org.elasticsearch.search.facet.FacetExecutor Maven / Gradle / Ivy
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* 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
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* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.search.facet;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.Scorer;
import org.elasticsearch.common.lucene.docset.AndDocIdSet;
import org.elasticsearch.common.lucene.docset.ContextDocIdSet;
import org.elasticsearch.common.lucene.search.XCollector;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* A facet processor ends up actually executing the relevant facet for a specific
* search request.
*
* The facet executor requires at least the {@link #collector()} method to be implemented,
* with an optional {@link #post()} implementation if specific optimizations can be done.
*/
public abstract class FacetExecutor {
/**
* A post class extends this class to implement post hits processing.
*/
public static abstract class Post {
public abstract void executePost(List docSets) throws IOException;
/**
* A filtered post execution.
*/
public static class Filtered extends Post {
private final Post post;
private final Filter filter;
public Filtered(Post post, Filter filter) {
this.post = post;
this.filter = filter;
}
@Override
public void executePost(List docSets) throws IOException {
List filteredEntries = new ArrayList(docSets.size());
for (int i = 0; i < docSets.size(); i++) {
ContextDocIdSet entry = docSets.get(i);
DocIdSet filteredSet = filter.getDocIdSet(entry.context, null);
if (filteredSet != null) {
filteredEntries.add(new ContextDocIdSet(
entry.context,
// TODO: can we be smart here, maybe AndDocIdSet is not always fastest?
new AndDocIdSet(new DocIdSet[]{entry.docSet, filteredSet})
));
}
}
post.executePost(filteredEntries);
}
}
/**
* A {@link FacetExecutor.Collector} based post.
*/
public static class Collector extends Post {
private final FacetExecutor.Collector collector;
public Collector(FacetExecutor.Collector collector) {
this.collector = collector;
}
@Override
public void executePost(List docSets) throws IOException {
for (int i = 0; i < docSets.size(); i++) {
ContextDocIdSet docSet = docSets.get(i);
collector.setNextReader(docSet.context);
DocIdSetIterator it = docSet.docSet.iterator();
int doc;
while ((doc = it.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
collector.collect(doc);
}
}
collector.postCollection();
}
}
}
/**
* Simple extension to {@link XCollector} that implements methods that are typically
* not needed when doing collector based faceting.
*/
public static abstract class Collector extends XCollector {
@Override
public void setScorer(Scorer scorer) throws IOException {
}
@Override
public boolean acceptsDocsOutOfOrder() {
return true;
}
@Override
public abstract void postCollection();
}
/**
* The mode of the execution.
*/
public static enum Mode {
/**
* Collector mode, maps to {@link #collector()}.
*/
COLLECTOR,
/**
* Post mode, maps to {@link #post()}.
*/
POST
}
/**
* Builds the facet.
*/
public abstract InternalFacet buildFacet(String facetName);
/**
* A collector based facet implementation, collection the facet as hits match.
*/
public abstract Collector collector();
/**
* A post based facet that executes the facet using the aggregated docs. By default
* uses the {@link Post.Collector} based implementation.
*
* Can be overridden if a more optimized non collector based implementation can be implemented.
*/
public Post post() {
return new Post.Collector(collector());
}
}