Remove assertion about deviation when casting to a float. (#25806)

We cannot guarantee that the result of computations will be in the float range,
since it depends on the data and how scores are computed. We already use doubles
as intermediate representations and cast to a float as a final step, which is
the right thing to do. Small doubles will just be rounded to zero, there is not
much we can or should do about it.

Closes #25330

core/src/main/java/org/elasticsearch/common/lucene/search/function/CombineFunction.java

@@ -31,7 +31,7 @@ public enum CombineFunction implements Writeable {
     MULTIPLY {
         @Override
         public float combine(double queryScore, double funcScore, double maxBoost) {
-            return toFloat(queryScore * Math.min(funcScore, maxBoost));
+            return (float) (queryScore * Math.min(funcScore, maxBoost));
         }
 
         @Override
@@ -48,7 +48,7 @@ public enum CombineFunction implements Writeable {
     REPLACE {
         @Override
         public float combine(double queryScore, double funcScore, double maxBoost) {
-            return toFloat(Math.min(funcScore, maxBoost));
+            return (float) (Math.min(funcScore, maxBoost));
         }
 
         @Override
@@ -64,7 +64,7 @@ public enum CombineFunction implements Writeable {
     SUM {
         @Override
         public float combine(double queryScore, double funcScore, double maxBoost) {
-            return toFloat(queryScore + Math.min(funcScore, maxBoost));
+            return (float) (queryScore + Math.min(funcScore, maxBoost));
         }
 
         @Override
@@ -79,7 +79,7 @@ public enum CombineFunction implements Writeable {
     AVG {
         @Override
         public float combine(double queryScore, double funcScore, double maxBoost) {
-            return toFloat((Math.min(funcScore, maxBoost) + queryScore) / 2.0);
+            return (float) ((Math.min(funcScore, maxBoost) + queryScore) / 2.0);
         }
 
         @Override
@@ -87,7 +87,7 @@ public enum CombineFunction implements Writeable {
             Explanation minExpl = Explanation.match(Math.min(funcExpl.getValue(), maxBoost), "min of:",
                     funcExpl, Explanation.match(maxBoost, "maxBoost"));
             return Explanation.match(
-                    toFloat((Math.min(funcExpl.getValue(), maxBoost) + queryExpl.getValue()) / 2.0), "avg of",
+                    (float) ((Math.min(funcExpl.getValue(), maxBoost) + queryExpl.getValue()) / 2.0), "avg of",
                     queryExpl, minExpl);
         }
 
@@ -95,7 +95,7 @@ public enum CombineFunction implements Writeable {
     MIN {
         @Override
         public float combine(double queryScore, double funcScore, double maxBoost) {
-            return toFloat(Math.min(queryScore, Math.min(funcScore, maxBoost)));
+            return (float) (Math.min(queryScore, Math.min(funcScore, maxBoost)));
         }
 
         @Override
@@ -112,7 +112,7 @@ public enum CombineFunction implements Writeable {
     MAX {
         @Override
         public float combine(double queryScore, double funcScore, double maxBoost) {
-            return toFloat(Math.max(queryScore, Math.min(funcScore, maxBoost)));
+            return (float) (Math.max(queryScore, Math.min(funcScore, maxBoost)));
         }
 
         @Override
@@ -129,16 +129,6 @@ public enum CombineFunction implements Writeable {
 
     public abstract float combine(double queryScore, double funcScore, double maxBoost);
 
-    public static float toFloat(double input) {
-        assert deviation(input) <= 0.001 : "input " + input + " out of float scope for function score deviation: " + deviation(input);
-        return (float) input;
-    }
-
-    private static double deviation(double input) { // only with assert!
-        float floatVersion = (float) input;
-        return Double.compare(floatVersion, input) == 0 || input == 0.0d ? 0 : 1.d - (floatVersion) / input;
-    }
-
     public abstract Explanation explain(Explanation queryExpl, Explanation funcExpl, float maxBoost);
 
     @Override

core/src/main/java/org/elasticsearch/common/lucene/search/function/FieldValueFactorFunction.java

@@ -96,7 +96,7 @@ public class FieldValueFactorFunction extends ScoreFunction {
                 String defaultStr = missing != null ? "?:" + missing : "";
                 double score = score(docId, subQueryScore.getValue());
                 return Explanation.match(
-                        CombineFunction.toFloat(score),
+                        (float) score,
                         String.format(Locale.ROOT,
                                 "field value function: %s(doc['%s'].value%s * factor=%s)", modifierStr, field, defaultStr, boostFactor));
             }

core/src/main/java/org/elasticsearch/common/lucene/search/function/FiltersFunctionScoreQuery.java

@@ -206,7 +206,7 @@ public class FiltersFunctionScoreQuery extends Query {
                     FilterFunction filterFunction = filterFunctions[i];
                     Explanation functionExplanation = filterFunction.function.getLeafScoreFunction(context).explainScore(doc, expl);
                     double factor = functionExplanation.getValue();
-                    float sc = CombineFunction.toFloat(factor);
+                    float sc = (float) factor;
                     Explanation filterExplanation = Explanation.match(sc, "function score, product of:",
                             Explanation.match(1.0f, "match filter: " + filterFunction.filter.toString()), functionExplanation);
                     filterExplanations.add(filterExplanation);
@@ -219,7 +219,7 @@ public class FiltersFunctionScoreQuery extends Query {
             Explanation factorExplanation;
             if (filterExplanations.size() > 0) {
                 factorExplanation = Explanation.match(
-                        CombineFunction.toFloat(score),
+                        (float) score,
                         "function score, score mode [" + scoreMode.toString().toLowerCase(Locale.ROOT) + "]",
                         filterExplanations);
 

core/src/main/java/org/elasticsearch/common/lucene/search/function/RandomScoreFunction.java

@@ -84,7 +84,7 @@ public class RandomScoreFunction extends ScoreFunction {
             public Explanation explainScore(int docId, Explanation subQueryScore) throws IOException {
                 String field = fieldData == null ? null : fieldData.getFieldName();
                 return Explanation.match(
-                        CombineFunction.toFloat(score(docId, subQueryScore.getValue())),
+                        (float) score(docId, subQueryScore.getValue()),
                         "random score function (seed: " + originalSeed + ", field: " + field + ")");
             }
         };

core/src/main/java/org/elasticsearch/common/lucene/search/function/ScriptScoreFunction.java

@@ -109,7 +109,7 @@ public class ScriptScoreFunction extends ScoreFunction {
                             subQueryScore.getValue(), "_score: ",
                             subQueryScore);
                     return Explanation.match(
-                            CombineFunction.toFloat(score), explanation,
+                            (float) score, explanation,
                             scoreExp);
                 }
                 return exp;

core/src/main/java/org/elasticsearch/index/query/functionscore/DecayFunctionBuilder.java

@@ -543,7 +543,7 @@ public abstract class DecayFunctionBuilder<DFB extends DecayFunctionBuilder<DFB>
                         return Explanation.noMatch("No value for the distance");
                     }
                     return Explanation.match(
-                            CombineFunction.toFloat(score(docId, subQueryScore.getValue())),
+                            (float) score(docId, subQueryScore.getValue()),
                             "Function for field " + getFieldName() + ":",
                             func.explainFunction(getDistanceString(ctx, docId), distance.doubleValue(), scale));
                 }