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

[Raymond Hettinger]

https://github.com/python/cpython/commit/ffdf1c30ab6940a5efe6f33e61678021d9fd14b6
commit: ffdf1c30ab6940a5efe6f33e61678021d9fd14b6
branch: master
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-01-31T15:03:38-08:00
summary:

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

files:
M Lib/functools.py
M Modules/_functoolsmodule.c

diff --git a/Lib/functools.py b/Lib/functools.py
index 6233c30c203e..fe47600caa1a 100644
--- 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
index 141210204ca5..d72aaff2b13c 100644
--- 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;
 }