org.elasticsearch.search.aggregations.bucket.DeferableBucketAggregator Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :server
There is a newer version: 8.13.2
/*
 * 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.bucket;

import org.elasticsearch.search.aggregations.Aggregator;
import org.elasticsearch.search.aggregations.AggregatorFactories;
import org.elasticsearch.search.aggregations.BucketCollector;
import org.elasticsearch.search.aggregations.MultiBucketCollector;
import org.elasticsearch.search.aggregations.bucket.global.GlobalAggregator;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
import org.elasticsearch.search.internal.SearchContext;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public abstract class DeferableBucketAggregator extends BucketsAggregator {

    private DeferringBucketCollector recordingWrapper;

    protected DeferableBucketAggregator(String name, AggregatorFactories factories, SearchContext context, Aggregator parent,
            List pipelineAggregators, Map metaData) throws IOException {
        super(name, factories, context, parent, pipelineAggregators, metaData);
    }

    @Override
    protected void doPreCollection() throws IOException {
        List collectors = new ArrayList<>();
        List deferredCollectors = new ArrayList<>();
        for (int i = 0; i < subAggregators.length; ++i) {
            if (shouldDefer(subAggregators[i])) {
                if (recordingWrapper == null) {
                    recordingWrapper = getDeferringCollector();
                }
                deferredCollectors.add(subAggregators[i]);
                subAggregators[i] = recordingWrapper.wrap(subAggregators[i]);
            } else {
                collectors.add(subAggregators[i]);
            }
        }
        if (recordingWrapper != null) {
            recordingWrapper.setDeferredCollector(deferredCollectors);
            collectors.add(recordingWrapper);
        }
        collectableSubAggregators = MultiBucketCollector.wrap(collectors);
    }

    public static boolean descendsFromGlobalAggregator(Aggregator parent) {
        while (parent != null) {
            if (parent.getClass() == GlobalAggregator.class) {
                return true;
            }
            parent = parent.parent();
        }
        return false;
    }

    public DeferringBucketCollector getDeferringCollector() {
        // Default impl is a collector that selects the best buckets
        // but an alternative defer policy may be based on best docs.
        return new BestBucketsDeferringCollector(context(), descendsFromGlobalAggregator(parent()));
    }

    /**
     * This method should be overridden by subclasses that want to defer
     * calculation of a child aggregation until a first pass is complete and a
     * set of buckets has been pruned. Deferring collection will require the
     * recording of all doc/bucketIds from the first pass and then the sub class
     * should call {@link #runDeferredCollections(long...)} for the selected set
     * of buckets that survive the pruning.
     *
     * @param aggregator
     *            the child aggregator
     * @return true if the aggregator should be deferred until a first pass at
     *         collection has completed
     */
    protected boolean shouldDefer(Aggregator aggregator) {
        return false;
    }

    protected final void runDeferredCollections(long... bucketOrds) throws IOException {
        // Being lenient here - ignore calls where there are no deferred
        // collections to playback
        if (recordingWrapper != null) {
            recordingWrapper.replay(bucketOrds);
        }
    }

}