feat: Allow using OIDC auth cache instead of session (#5746)

Co-authored-by: Michael Genson <71845777+michael-genson@users.noreply.github.com>

mealie/routes/auth/auth.py

@@ -19,6 +19,8 @@ from mealie.routes._base.routers import UserAPIRouter
 from mealie.schema.user import PrivateUser
 from mealie.schema.user.auth import CredentialsRequestForm
 
+from .auth_cache import AuthCache
+
 public_router = APIRouter(tags=["Users: Authentication"])
 user_router = UserAPIRouter(tags=["Users: Authentication"])
 logger = root_logger.get_logger("auth")
@@ -27,7 +29,7 @@ remember_me_duration = timedelta(days=14)
 
 settings = get_app_settings()
 if settings.OIDC_READY:
-    oauth = OAuth()
+    oauth = OAuth(cache=AuthCache())
     scope = None
     if settings.OIDC_SCOPES_OVERRIDE:
         scope = settings.OIDC_SCOPES_OVERRIDE

mealie/routes/auth/auth_cache.py

@@ -0,0 +1,51 @@
+import time
+from typing import Any
+
+
+class AuthCache:
+    def __init__(self, threshold: int = 500, default_timeout: float = 300):
+        self.default_timeout = default_timeout
+        self._cache: dict[str, tuple[float, Any]] = {}
+        self.clear = self._cache.clear
+        self._threshold = threshold
+
+    def _prune(self):
+        if len(self._cache) > self._threshold:
+            now = time.time()
+            toremove = []
+            for idx, (key, (expires, _)) in enumerate(self._cache.items()):
+                if (expires != 0 and expires <= now) or idx % 3 == 0:
+                    toremove.append(key)
+            for key in toremove:
+                self._cache.pop(key, None)
+
+    def _normalize_timeout(self, timeout: float | None) -> float:
+        if timeout is None:
+            timeout = self.default_timeout
+        if timeout > 0:
+            timeout = time.time() + timeout
+        return timeout
+
+    async def get(self, key: str) -> Any:
+        try:
+            expires, value = self._cache[key]
+            if expires == 0 or expires > time.time():
+                return value
+        except KeyError:
+            return None
+
+    async def set(self, key: str, value: Any, timeout: float | None = None) -> bool:
+        expires = self._normalize_timeout(timeout)
+        self._prune()
+        self._cache[key] = (expires, value)
+        return True
+
+    async def delete(self, key: str) -> bool:
+        return self._cache.pop(key, None) is not None
+
+    async def has(self, key: str) -> bool:
+        try:
+            expires, value = self._cache[key]
+            return expires == 0 or expires > time.time()
+        except KeyError:
+            return False