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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.search.aggregations.pipeline;
import org.elasticsearch.common.collect.EvictingQueue;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.search.DocValueFormat;
import org.elasticsearch.search.aggregations.InternalAggregation;
import org.elasticsearch.search.aggregations.InternalAggregation.ReduceContext;
import org.elasticsearch.search.aggregations.InternalAggregations;
import org.elasticsearch.search.aggregations.InternalMultiBucketAggregation;
import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation.Bucket;
import org.elasticsearch.search.aggregations.bucket.histogram.HistogramFactory;
import org.elasticsearch.search.aggregations.pipeline.BucketHelpers.GapPolicy;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;
import static org.elasticsearch.search.aggregations.pipeline.BucketHelpers.resolveBucketValue;
public class SerialDiffPipelineAggregator extends PipelineAggregator {
private DocValueFormat formatter;
private GapPolicy gapPolicy;
private int lag;
SerialDiffPipelineAggregator(
String name,
String[] bucketsPaths,
@Nullable DocValueFormat formatter,
GapPolicy gapPolicy,
int lag,
Map metadata
) {
super(name, bucketsPaths, metadata);
this.formatter = formatter;
this.gapPolicy = gapPolicy;
this.lag = lag;
}
/**
* Read from a stream.
*/
public SerialDiffPipelineAggregator(StreamInput in) throws IOException {
super(in);
formatter = in.readNamedWriteable(DocValueFormat.class);
gapPolicy = GapPolicy.readFrom(in);
lag = in.readVInt();
}
@Override
public void doWriteTo(StreamOutput out) throws IOException {
out.writeNamedWriteable(formatter);
gapPolicy.writeTo(out);
out.writeVInt(lag);
}
@Override
public String getWriteableName() {
return SerialDiffPipelineAggregationBuilder.NAME;
}
@Override
public InternalAggregation reduce(InternalAggregation aggregation, ReduceContext reduceContext) {
@SuppressWarnings("rawtypes")
InternalMultiBucketAggregation<
? extends InternalMultiBucketAggregation,
? extends InternalMultiBucketAggregation.InternalBucket> histo = (InternalMultiBucketAggregation<
? extends InternalMultiBucketAggregation,
? extends InternalMultiBucketAggregation.InternalBucket>) aggregation;
List buckets = histo.getBuckets();
HistogramFactory factory = (HistogramFactory) histo;
List newBuckets = new ArrayList<>();
EvictingQueue lagWindow = new EvictingQueue<>(lag);
int counter = 0;
for (InternalMultiBucketAggregation.InternalBucket bucket : buckets) {
Double thisBucketValue = resolveBucketValue(histo, bucket, bucketsPaths()[0], gapPolicy);
Bucket newBucket = bucket;
counter += 1;
// Still under the initial lag period, add nothing and move on
Double lagValue;
if (counter <= lag) {
lagValue = Double.NaN;
} else {
lagValue = lagWindow.peek(); // Peek here, because we rely on add'ing to always move the window
}
// Normalize null's to NaN
if (thisBucketValue == null) {
thisBucketValue = Double.NaN;
}
// Both have values, calculate diff and replace the "empty" bucket
if (Double.isNaN(thisBucketValue) == false && Double.isNaN(lagValue) == false) {
double diff = thisBucketValue - lagValue;
List aggs = StreamSupport.stream(bucket.getAggregations().spliterator(), false)
.map((p) -> (InternalAggregation) p)
.collect(Collectors.toList());
aggs.add(new InternalSimpleValue(name(), diff, formatter, metadata()));
newBucket = factory.createBucket(factory.getKey(bucket), bucket.getDocCount(), InternalAggregations.from(aggs));
}
newBuckets.add(newBucket);
lagWindow.add(thisBucketValue);
}
return factory.createAggregation(newBuckets);
}
}