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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.random;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
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.index.fielddata.IndexFieldData;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.query.QueryShardContext;
import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilder;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.search.internal.SearchContext;
import java.io.IOException;
import java.util.Objects;
/**
* A function that computes a random score for the matched documents
*/
public class RandomScoreFunctionBuilder extends ScoreFunctionBuilder<RandomScoreFunctionBuilder> {
private Integer seed;
public RandomScoreFunctionBuilder() {
}
@Override
public String getName() {
return RandomScoreFunctionParser.NAMES[0];
}
/**
* 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;
}
@Override
public void doXContent(XContentBuilder builder, Params params) throws IOException {
builder.startObject(getName());
if (seed != null) {
builder.field("seed", seed);
}
builder.endObject();
}
@Override
protected RandomScoreFunctionBuilder doReadFrom(StreamInput in) throws IOException {
RandomScoreFunctionBuilder randomScoreFunctionBuilder = new RandomScoreFunctionBuilder();
randomScoreFunctionBuilder.seed = in.readInt();
return randomScoreFunctionBuilder;
}
@Override
protected void doWriteTo(StreamOutput out) throws IOException {
out.writeInt(seed);
}
@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 MappedFieldType fieldType = context.getMapperService().fullName("_uid");
if (fieldType == null) {
// mapper could be null if we are on a shard with no docs yet, so this won't actually be used
return new RandomScoreFunction();
}
//TODO find a way to not get the shard_id from the current search context? make it available in QueryShardContext?
//this currently causes NPE in FunctionScoreQueryBuilderTests#testToQuery
final ShardId shardId = SearchContext.current().indexShard().shardId();
final int salt = (context.index().name().hashCode() << 10) | shardId.id();
final IndexFieldData<?> uidFieldData = context.getForField(fieldType);
return new RandomScoreFunction(this.seed == null ? hash(context.nowInMillis()) : seed, salt, uidFieldData);
}
private static int hash(long value) {
return Long.hashCode(value);
}
}
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