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com.tangosol.net.partition
Class DefaultKeyPartitioningStrategy

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.net.partition.DefaultKeyPartitioningStrategy

All Implemented Interfaces:

KeyPartitioningStrategy

Direct Known Subclasses:

BroadKeyPartitioningStrategy

public class DefaultKeyPartitioningStrategy

extends ExternalizableHelper

implements KeyPartitioningStrategy

DefaultKeyPartitioningStrategy provides a simple strategy for assigning keys to partitions which is based on the hash code of keys in internal (serialized to Binary) form.

Since:

Coherence 3.6

Author:

gg 2010.05.19

Nested Class Summary

Nested classes/interfaces inherited from interface com.tangosol.net.partition.KeyPartitioningStrategy

KeyPartitioningStrategy.PartitionAwareKey

Field Summary

protected PartitionedService

m_service The PartitionedService that this strategy is bound to.

Constructor Summary

DefaultKeyPartitioningStrategy()
Default constructor.

Method Summary

static int	calculateBasePartitionHash(PartitionedService service, java.lang.Object oKey) Determine the partition-hash of the given key.
static int	calculateKeyPartition(PartitionedService service, java.lang.Object oKey) Determine the partition to which the given key should be assigned for the specified PartitionService, taking into consideration the associations provided by the service's KeyAssociator.
static int	calculateKeyPartitionHash(PartitionedService service, java.lang.Object oKey) Determine the partition-hash of the given key.
static int	calculatePartition(PartitionedService service, int nHash) Return the partition associated with the specified hash value in the specified PartitionedService.
PartitionSet	getAssociatedPartitions(java.lang.Object oKey) Determine the set of partitions that all keys associated with the specified key are assigned to.
int	getKeyPartition(java.lang.Object oKey) Determine the partition to which a particular key should be assigned.
void	init(PartitionedService service) Initialize the KeyPartitioningStrategy and bind it to the specified PartitionedService.

Methods inherited from class com.tangosol.util.BitHelper

countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString, toBytes, toBytes, toBytes, toBytes, toInt, toInt, toLong, toLong

Field Detail

m_service

protected PartitionedService m_service

The PartitionedService that this strategy is bound to.

Constructor Detail

DefaultKeyPartitioningStrategy

public DefaultKeyPartitioningStrategy()

Default constructor.

Method Detail

init

public void init(PartitionedService service)

Initialize the KeyPartitioningStrategy and bind it to the specified PartitionedService.

Specified by:

init in interface KeyPartitioningStrategy

Parameters:

service - the PartitionedService that this strategy is being bound to

getKeyPartition

public int getKeyPartition(java.lang.Object oKey)

Determine the partition to which a particular key should be assigned.

In general, implementations are expected to respect the associations provided by the service's KeyAssociator in such a way that keys that return the same associated key would be assigned to the same partition. Furthermore, implementations are also expected to respect explicit partition-assignments dictated by the KeyPartitioningStrategy.PartitionAwareKey interface. Naturally, those two interfaces should not be combined for a given key.

The resulting partition must be in the range [0..N-1], where N is the value returned from PartitionedService.getPartitionCount().

Specified by:

getKeyPartition in interface KeyPartitioningStrategy

Parameters:

oKey - a key in its Object form

Returns:

the partition ID that the specified key is assigned to

See Also:

PartitionedService.getPartitionOwner(int)

getAssociatedPartitions

public PartitionSet getAssociatedPartitions(java.lang.Object oKey)

Determine the set of partitions that all keys associated with the specified key are assigned to. Most commonly, this method returns a partition set containing a single partition returned by the getKeyPartition method.

Specified by:

getAssociatedPartitions in interface KeyPartitioningStrategy

Parameters:

oKey - a key in its Object form

Returns:

the PartitionSet associated with the specified key

calculateKeyPartition

public static int calculateKeyPartition(PartitionedService service,
                                        java.lang.Object oKey)

Determine the partition to which the given key should be assigned for the specified PartitionService, taking into consideration the associations provided by the service's KeyAssociator.

The resulting partition will be in the range [0..N), where N is the value returned from the PartitionedService.getPartitionCount() method.

Parameters:

service - the PartitionedService

oKey - a key in its original (Object) format

Returns:

the partition that the corresponding key is assigned to

calculateKeyPartitionHash

public static int calculateKeyPartitionHash(PartitionedService service,
                                            java.lang.Object oKey)

Determine the partition-hash of the given key. The partition-hash is a property of the key identity itself, irrespective of the associated PartitionService's configured partition-count. The returned partition-hash is calculated by taking into consideration the associations provided by the service's KeyAssociator.

Parameters:

service - the PartitionedService

oKey - a key in its original (Object) format

Returns:

the partition-hash of the corresponding key

calculateBasePartitionHash

public static int calculateBasePartitionHash(PartitionedService service,
                                             java.lang.Object oKey)

Determine the partition-hash of the given key. The partition-hash is a property of the key identity itself, irrespective of the associated PartitionService's configured partition-count.

Parameters:

service - the PartitionedService

oKey - a key in its original (Object) format

Returns:

the partition-hash of the corresponding key

calculatePartition

public static int calculatePartition(PartitionedService service,
                                     int nHash)

Return the partition associated with the specified hash value in the specified PartitionedService.

Parameters:

service - the PartitionedService

nHash - the hash value

Returns:

the partition-id that the specified hash value belongs to

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