org.elasticsearch.search.aggregations.pipeline.BucketSortPipelineAggregator 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.pipeline;


import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.search.aggregations.InternalAggregation;
import org.elasticsearch.search.aggregations.InternalAggregation.ReduceContext;
import org.elasticsearch.search.aggregations.InternalMultiBucketAggregation;
import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation;
import org.elasticsearch.search.aggregations.pipeline.BucketHelpers.GapPolicy;
import org.elasticsearch.search.sort.FieldSortBuilder;
import org.elasticsearch.search.sort.SortOrder;

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

public class BucketSortPipelineAggregator extends PipelineAggregator {

    private final List sorts;
    private final int from;
    private final Integer size;
    private final GapPolicy gapPolicy;

    BucketSortPipelineAggregator(String name, List sorts, int from, Integer size, GapPolicy gapPolicy,
                                        Map metadata) {
        super(name, sorts.stream().map(FieldSortBuilder::getFieldName).toArray(String[]::new), metadata);
        this.sorts = sorts;
        this.from = from;
        this.size = size;
        this.gapPolicy = gapPolicy;
    }

    /**
     * Read from a stream.
     */
    public BucketSortPipelineAggregator(StreamInput in) throws IOException {
        super(in);
        sorts = in.readList(FieldSortBuilder::new);
        from = in.readVInt();
        size = in.readOptionalVInt();
        gapPolicy = GapPolicy.readFrom(in);
    }

    @Override
    protected void doWriteTo(StreamOutput out) throws IOException {
        out.writeList(sorts);
        out.writeVInt(from);
        out.writeOptionalVInt(size);
        gapPolicy.writeTo(out);
    }

    @Override
    public String getWriteableName() {
        return BucketSortPipelineAggregationBuilder.NAME;
    }

    @Override
    public InternalAggregation reduce(InternalAggregation aggregation, ReduceContext reduceContext) {
        InternalMultiBucketAggregation originalAgg =
                (InternalMultiBucketAggregation) aggregation;
        List buckets = originalAgg.getBuckets();
        int bucketsCount = buckets.size();
        int currentSize = size == null ? bucketsCount : size;

        if (from >= bucketsCount) {
            return originalAgg.create(Collections.emptyList());
        }

        // If no sorting needs to take place, we just truncate and return
        if (sorts.size() == 0) {
            return originalAgg.create(new ArrayList<>(buckets.subList(from, Math.min(from + currentSize, bucketsCount))));
        }

        List ordered = new ArrayList<>();
        for (InternalMultiBucketAggregation.InternalBucket bucket : buckets) {
            ComparableBucket comparableBucket = new ComparableBucket(originalAgg, bucket);
            if (comparableBucket.skip() == false) {
                ordered.add(comparableBucket);
            }
        }

        Collections.sort(ordered);

        // We just have to get as many elements as we expect in results and store them in the same order starting from
        // the specified offset and taking currentSize into consideration.
        int limit = Math.min(from + currentSize, ordered.size());
        List newBuckets = new ArrayList<>();
        for (int i = from; i < limit; ++i) {
            newBuckets.add(ordered.get(i).internalBucket);
        }
        return originalAgg.create(newBuckets);
    }

    private class ComparableBucket implements Comparable {

        private final MultiBucketsAggregation parentAgg;
        private final InternalMultiBucketAggregation.InternalBucket internalBucket;
        private final Map> sortValues;

        private ComparableBucket(MultiBucketsAggregation parentAgg, InternalMultiBucketAggregation.InternalBucket internalBucket) {
            this.parentAgg = parentAgg;
            this.internalBucket = internalBucket;
            this.sortValues = resolveAndCacheSortValues();
        }

        private Map> resolveAndCacheSortValues() {
            Map> resolved = new HashMap<>();
            for (FieldSortBuilder sort : sorts) {
                String sortField = sort.getFieldName();
                if ("_key".equals(sortField)) {
                    resolved.put(sort, (Comparable