org.elasticsearch.search.aggregations.BucketCollector Maven / Gradle / Ivy
/*
* 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 com.google.common.collect.Iterables;
import org.apache.lucene.index.AtomicReaderContext;
import org.elasticsearch.common.lucene.ReaderContextAware;
import org.elasticsearch.search.aggregations.Aggregator.BucketAggregationMode;
import java.io.IOException;
/**
* A Collector that can collect data in separate buckets.
*/
public abstract class BucketCollector implements ReaderContextAware {
/**
* Used to gather a summary from a bucket
*/
public interface BucketAnalysisCollector{
/**
* Used to ask {@link BucketCollector}s for their analysis of the content collected in a bucket
* @param analysis an object that represents the summary of a bucket as an {@link Aggregation}
*/
void add(Aggregation aggregation);
}
public final static BucketCollector NO_OP_COLLECTOR = new BucketCollector() {
@Override
public void collect(int docId, long bucketOrdinal) throws IOException {
// no-op
}
@Override
public void setNextReader(AtomicReaderContext reader) {
// no-op
}
@Override
public void postCollection() throws IOException {
// no-op
}
@Override
public void gatherAnalysis(BucketAnalysisCollector analysisCollector, long bucketOrdinal) {
// no-op
}
};
/**
* Wrap the given collectors into a single instance.
*/
public static BucketCollector wrap(Iterable collectorList) {
final BucketCollector[] collectors = Iterables.toArray(collectorList, BucketCollector.class);
switch (collectors.length) {
case 0:
return NO_OP_COLLECTOR;
case 1:
return collectors[0];
default:
return new BucketCollector() {
@Override
public void collect(int docId, long bucketOrdinal) throws IOException {
for (BucketCollector collector : collectors) {
collector.collect(docId, bucketOrdinal);
}
}
@Override
public void setNextReader(AtomicReaderContext reader) {
for (BucketCollector collector : collectors) {
collector.setNextReader(reader);
}
}
@Override
public void postCollection() throws IOException {
for (BucketCollector collector : collectors) {
collector.postCollection();
}
}
@Override
public void gatherAnalysis(BucketAnalysisCollector results, long bucketOrdinal) {
for (BucketCollector collector : collectors) {
collector.gatherAnalysis(results, bucketOrdinal);
}
}
};
}
}
/**
* Called during the query phase, to collect & aggregate the given document.
*
* @param doc The document to be collected/aggregated
* @param bucketOrdinal 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 docId, long bucketOrdinal) throws IOException;
/**
* Post collection callback.
*/
public abstract void postCollection() throws IOException;
/**
* Called post-collection to gather the results from surviving buckets.
* @param analysisCollector
* @param bucketOrdinal
*/
public abstract void gatherAnalysis(BucketAnalysisCollector analysisCollector, long bucketOrdinal);
}