SERVER-41432 Add ExprMatchExpressionMatchesReturnsFalseOnException failpoint

2 files changed, 24 insertions, 2 deletions

diff --git a/src/mongo/db/matcher/expression_expr.cpp b/src/mongo/db/matcher/expression_expr.cpp
index 39d701bdb1a..de1c1f956eb 100644
--- a/src/mongo/db/matcher/expression_expr.cpp
+++ b/src/mongo/db/matcher/expression_expr.cpp
@@ -31,7 +31,12 @@
 
 #include "mongo/db/matcher/expression_expr.h"
 
+#include "mongo/util/fail_point_service.h"
+
 namespace mongo {
+
+MONGO_FAIL_POINT_DEFINE(ExprMatchExpressionMatchesReturnsFalseOnException);
+
 ExprMatchExpression::ExprMatchExpression(boost::intrusive_ptr<Expression> expr,
                                          const boost::intrusive_ptr<ExpressionContext>& expCtx)
     : MatchExpression(MatchType::EXPRESSION), _expCtx(expCtx), _expression(expr) {}
@@ -48,8 +53,16 @@ bool ExprMatchExpression::matches(const MatchableDocument* doc, MatchDetails* de
     }
 
     Document document(doc->toBSON());
-    auto value = _expression->evaluate(document);
-    return value.coerceToBool();
+    try {
+        auto value = _expression->evaluate(document);
+        return value.coerceToBool();
+    } catch (const DBException&) {
+        if (MONGO_FAIL_POINT(ExprMatchExpressionMatchesReturnsFalseOnException)) {
+            return false;
+        }
+
+        throw;
+    }
 }
 
 void ExprMatchExpression::serialize(BSONObjBuilder* out) const {
diff --git a/src/mongo/db/matcher/expression_expr_test.cpp b/src/mongo/db/matcher/expression_expr_test.cpp
index 7473dfa1a0c..ce97e822b37 100644
--- a/src/mongo/db/matcher/expression_expr_test.cpp
+++ b/src/mongo/db/matcher/expression_expr_test.cpp
@@ -590,6 +590,15 @@ TEST_F(ExprMatchTest, FailGracefullyOnInvalidExpression) {
         17041);
 }
 
+TEST_F(ExprMatchTest, ReturnsFalseInsteadOfErrorWithFailpointSet) {
+    createMatcher(fromjson("{$expr: {$divide: [10, '$divisor']}}"));
+    ASSERT_THROWS_CODE(matches(BSON("divisor" << 0)), AssertionException, 16608);
+
+    FailPointEnableBlock scopedFailpoint("ExprMatchExpressionMatchesReturnsFalseOnException");
+    createMatcher(fromjson("{$expr: {$divide: [10, '$divisor']}}"));
+    ASSERT_FALSE(matches(BSON("divisor" << 0)));
+}
+
 TEST(ExprMatchTest, IdenticalPostOptimizedExpressionsAreEquivalent) {
     BSONObj expression = BSON("$expr" << BSON("$multiply" << BSON_ARRAY(2 << 2)));
     BSONObj expressionEquiv = BSON("$expr" << BSON("$const" << 4));