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"""
Cached, database-backed sessions.
"""
import logging
from django.contrib.sessions.backends.db import SessionStore as DBStore
from django.core.cache import cache
from django.core.exceptions import SuspiciousOperation
from django.utils import timezone
from django.utils.encoding import force_text
KEY_PREFIX = "django.contrib.sessions.cached_db"
class SessionStore(DBStore):
"""
Implements cached, database backed sessions.
"""
def __init__(self, session_key=None):
super(SessionStore, self).__init__(session_key)
@property
def cache_key(self):
return KEY_PREFIX + self._get_or_create_session_key()
def load(self):
try:
data = cache.get(self.cache_key, None)
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 = Session.objects.get(
session_key=self.session_key,
expire_date__gt=timezone.now()
)
data = self.decode(s.session_data)
cache.set(self.cache_key, data,
self.get_expiry_age(expiry=s.expire_date))
except (Session.DoesNotExist, SuspiciousOperation) as e:
if isinstance(e, SuspiciousOperation):
logger = logging.getLogger('django.security.%s' %
e.__class__.__name__)
logger.warning(force_text(e))
self.create()
data = {}
return data
def exists(self, session_key):
if (KEY_PREFIX + session_key) in cache:
return True
return super(SessionStore, self).exists(session_key)
def save(self, must_create=False):
super(SessionStore, self).save(must_create)
cache.set(self.cache_key, self._session, self.get_expiry_age())
def delete(self, session_key=None):
super(SessionStore, self).delete(session_key)
if session_key is None:
if self.session_key is None:
return
session_key = self.session_key
cache.delete(KEY_PREFIX + session_key)
def flush(self):
"""
Removes the current session data from the database and regenerates the
key.
"""
self.clear()
self.delete(self.session_key)
self.create()
# At bottom to avoid circular import
from django.contrib.sessions.models import Session
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