SERVER-38226 Support storing a reserved RecordId in biggie SortedDataInterface

Also add new unit test for storing a reserved RecordId to the general SortedDataInterface
testing framework.

Author: GeertBosch

src/mongo/db/storage/biggie/biggie_sorted_impl.cpp

@@ -190,7 +190,7 @@ StatusWith<SpecialFormatInserted> SortedDataBuilderInterface::addKey(const BSONO
                                                                      const RecordId& loc) {
     StringStore* workingCopy(RecoveryUnit::get(_opCtx)->getHead());
 
-    invariant(loc.isNormal());
+    invariant(loc.isNormal() || loc.isReserved());
     invariant(!hasFieldNames(key));
 
     std::unique_ptr<KeyString> newKS = keyToKeyString(key, _order);

src/mongo/db/storage/sorted_data_interface_test_bulkbuilder.cpp

@@ -65,6 +65,33 @@ TEST(SortedDataInterface, BuilderAddKey) {
     }
 }
 
+// Add a reserved RecordId using a bulk builder.
+TEST(SortedDataInterface, BuilderAddKeyWithReservedRecordId) {
+    const auto harnessHelper(newSortedDataInterfaceHarnessHelper());
+    const std::unique_ptr<SortedDataInterface> sorted(harnessHelper->newSortedDataInterface(false));
+    {
+        const ServiceContext::UniqueOperationContext opCtx(harnessHelper->newOperationContext());
+        ASSERT(sorted->isEmpty(opCtx.get()));
+    }
+
+    {
+        const ServiceContext::UniqueOperationContext opCtx(harnessHelper->newOperationContext());
+        const std::unique_ptr<SortedDataBuilderInterface> builder(
+            sorted->getBulkBuilder(opCtx.get(), true));
+
+        RecordId reservedLoc(RecordId::ReservedId::kWildcardMultikeyMetadataId);
+        ASSERT(reservedLoc.isReserved());
+
+        ASSERT_OK(builder->addKey(key1, reservedLoc));
+        ASSERT_EQUALS(SpecialFormatInserted::NoSpecialFormatInserted, builder->commit(false));
+    }
+
+    {
+        const ServiceContext::UniqueOperationContext opCtx(harnessHelper->newOperationContext());
+        ASSERT_EQUALS(1, sorted->numEntries(opCtx.get()));
+    }
+}
+
 // Add a compound key using a bulk builder.
 TEST(SortedDataInterface, BuilderAddCompoundKey) {
     const auto harnessHelper(newSortedDataInterfaceHarnessHelper());

src/mongo/db/storage/sorted_data_interface_test_insert.cpp

@@ -367,5 +367,18 @@ TEST(SortedDataInterface, InsertMultipleCompoundKeys) {
     }
 }
 
+TEST(SortedDataInterface, InsertReservedRecordId) {
+    const auto harnessHelper(newSortedDataInterfaceHarnessHelper());
+    const std::unique_ptr<SortedDataInterface> sorted(harnessHelper->newSortedDataInterface(false));
+    const ServiceContext::UniqueOperationContext opCtx(harnessHelper->newOperationContext());
+    ASSERT(sorted->isEmpty(opCtx.get()));
+    WriteUnitOfWork uow(opCtx.get());
+    RecordId reservedLoc(RecordId::ReservedId::kWildcardMultikeyMetadataId);
+    ASSERT(reservedLoc.isReserved());
+    ASSERT_OK(sorted->insert(opCtx.get(), key1, reservedLoc, /*dupsAllowed*/ true));
+    uow.commit();
+    ASSERT_EQUALS(1, sorted->numEntries(opCtx.get()));
+}
+
 }  // namespace
 }  // namespace mongo