/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.search.aggregations.metrics.cardinality;
import org.elasticsearch.search.aggregations.AggregationExecutionException;
import org.elasticsearch.search.aggregations.Aggregator;
import org.elasticsearch.search.aggregations.Aggregator.BucketAggregationMode;
import org.elasticsearch.search.aggregations.support.AggregationContext;
import org.elasticsearch.search.aggregations.support.ValuesSource;
import org.elasticsearch.search.aggregations.support.ValuesSourceAggregatorFactory;
import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
import java.util.Map;
final class CardinalityAggregatorFactory extends ValuesSourceAggregatorFactory<ValuesSource, Map<String, Object>> {
private final long precisionThreshold;
private final boolean rehash;
CardinalityAggregatorFactory(String name, ValuesSourceConfig config, long precisionThreshold, boolean rehash) {
super(name, InternalCardinality.TYPE.name(), config);
this.precisionThreshold = precisionThreshold;
this.rehash = rehash;
}
private int precision(Aggregator parent) {
return precisionThreshold < 0 ? defaultPrecision(parent) : HyperLogLogPlusPlus.precisionFromThreshold(precisionThreshold);
}
@Override
protected Aggregator createUnmapped(AggregationContext context, Aggregator parent, Map<String, Object> metaData) {
return new CardinalityAggregator(name, parent == null ? 1 : parent.estimatedBucketCount(), null, true, precision(parent), context, parent, metaData);
}
@Override
protected Aggregator create(ValuesSource valuesSource, long expectedBucketsCount, AggregationContext context, Aggregator parent, Map<String, Object> metaData) {
if (!(valuesSource instanceof ValuesSource.Numeric) && !rehash) {
throw new AggregationExecutionException("Turning off rehashing for cardinality aggregation [" + name + "] on non-numeric values in not allowed");
}
return new CardinalityAggregator(name, parent == null ? 1 : parent.estimatedBucketCount(), valuesSource, rehash, precision(parent), context, parent, metaData);
}
/*
* If one of the parent aggregators is a MULTI_BUCKET one, we might want to lower the precision
* because otherwise it might be memory-intensive. On the other hand, for top-level aggregators
* we try to focus on accuracy.
*/
private int defaultPrecision(Aggregator parent) {
int precision = HyperLogLogPlusPlus.DEFAULT_PRECISION;
while (parent != null) {
if (parent.bucketAggregationMode() == BucketAggregationMode.PER_BUCKET) {
// if the parent is a per-bucket aggregator, we substract 5 to the precision,
// which will effectively divide the memory usage of each counter by 32
precision -= 5;
}
parent = parent.parent();
}
return Math.max(precision, HyperLogLogPlusPlus.MIN_PRECISION);
}
}