gh-103193: cache calls to `inspect._shadowed_dict` in `inspect.getattr_static` (#104267)

Co-authored-by: Carl Meyer <carl@oddbird.net>

1 files changed, 6 insertions, 2 deletions

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 95da7fb..a64e85e 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1794,8 +1794,9 @@ def _check_class(klass, attr):
             return entry.__dict__[attr]
     return _sentinel
 
-def _shadowed_dict(klass):
-    for entry in _static_getmro(klass):
+@functools.lru_cache()
+def _shadowed_dict_from_mro_tuple(mro):
+    for entry in mro:
         dunder_dict = _get_dunder_dict_of_class(entry)
         if '__dict__' in dunder_dict:
             class_dict = dunder_dict['__dict__']
@@ -1805,6 +1806,9 @@ def _shadowed_dict(klass):
                 return class_dict
     return _sentinel
 
+def _shadowed_dict(klass):
+    return _shadowed_dict_from_mro_tuple(_static_getmro(klass))
+
 def getattr_static(obj, attr, default=_sentinel):
     """Retrieve attributes without triggering dynamic lookup via the
        descriptor protocol,  __getattr__ or __getattribute__.