def _save(self, must_create, session):
if must_create and (
cache.get('session-' + self.session_key) is not None or
Session.get_by_key_name('k:' + self.session_key)):
raise CreateError
cache.delete('session-' + self.session_key)
entity = Session(key_name='k:' + self.session_key,
data=self.encode(session),
expiry=self.get_expiry_date())
entity.put()
cache.set('session-' + self.session_key, session, 1200)
