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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.index.query.functionscore;
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.DeprecationCategory;
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.index.mapper.IdFieldMapper;
import org.elasticsearch.index.query.SearchExecutionContext;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
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 deprecationLogger = DeprecationLogger.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(SearchExecutionContext 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 {
String fieldName;
if (field == null) {
deprecationLogger.warn(
DeprecationCategory.QUERIES,
"seed_requires_field",
"As of version 7.0 Elasticsearch will require that a [field] parameter is provided when a [seed] is set"
);
fieldName = IdFieldMapper.NAME;
} else {
fieldName = field;
}
if (context.isFieldMapped(fieldName) == false) {
if (context.hasMappings() == false) {
// 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 = this.seed == null ? hash(context.nowInMillis()) : this.seed;
return new RandomScoreFunction(seed, salt, context.getForField(context.getFieldType(fieldName)));
}
}
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;
}
}