org.elasticsearch.index.query.functionscore.RandomScoreFunctionBuilder Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :server
/*
* 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.query.functionscore;
import org.apache.logging.log4j.LogManager;
import org.elasticsearch.Version;
import org.elasticsearch.common.ParsingException;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.logging.DeprecationLogger;
import org.elasticsearch.common.lucene.search.function.RandomScoreFunction;
import org.elasticsearch.common.lucene.search.function.ScoreFunction;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.index.mapper.IdFieldMapper;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.UidFieldMapper;
import org.elasticsearch.index.query.QueryShardContext;
import java.io.IOException;
import java.util.Objects;
/**
* A function that computes a random score for the matched documents
*/
public class RandomScoreFunctionBuilder extends ScoreFunctionBuilder {
private static final DeprecationLogger DEPRECATION_LOGGER = new DeprecationLogger(
LogManager.getLogger(RandomScoreFunctionBuilder.class));
public static final String NAME = "random_score";
private String field;
private Integer seed;
public RandomScoreFunctionBuilder() {
}
/**
* Read from a stream.
*/
public RandomScoreFunctionBuilder(StreamInput in) throws IOException {
super(in);
if (in.readBoolean()) {
seed = in.readInt();
}
if (in.getVersion().onOrAfter(Version.V_6_0_0_beta1)) {
field = in.readOptionalString();
}
}
@Override
protected void doWriteTo(StreamOutput out) throws IOException {
if (seed != null) {
out.writeBoolean(true);
out.writeInt(seed);
} else {
out.writeBoolean(false);
}
if (out.getVersion().onOrAfter(Version.V_6_0_0_beta1)) {
out.writeOptionalString(field);
}
}
@Override
public String getName() {
return NAME;
}
/**
* Sets the seed based on which the random number will be generated. Using the same seed is guaranteed to generate the same
* random number for a specific doc.
*
* @param seed The seed.
*/
public RandomScoreFunctionBuilder seed(int seed) {
this.seed = seed;
return this;
}
/**
* seed variant taking a long value.
* @see #seed(int)
*/
public RandomScoreFunctionBuilder seed(long seed) {
this.seed = hash(seed);
return this;
}
/**
* seed variant taking a String value.
* @see #seed(int)
*/
public RandomScoreFunctionBuilder seed(String seed) {
if (seed == null) {
throw new IllegalArgumentException("random_score function: seed must not be null");
}
this.seed = seed.hashCode();
return this;
}
public Integer getSeed() {
return seed;
}
/**
* Set the field to be used for random number generation. This parameter is compulsory
* when a {@link #seed(int) seed} is set and ignored otherwise. Note that documents that
* have the same value for a field will get the same score.
*/
public RandomScoreFunctionBuilder setField(String field) {
this.field = field;
return this;
}
/**
* Get the field to use for random number generation.
* @see #setField(String)
*/
public String getField() {
return field;
}
@Override
public void doXContent(XContentBuilder builder, Params params) throws IOException {
builder.startObject(getName());
if (seed != null) {
builder.field("seed", seed);
}
if (field != null) {
builder.field("field", field);
}
builder.endObject();
}
@Override
protected boolean doEquals(RandomScoreFunctionBuilder functionBuilder) {
return Objects.equals(this.seed, functionBuilder.seed);
}
@Override
protected int doHashCode() {
return Objects.hash(this.seed);
}
@Override
protected ScoreFunction doToFunction(QueryShardContext context) {
final int salt = (context.index().getName().hashCode() << 10) | context.getShardId();
if (seed == null) {
// DocID-based random score generation
return new RandomScoreFunction(hash(context.nowInMillis()), salt, null);
} else {
final MappedFieldType fieldType;
if (field != null) {
fieldType = context.getMapperService().fullName(field);
} else {
DEPRECATION_LOGGER.deprecated(
"As of version 7.0 Elasticsearch will require that a [field] parameter is provided when a [seed] is set");
if (context.getIndexSettings().isSingleType()) {
fieldType = context.getMapperService().fullName(IdFieldMapper.NAME);
} else {
fieldType = context.getMapperService().fullName(UidFieldMapper.NAME);
}
}
if (fieldType == null) {
if (context.getMapperService().types().isEmpty()) {
// no mappings: the index is empty anyway
return new RandomScoreFunction(hash(context.nowInMillis()), salt, null);
}
throw new IllegalArgumentException("Field [" + field + "] is not mapped on [" + context.index() +
"] and cannot be used as a source of random numbers.");
}
int seed;
if (this.seed != null) {
seed = this.seed;
} else {
seed = hash(context.nowInMillis());
}
return new RandomScoreFunction(seed, salt, context.getForField(fieldType));
}
}
private static int hash(long value) {
return Long.hashCode(value);
}
public static RandomScoreFunctionBuilder fromXContent(XContentParser parser)
throws IOException, ParsingException {
RandomScoreFunctionBuilder randomScoreFunctionBuilder = new RandomScoreFunctionBuilder();
String currentFieldName = null;
XContentParser.Token token;
while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
if (token == XContentParser.Token.FIELD_NAME) {
currentFieldName = parser.currentName();
} else if (token.isValue()) {
if ("seed".equals(currentFieldName)) {
if (token == XContentParser.Token.VALUE_NUMBER) {
if (parser.numberType() == XContentParser.NumberType.INT) {
randomScoreFunctionBuilder.seed(parser.intValue());
} else if (parser.numberType() == XContentParser.NumberType.LONG) {
randomScoreFunctionBuilder.seed(parser.longValue());
} else {
throw new ParsingException(parser.getTokenLocation(), "random_score seed must be an int, long or string, not '"
+ token.toString() + "'");
}
} else if (token == XContentParser.Token.VALUE_STRING) {
randomScoreFunctionBuilder.seed(parser.text());
} else {
throw new ParsingException(parser.getTokenLocation(), "random_score seed must be an int/long or string, not '"
+ token.toString() + "'");
}
} else if ("field".equals(currentFieldName)) {
randomScoreFunctionBuilder.setField(parser.text());
} else {
throw new ParsingException(parser.getTokenLocation(), NAME + " query does not support [" + currentFieldName + "]");
}
}
}
return randomScoreFunctionBuilder;
}
}