[PR #9054/c3da10cd backport][3.10] Sync reify Cython implementation w…

…ith yarl (#9057)

Co-authored-by: J. Nick Koston <nick@koston.org>

CHANGES/9054.misc.rst

@@ -0,0 +1 @@
+Improved performance of reify Cython implementation -- by :user:`bdraco`.

aiohttp/_helpers.pyx

@@ -1,3 +1,6 @@
+
+cdef _sentinel = object()
+
 cdef class reify:
     """Use as a class method decorator.  It operates almost exactly like
     the Python `@property` decorator, but it puts the result of the
@@ -19,17 +22,14 @@ cdef class reify:
         return self.wrapped.__doc__
 
     def __get__(self, inst, owner):
-        try:
-            try:
-                return inst._cache[self.name]
-            except KeyError:
-                val = self.wrapped(inst)
-                inst._cache[self.name] = val
-                return val
-        except AttributeError:
-            if inst is None:
-                return self
-            raise
+        if inst is None:
+            return self
+        cdef dict cache = inst._cache
+        val = cache.get(self.name, _sentinel)
+        if val is _sentinel:
+            val = self.wrapped(inst)
+            cache[self.name] = val
+        return val
 
     def __set__(self, inst, value):
         raise AttributeError("reified property is read-only")