SERVER-50984 Add CollectionPtr to replace usage of const Collection*

It implements a yieldable interface that is used to re-load the
Collection pointer from the catalog after a yield that released locks.
With lock-free reads and copy-on-write on Collection instances releasing
locks without notifying an AutoGetCollection at a higher level may cause
its pointers to dangle if a MODE_X writer installs a new Collection
instance in the catalog.

CollectionPtr should be passed by const reference so a yield can notify
all the way up.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/mongo/db/transaction_participant.cpp b/src/mongo/db/transaction_participant.cpp
index de5874ae3a6..5284c8c2300 100644
--- a/src/mongo/db/transaction_participant.cpp
+++ b/src/mongo/db/transaction_participant.cpp
@@ -206,18 +206,18 @@ void updateSessionEntry(OperationContext* opCtx, const UpdateRequest& updateRequ
     // Current code only supports replacement update.
     dassert(UpdateDriver::isDocReplacement(updateRequest.getUpdateModification()));
 
-    AutoGetCollection autoColl(opCtx, NamespaceString::kSessionTransactionsTableNamespace, MODE_IX);
+    AutoGetCollection collection(
+        opCtx, NamespaceString::kSessionTransactionsTableNamespace, MODE_IX);
 
     uassert(40527,
             str::stream() << "Unable to persist transaction state because the session transaction "
                              "collection is missing. This indicates that the "
                           << NamespaceString::kSessionTransactionsTableNamespace.ns()
                           << " collection has been manually deleted.",
-            autoColl.getCollection());
+            collection.getCollection());
 
     WriteUnitOfWork wuow(opCtx);
 
-    auto collection = autoColl.getCollection();
     auto idIndex = collection->getIndexCatalog()->findIdIndex(opCtx);
 
     uassert(40672,