/*
* 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.facebook.presto.operator.aggregation;
import com.facebook.presto.operator.aggregation.state.HyperLogLogState;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import io.airlift.stats.cardinality.HyperLogLog;
import static com.facebook.presto.spi.type.HyperLogLogType.HYPER_LOG_LOG;
public class MergeHyperLogLogAggregation
extends AbstractSimpleAggregationFunction<HyperLogLogState>
{
public MergeHyperLogLogAggregation()
{
super(HYPER_LOG_LOG, HYPER_LOG_LOG, HYPER_LOG_LOG);
}
@Override
protected void processInput(HyperLogLogState state, Block block, int index)
{
HyperLogLog input = HyperLogLog.newInstance(block.getSlice(index));
HyperLogLog previous = state.getHyperLogLog();
if (previous == null) {
state.setHyperLogLog(input);
state.addMemoryUsage(input.estimatedInMemorySize());
}
else {
state.addMemoryUsage(-previous.estimatedInMemorySize());
previous.mergeWith(input);
state.addMemoryUsage(previous.estimatedInMemorySize());
}
}
@Override
protected void evaluateFinal(HyperLogLogState state, BlockBuilder out)
{
getStateSerializer().serialize(state, out);
}
}