Issue #18112: PEP 442 implementation (safe object finalization).

1 files changed, 32 insertions, 71 deletions

diff --git a/Objects/genobject.c b/Objects/genobject.c
index 016bfa2975..dfd90aa4b1 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -16,6 +16,31 @@ gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
 }
 
 static void
+gen_finalize(PyObject *self)
+{
+    PyGenObject *gen = (PyGenObject *)self;
+    PyObject *res;
+    PyObject *error_type, *error_value, *error_traceback;
+
+    if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)
+        /* Generator isn't paused, so no need to close */
+        return;
+
+    /* Save the current exception, if any. */
+    PyErr_Fetch(&error_type, &error_value, &error_traceback);
+
+    res = gen_close(gen, NULL);
+
+    if (res == NULL)
+        PyErr_WriteUnraisable(self);
+    else
+        Py_DECREF(res);
+
+    /* Restore the saved exception. */
+    PyErr_Restore(error_type, error_value, error_traceback);
+}
+
+static void
 gen_dealloc(PyGenObject *gen)
 {
     PyObject *self = (PyObject *) gen;
@@ -27,12 +52,8 @@ gen_dealloc(PyGenObject *gen)
 
     _PyObject_GC_TRACK(self);
 
-    if (gen->gi_frame != NULL && gen->gi_frame->f_stacktop != NULL) {
-        /* Generator is paused, so we need to close */
-        Py_TYPE(gen)->tp_del(self);
-        if (self->ob_refcnt > 0)
-            return;                     /* resurrected.  :( */
-    }
+    if (PyObject_CallFinalizerFromDealloc(self))
+        return;                     /* resurrected.  :( */
 
     _PyObject_GC_UNTRACK(self);
     Py_CLEAR(gen->gi_frame);
@@ -40,7 +61,6 @@ gen_dealloc(PyGenObject *gen)
     PyObject_GC_Del(gen);
 }
 
-
 static PyObject *
 gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
 {
@@ -222,68 +242,6 @@ gen_close(PyGenObject *gen, PyObject *args)
     return NULL;
 }
 
-static void
-gen_del(PyObject *self)
-{
-    PyObject *res;
-    PyObject *error_type, *error_value, *error_traceback;
-    PyGenObject *gen = (PyGenObject *)self;
-
-    if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)
-        /* Generator isn't paused, so no need to close */
-        return;
-
-    /* Temporarily resurrect the object. */
-    assert(self->ob_refcnt == 0);
-    self->ob_refcnt = 1;
-
-    /* Save the current exception, if any. */
-    PyErr_Fetch(&error_type, &error_value, &error_traceback);
-
-    res = gen_close(gen, NULL);
-
-    if (res == NULL)
-        PyErr_WriteUnraisable(self);
-    else
-        Py_DECREF(res);
-
-    /* Restore the saved exception. */
-    PyErr_Restore(error_type, error_value, error_traceback);
-
-    /* Undo the temporary resurrection; can't use DECREF here, it would
-     * cause a recursive call.
-     */
-    assert(self->ob_refcnt > 0);
-    if (--self->ob_refcnt == 0)
-        return; /* this is the normal path out */
-
-    /* close() resurrected it!  Make it look like the original Py_DECREF
-     * never happened.
-     */
-    {
-        Py_ssize_t refcnt = self->ob_refcnt;
-        _Py_NewReference(self);
-        self->ob_refcnt = refcnt;
-    }
-    assert(PyType_IS_GC(Py_TYPE(self)) &&
-           _Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);
-
-    /* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
-     * we need to undo that. */
-    _Py_DEC_REFTOTAL;
-    /* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
-     * chain, so no more to do there.
-     * If COUNT_ALLOCS, the original decref bumped tp_frees, and
-     * _Py_NewReference bumped tp_allocs:  both of those need to be
-     * undone.
-     */
-#ifdef COUNT_ALLOCS
-    --(Py_TYPE(self)->tp_frees);
-    --(Py_TYPE(self)->tp_allocs);
-#endif
-}
-
-
 
 PyDoc_STRVAR(throw_doc,
 "throw(typ[,val[,tb]]) -> raise exception in generator,\n\
@@ -517,7 +475,8 @@ PyTypeObject PyGen_Type = {
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+        Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)gen_traverse,                 /* tp_traverse */
     0,                                          /* tp_clear */
@@ -544,7 +503,9 @@ PyTypeObject PyGen_Type = {
     0,                                          /* tp_cache */
     0,                                          /* tp_subclasses */
     0,                                          /* tp_weaklist */
-    gen_del,                                    /* tp_del */
+    0,                                          /* tp_del */
+    0,                                          /* tp_version_tag */
+    gen_finalize,                               /* tp_finalize */
 };
 
 PyObject *