global

def update_single_session_key 

def update_single_session_key
  key = random_key
  set_session_value(single_session_session_key, key)
  if single_session_ds.update(single_session_key_column=>key) == 0
    # Don't handle uniqueness violations here.  While we could get the stored key from the
    # database, it could lead to two sessions sharing the same key, which this feature is
    # designed to prevent.
    single_session_ds.insert(single_session_id_column=>session_value, single_session_key_column=>key)
  end
end