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- """
- 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
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