How to check reentrant database queue?

Question

I wonder if I can perform similar check in my methods to handle case of nested calls inDatabase... methods. kDispatchQueueSpecificKey is private and _queue too in FMDatabaseQueue class, so I cannot use dispatch_get_specific method

FMDatabaseQueue *currentSyncQueue = (__bridge id)dispatch_get_specific(kDispatchQueueSpecificKey);
assert(currentSyncQueue != self && "inDatabase: was called reentrantly on the same queue, which would lead to a deadlock");