Issue #18112: PEP 442 implementation (safe object finalization).
diff --git a/Objects/object.c b/Objects/object.c
index 47d3ebd..c83109d 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -255,6 +255,72 @@
return PyObject_INIT_VAR(op, tp, nitems);
}
+void
+PyObject_CallFinalizer(PyObject *self)
+{
+ PyTypeObject *tp = Py_TYPE(self);
+
+ /* The former could happen on heaptypes created from the C API, e.g.
+ PyType_FromSpec(). */
+ if (!PyType_HasFeature(tp, Py_TPFLAGS_HAVE_FINALIZE) ||
+ tp->tp_finalize == NULL)
+ return;
+ /* tp_finalize should only be called once. */
+ if (PyType_IS_GC(tp) && _PyGC_FINALIZED(self))
+ return;
+
+ tp->tp_finalize(self);
+ if (PyType_IS_GC(tp))
+ _PyGC_SET_FINALIZED(self, 1);
+}
+
+int
+PyObject_CallFinalizerFromDealloc(PyObject *self)
+{
+ Py_ssize_t refcnt;
+
+ /* Temporarily resurrect the object. */
+ if (self->ob_refcnt != 0) {
+ Py_FatalError("PyObject_CallFinalizerFromDealloc called on "
+ "object with a non-zero refcount");
+ }
+ self->ob_refcnt = 1;
+
+ PyObject_CallFinalizer(self);
+
+ /* 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 0; /* this is the normal path out */
+
+ /* tp_finalize resurrected it! Make it look like the original Py_DECREF
+ * never happened.
+ */
+ refcnt = self->ob_refcnt;
+ _Py_NewReference(self);
+ self->ob_refcnt = refcnt;
+
+ if (PyType_IS_GC(Py_TYPE(self))) {
+ assert(_PyGC_REFS(self) != _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
+ return -1;
+}
+
int
PyObject_Print(PyObject *op, FILE *fp, int flags)
{
@@ -1981,7 +2047,7 @@
_PyTrash_deposit_object(PyObject *op)
{
assert(PyObject_IS_GC(op));
- assert(_Py_AS_GC(op)->gc.gc_refs == _PyGC_REFS_UNTRACKED);
+ assert(_PyGC_REFS(op) == _PyGC_REFS_UNTRACKED);
assert(op->ob_refcnt == 0);
_Py_AS_GC(op)->gc.gc_prev = (PyGC_Head *)_PyTrash_delete_later;
_PyTrash_delete_later = op;
@@ -1993,7 +2059,7 @@
{
PyThreadState *tstate = PyThreadState_GET();
assert(PyObject_IS_GC(op));
- assert(_Py_AS_GC(op)->gc.gc_refs == _PyGC_REFS_UNTRACKED);
+ assert(_PyGC_REFS(op) == _PyGC_REFS_UNTRACKED);
assert(op->ob_refcnt == 0);
_Py_AS_GC(op)->gc.gc_prev = (PyGC_Head *) tstate->trash_delete_later;
tstate->trash_delete_later = op;