class RedisSessionStore(SessionStore):
    def __init__(self, expire = 1800, key_prefix=''):
        SessionStore.__init__(self)
        self.redis = redis.Redis(tools.config.get('redis_host', 'localhost'), 
                                 int(tools.config.get('redis_port', 6379)), 
                                 int(tools.config.get('redis_dbindex', 1)), 
                                 password=tools.config.get('redis_pass', None))
        self.path = session_path()
        self.expire = expire
        self.key_prefix = key_prefix
        
    def save(self, session):
        key = self._get_session_key(session.sid)
        data = cPickle.dumps(dict(session))
        self.redis.setex(key, data, self.expire)

    def delete(self, session):
        key = self._get_session_key(session.sid)
        self.redis.delete(key)
    
    def _get_session_key(self,sid):
        key = self.key_prefix + sid
        if isinstance(key, unicode):
          key = key.encode('utf-8')
        return key
    
    def get(self, sid):
        key = self._get_session_key(sid)
        data = self.redis.get(key)
        if data:
            self.redis.setex(key, data, self.expire)
            data = cPickle.loads(data)
        else:
            data = {}
        return self.session_class(data, sid, False)