Use ParamSpec for LRU Cache Typing (#2629)

falcon/util/misc/lru_typed.py

@@ -0,0 +1,26 @@
+from __future__ import annotations
+import functools
+from typing import TypeVar, Callable, ParamSpec
+P = ParamSpec("P"); R = TypeVar("R")
+def lru_cache(maxsize=128):
+    def decorator(func: Callable[P,R]) -> Callable[P,R]:
+        c = functools.lru_cache(maxsize=maxsize)(func)
+        @functools.wraps(func)
+        def w(*a:P.args,**k:P.kwargs): return c(*a,**k)
+        w.cache_info=c.cache_info; w.cache_clear=c.cache_clear; return w
+    return decorator
+def ttl_cache(ttl=60.0,maxsize=128):
+    import time
+    def d(func:Callable[P,R])->Callable[P,R]:
+        cache={}
+        @functools.wraps(func)
+        def w(*a:P.args,**k:P.kwargs):
+            key=functools.make_key(a,k,False); t=time.time()
+            if key in cache:
+                r,ts=cache[key]
+                if t-ts<ttl: return r
+            r=func(*a,**k); cache[key]=(r,t)
+            if len(cache)>maxsize: del cache[min(cache,key=lambda k:cache[k][1])]
+            return r
+        w.cache_clear=cache.clear; return w
+    return d