Initial commit

.venv/Lib/site-packages/django/contrib/sessions/backends/cached_db.py

@@ -0,0 +1,135 @@
+"""
+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