Consistently move the misses update to just before the user function call (GH-11715)

rhettinger · web-flow · commit ffdf1c30ab69 · 2019-01-31T15:03:38.000-08:00
diff --git a/Lib/functools.py b/Lib/functools.py
@@ -541,10 +541,10 @@ def _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo):
     if maxsize == 0:
 
         def wrapper(*args, **kwds):
-            # No caching -- just a statistics update after a successful call
+            # No caching -- just a statistics update
             nonlocal misses
-            result = user_function(*args, **kwds)
             misses += 1
+            result = user_function(*args, **kwds)
             return result
 
     elif maxsize is None:
@@ -557,9 +557,9 @@ def wrapper(*args, **kwds):
             if result is not sentinel:
                 hits += 1
                 return result
+            misses += 1
             result = user_function(*args, **kwds)
             cache[key] = result
-            misses += 1
             return result
 
     else:
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
@@ -796,10 +796,12 @@ lru_cache_make_key(PyObject *args, PyObject *kwds, int typed)
 static PyObject *
 uncached_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds)
 {
-    PyObject *result = PyObject_Call(self->func, args, kwds);
+    PyObject *result;
+
+    self->misses++;
+    result = PyObject_Call(self->func, args, kwds);
     if (!result)
         return NULL;
-    self->misses++;
     return result;
 }
 
@@ -827,6 +829,7 @@ infinite_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwd
         Py_DECREF(key);
         return NULL;
     }
+    self->misses++;
     result = PyObject_Call(self->func, args, kwds);
     if (!result) {
         Py_DECREF(key);
@@ -838,7 +841,6 @@ infinite_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwd
         return NULL;
     }
     Py_DECREF(key);
-    self->misses++;
     return result;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -796,10 +796,12 @@ lru_cache_make_key(PyObject args, PyObject kwds, int typed)`
`796`	`796`	`static PyObject *`
`797`	`797`	`uncached_lru_cache_wrapper(lru_cache_object self, PyObject args, PyObject *kwds)`
`798`	`798`	`{`
`799`		`- PyObject *result = PyObject_Call(self->func, args, kwds);`
	`799`	`+ PyObject *result;`
	`800`	`+`
	`801`	`+ self->misses++;`
	`802`	`+ result = PyObject_Call(self->func, args, kwds);`
`800`	`803`	`if (!result)`
`801`	`804`	`return NULL;`
`802`		`- self->misses++;`
`803`	`805`	`return result;`
`804`	`806`	`}`
`805`	`807`
`@@ -827,6 +829,7 @@ infinite_lru_cache_wrapper(lru_cache_object self, PyObject args, PyObject *kwd`
`827`	`829`	`Py_DECREF(key);`
`828`	`830`	`return NULL;`
`829`	`831`	`}`
	`832`	`+ self->misses++;`
`830`	`833`	`result = PyObject_Call(self->func, args, kwds);`
`831`	`834`	`if (!result) {`
`832`	`835`	`Py_DECREF(key);`
`@@ -838,7 +841,6 @@ infinite_lru_cache_wrapper(lru_cache_object self, PyObject args, PyObject *kwd`
`838`	`841`	`return NULL;`
`839`	`842`	`}`
`840`	`843`	`Py_DECREF(key);`
`841`		`- self->misses++;`
`842`	`844`	`return result;`
`843`	`845`	`}`
`844`	`846`