gh-111262: Add PyDict_Pop() function (#112028)

_PyDict_Pop_KnownHash(): remove the default value and the return type
becomes an int.

Co-authored-by: Stefan Behnel <stefan_ml@behnel.de>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>

Modules/_functoolsmodule.c

@@ -1087,19 +1087,9 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
        The cache dict holds one reference to the link.
        We created one other reference when the link was created.
        The linked list only has borrowed references. */
-    popresult = _PyDict_Pop_KnownHash(self->cache, link->key,
-                                      link->hash, Py_None);
-    if (popresult == Py_None) {
-        /* Getting here means that the user function call or another
-           thread has already removed the old key from the dictionary.
-           This link is now an orphan.  Since we don't want to leave the
-           cache in an inconsistent state, we don't restore the link. */
-        Py_DECREF(popresult);
-        Py_DECREF(link);
-        Py_DECREF(key);
-        return result;
-    }
-    if (popresult == NULL) {
+    int res = _PyDict_Pop_KnownHash((PyDictObject*)self->cache, link->key,
+                                    link->hash, &popresult);
+    if (res < 0) {
         /* An error arose while trying to remove the oldest key (the one
            being evicted) from the cache.  We restore the link to its
            original position as the oldest link.  Then we allow the
@@ -1110,10 +1100,22 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
         Py_DECREF(result);
         return NULL;
     }
+    if (res == 0) {
+        /* Getting here means that the user function call or another
+           thread has already removed the old key from the dictionary.
+           This link is now an orphan.  Since we don't want to leave the
+           cache in an inconsistent state, we don't restore the link. */
+        assert(popresult == NULL);
+        Py_DECREF(link);
+        Py_DECREF(key);
+        return result;
+    }
+
     /* Keep a reference to the old key and old result to prevent their
        ref counts from going to zero during the update. That will
        prevent potentially arbitrary object clean-up code (i.e. __del__)
        from running while we're still adjusting the links. */
+    assert(popresult != NULL);
     oldkey = link->key;
     oldresult = link->result;
 

Modules/_testcapi/dict.c

@@ -331,6 +331,88 @@ dict_mergefromseq2(PyObject *self, PyObject *args)
 }
 
 
+static PyObject *
+dict_pop(PyObject *self, PyObject *args)
+{
+    // Test PyDict_Pop(dict, key, &value)
+    PyObject *dict, *key;
+    if (!PyArg_ParseTuple(args, "OO", &dict, &key)) {
+        return NULL;
+    }
+    NULLABLE(dict);
+    NULLABLE(key);
+    PyObject *result = UNINITIALIZED_PTR;
+    int res = PyDict_Pop(dict, key,  &result);
+    if (res < 0) {
+        assert(result == NULL);
+        return NULL;
+    }
+    if (res == 0) {
+        assert(result == NULL);
+        result = Py_NewRef(Py_None);
+    }
+    else {
+        assert(result != NULL);
+    }
+    return Py_BuildValue("iN", res, result);
+}
+
+
+static PyObject *
+dict_pop_null(PyObject *self, PyObject *args)
+{
+    // Test PyDict_Pop(dict, key, NULL)
+    PyObject *dict, *key;
+    if (!PyArg_ParseTuple(args, "OO", &dict, &key)) {
+        return NULL;
+    }
+    NULLABLE(dict);
+    NULLABLE(key);
+    RETURN_INT(PyDict_Pop(dict, key,  NULL));
+}
+
+
+static PyObject *
+dict_popstring(PyObject *self, PyObject *args)
+{
+    PyObject *dict;
+    const char *key;
+    Py_ssize_t key_size;
+    if (!PyArg_ParseTuple(args, "Oz#", &dict, &key, &key_size)) {
+        return NULL;
+    }
+    NULLABLE(dict);
+    PyObject *result = UNINITIALIZED_PTR;
+    int res = PyDict_PopString(dict, key,  &result);
+    if (res < 0) {
+        assert(result == NULL);
+        return NULL;
+    }
+    if (res == 0) {
+        assert(result == NULL);
+        result = Py_NewRef(Py_None);
+    }
+    else {
+        assert(result != NULL);
+    }
+    return Py_BuildValue("iN", res, result);
+}
+
+
+static PyObject *
+dict_popstring_null(PyObject *self, PyObject *args)
+{
+    PyObject *dict;
+    const char *key;
+    Py_ssize_t key_size;
+    if (!PyArg_ParseTuple(args, "Oz#", &dict, &key, &key_size)) {
+        return NULL;
+    }
+    NULLABLE(dict);
+    RETURN_INT(PyDict_PopString(dict, key,  NULL));
+}
+
+
 static PyMethodDef test_methods[] = {
     {"dict_check", dict_check, METH_O},
     {"dict_checkexact", dict_checkexact, METH_O},
@@ -358,7 +440,10 @@ static PyMethodDef test_methods[] = {
     {"dict_merge", dict_merge, METH_VARARGS},
     {"dict_update", dict_update, METH_VARARGS},
     {"dict_mergefromseq2", dict_mergefromseq2, METH_VARARGS},
-
+    {"dict_pop", dict_pop, METH_VARARGS},
+    {"dict_pop_null", dict_pop_null, METH_VARARGS},
+    {"dict_popstring", dict_popstring, METH_VARARGS},
+    {"dict_popstring_null", dict_popstring_null, METH_VARARGS},
     {NULL},
 };
 

Modules/_threadmodule.c

@@ -967,11 +967,8 @@ local_clear(localobject *self)
         HEAD_UNLOCK(runtime);
         while (tstate) {
             if (tstate->dict) {
-                PyObject *v = _PyDict_Pop(tstate->dict, self->key, Py_None);
-                if (v != NULL) {
-                    Py_DECREF(v);
-                }
-                else {
+                if (PyDict_Pop(tstate->dict, self->key, NULL) < 0) {
+                    // Silently ignore error
                     PyErr_Clear();
                 }
             }

Modules/socketmodule.c

@@ -392,16 +392,10 @@ remove_unusable_flags(PyObject *m)
             break;
         }
         else {
-            PyObject *flag_name = PyUnicode_FromString(win_runtime_flags[i].flag_name);
-            if (flag_name == NULL) {
+            if (PyDict_PopString(dict, win_runtime_flags[i].flag_name,
+                                 NULL) < 0) {
                 return -1;
             }
-            PyObject *v = _PyDict_Pop(dict, flag_name, Py_None);
-            Py_DECREF(flag_name);
-            if (v == NULL) {
-                return -1;
-            }
-            Py_DECREF(v);
         }
     }
     return 0;