backupNodes()

mapInt

Partition mapInt(int key)

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.

Parameters:

key - Data key.

Returns:

Partition.

See Also:

Partition.primaryNode(), Partition.backupNodes()

partitions

int partitions()

Returns the total amount of partitions.

Returns:

Total amount of partitions

partition

Partition partition(int id)

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

Parameters:

id - See Partition.id().

Returns:

Partition.

backupNodes

int backupNodes()

Returns the amount of backup nodes that should be assigned to each partition.

Returns:

Amount of backup nodes that should be assigned to each partition.

topology

ClusterTopology topology()

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

PartitionMapper snapshot()

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:

isSnapshot()

isSnapshot

boolean isSnapshot()

Returns true if this instance is a snapshot.

Returns:

true if this instance is a snapshot.

See Also:

snapshot()

copy

PartitionMapper copy(ClusterTopologySupport cluster)
              throws UnsupportedOperationException

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 isSnapshot()).

Parameters:

cluster - Cluster topology.

Returns:

New mapper.

Throws:

UnsupportedOperationException - if this partition mapper doesn't support copying.