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Elasticsearch subproject :server
/*
* 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.common.lucene.search.function;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.Explanation;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.index.fielddata.FieldData;
import org.elasticsearch.index.fielddata.IndexNumericFieldData;
import org.elasticsearch.index.fielddata.SortedNumericDoubleValues;
import java.io.IOException;
import java.util.Locale;
import java.util.Objects;
/**
* A function_score function that multiplies the score with the value of a
* field from the document, optionally multiplying the field by a factor first,
* and applying a modification (log, ln, sqrt, square, etc) afterwards.
*/
public class FieldValueFactorFunction extends ScoreFunction {
private final String field;
private final float boostFactor;
private final Modifier modifier;
/**
* Value used if the document is missing the field.
*/
private final Double missing;
private final IndexNumericFieldData indexFieldData;
public FieldValueFactorFunction(
String field,
float boostFactor,
Modifier modifierType,
Double missing,
IndexNumericFieldData indexFieldData
) {
super(CombineFunction.MULTIPLY);
this.field = field;
this.boostFactor = boostFactor;
this.modifier = modifierType;
this.indexFieldData = indexFieldData;
this.missing = missing;
}
@Override
public LeafScoreFunction getLeafScoreFunction(LeafReaderContext ctx) {
final SortedNumericDoubleValues values;
if (indexFieldData == null) {
values = FieldData.emptySortedNumericDoubles();
} else {
values = this.indexFieldData.load(ctx).getDoubleValues();
}
return new LeafScoreFunction() {
@Override
public double score(int docId, float subQueryScore) throws IOException {
double value;
if (values.advanceExact(docId)) {
value = values.nextValue();
} else {
if (missing != null) {
value = missing;
} else {
throw new ElasticsearchException("Missing value for field [" + field + "]");
}
}
double val = value * boostFactor;
double result = modifier.apply(val);
if (result < 0f) {
String message = "field value function must not produce negative scores, but got: "
+ "["
+ result
+ "] for field value: ["
+ value
+ "]";
if (modifier == Modifier.LN) {
message += "; consider using ln1p or ln2p instead of ln to avoid negative scores";
} else if (modifier == Modifier.LOG) {
message += "; consider using log1p or log2p instead of log to avoid negative scores";
}
throw new IllegalArgumentException(message);
}
return result;
}
@Override
public Explanation explainScore(int docId, Explanation subQueryScore) throws IOException {
String modifierStr = modifier != null ? modifier.toString() : "";
String defaultStr = missing != null ? "?:" + missing : "";
double score = score(docId, subQueryScore.getValue().floatValue());
return Explanation.match(
(float) score,
String.format(
Locale.ROOT,
"field value function: %s(doc['%s'].value%s * factor=%s)",
modifierStr,
field,
defaultStr,
boostFactor
)
);
}
};
}
@Override
public boolean needsScores() {
return false;
}
@Override
protected boolean doEquals(ScoreFunction other) {
FieldValueFactorFunction fieldValueFactorFunction = (FieldValueFactorFunction) other;
return this.boostFactor == fieldValueFactorFunction.boostFactor
&& Objects.equals(this.field, fieldValueFactorFunction.field)
&& Objects.equals(this.modifier, fieldValueFactorFunction.modifier);
}
@Override
protected int doHashCode() {
return Objects.hash(boostFactor, field, modifier);
}
/**
* The Type class encapsulates the modification types that can be applied
* to the score/value product.
*/
public enum Modifier implements Writeable {
NONE {
@Override
public double apply(double n) {
return n;
}
},
LOG {
@Override
public double apply(double n) {
return Math.log10(n);
}
},
LOG1P {
@Override
public double apply(double n) {
return Math.log10(n + 1);
}
},
LOG2P {
@Override
public double apply(double n) {
return Math.log10(n + 2);
}
},
LN {
@Override
public double apply(double n) {
return Math.log(n);
}
},
LN1P {
@Override
public double apply(double n) {
return Math.log1p(n);
}
},
LN2P {
@Override
public double apply(double n) {
return Math.log1p(n + 1);
}
},
SQUARE {
@Override
public double apply(double n) {
return Math.pow(n, 2);
}
},
SQRT {
@Override
public double apply(double n) {
return Math.sqrt(n);
}
},
RECIPROCAL {
@Override
public double apply(double n) {
return 1.0 / n;
}
};
public abstract double apply(double n);
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeEnum(this);
}
public static Modifier readFromStream(StreamInput in) throws IOException {
return in.readEnum(Modifier.class);
}
@Override
public String toString() {
return super.toString().toLowerCase(Locale.ROOT);
}
public static Modifier fromString(String modifier) {
return valueOf(modifier.toUpperCase(Locale.ROOT));
}
}
}