Add null check for FunctionFactorScorer

[rohanbadgujar20011]

Added null check for scorer before advancing document.

Description

[Describe what this change achieves]

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review Inconsistent doc parameter After scorer.iterator().advance(doc), the returned actualDoc may differ from doc (e.g., when the scorer's iterator skips ahead). The original code asserted equality, but if the null-check path indicates the scorer may not always align, computeScore is still called with doc rather than actualDoc. If the intent of the null check is to handle scorer mismatches, computeScore should likely use actualDoc, or the explanation should return noMatch when actualDoc != doc. int actualDoc = scorer.iterator().advance(doc); assert actualDoc == doc; double score = scorer.computeScore( doc, expl.getValue().floatValue() ); Possible Compilation Error The variable score is referenced in Explanation.match((float) score, ...) but its declaration/assignment has been moved inside a nested block scope (the added indentation suggests an extra block). If score is declared inside that inner scope, it will be out of scope where factorExplanation uses it, causing a compile error. Verify the brace structure matches the indentation shown. if (scorer == null) { return Explanation.noMatch( "No matching scorer for segment" ); } int actualDoc = scorer.iterator().advance(doc); assert actualDoc == doc; double score = scorer.computeScore( doc, expl.getValue().floatValue() ); factorExplanation = Explanation.match( (float) score,

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Avoid early return breaking explanation flow Returning Explanation.noMatch early bypasses the surrounding Explanation.match construction that includes functionsExplanations and the score mode label, producing an inconsistent explanation. Instead, assign a fallback factorExplanation (e.g., Explanation.noMatch(...)) so that the outer combining logic below still executes and returns a properly composed explanation. server/src/main/java/org/opensearch/common/lucene/search/function/FunctionScoreQuery.java [475-490] FunctionFactorScorer scorer = functionScorer(context); - - if (scorer == null) { - return Explanation.noMatch( - "No matching scorer for segment" - ); - } - +if (scorer == null) { + factorExplanation = Explanation.noMatch("No matching scorer for segment", functionsExplanations); +} else { int actualDoc = scorer.iterator().advance(doc); assert actualDoc == doc; - - double score = scorer.computeScore( - doc, - expl.getValue().floatValue() + double score = scorer.computeScore(doc, expl.getValue().floatValue()); + factorExplanation = Explanation.match( + (float) score, + "function score, score mode [" + scoreMode.toString().toLowerCase(Locale.ROOT) + "]", + functionsExplanations ); +} Suggestion importance[1-10]: 7 __ Why: The suggestion correctly identifies that the early return Explanation.noMatch(...) bypasses the outer combining logic that builds the full explanation with functionsExplanations and score mode, and proposes a cleaner fallback assignment. However, the score variable's declaration/scoping in the outer block also needs consideration, so the fix is directionally correct but not entirely complete.	Medium

[github-actions]

❌ Gradle check result for f72d7c1: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?