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      1 # -*- coding: utf-8 -*-
      2 """
      3     webapp2_extras.appengine.sessions_memcache
      4     ==========================================
      5 
      6     Extended sessions stored in memcache.
      7 
      8     :copyright: 2011 by tipfy.org.
      9     :license: Apache Sotware License, see LICENSE for details.
     10 """
     11 from google.appengine.api import memcache
     12 
     13 from webapp2_extras import sessions
     14 
     15 
     16 class MemcacheSessionFactory(sessions.CustomBackendSessionFactory):
     17     """A session factory that stores data serialized in memcache.
     18 
     19     To use memcache sessions, pass this class as the `factory` keyword to
     20     :meth:`webapp2_extras.sessions.SessionStore.get_session`::
     21 
     22         from webapp2_extras import sessions_memcache
     23 
     24         # [...]
     25 
     26         session = self.session_store.get_session(
     27             name='mc_session',
     28             factory=sessions_memcache.MemcacheSessionFactory)
     29 
     30     See in :meth:`webapp2_extras.sessions.SessionStore` an example of how to
     31     make sessions available in a :class:`webapp2.RequestHandler`.
     32     """
     33 
     34     def _get_by_sid(self, sid):
     35         """Returns a session given a session id."""
     36         if self._is_valid_sid(sid):
     37             data = memcache.get(sid)
     38             if data is not None:
     39                 self.sid = sid
     40                 return sessions.SessionDict(self, data=data)
     41 
     42         self.sid = self._get_new_sid()
     43         return sessions.SessionDict(self, new=True)
     44 
     45     def save_session(self, response):
     46         if self.session is None or not self.session.modified:
     47             return
     48 
     49         memcache.set(self.sid, dict(self.session))
     50         self.session_store.save_secure_cookie(
     51             response, self.name, {'_sid': self.sid}, **self.session_args)
     52