39fb2fadec
This code retries to load sessions three times. If not an error will be thrown. There are other solutions (Like not throwing the error), but I would like to see errors in production usage to see, if this helps or not.
120 lines
3.6 KiB
Python
120 lines
3.6 KiB
Python
# type: ignore
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from time import sleep
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from asgiref.sync import async_to_sync
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from django.conf import settings
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from django.contrib.sessions.backends.base import (
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VALID_KEY_CHARS,
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CreateError,
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SessionBase,
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)
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from django.utils.crypto import get_random_string, salted_hmac
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from django.utils.encoding import force_str
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from .redis import get_connection
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REDIS_SESSION_PREFIX = getattr(settings, "REDIS_SESSION_PREFIX", "session:")
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def to_redis_key(session_key):
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return f"{REDIS_SESSION_PREFIX}{session_key}"
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class SessionStore(SessionBase):
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"""
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Implements Redis database session store.
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"""
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def __init__(self, session_key=None):
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super(SessionStore, self).__init__(session_key)
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def _hash(self, value):
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key_salt = "openslides.utils.sessions.SessionStore"
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return salted_hmac(key_salt, value).hexdigest()
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def load(self):
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retries = 0
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while True:
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try:
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return async_to_sync(self._load)()
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except TimeoutError as e:
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if retries < 3:
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sleep(0.1)
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else:
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raise e
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retries += 1
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async def _load(self):
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async with get_connection(read_only=True) as redis:
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try:
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key = to_redis_key(self._get_or_create_session_key())
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session_data = await redis.get(key)
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return self.decode(force_str(session_data))
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except Exception:
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self._session_key = None
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return {}
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def exists(self, session_key):
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return async_to_sync(self._load)(session_key)
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async def _exists(self, session_key):
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async with get_connection(read_only=True) as redis:
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key = to_redis_key(session_key)
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return await redis.exists(key)
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def create(self):
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async_to_sync(self._create)()
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async def _create(self):
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while True:
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self._session_key = await self._async_get_new_session_key()
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try:
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await self._save(must_create=True)
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except CreateError:
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# Key wasn't unique. Try again.
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continue
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self.modified = True
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return
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def save(self, must_create=False):
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async_to_sync(self._save)(must_create)
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async def _save(self, must_create=False):
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async with get_connection() as redis:
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if self.session_key is None:
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return await self._create()
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if must_create and await self._exists(self._get_or_create_session_key()):
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raise CreateError
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data = self.encode(self._get_session(no_load=must_create))
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await redis.setex(
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to_redis_key(self._get_or_create_session_key()),
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self.get_expiry_age(),
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data,
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)
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def delete(self, session_key=None):
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async_to_sync(self._delete)(session_key)
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async def _delete(self, session_key=None):
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if session_key is None:
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if self.session_key is None:
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return
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session_key = self.session_key
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async with get_connection() as redis:
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await redis.delete(to_redis_key(session_key))
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# This must be overwritten to stay inside async code...
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async def _async_get_new_session_key(self):
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"Return session key that isn't being used."
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while True:
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session_key = get_random_string(32, VALID_KEY_CHARS)
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if not await self._exists(session_key):
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return session_key
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@classmethod
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def clear_expired(cls):
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pass
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