com.hazelcast.spi.merge

Class LatestAccessMergePolicy

java.lang.Object

com.hazelcast.spi.merge.LatestAccessMergePolicy

All Implemented Interfaces:

DataSerializable, IdentifiedDataSerializable, SplitBrainMergePolicy

public class LatestAccessMergePolicy
extends Object

Merges data structure entries from source to destination data structure if the source entry has been accessed more recently than the destination entry.

Note: This policy can only be used if the clocks of the nodes are in sync.

Since:

3.10

Method Summary

Modifier and Type	Method and Description
int	getFactoryId() Returns DataSerializableFactory factory ID for this class.
int	getId() Returns type identifier for this class.
<K,V> V	merge(SplitBrainMergeEntryView<K,V> mergingEntry, SplitBrainMergeEntryView<K,V> existingEntry) Selects one of the merging and existing data structure entries to be merged.
void	readData(ObjectDataInput in) Reads fields from the input stream
void	setSerializationService(SerializationService serializationService) Sets the SerializationService for this merge policy.
void	writeData(ObjectDataOutput out) Writes object fields to output stream

Methods inherited from class java.lang.Object

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

Method Detail

merge

public <K,V> V merge(SplitBrainMergeEntryView<K,V> mergingEntry,
                     SplitBrainMergeEntryView<K,V> existingEntry)

Description copied from interface: SplitBrainMergePolicy

Selects one of the merging and existing data structure entries to be merged.

Note that as mentioned also in arguments, the SplitBrainMergeEntryView instance that represents the existing data structure entry may be null if there is no existing entry for the specified key in the SplitBrainMergeEntryView instance that represents the merging data structure entry.

Type Parameters:

K - the type of the key

V - the type of the value

Parameters:

mergingEntry - SplitBrainMergeEntryView instance that has the data structure entry to be merged

existingEntry - SplitBrainMergeEntryView instance that has the existing data structure entry or null if there is no existing data structure entry

Returns:

the selected value for merging

getId

public int getId()

Description copied from interface: IdentifiedDataSerializable

Returns type identifier for this class. It should be unique per DataSerializableFactory.

Returns:

type ID

setSerializationService

public void setSerializationService(SerializationService serializationService)

Description copied from interface: SplitBrainMergePolicy

Sets the SerializationService for this merge policy.

The keys and values of merging and existing SplitBrainMergeEntryViews are always in the in-memory format of the backing data structure. This can be a serialized format, so the content cannot be processed without deserialization. For most merge policies this will be fine, since the key or value are not used. If your implementation needs the deserialized data, you can use SerializationService.toObject(Object) of the injected SerializationService.

The deserialization is not done eagerly for two main reasons:

• The deserialization is quite expensive and should be avoided, if the result is not needed.
• There is no need to locate classes of stored entries on the server side, when the entries are not deserialized. So you can put entries from a client by using InMemoryFormat.BINARY with a different classpath on client and server. In this case a deserialization could throw a ClassNotFoundException.

Specified by:

setSerializationService in interface SplitBrainMergePolicy

Parameters:

serializationService - the SerializationService

getFactoryId

public int getFactoryId()

Description copied from interface: IdentifiedDataSerializable

Returns DataSerializableFactory factory ID for this class.

Specified by:

getFactoryId in interface IdentifiedDataSerializable

Returns:

factory ID

writeData

public void writeData(ObjectDataOutput out)

Description copied from interface: DataSerializable

Writes object fields to output stream

Specified by:

writeData in interface DataSerializable

Parameters:

out - output

readData

public void readData(ObjectDataInput in)

Description copied from interface: DataSerializable

Reads fields from the input stream

Specified by:

readData in interface DataSerializable

Parameters:

in - input