| from django.contrib.sessions.backends.base import SessionBase, CreateError |
| from django.core.cache import cache |
| |
| class SessionStore(SessionBase): |
| """ |
| A cache-based session store. |
| """ |
| def __init__(self, session_key=None): |
| self._cache = cache |
| super(SessionStore, self).__init__(session_key) |
| |
| def load(self): |
| session_data = self._cache.get(self.session_key) |
| if session_data is not None: |
| return session_data |
| self.create() |
| return {} |
| |
| def create(self): |
| # Because a cache can fail silently (e.g. memcache), we don't know if |
| # we are failing to create a new session because of a key collision or |
| # because the cache is missing. So we try for a (large) number of times |
| # and then raise an exception. That's the risk you shoulder if using |
| # cache backing. |
| for i in xrange(10000): |
| self.session_key = self._get_new_session_key() |
| try: |
| self.save(must_create=True) |
| except CreateError: |
| continue |
| self.modified = True |
| return |
| raise RuntimeError("Unable to create a new session key.") |
| |
| def save(self, must_create=False): |
| if must_create: |
| func = self._cache.add |
| else: |
| func = self._cache.set |
| result = func(self.session_key, self._get_session(no_load=must_create), |
| self.get_expiry_age()) |
| if must_create and not result: |
| raise CreateError |
| |
| def exists(self, session_key): |
| if self._cache.has_key(session_key): |
| return True |
| return False |
| |
| def delete(self, session_key=None): |
| if session_key is None: |
| if self._session_key is None: |
| return |
| session_key = self._session_key |
| self._cache.delete(session_key) |
| |
