CalcAggregator.java

/*
 * Licensed to ElasticSearch and Shay Banon under one
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 * 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
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package org.elasticsearch.search.aggregations.calc;

import org.elasticsearch.search.aggregations.Aggregator;
import org.elasticsearch.search.aggregations.InternalAggregation;
import org.elasticsearch.search.aggregations.context.AggregationContext;

/** Base class for calc aggregators. These aggregators don't have children and are usually used to compute statistics about the matching documents. */
public abstract class CalcAggregator extends Aggregator {

    protected CalcAggregator(String name, AggregationContext context, Aggregator parent) {
        super(name, context, parent);
    }

    /** Create a new {@link CalcCollector} with a configured number of buckets. */
    public abstract CalcCollector collector(long numBuckets);

    public static interface CalcCollector {

        /** Return the current capacity of this {@link CalcCollector}, which is the number of buckets that it can handle. */
        long capacity();

        /** Grow the collector so that it can handle the provided number of buckets. Data about existing buckets will be preserved. */
        void grow(long numBuckets);

        /** Collect information about <code>doc</code> in the provided bucketId. <code>bucketId</code> must be in <code>[0, #capacity()]</code>.  */
        void collect(long bucketId, int doc);

        /** Called when collection is finished. */
        void postCollection();

    }

    /** Build aggregations  */
    public abstract InternalAggregation buildAggregation(long bucketId);

}