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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.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.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 deprecationLogger = 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().fieldType(field);
} else {
deprecationLogger.deprecated(
"As of version 7.0 Elasticsearch will require that a [field] parameter is provided when a [seed] is set");
fieldType = context.getMapperService().fieldType(IdFieldMapper.NAME);
}
if (fieldType == null) {
if (context.getMapperService().documentMapper() == null) {
// 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;
}
}