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Original file line number | Diff line number | Diff line change |
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from django.conf import settings | ||
from django.contrib import auth | ||
from django.contrib.sessions.backends.base import SessionBase, CreateError | ||
from django.core.cache import caches | ||
from django.utils.six.moves import xrange | ||
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KEY_PREFIX = "user_sessions.cache" | ||
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class SessionStore(SessionBase): | ||
""" | ||
Implements cache-based session store. | ||
""" | ||
def __init__(self, user_agent, ip, session_key=None): | ||
self._cache = caches[settings.SESSION_CACHE_ALIAS] | ||
super(SessionStore, self).__init__(session_key) | ||
self.user_agent, self.ip, self.user_id = user_agent, ip, None | ||
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def __setitem__(self, key, value): | ||
if key == auth.SESSION_KEY: | ||
self.user_id = value | ||
super(SessionStore, self).__setitem__(key, value) | ||
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@property | ||
def cache_key(self): | ||
return KEY_PREFIX + self._get_or_create_session_key() | ||
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def load(self): | ||
try: | ||
s = self._cache.get(self.cache_key, None) | ||
self.user_id = s['user_id'] | ||
# do not overwrite user_agent/ip, as those might have been updated | ||
if self.user_agent != s['user_agent'] or self.ip != s['ip']: | ||
self.modified = True | ||
except Exception: | ||
# Some backends (e.g. memcache) raise an exception on invalid | ||
# cache keys. If this happens, reset the session. See #17810. | ||
s = None | ||
if s is not None: | ||
return s['session_data'] | ||
self.create() | ||
return {} | ||
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def exists(self, session_key): | ||
return (KEY_PREFIX + session_key) in self._cache | ||
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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. " | ||
"It is likely that the cache is unavailable.") | ||
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def save(self, must_create=False): | ||
if must_create: | ||
func = self._cache.add | ||
else: | ||
func = self._cache.set | ||
result = func(self.cache_key, { | ||
'session_data': self._get_session(no_load=must_create), | ||
'user_agent': self.user_agent, | ||
'user_id': self.user_id, | ||
'ip': self.ip | ||
}, | ||
self.get_expiry_age()) | ||
if must_create and not result: | ||
raise CreateError | ||
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def clear(self): | ||
super(SessionStore, self).clear() | ||
self.user_id = None | ||
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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(KEY_PREFIX + session_key) | ||
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@classmethod | ||
def clear_expired(cls): | ||
pass |