cached_db.py 文件源码

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:
            # Duplicate DBStore.load, because we need to keep track
            # of the expiry date to set it properly in the cache.
            try:
                s = self.model.objects.get(
                    session_key=self.session_key,
                    expire_date__gt=timezone.now()
                )
                data = self.decode(s.session_data)
                self._cache.set(self.cache_key, data, self.get_expiry_age(expiry=s.expire_date))
            except (self.model.DoesNotExist, SuspiciousOperation) as e:
                if isinstance(e, SuspiciousOperation):
                    logger = logging.getLogger('django.security.%s' % e.__class__.__name__)
                    logger.warning(force_text(e))
                self._session_key = None
                data = {}
        return data