Issue #18112: PEP 442 implementation (safe object finalization).
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 6a885cf..6fe5d58 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -190,7 +190,8 @@
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+ | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
bufferediobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@@ -209,6 +210,16 @@
0, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
@@ -220,7 +231,7 @@
int detached;
int readable;
int writable;
- int deallocating;
+ char finalizing;
/* True if this is a vanilla Buffered object (rather than a user derived
class) *and* the raw stream is a vanilla FileIO object. */
@@ -384,8 +395,8 @@
static void
buffered_dealloc(buffered *self)
{
- self->deallocating = 1;
- if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
+ self->finalizing = 1;
+ if (_PyIOBase_finalize((PyObject *) self) < 0)
return;
_PyObject_GC_UNTRACK(self);
self->ok = 0;
@@ -428,8 +439,6 @@
static int
buffered_clear(buffered *self)
{
- if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
- return -1;
self->ok = 0;
Py_CLEAR(self->raw);
Py_CLEAR(self->dict);
@@ -508,7 +517,7 @@
goto end;
}
- if (self->deallocating) {
+ if (self->finalizing) {
PyObject *r = buffered_dealloc_warn(self, (PyObject *) self);
if (r)
Py_DECREF(r);
@@ -1749,6 +1758,7 @@
static PyMemberDef bufferedreader_members[] = {
{"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
+ {"_finalizing", T_BOOL, offsetof(buffered, finalizing), 0},
{NULL}
};
@@ -1781,7 +1791,7 @@
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
bufferedreader_doc, /* tp_doc */
(traverseproc)buffered_traverse, /* tp_traverse */
(inquiry)buffered_clear, /* tp_clear */
@@ -1800,6 +1810,16 @@
(initproc)bufferedreader_init, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
@@ -2130,6 +2150,7 @@
static PyMemberDef bufferedwriter_members[] = {
{"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
+ {"_finalizing", T_BOOL, offsetof(buffered, finalizing), 0},
{NULL}
};
@@ -2162,7 +2183,7 @@
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
bufferedwriter_doc, /* tp_doc */
(traverseproc)buffered_traverse, /* tp_traverse */
(inquiry)buffered_clear, /* tp_clear */
@@ -2181,6 +2202,16 @@
(initproc)bufferedwriter_init, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
@@ -2416,7 +2447,7 @@
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /* tp_flags */
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
bufferedrwpair_doc, /* tp_doc */
(traverseproc)bufferedrwpair_traverse, /* tp_traverse */
(inquiry)bufferedrwpair_clear, /* tp_clear */
@@ -2435,6 +2466,16 @@
(initproc)bufferedrwpair_init, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
@@ -2522,6 +2563,7 @@
static PyMemberDef bufferedrandom_members[] = {
{"raw", T_OBJECT, offsetof(buffered, raw), READONLY},
+ {"_finalizing", T_BOOL, offsetof(buffered, finalizing), 0},
{NULL}
};
@@ -2554,7 +2596,7 @@
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
bufferedrandom_doc, /* tp_doc */
(traverseproc)buffered_traverse, /* tp_traverse */
(inquiry)buffered_clear, /* tp_clear */
@@ -2573,4 +2615,14 @@
(initproc)bufferedrandom_init, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 5280991..e88ae87 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -51,7 +51,7 @@
unsigned int writable : 1;
signed int seekable : 2; /* -1 means unknown */
unsigned int closefd : 1;
- unsigned int deallocating: 1;
+ char finalizing;
PyObject *weakreflist;
PyObject *dict;
} fileio;
@@ -128,7 +128,7 @@
self->fd = -1;
Py_RETURN_NONE;
}
