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         if old_version == 1:
  27             # In schema version 2, we added indexes and primary keys
  28             # pylint: disable=protected-access
  29             table = self._query(self._db, 'sessions', SESSION_TABLE,
  30                                 trans=False)._table
  31             self._db.add_constraint(table.primary_key)
  32             for index in table.indexes:
  33                 self._db.add_index(index)
  34             return 2
  35         else:
  36             raise NotImplementedError()
  37
  38
  39 class SqlSession(Session):
  40
  41     dburi = None
  42     _db = None
  43     _store = None
  44     _proto = 2
  45     locks = {}
  46
  47     @classmethod
  48     def setup(cls, **kwargs):
  49         """Initialization from cherrypy"""
  50
  51         for k, v in kwargs.items():
  52             if k == 'storage_dburi':
  53                 cls.dburi = v
  54
  55         cls._store = SessionStore(database_url=cls.dburi)
  56         # pylint: disable=protected-access
  57         cls._db = cls._store._db
  58
  59     def _exists(self):
  60         q = SqlQuery(self._db, 'sessions', SESSION_TABLE)
  61         result = q.select({'id': self.id})
  62         return True if result.fetchone() else False
  63
  64     def _load(self):
  65         q = SqlQuery(self._db, 'sessions', SESSION_TABLE)
  66         result = q.select({'id': self.id})
  67         r = result.fetchone()
  68         if r:
  69             data = str(base64.b64decode(r[1]))
  70             return pickle.loads(data)
  71
  72     def _save(self, expiration_time):
  73         q = None
  74         try:
  75             q = SqlQuery(self._db, 'sessions', SESSION_TABLE, trans=True)
  76             q.delete({'id': self.id})
  77             data = pickle.dumps((self._data, expiration_time), self._proto)
  78             q.insert((self.id, base64.b64encode(data), expiration_time))
  79             q.commit()
  80         except Exception:  # pylint: disable=broad-except
  81             if q:
  82                 q.rollback()
  83             raise
  84
  85     def _delete(self):
  86         q = SqlQuery(self._db, 'sessions', SESSION_TABLE)
  87         q.delete({'id': self.id})
  88
  89     # copy what RamSession does for now
  90     def acquire_lock(self):
  91         """Acquire an exclusive lock on the currently-loaded session data."""
  92         self.locked = True
  93         self.locks.setdefault(self.id, threading.RLock()).acquire()
  94
  95     def release_lock(self):
  96         """Release the lock on the currently-loaded session data."""
  97         self.locks[self.id].release()
  98         self.locked = False