def _add_to_queue_(self, lst):
try:
self._lock.acquire()
obj_set, obj_event = self._get_conflicted_list_(lst)
if obj_event:
return obj_event
event = Event()
event.clear()
obj_set = set(lst)
event.transaction_id = self._get_root_transaction_id_()
self._active_lists[id(lst)] = obj_set, event
return None
finally:
self._lock.release()