- if (self->deallocating) {
+ if (self->finalizing) {
PyObject *r = fileio_dealloc_warn(self, (PyObject *) self);
if (r)
Py_DECREF(r);
@@ -447,7 +447,7 @@
static void
fileio_dealloc(fileio *self)
{
- self->deallocating = 1;
+ self->finalizing = 1;
if (_PyIOBase_finalize((PyObject *) self) < 0)
return;
_PyObject_GC_UNTRACK(self);
@@ -1182,6 +1182,11 @@
{NULL},
};
+static PyMemberDef fileio_members[] = {
+ {"_finalizing", T_BOOL, offsetof(fileio, finalizing), 0},
+ {NULL}
+};
+
PyTypeObject PyFileIO_Type = {
PyVarObject_HEAD_INIT(NULL, 0)
"_io.FileIO",
@@ -1203,7 +1208,7 @@
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /* tp_flags */
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
fileio_doc, /* tp_doc */
(traverseproc)fileio_traverse, /* tp_traverse */
(inquiry)fileio_clear, /* tp_clear */
@@ -1212,7 +1217,7 @@
0, /* tp_iter */
0, /* tp_iternext */
fileio_methods, /* tp_methods */
- 0, /* tp_members */
+ fileio_members, /* tp_members */
fileio_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
@@ -1223,4 +1228,13 @@
PyType_GenericAlloc, /* tp_alloc */
fileio_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index e38473a..a4f2c0e 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -196,21 +196,17 @@
/* Finalization and garbage collection support */
-int
-_PyIOBase_finalize(PyObject *self)
+static void
+iobase_finalize(PyObject *self)
{
PyObject *res;
- PyObject *tp, *v, *tb;
- int closed = 1;
- int is_zombie;
+ PyObject *error_type, *error_value, *error_traceback;
+ int closed;
+ _Py_IDENTIFIER(_finalizing);
- /* If _PyIOBase_finalize() is called from a destructor, we need to
- resurrect the object as calling close() can invoke arbitrary code. */
- is_zombie = (Py_REFCNT(self) == 0);
- if (is_zombie) {
- ++Py_REFCNT(self);
- }
- PyErr_Fetch(&tp, &v, &tb);
+ /* Save the current exception, if any. */
+ PyErr_Fetch(&error_type, &error_value, &error_traceback);
+
/* If `closed` doesn't exist or can't be evaluated as bool, then the
object is probably in an unusable state, so ignore. */
res = PyObject_GetAttr(self, _PyIO_str_closed);
@@ -223,6 +219,10 @@
PyErr_Clear();
}
if (closed == 0) {
+ /* Signal close() that it was called as part of the object
+ finalization process. */
+ if (_PyObject_SetAttrId(self, &PyId__finalizing, Py_True))
+ PyErr_Clear();
res = PyObject_CallMethodObjArgs((PyObject *) self, _PyIO_str_close,
NULL);
/* Silencing I/O errors is bad, but printing spurious tracebacks is
@@ -233,31 +233,25 @@
else
Py_DECREF(res);
}
- PyErr_Restore(tp, v, tb);
- if (is_zombie) {
- if (--Py_REFCNT(self) != 0) {
- /* The object lives again. The following code is taken from
- slot_tp_del in typeobject.c. */
- Py_ssize_t refcnt = Py_REFCNT(self);
- _Py_NewReference(self);
- Py_REFCNT(self) = refcnt;
- /* 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;
- }
+
+ /* Restore the saved exception. */
+ PyErr_Restore(error_type, error_value, error_traceback);
+}
+
+int
+_PyIOBase_finalize(PyObject *self)
+{
+ int is_zombie;
+
+ /* If _PyIOBase_finalize() is called from a destructor, we need to
+ resurrect the object as calling close() can invoke arbitrary code. */
+ is_zombie = (Py_REFCNT(self) == 0);
+ if (is_zombie)
+ return PyObject_CallFinalizerFromDealloc(self);
+ else {
+ PyObject_CallFinalizer(self);
+ return 0;
}
- return 0;
}
static int
@@ -270,8 +264,6 @@
static int
iobase_clear(iobase *self)
{
- if (_PyIOBase_finalize((PyObject *) self) < 0)
- return -1;
Py_CLEAR(self->dict);
return 0;
}
@@ -741,7 +733,7 @@
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
iobase_doc, /* tp_doc */
