""" Cached, database-backed sessions. """ import logging from django.conf import settings from django.contrib.sessions.backends.db import SessionStore as DBStore from django.core.cache import caches KEY_PREFIX = "django.contrib.sessions.cached_db" logger = logging.getLogger("django.contrib.sessions") class SessionStore(DBStore): """ Implement cached, database backed sessions. """ cache_key_prefix = KEY_PREFIX def __init__(self, session_key=None): self._cache = caches[settings.SESSION_CACHE_ALIAS] super().__init__(session_key) @property def cache_key(self): return self.cache_key_prefix + self._get_or_create_session_key() async def acache_key(self): return self.cache_key_prefix + await self._aget_or_create_session_key() def load(self): try: data = self._cache.get(self.cache_key) except Exception: # Some backends (e.g. memcache) raise an exception on invalid # cache keys. If this happens, reset the session. See #17810. data = None if data is None: s = self._get_session_from_db() if s: data = self.decode(s.session_data) self._cache.set( self.cache_key, data, self.get_expiry_age(expiry=s.expire_date) ) else: data = {} return data async def aload(self): try: data = await self._cache.aget(await self.acache_key()) except Exception: # Some backends (e.g. memcache) raise an exception on invalid # cache keys. If this happens, reset the session. See #17810. data = None if data is None: s = await self._aget_session_from_db() if s: data = self.decode(s.session_data) await self._cache.aset( await self.acache_key(), data, await self.aget_expiry_age(expiry=s.expire_date), ) else: data = {} return data def exists(self, session_key): return ( session_key and (self.cache_key_prefix + session_key) in self._cache or super().exists(session_key) ) async def aexists(self, session_key): return ( session_key and (self.cache_key_prefix + session_key) in self._cache or await super().aexists(session_key) ) def save(self, must_create=False): super().save(must_create) try: self._cache.set(self.cache_key, self._session, self.get_expiry_age()) except Exception: logger.exception("Error saving to cache (%s)", self._cache) async def asave(self, must_create=False): await super().asave(must_create) try: await self._cache.aset( await self.acache_key(), self._session, await self.aget_expiry_age(), ) except Exception: logger.exception("Error saving to cache (%s)", self._cache) def delete(self, session_key=None): super().delete(session_key) if session_key is None: if self.session_key is None: return session_key = self.session_key self._cache.delete(self.cache_key_prefix + session_key) async def adelete(self, session_key=None): await super().adelete(session_key) if session_key is None: if self.session_key is None: return session_key = self.session_key await self._cache.adelete(self.cache_key_prefix + session_key) def flush(self): """ Remove the current session data from the database and regenerate the key. """ self.clear() self.delete(self.session_key) self._session_key = None async def aflush(self): """See flush().""" self.clear() await self.adelete(self.session_key) self._session_key = None