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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;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.NamedWriteable;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.rest.action.search.RestSearchAction;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator.PipelineTree;
import org.elasticsearch.search.aggregations.support.AggregationPath;
import org.elasticsearch.search.aggregations.support.SamplingContext;
import org.elasticsearch.search.sort.SortValue;
import org.elasticsearch.xcontent.XContentBuilder;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* An internal implementation of {@link Aggregation}. Serves as a base class for all aggregation implementations.
*/
public abstract class InternalAggregation implements Aggregation, NamedWriteable {
protected final String name;
protected final Map metadata;
/**
* Constructs an aggregation result with a given name.
*
* @param name The name of the aggregation.
*/
protected InternalAggregation(String name, Map metadata) {
this.name = name;
this.metadata = metadata;
}
/**
* Read from a stream.
*/
protected InternalAggregation(StreamInput in) throws IOException {
name = in.readString();
metadata = in.readMap();
}
@Override
public final void writeTo(StreamOutput out) throws IOException {
out.writeString(name);
out.writeGenericValue(metadata);
doWriteTo(out);
}
protected abstract void doWriteTo(StreamOutput out) throws IOException;
@Override
public String getName() {
return name;
}
/**
* Rewrite the sub-aggregations in the buckets in this aggregation.
* Returns a copy of this {@linkplain InternalAggregation} with the
* rewritten buckets, or, if there aren't any modifications to
* the buckets then this method will return this aggregation. Either
* way, it doesn't modify this aggregation.
*
* Implementers of this should call the {@code rewriter} once per bucket
* with its {@linkplain InternalAggregations}. The {@code rewriter}
* should return {@code null} if it doen't have any rewriting to do or
* it should return a new {@linkplain InternalAggregations} to make
* changs.
*
* The default implementation throws an exception because most
* aggregations don't have buckets in them. It
* should be overridden by aggregations that contain buckets. Implementers
* should respect the description above.
*/
public InternalAggregation copyWithRewritenBuckets(Function rewriter) {
throw new IllegalStateException(
"Aggregation [" + getName() + "] must be a bucket aggregation but was [" + getWriteableName() + "]"
);
}
/**
* Run a {@linkplain Consumer} over all buckets in this aggregation.
*/
public void forEachBucket(Consumer consumer) {}
/**
* Creates the output from all pipeline aggs that this aggregation is associated with. Should only
* be called after all aggregations have been fully reduced
*/
public InternalAggregation reducePipelines(
InternalAggregation reducedAggs,
AggregationReduceContext reduceContext,
PipelineTree pipelinesForThisAgg
) {
assert reduceContext.isFinalReduce();
for (PipelineAggregator pipelineAggregator : pipelinesForThisAgg.aggregators()) {
reducedAggs = pipelineAggregator.reduce(reducedAggs, reduceContext);
}
return reducedAggs;
}
/**
* Reduces the given aggregations to a single one and returns it. In most cases, the assumption will be the all given
* aggregations are of the same type (the same type as this aggregation). For best efficiency, when implementing,
* try reusing an existing instance (typically the first in the given list) to save on redundant object
* construction.
*
* @see #mustReduceOnSingleInternalAgg()
*/
public abstract InternalAggregation reduce(List aggregations, AggregationReduceContext reduceContext);
/**
* Called by the parent sampling context. Should only ever be called once as some aggregations scale their internal values
* @param samplingContext the current sampling context
* @return new aggregation with the sampling context applied, could be the same aggregation instance if nothing needs to be done
*/
public InternalAggregation finalizeSampling(SamplingContext samplingContext) {
throw new UnsupportedOperationException(getWriteableName() + " aggregation [" + getName() + "] does not support sampling");
}
/**
* Signal the framework if the {@linkplain InternalAggregation#reduce(List, AggregationReduceContext)} phase needs to be called
* when there is only one {@linkplain InternalAggregation}.
*/
protected abstract boolean mustReduceOnSingleInternalAgg();
/**
* Return true if this aggregation is mapped, and can lead a reduction. If this agg returns
* false, it should return itself if asked to lead a reduction
*/
public boolean isMapped() {
return true;
}
/**
* Get the value of specified path in the aggregation.
*
* @param path
* the path to the property in the aggregation tree
* @return the value of the property
*/
public Object getProperty(String path) {
AggregationPath aggPath = AggregationPath.parse(path);
return getProperty(aggPath.getPathElementsAsStringList());
}
public abstract Object getProperty(List path);
/**
* Read a size under the assumption that a value of 0 means unlimited.
*/
protected static int readSize(StreamInput in) throws IOException {
final int size = in.readVInt();
return size == 0 ? Integer.MAX_VALUE : size;
}
/**
* Write a size under the assumption that a value of 0 means unlimited.
*/
protected static void writeSize(int size, StreamOutput out) throws IOException {
if (size == Integer.MAX_VALUE) {
size = 0;
}
out.writeVInt(size);
}
@Override
public Map getMetadata() {
return metadata;
}
@Override
public String getType() {
return getWriteableName();
}
@Override
public final XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
if (params.paramAsBoolean(RestSearchAction.TYPED_KEYS_PARAM, false)) {
// Concatenates the type and the name of the aggregation (ex: top_hits#foo)
builder.startObject(String.join(TYPED_KEYS_DELIMITER, getType(), getName()));
} else {
builder.startObject(getName());
}
if (this.metadata != null) {
builder.field(CommonFields.META.getPreferredName());
builder.map(this.metadata);
}
doXContentBody(builder, params);
builder.endObject();
return builder;
}
public abstract XContentBuilder doXContentBody(XContentBuilder builder, Params params) throws IOException;
@Override
public int hashCode() {
return Objects.hash(name, metadata);
}
@Override
public boolean equals(Object obj) {
if (obj == null || getClass() != obj.getClass()) {
return false;
}
if (obj == this) {
return true;
}
InternalAggregation other = (InternalAggregation) obj;
return Objects.equals(name, other.name) && Objects.equals(metadata, other.metadata);
}
@Override
public String toString() {
return Strings.toString(this);
}
/**
* Get value to use when sorting by this aggregation.
*/
public SortValue sortValue(String key) {
// subclasses will override this with a real implementation if they can be sorted
throw new IllegalArgumentException("Can't sort a [" + getType() + "] aggregation [" + getName() + "]");
}
/**
* Get value to use when sorting by a descendant of this aggregation.
*/
public SortValue sortValue(AggregationPath.PathElement head, Iterator tail) {
// subclasses will override this with a real implementation if you can sort on a descendant
throw new IllegalArgumentException("Can't sort by a descendant of a [" + getType() + "] aggregation [" + head + "]");
}
}