SERVER-29417 Attach logical session ids to cursors

1 files changed, 43 insertions, 0 deletions

diff --git a/src/mongo/db/db_raii.h b/src/mongo/db/db_raii.h
index 753909e3c6a..641b64e7988 100644
--- a/src/mongo/db/db_raii.h
+++ b/src/mongo/db/db_raii.h
@@ -128,12 +128,55 @@ private:
     const Lock::CollectionLock _collLock;
     Collection* const _coll;
 
+    friend class AutoGetCollectionOrView;
     friend class AutoGetCollectionForRead;
     friend class AutoGetCollectionForReadCommand;
     friend class AutoGetCollectionOrViewForReadCommand;
 };
 
 /**
+ * RAII-style class which acquires the appropriate hierarchy of locks for a collection or
+ * view. The pointer to a view definition is nullptr if it does not exist.
+ *
+ * Use this when you have not yet determined if the namespace is a view or a collection.
+ * For example, you can use this to access a namespace's CursorManager.
+ *
+ * It is guaranteed that locks will be released when this object goes out of scope, therefore
+ * the view returned by this class should not be retained.
+ */
+class AutoGetCollectionOrView {
+    MONGO_DISALLOW_COPYING(AutoGetCollectionOrView);
+
+public:
+    AutoGetCollectionOrView(OperationContext* opCtx, const NamespaceString& nss, LockMode modeAll);
+
+    /**
+     * Returns nullptr if the database didn't exist.
+     */
+    Database* getDb() const {
+        return _autoColl.getDb();
+    }
+
+    /**
+     * Returns nullptr if the collection didn't exist.
+     */
+    Collection* getCollection() const {
+        return _autoColl.getCollection();
+    }
+
+    /**
+     * Returns nullptr if the view didn't exist.
+     */
+    ViewDefinition* getView() const {
+        return _view.get();
+    }
+
+private:
+    const AutoGetCollection _autoColl;
+    std::shared_ptr<ViewDefinition> _view;
+};
+
+/**
  * RAII-style class, which acquires a lock on the specified database in the requested mode and
  * obtains a reference to the database, creating it was non-existing. Used as a shortcut for
  * calls to dbHolder().openDb(), taking care of locking details. The requested mode must be