com.hazelcast.spi.merge.HyperLogLogMergePolicy Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2024, 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.spi.merge;
import com.hazelcast.cardinality.impl.hyperloglog.HyperLogLog;
import com.hazelcast.spi.impl.merge.AbstractSplitBrainMergePolicy;
import com.hazelcast.spi.impl.merge.CardinalityEstimatorMergingEntry;
import com.hazelcast.spi.merge.SplitBrainMergeTypes.CardinalityEstimatorMergeTypes;
import static com.hazelcast.spi.impl.merge.SplitBrainDataSerializerHook.HYPER_LOG_LOG;
/**
* Only available for HyperLogLog backed {@link com.hazelcast.cardinality.CardinalityEstimator}.
*
* Uses the default merge algorithm from HyperLogLog research, keeping the max register value of the two given instances.
* The result should be the union to the two HyperLogLog estimations.
*
* @since 3.10
*/
public class HyperLogLogMergePolicy
extends AbstractSplitBrainMergePolicy {
public HyperLogLogMergePolicy() {
}
@Override
public HyperLogLog merge(CardinalityEstimatorMergeTypes mergingValue,
CardinalityEstimatorMergeTypes existingValue) {
HyperLogLog merging = ((CardinalityEstimatorMergingEntry) mergingValue).getRawValue();
if (existingValue == null) {
return merging;
}
merging.merge(((CardinalityEstimatorMergingEntry) existingValue).getRawValue());
return merging;
}
@Override
public int getClassId() {
return HYPER_LOG_LOG;
}
}