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/*
* 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;
import org.elasticsearch.common.lease.Releasable;
import org.elasticsearch.common.lease.Releasables;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.search.aggregations.support.AggregationContext;
import org.elasticsearch.search.internal.SearchContext;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public abstract class Aggregator implements Releasable {
/**
* Defines the nature of the aggregator's aggregation execution when nested in other aggregators and the buckets they create.
*/
public static enum BucketAggregationMode {
/**
* In this mode, a new aggregator instance will be created per bucket (created by the parent aggregator)
*/
PER_BUCKET,
/**
* In this mode, a single aggregator instance will be created per parent aggregator, that will handle the aggregations of all its buckets.
*/
MULTI_BUCKETS
}
protected final String name;
protected final Aggregator parent;
protected final AggregationContext context;
protected final int depth;
protected final long estimatedBucketCount;
protected final BucketAggregationMode bucketAggregationMode;
protected final AggregatorFactories factories;
protected final Aggregator[] subAggregators;
/**
* Constructs a new Aggregator.
*
* @param name The name of the aggregation
* @param bucketAggregationMode The nature of execution as a sub-aggregator (see {@link BucketAggregationMode})
* @param factories The factories for all the sub-aggregators under this aggregator
* @param estimatedBucketsCount When served as a sub-aggregator, indicate how many buckets the parent aggregator will generate.
* @param context The aggregation context
* @param parent The parent aggregator (may be {@code null} for top level aggregators)
*/
protected Aggregator(String name, BucketAggregationMode bucketAggregationMode, AggregatorFactories factories, long estimatedBucketsCount, AggregationContext context, Aggregator parent) {
this.name = name;
this.parent = parent;
this.estimatedBucketCount = estimatedBucketsCount;
this.context = context;
this.depth = parent == null ? 0 : 1 + parent.depth();
this.bucketAggregationMode = bucketAggregationMode;
assert factories != null : "sub-factories provided to BucketAggregator must not be null, use AggragatorFactories.EMPTY instead";
this.factories = factories;
this.subAggregators = factories.createSubAggregators(this, estimatedBucketsCount);
}
/**
* @return The name of the aggregation.
*/
public String name() {
return name;
}
/** Return the estimated number of buckets. */
public final long estimatedBucketCount() {
return estimatedBucketCount;
}
/** Return the depth of this aggregator in the aggregation tree. */
public final int depth() {
return depth;
}
/**
* @return The parent aggregator of this aggregator. The addAggregation are hierarchical in the sense that some can
* be composed out of others (more specifically, bucket addAggregation can define other addAggregation that will
* be aggregated per bucket). This method returns the direct parent aggregator that contains this aggregator, or
* {@code null} if there is none (meaning, this aggregator is a top level one)
*/
public Aggregator parent() {
return parent;
}
public Aggregator[] subAggregators() {
return subAggregators;
}
/**
* @return The current aggregation context.
*/
public AggregationContext context() {
return context;
}
/**
* @return The bucket aggregation mode of this aggregator. This mode defines the nature in which the aggregation is executed
* @see BucketAggregationMode
*/
public BucketAggregationMode bucketAggregationMode() {
return bucketAggregationMode;
}
/**
* @return Whether this aggregator is in the state where it can collect documents. Some aggregators can do their aggregations without
* actually collecting documents, for example, an aggregator that computes stats over unmapped fields doesn't need to collect
* anything as it knows to just return "empty" stats as the aggregation result.
*/
public abstract boolean shouldCollect();
/**
* Called during the query phase, to collect & aggregate the given document.
*
* @param doc The document to be collected/aggregated
* @param owningBucketOrdinal The ordinal of the bucket this aggregator belongs to, assuming this aggregator is not a top level aggregator.
* Typically, aggregators with {@code #bucketAggregationMode} set to {@link BucketAggregationMode#MULTI_BUCKETS}
* will heavily depend on this ordinal. Other aggregators may or may not use it and can see this ordinal as just
* an extra information for the aggregation context. For top level aggregators, the ordinal will always be
* equal to 0.
* @throws IOException
*/
public abstract void collect(int doc, long owningBucketOrdinal) throws IOException;
/**
* Called after collection of all document is done.
*/
public final void postCollection() {
for (int i = 0; i < subAggregators.length; i++) {
subAggregators[i].postCollection();
}
doPostCollection();
}
/** Called upon release of the aggregator. */
@Override
public boolean release() {
boolean success = false;
try {
doRelease();
success = true;
} finally {
Releasables.release(success, subAggregators);
}
return true;
}
/** Release instance-specific data. */
protected void doRelease() {}
/**
* Can be overriden by aggregator implementation to be called back when the collection phase ends.
*/
protected void doPostCollection() {
}
/**
* @return The aggregated & built aggregation
*/
public abstract InternalAggregation buildAggregation(long owningBucketOrdinal);
public abstract InternalAggregation buildEmptyAggregation();
protected final InternalAggregations buildEmptySubAggregations() {
List aggs = new ArrayList();
for (Aggregator aggregator : subAggregators) {
aggs.add(aggregator.buildEmptyAggregation());
}
return new InternalAggregations(aggs);
}
/**
* Parses the aggregation request and creates the appropriate aggregator factory for it.
*
* @see {@link AggregatorFactory}
*/
public static interface Parser {
/**
* @return The aggregation type this parser is associated with.
*/
String type();
/**
* Returns the aggregator factory with which this parser is associated, may return {@code null} indicating the
* aggregation should be skipped (e.g. when trying to aggregate on unmapped fields).
*
* @param aggregationName The name of the aggregation
* @param parser The xcontent parser
* @param context The search context
* @return The resolved aggregator factory or {@code null} in case the aggregation should be skipped
* @throws java.io.IOException When parsing fails
*/
AggregatorFactory parse(String aggregationName, XContentParser parser, SearchContext context) throws IOException;
}
}
