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 SqlStore, SqlQuery
   6 import threading
   7 try:
   8     import cPickle as pickle
   9 except ImportError:
  10     import pickle
  11
  12
  13 SESSION_COLUMNS = ['id', 'data', 'expiration_time']
  14
  15
  16 class SqlSession(Session):
  17
  18     dburi = None
  19     _db = None
  20     _proto = 2
  21     locks = {}
  22
  23     @classmethod
  24     def setup(cls, **kwargs):
  25         """Initialization from cherrypy"""
  26
  27         for k, v in kwargs.items():
  28             if k == 'storage_dburi':
  29                 cls.dburi = v
  30
  31         cls._db = SqlStore(cls.dburi)
  32
  33     def _exists(self):
  34         q = SqlQuery(self._db, 'sessions', SESSION_COLUMNS)
  35         result = q.select({'id': self.id})
  36         return True if result.fetchone() else False
  37
  38     def _load(self):
  39         q = SqlQuery(self._db, 'sessions', SESSION_COLUMNS)
  40         result = q.select({'id': self.id})
  41         r = result.fetchone()
  42         if r:
  43             data = str(base64.b64decode(r[1]))
  44             return pickle.loads(data)
  45
  46     def _save(self, expiration_time):
  47         q = None
  48         try:
  49             q = SqlQuery(self._db, 'sessions', SESSION_COLUMNS, trans=True)
  50             q.delete({'id': self.id})
  51             data = pickle.dumps((self._data, expiration_time), self._proto)
  52             q.insert((self.id, base64.b64encode(data), expiration_time))
  53             q.commit()
  54         except Exception:  # pylint: disable=broad-except
  55             if q:
  56                 q.rollback()
  57             raise
  58
  59     def _delete(self):
  60         q = SqlQuery(self._db, 'sessions', SESSION_COLUMNS)
  61         q.delete({'id': self.id})
  62
  63     # copy what RamSession does for now
  64     def acquire_lock(self):
  65         """Acquire an exclusive lock on the currently-loaded session data."""
  66         self.locked = True
  67         self.locks.setdefault(self.id, threading.RLock()).acquire()
  68
  69     def release_lock(self):
  70         """Release the lock on the currently-loaded session data."""
  71         self.locks[self.id].release()
  72         self.locked = False