com.hazelcast.map.merge.MapMergePolicy Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.map.merge;
import com.hazelcast.core.EntryView;
import com.hazelcast.nio.serialization.DataSerializable;
/**
* A policy for merging maps after a splitbrain was detected and the different network partitions need
* to be merged.
*
* @see com.hazelcast.map.merge.MapMergePolicy
* @see com.hazelcast.map.merge.PutIfAbsentMapMergePolicy
* @see com.hazelcast.map.merge.LatestUpdateMapMergePolicy
* @see com.hazelcast.map.merge.PassThroughMergePolicy
* @see com.hazelcast.map.merge.HigherHitsMapMergePolicy
*/
public interface MapMergePolicy extends DataSerializable {
/**
* Returns the value of the entry after the merge
* of entries with the same key.
* You should consider the case where existingEntry's value is null.
*
* @param mapName name of the map
* @param mergingEntry entry merging into the destination cluster
* @param existingEntry existing entry in the destination cluster
* @return final value of the entry. If returns null, then the entry will be removed.
*/
Object merge(String mapName, EntryView mergingEntry, EntryView existingEntry);
}