pythongh-120974: Make _asyncio._leave_task atomic in the free-threaded build

Update `_PyDict_DelItemIf` to allow for an argument to be passed to the
predicate.

Author: colesbury

Include/internal/pycore_dict.h

@@ -14,8 +14,10 @@ extern "C" {
 // Unsafe flavor of PyDict_GetItemWithError(): no error checking
 extern PyObject* _PyDict_GetItemWithError(PyObject *dp, PyObject *key);
 
-extern int _PyDict_DelItemIf(PyObject *mp, PyObject *key,
-                             int (*predicate)(PyObject *value));
+// Export for '_asyncio' shared extension
+PyAPI_FUNC(int) _PyDict_DelItemIf(PyObject *mp, PyObject *key,
+                                  int (*predicate)(PyObject *value, void *arg),
+                                  void *arg);
 
 // "KnownHash" variants
 // Export for '_asyncio' shared extension

Modules/_asynciomodule.c

@@ -2031,18 +2031,9 @@ enter_task(asyncio_state *state, PyObject *loop, PyObject *task)
     return _PyDict_SetItem_KnownHash(state->current_tasks, loop, task, hash);
 }
 
-
 static int
-leave_task(asyncio_state *state, PyObject *loop, PyObject *task)
-/*[clinic end generated code: output=0ebf6db4b858fb41 input=51296a46313d1ad8]*/
+leave_task_predicate(PyObject *item, void *task)
 {
-    PyObject *item;
-    Py_hash_t hash;
-    hash = PyObject_Hash(loop);
-    if (hash == -1) {
-        return -1;
-    }
-    item = _PyDict_GetItem_KnownHash(state->current_tasks, loop, hash);
     if (item != task) {
         if (item == NULL) {
             /* Not entered, replace with None */
@@ -2054,7 +2045,15 @@ leave_task(asyncio_state *state, PyObject *loop, PyObject *task)
             task, item, NULL);
         return -1;
     }
-    return _PyDict_DelItem_KnownHash(state->current_tasks, loop, hash);
+    return 1;
+}
+
+static int
+leave_task(asyncio_state *state, PyObject *loop, PyObject *task)
+/*[clinic end generated code: output=0ebf6db4b858fb41 input=51296a46313d1ad8]*/
+{
+    return _PyDict_DelItemIf(state->current_tasks, loop, leave_task_predicate,
+                             task);
 }
 
 static PyObject *

Modules/_weakref.c

@@ -31,7 +31,7 @@ _weakref_getweakrefcount_impl(PyObject *module, PyObject *object)
 
 
 static int
-is_dead_weakref(PyObject *value)
+is_dead_weakref(PyObject *value, void *unused)
 {
     if (!PyWeakref_Check(value)) {
         PyErr_SetString(PyExc_TypeError, "not a weakref");
@@ -56,15 +56,8 @@ _weakref__remove_dead_weakref_impl(PyObject *module, PyObject *dct,
                                    PyObject *key)
 /*[clinic end generated code: output=d9ff53061fcb875c input=19fc91f257f96a1d]*/
 {
-    if (_PyDict_DelItemIf(dct, key, is_dead_weakref) < 0) {
-        if (PyErr_ExceptionMatches(PyExc_KeyError))
-            /* This function is meant to allow safe weak-value dicts
-               with GC in another thread (see issue #28427), so it's
-               ok if the key doesn't exist anymore.
-               */
-            PyErr_Clear();
-        else
-            return NULL;
+    if (_PyDict_DelItemIf(dct, key, is_dead_weakref, NULL) < 0) {
+        return NULL;
     }
     Py_RETURN_NONE;
 }

Objects/dictobject.c

@@ -2608,7 +2608,8 @@ _PyDict_DelItem_KnownHash(PyObject *op, PyObject *key, Py_hash_t hash)
 
 static int
 delitemif_lock_held(PyObject *op, PyObject *key,
-                    int (*predicate)(PyObject *value))
+                    int (*predicate)(PyObject *value, void *arg),
+                    void *arg)
 {
     Py_ssize_t ix;
     PyDictObject *mp;
@@ -2618,10 +2619,6 @@ delitemif_lock_held(PyObject *op, PyObject *key,
 
     ASSERT_DICT_LOCKED(op);
 
-    if (!PyDict_Check(op)) {
-        PyErr_BadInternalCall();
-        return -1;
-    }
     assert(key);
     hash = PyObject_Hash(key);
     if (hash == -1)
@@ -2630,12 +2627,8 @@ delitemif_lock_held(PyObject *op, PyObject *key,
     ix = _Py_dict_lookup(mp, key, hash, &old_value);
     if (ix == DKIX_ERROR)
         return -1;
-    if (ix == DKIX_EMPTY || old_value == NULL) {
-        _PyErr_SetKeyError(key);
-        return -1;
-    }
 
-    res = predicate(old_value);
+    res = predicate(old_value, arg);
     if (res == -1)
         return -1;
 
@@ -2655,11 +2648,16 @@ delitemif_lock_held(PyObject *op, PyObject *key,
  */
 int
 _PyDict_DelItemIf(PyObject *op, PyObject *key,
-                  int (*predicate)(PyObject *value))
+                  int (*predicate)(PyObject *value, void *arg),
+                  void *arg)
 {
+    if (!PyDict_Check(op)) {
+        PyErr_BadInternalCall();
+        return -1;
+    }
     int res;
     Py_BEGIN_CRITICAL_SECTION(op);
-    res = delitemif_lock_held(op, key, predicate);
+    res = delitemif_lock_held(op, key, predicate, arg);
     Py_END_CRITICAL_SECTION();
     return res;
 }