com.hazelcast.spi

Interface SplitBrainMergePolicy

All Known Implementing Classes:

DiscardMergePolicy, HigherHitsMergePolicy, LatestAccessMergePolicy, LatestUpdateMergePolicy, PassThroughMergePolicy, PutIfAbsentMergePolicy

public interface SplitBrainMergePolicy

Policy for merging data structure entries after a split-brain has been healed.

Since:

3.10

Method Summary

Modifier and Type	Method and Description
<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	setSerializationService(SerializationService serializationService) Sets the SerializationService for this merge policy.

Method Detail

merge

<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.

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

setSerializationService

void setSerializationService(SerializationService serializationService)

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.

Parameters:

serializationService - the SerializationService