ipsilon/util/sessions.py

   1 # Copyright (C) 2014 Ipsilon project Contributors, for license see COPYING
   2
   3 import base64
   4 from cherrypy.lib.sessions import Session
   5 from ipsilon.util.data import Store, SqlQuery
   6 import threading
   7 try:
   8     import cPickle as pickle
   9 except ImportError:
  10     import pickle
  11
  12
  13 SESSION_TABLE = {'columns': ['id', 'data', 'expiration_time'],
  14                  'primary_key': ('id', ),
  15                  'indexes': [('expiration_time',)]
  16                  }
  17
  18
  19 class SessionStore(Store):
  20     def _initialize_schema(self):
  21         q = self._query(self._db, 'sessions', SESSION_TABLE,
  22                         trans=False)
  23         q.create()
  24
  25     def _upgrade_schema(self, old_version):
  26         raise NotImplementedError()
  27
  28
  29 class SqlSession(Session):
  30
  31     dburi = None
  32     _db = None
  33     _store = None
  34     _proto = 2
  35     locks = {}
  36
  37     @classmethod
  38     def setup(cls, **kwargs):
  39         """Initialization from cherrypy"""
  40
  41         for k, v in kwargs.items():
  42             if k == 'storage_dburi':
  43                 cls.dburi = v
  44
  45         cls._store = SessionStore(database_url=cls.dburi)
  46         # pylint: disable=protected-access
  47         cls._db = cls._store._db
  48
  49     def _exists(self):
  50         q = SqlQuery(self._db, 'sessions', SESSION_TABLE)
  51         result = q.select({'id': self.id})
  52         return True if result.fetchone() else False
  53
  54     def _load(self):
  55         q = SqlQuery(self._db, 'sessions', SESSION_TABLE)
  56         result = q.select({'id': self.id})
  57         r = result.fetchone()
  58         if r:
  59             data = str(base64.b64decode(r[1]))
  60             return pickle.loads(data)
  61
  62     def _save(self, expiration_time):
  63         q = None
  64         try:
  65             q = SqlQuery(self._db, 'sessions', SESSION_TABLE, trans=True)
  66             q.delete({'id': self.id})
  67             data = pickle.dumps((self._data, expiration_time), self._proto)
  68             q.insert((self.id, base64.b64encode(data), expiration_time))
  69             q.commit()
  70         except Exception:  # pylint: disable=broad-except
  71             if q:
  72                 q.rollback()
  73             raise
  74
  75     def _delete(self):
  76         q = SqlQuery(self._db, 'sessions', SESSION_TABLE)
  77         q.delete({'id': self.id})
  78
  79     # copy what RamSession does for now
  80     def acquire_lock(self):
  81         """Acquire an exclusive lock on the currently-loaded session data."""
  82         self.locked = True
  83         self.locks.setdefault(self.id, threading.RLock()).acquire()
  84
  85     def release_lock(self):
  86         """Release the lock on the currently-loaded session data."""
  87         self.locks[self.id].release()
  88         self.locked = False