SERVER-62861 Use `null` instead of empty string for `actualNamespace` in `CollectionUUIDMismatch` error response

5 files changed, 24 insertions, 18 deletions

diff --git a/src/mongo/db/catalog/collection_uuid_mismatch.cpp b/src/mongo/db/catalog/collection_uuid_mismatch.cpp
index 1eb6d30c931..ad79a15f02e 100644
--- a/src/mongo/db/catalog/collection_uuid_mismatch.cpp
+++ b/src/mongo/db/catalog/collection_uuid_mismatch.cpp
@@ -49,11 +49,8 @@ void checkCollectionUUIDMismatch(OperationContext* opCtx,
                 feature_flags::gCommandsAcceptCollectionUUID.isEnabled(
                     serverGlobalParams.featureCompatibility));
 
-    uassert((CollectionUUIDMismatchInfo{*uuid,
-                                        ns,
-                                        CollectionCatalog::get(opCtx)
-                                            ->lookupNSSByUUID(opCtx, *uuid)
-                                            .value_or(NamespaceString{})}),
+    uassert((CollectionUUIDMismatchInfo{
+                *uuid, ns, CollectionCatalog::get(opCtx)->lookupNSSByUUID(opCtx, *uuid)}),
             "Collection UUID does not match that specified",
             coll && coll->uuid() == *uuid);
 }
diff --git a/src/mongo/db/catalog/collection_uuid_mismatch_info.cpp b/src/mongo/db/catalog/collection_uuid_mismatch_info.cpp
index 3813615916a..5313b459b67 100644
--- a/src/mongo/db/catalog/collection_uuid_mismatch_info.cpp
+++ b/src/mongo/db/catalog/collection_uuid_mismatch_info.cpp
@@ -35,18 +35,29 @@
 namespace mongo {
 namespace {
 MONGO_INIT_REGISTER_ERROR_EXTRA_INFO(CollectionUUIDMismatchInfo);
+
+constexpr StringData kCollectionUUIDFieldName = "collectionUUID"_sd;
+constexpr StringData kExpectedNamespaceFieldName = "expectedNamespace"_sd;
+constexpr StringData kActualNamespaceFieldName = "actualNamespace"_sd;
 }  // namespace
 
 std::shared_ptr<const ErrorExtraInfo> CollectionUUIDMismatchInfo::parse(const BSONObj& obj) {
+    auto actualNamespace = obj[kActualNamespaceFieldName];
     return std::make_shared<CollectionUUIDMismatchInfo>(
-        UUID::parse(obj["collectionUUID"]).getValue(),
-        NamespaceString{obj.getStringField("expectedNamespace")},
-        NamespaceString{obj.getStringField("actualNamespace")});
+        UUID::parse(obj[kCollectionUUIDFieldName]).getValue(),
+        NamespaceString{obj.getStringField(kExpectedNamespaceFieldName)},
+        actualNamespace.isNull()
+            ? boost::none
+            : boost::make_optional(NamespaceString{actualNamespace.valueStringData()}));
 }
 
 void CollectionUUIDMismatchInfo::serialize(BSONObjBuilder* builder) const {
-    _collectionUUID.appendToBuilder(builder, "collectionUUID");
-    builder->append("expectedNamespace", _expectedNamespace.ns());
-    builder->append("actualNamespace", _actualNamespace.ns());
+    _collectionUUID.appendToBuilder(builder, kCollectionUUIDFieldName);
+    builder->append(kExpectedNamespaceFieldName, _expectedNamespace.ns());
+    if (_actualNamespace) {
+        builder->append(kActualNamespaceFieldName, _actualNamespace->ns());
+    } else {
+        builder->appendNull(kActualNamespaceFieldName);
+    }
 }
 }  // namespace mongo
diff --git a/src/mongo/db/catalog/collection_uuid_mismatch_info.h b/src/mongo/db/catalog/collection_uuid_mismatch_info.h
index c851c57e36d..538527b14c9 100644
--- a/src/mongo/db/catalog/collection_uuid_mismatch_info.h
+++ b/src/mongo/db/catalog/collection_uuid_mismatch_info.h
@@ -40,7 +40,7 @@ public:
 
     explicit CollectionUUIDMismatchInfo(const UUID& collectionUUID,
                                         const NamespaceString& expectedNamespace,
-                                        const NamespaceString& actualNamespace)
+                                        const boost::optional<NamespaceString>& actualNamespace)
         : _collectionUUID(collectionUUID),
           _expectedNamespace(expectedNamespace),
           _actualNamespace(actualNamespace) {}
@@ -56,6 +56,6 @@ public:
 private:
     UUID _collectionUUID;
     NamespaceString _expectedNamespace;
-    NamespaceString _actualNamespace;
+    boost::optional<NamespaceString> _actualNamespace;
 };
 }  // namespace mongo
diff --git a/src/mongo/s/cluster_commands_helpers.cpp b/src/mongo/s/cluster_commands_helpers.cpp
index 32bc6e50137..abeec91696c 100644
--- a/src/mongo/s/cluster_commands_helpers.cpp
+++ b/src/mongo/s/cluster_commands_helpers.cpp
@@ -626,16 +626,14 @@ RawResponsesResult appendRawResponses(
     auto& firstError = genericErrorsReceived.front().second;
 
     if (firstError.code() == ErrorCodes::CollectionUUIDMismatch &&
-        firstError.extraInfo<CollectionUUIDMismatchInfo>()->actualNamespace().isEmpty()) {
+        !firstError.extraInfo<CollectionUUIDMismatchInfo>()->actualNamespace()) {
         // The first error is a CollectionUUIDMismatchInfo but it doesn't contain an actual
         // namespace. It's possible that the acutal namespace is unsharded, in which case only the
         // error from the primary shard will contain this information. Iterate through the errors to
         // see if this is the case.
         for (const auto& error : genericErrorsReceived) {
             if (error.second.code() == ErrorCodes::CollectionUUIDMismatch &&
-                !error.second.extraInfo<CollectionUUIDMismatchInfo>()
-                     ->actualNamespace()
-                     .isEmpty()) {
+                error.second.extraInfo<CollectionUUIDMismatchInfo>()->actualNamespace()) {
                 firstError = error.second;
                 break;
             }
diff --git a/src/mongo/s/query/establish_cursors.cpp b/src/mongo/s/query/establish_cursors.cpp
index f73a1672efb..c37de60e22d 100644
--- a/src/mongo/s/query/establish_cursors.cpp
+++ b/src/mongo/s/query/establish_cursors.cpp
@@ -254,7 +254,7 @@ void CursorEstablisher::_favorCollectionUUIDMismatchError(Status newError) noexc
     // Favor 'CollectionUUIDMismatchError' that has a non empty 'actualNamespace'.
     auto errorInfo = _maybeFailure->extraInfo<CollectionUUIDMismatchInfo>();
     invariant(errorInfo);
-    if (errorInfo->actualNamespace().ns().empty()) {
+    if (!errorInfo->actualNamespace()) {
         _maybeFailure = std::move(newError);
     }
 }