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.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/mongo/db/catalog/catalog_control.cpp b/src/mongo/db/catalog/catalog_control.cpp
index bbcea9f741c..351d709b5d0 100644
--- a/src/mongo/db/catalog/catalog_control.cpp
+++ b/src/mongo/db/catalog/catalog_control.cpp
@@ -145,7 +145,7 @@ void openCatalog(OperationContext* opCtx, const MinVisibleTimestampMap& minVisib
     for (const auto& entry : nsToIndexNameObjMap) {
         NamespaceString collNss(entry.first);
 
-        auto collection = CollectionCatalog::get(opCtx).lookupCollectionByNamespace(collNss);
+        auto collection = CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, collNss);
         invariant(collection, str::stream() << "couldn't get collection " << collNss.toString());
 
         for (const auto& indexName : entry.second.first) {
@@ -175,7 +175,8 @@ void openCatalog(OperationContext* opCtx, const MinVisibleTimestampMap& minVisib
         for (auto&& collNss :
              CollectionCatalog::get(opCtx).getAllCollectionNamesFromDb(opCtx, dbName)) {
             // Note that the collection name already includes the database component.
-            auto collection = CollectionCatalog::get(opCtx).lookupCollectionByNamespace(collNss);
+            auto collection =
+                CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, collNss);
             invariant(collection,
                       str::stream()
                           << "failed to get valid collection pointer for namespace " << collNss);