fix: Include the big segments status on evaluation reasons for failed evaluations

src/LaunchDarkly/Impl/Evaluation/Evaluator.php

@@ -70,13 +70,26 @@ public function evaluate(FeatureFlag $flag, LDContext $context, ?callable $prere
 
             return $evalResult;
         } catch (EvaluationException $e) {
-            return new EvalResult(new EvaluationDetail(null, null, EvaluationReason::error($e->getErrorKind())), false, $state);
+            $reason = self::withBigSegmentsStatus(EvaluationReason::error($e->getErrorKind()), $state);
+            return new EvalResult(new EvaluationDetail(null, null, $reason), false, $state);
         } catch (\Throwable $e) {
             Util::logExceptionAtErrorLevel($this->_logger, $e, 'Unexpected error when evaluating flag ' . $flag->getKey());
-            return new EvalResult(new EvaluationDetail(null, null, EvaluationReason::exception($e)), false, $state);
+            $reason = self::withBigSegmentsStatus(EvaluationReason::exception($e), $state);
+            return new EvalResult(new EvaluationDetail(null, null, $reason), false, $state);
         }
     }
 
+    /**
+     * Adds the big segments status to an error reason. A big segment query can run before the error occurs.
+     */
+    private static function withBigSegmentsStatus(EvaluationReason $reason, EvaluatorState $state): EvaluationReason
+    {
+        if ($state->bigSegmentsEvaluationStatus === null) {
+            return $reason;
+        }
+        return $reason->withBigSegmentsEvaluationStatus($state->bigSegmentsEvaluationStatus);
+    }
+
     private function evaluateInternal(
         FeatureFlag $flag,
         LDContext $context,

tests/Impl/Evaluation/EvaluatorBigSegmentsTest.php

@@ -2,6 +2,8 @@
 
 namespace LaunchDarkly\Tests\Impl\Evaluation;
 
+use LaunchDarkly\BigSegmentsEvaluationStatus;
+use LaunchDarkly\EvaluationReason;
 use LaunchDarkly\Impl\BigSegments\StoreManager;
 use LaunchDarkly\Impl\Evaluation\Evaluator;
 use LaunchDarkly\Impl\Model\Segment;
@@ -160,6 +162,61 @@ public function testSegmentLogicFallsThroughToRulesWhenMembershipHasNoEntryForSe
         $this->assertTrue(self::bigSegmentsMatchesContext($store, $segment, $defaultContext));
     }
 
+    public function testBigSegmentsStatusIsKeptWhenLaterSegmentCausesEvaluationError(): void
+    {
+        global $defaultContext;
+        $bigSegment = ModelBuilders::segmentBuilder('big')
+            ->generation(100)
+            ->unbounded(true)
+            ->build();
+        // The circular segment causes an EvaluationException after the big segment query.
+        $circularSegment = ModelBuilders::segmentBuilder('circular')
+            ->rule(
+                ModelBuilders::segmentRuleBuilder()
+                    ->clause(ModelBuilders::clause(null, '', 'segmentMatch', 'circular'))
+                    ->build()
+            )
+            ->build();
+
+        $store = new BigSegmentsStoreImpl([new BigSegmentsStoreMetadata(10)], [[]]);
+        $evaluator = self::getEvaluator($store, $defaultContext, [$bigSegment, $circularSegment]);
+        $flag = ModelBuilders::booleanFlagWithRules(
+            ModelBuilders::flagRuleWithClauses(1, ModelBuilders::clauseMatchingSegment($bigSegment)),
+            ModelBuilders::flagRuleWithClauses(1, ModelBuilders::clauseMatchingSegment($circularSegment))
+        );
+
+        $reason = $evaluator->evaluate($flag, $defaultContext, EvaluatorTestUtil::expectNoPrerequisiteEvals())
+            ->getDetail()->getReason();
+        $this->assertEquals(EvaluationReason::ERROR, $reason->getKind());
+        $this->assertEquals(EvaluationReason::MALFORMED_FLAG_ERROR, $reason->getErrorKind());
+        $this->assertEquals(BigSegmentsEvaluationStatus::STALE, $reason->bigSegmentsEvaluationStatus());
+    }
+
+    public function testBigSegmentsStatusIsKeptWhenLaterSegmentLookupThrows(): void
+    {
+        global $defaultContext;
+        $bigSegment = ModelBuilders::segmentBuilder('big')
+            ->generation(100)
+            ->unbounded(true)
+            ->build();
+        // The requester does not know this segment, so the lookup throws.
+        $unknownSegment = ModelBuilders::segmentBuilder('unknown')->build();
+
+        $store = new BigSegmentsStoreImpl([new BigSegmentsStoreMetadata(10)], [[]]);
+        $evaluator = self::getEvaluator($store, $defaultContext, [$bigSegment]);
+        $flag = ModelBuilders::booleanFlagWithRules(
+            ModelBuilders::flagRuleWithClauses(1, ModelBuilders::clauseMatchingSegment($bigSegment)),
+            ModelBuilders::flagRuleWithClauses(1, ModelBuilders::clauseMatchingSegment($unknownSegment))
+        );
+
+        $reason = $evaluator->evaluate($flag, $defaultContext, EvaluatorTestUtil::expectNoPrerequisiteEvals())
+            ->getDetail()->getReason();
+        $this->assertEquals(EvaluationReason::ERROR, $reason->getKind());
+        $this->assertEquals(EvaluationReason::EXCEPTION_ERROR, $reason->getErrorKind());
+        $this->assertInstanceOf(\InvalidArgumentException::class, $reason->getException());
+        $this->assertEquals(BigSegmentsEvaluationStatus::STALE, $reason->bigSegmentsEvaluationStatus());
+    }
+
     private static function bigSegmentsMatchesContext(BigSegmentsStore $store, Segment $segment, LDContext $context): bool
     {
         $evaluator = self::getEvaluator($store, $context, [$segment]);