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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.index.similarity;
import org.apache.lucene.search.similarities.PerFieldSimilarityWrapper;
import org.apache.lucene.search.similarities.Similarity;
import org.elasticsearch.Version;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.index.AbstractIndexComponent;
import org.elasticsearch.index.IndexModule;
import org.elasticsearch.index.IndexSettings;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.MapperService;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.function.BiFunction;
public final class SimilarityService extends AbstractIndexComponent {
public static final String DEFAULT_SIMILARITY = "BM25";
private final Similarity defaultSimilarity;
private final Similarity baseSimilarity;
private final Map similarities;
static final Map> DEFAULTS;
public static final Map> BUILT_IN;
static {
Map> defaults = new HashMap<>();
Map> buildIn = new HashMap<>();
defaults.put("classic", ClassicSimilarityProvider::new);
defaults.put("BM25", BM25SimilarityProvider::new);
buildIn.put("classic", ClassicSimilarityProvider::new);
buildIn.put("BM25", BM25SimilarityProvider::new);
buildIn.put("DFR", DFRSimilarityProvider::new);
buildIn.put("IB", IBSimilarityProvider::new);
buildIn.put("LMDirichlet", LMDirichletSimilarityProvider::new);
buildIn.put("LMJelinekMercer", LMJelinekMercerSimilarityProvider::new);
buildIn.put("DFI", DFISimilarityProvider::new);
DEFAULTS = Collections.unmodifiableMap(defaults);
BUILT_IN = Collections.unmodifiableMap(buildIn);
}
public SimilarityService(IndexSettings indexSettings, Map> similarities) {
super(indexSettings);
Map providers = new HashMap<>(similarities.size());
Map similaritySettings = this.indexSettings.getSettings().getGroups(IndexModule.SIMILARITY_SETTINGS_PREFIX);
for (Map.Entry entry : similaritySettings.entrySet()) {
String name = entry.getKey();
// Starting with v5.0 indices, it should no longer be possible to redefine built-in similarities
if(BUILT_IN.containsKey(name) && indexSettings.getIndexVersionCreated().onOrAfter(Version.V_5_0_0_alpha1)) {
throw new IllegalArgumentException("Cannot redefine built-in Similarity [" + name + "]");
}
Settings settings = entry.getValue();
String typeName = settings.get("type");
if (typeName == null) {
throw new IllegalArgumentException("Similarity [" + name + "] must have an associated type");
} else if ((similarities.containsKey(typeName) || BUILT_IN.containsKey(typeName)) == false) {
throw new IllegalArgumentException("Unknown Similarity type [" + typeName + "] for [" + name + "]");
}
BiFunction factory = similarities.getOrDefault(typeName, BUILT_IN.get(typeName));
if (settings == null) {
settings = Settings.Builder.EMPTY_SETTINGS;
}
providers.put(name, factory.apply(name, settings));
}
for (Map.Entry entry : addSimilarities(similaritySettings, DEFAULTS).entrySet()) {
// Avoid overwriting custom providers for indices older that v5.0
if (providers.containsKey(entry.getKey()) && indexSettings.getIndexVersionCreated().before(Version.V_5_0_0_alpha1)) {
continue;
}
providers.put(entry.getKey(), entry.getValue());
}
this.similarities = providers;
defaultSimilarity = (providers.get("default") != null) ? providers.get("default").get()
: providers.get(SimilarityService.DEFAULT_SIMILARITY).get();
// Expert users can configure the base type as being different to default, but out-of-box we use default.
baseSimilarity = (providers.get("base") != null) ? providers.get("base").get() :
defaultSimilarity;
}
public Similarity similarity(MapperService mapperService) {
// TODO we can maybe factor out MapperService here entirely by introducing an interface for the lookup?
return (mapperService != null) ? new PerFieldSimilarity(defaultSimilarity, baseSimilarity, mapperService) :
defaultSimilarity;
}
private Map addSimilarities(Map similaritySettings,
Map> similarities) {
Map providers = new HashMap<>(similarities.size());
for (Map.Entry> entry : similarities.entrySet()) {
String name = entry.getKey();
BiFunction factory = entry.getValue();
Settings settings = similaritySettings.get(name);
if (settings == null) {
settings = Settings.Builder.EMPTY_SETTINGS;
}
providers.put(name, factory.apply(name, settings));
}
return providers;
}
public SimilarityProvider getSimilarity(String name) {
return similarities.get(name);
}
Similarity getDefaultSimilarity() {
return defaultSimilarity;
}
static class PerFieldSimilarity extends PerFieldSimilarityWrapper {
private final Similarity defaultSimilarity;
private final MapperService mapperService;
PerFieldSimilarity(Similarity defaultSimilarity, Similarity baseSimilarity, MapperService mapperService) {
super(baseSimilarity);
this.defaultSimilarity = defaultSimilarity;
this.mapperService = mapperService;
}
@Override
public Similarity get(String name) {
MappedFieldType fieldType = mapperService.fullName(name);
return (fieldType != null && fieldType.similarity() != null) ? fieldType.similarity().get() : defaultSimilarity;
}
}
}