SERVER-43859: Take MODE_IX locks for collection creation.

Two concurrent storage transactions can now create collections with the same
collection name. These transactions will conflict at commit time; the first
committer will win and register their collection into the global catalog. The
losing transactions will bubble a WriteConflictException.

Top-level callers that should fail if the collection already existed must now
check and fail with a NamespaceExists error code. Previously, those callers
could rely on lower level code returning the NamespaceExists error.

Callers that were implicitly creating a collection may retry the operation,
using the now-registered collection.

These transaction-local collections (UncommittedCollections) are returned when
doing any CollectionCatalog::lookup* call.

2 files changed, 3 insertions, 9 deletions

diff --git a/src/mongo/db/storage/kv/durable_catalog_feature_tracker_test.cpp b/src/mongo/db/storage/kv/durable_catalog_feature_tracker_test.cpp
index 82d69cf454d..d5a2594b37c 100644
--- a/src/mongo/db/storage/kv/durable_catalog_feature_tracker_test.cpp
+++ b/src/mongo/db/storage/kv/durable_catalog_feature_tracker_test.cpp
@@ -107,12 +107,6 @@ private:
     std::unique_ptr<DurableCatalogImpl::FeatureTracker> _featureTracker;
 };
 
-TEST_F(DurableCatalogFeatureTrackerTest, FeatureDocumentIsNotEagerlyCreated) {
-    auto opCtx = newOperationContext();
-    auto cursor = getRecordStore()->getCursor(opCtx.get());
-    ASSERT_FALSE(static_cast<bool>(cursor->next()));
-}
-
 TEST_F(DurableCatalogFeatureTrackerTest, CanMarkNonRepairableFeatureAsInUse) {
     {
         auto opCtx = newOperationContext();
diff --git a/src/mongo/db/storage/kv/durable_catalog_test.cpp b/src/mongo/db/storage/kv/durable_catalog_test.cpp
index 5a2da09c0ea..c5b5b469f09 100644
--- a/src/mongo/db/storage/kv/durable_catalog_test.cpp
+++ b/src/mongo/db/storage/kv/durable_catalog_test.cpp
@@ -88,9 +88,9 @@ public:
             ASSERT_OK(swColl.getStatus());
             std::pair<RecordId, std::unique_ptr<RecordStore>> coll = std::move(swColl.getValue());
             _catalogId = coll.first;
-            auto collection = std::make_unique<CollectionMock>(_nss);
-            CollectionCatalog::get(opCtx.get())
-                .registerCollection(options.uuid.get(), std::move(collection));
+            std::unique_ptr<Collection> collection =
+                std::make_unique<CollectionMock>(_nss, _catalogId);
+            CollectionCatalog::get(opCtx.get()).registerCollection(options.uuid.get(), &collection);
             wuow.commit();
         }
     }