Session for Tornado(Redis)，tornadoredis,session id的生

Session for Tornado(Redis)，tornadoredis,session id的生

session id的生成借用了web.py。

使用了 redis 的 hash 储存。

只有在为session赋值的时候才会生成session_id，是为了必要的情况下的使用（例如oAuth2的state和验证码）

#coding=utf8import os, timefrom core.options import optionsfrom hashlib import sha1class Session(object):    _prefix = "_session:"    _id = None    _skip = ['_redis','_request','_id']    def __init__(self,request):        self._redis = request.redis        self._request = request        #init session id        id = request.get_secure_cookie('sessionid')        if id and self._redis.exists(id):            self._id = id    def init_session(self):        """初始化"""        if not self._id:            self._id = self.generate_session_id()            self._request.set_secure_cookie('sessionid',self._id)        #延期过期时间        self._redis.hset(self._id,'lastActive',time.time())        self._redis.expire(self._id,options.session_maxlifetime)    def generate_session_id(self):        """Generate a random id for session"""        secret_key = self._request.settings['cookie_secret']        ip = self._request.request.remote_ip        while True:            rand = os.urandom(16)            now = time.time()            sessionid = sha1("%s%s%s%s" % (rand, now,ip, secret_key))            sessionid = self._prefix + sessionid.hexdigest()            if not self._redis.exists(sessionid):                break        return sessionid    def __getattr__(self, name):        if self._id:            return self._redis.hget(self._id,name)        return object.__getattribute__(self, name)    def __setattr__(self, name, value):        if not name in self._skip:            self.init_session()            self._redis.hset(self._id,name,value)        object.__setattr__(self, name, value)    def __delattr__(self, name):        if not name in self._skip:            return self._redis.hdel(self._id,name)        object.__delattr__(self, name)#该片段来自于http://byrx.net