(traverseproc)iobase_traverse, /* tp_traverse */
(inquiry)iobase_clear, /* tp_clear */
@@ -760,6 +752,16 @@
0, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ (destructor)iobase_finalize, /* tp_finalize */
};
@@ -905,7 +907,7 @@
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
rawiobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@@ -924,4 +926,14 @@
0, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 283411b..5d2438d 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -173,7 +173,8 @@
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+ | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
textiobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@@ -192,6 +193,16 @@
0, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
@@ -691,7 +702,7 @@
char seekable;
char has_read1;
char telling;
- char deallocating;
+ char finalizing;
/* Specialized encoding func (see below) */
encodefunc_t encodefunc;
/* Whether or not it's the start of the stream */
@@ -1112,8 +1123,6 @@
static int
_textiowrapper_clear(textio *self)
{
- if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
- return -1;
self->ok = 0;
Py_CLEAR(self->buffer);
Py_CLEAR(self->encoding);
@@ -1131,9 +1140,10 @@
static void
textiowrapper_dealloc(textio *self)
{
- self->deallocating = 1;
- if (_textiowrapper_clear(self) < 0)
+ self->finalizing = 1;
+ if (_PyIOBase_finalize((PyObject *) self) < 0)
return;
+ _textiowrapper_clear(self);
_PyObject_GC_UNTRACK(self);
if (self->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *)self);
@@ -2573,7 +2583,7 @@
}
else {
PyObject *exc = NULL, *val, *tb;
- if (self->deallocating) {
+ if (self->finalizing) {
res = _PyObject_CallMethodId(self->buffer, &PyId__dealloc_warn, "O", self);
if (res)
Py_DECREF(res);
@@ -2734,6 +2744,7 @@
{"encoding", T_OBJECT, offsetof(textio, encoding), READONLY},
{"buffer", T_OBJECT, offsetof(textio, buffer), READONLY},
{"line_buffering", T_BOOL, offsetof(textio, line_buffering), READONLY},
+ {"_finalizing", T_BOOL, offsetof(textio, finalizing), 0},
{NULL}
};
@@ -2770,7 +2781,7 @@
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
textiowrapper_doc, /* tp_doc */
(traverseproc)textiowrapper_traverse, /* tp_traverse */
(inquiry)textiowrapper_clear, /* tp_clear */
@@ -2789,4 +2800,14 @@
(initproc)textiowrapper_init, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
+ 0, /* tp_free */
+ 0, /* tp_is_gc */
+ 0, /* tp_bases */
+ 0, /* tp_mro */
+ 0, /* tp_cache */
+ 0, /* tp_subclasses */
+ 0, /* tp_weaklist */
+ 0, /* tp_del */
+ 0, /* tp_version_tag */
+ 0, /* tp_finalize */
};
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 9463227..6527a53 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -2491,6 +2491,85 @@
return Py_BuildValue("Nl", _PyLong_FromTime_t(sec), nsec);
}
+static void
+slot_tp_del(PyObject *self)
+{
+ _Py_IDENTIFIER(__tp_del__);
+ PyObject *del, *res;
+ PyObject *error_type, *error_value, *error_traceback;
+
+ /* 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);
+
+ /* Execute __del__ method, if any. */
+ del = _PyObject_LookupSpecial(self, &PyId___tp_del__);
+ if (del != NULL) {
+ res = PyEval_CallObject(del, NULL);
+ if (res == NULL)
+ PyErr_WriteUnraisable(del);
+ else
+ Py_DECREF(res);
+ Py_DECREF(del);
+ }
+
+ /* 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 */
+
+ /* __del__ 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
+}
+
+static PyObject *
+with_tp_del(PyObject *self, PyObject *args)
+{
+ PyObject *obj;
+ PyTypeObject *tp;
+
+ if (!PyArg_ParseTuple(args, "O:with_tp_del", &obj))
+ return NULL;
+ tp = (PyTypeObject *) obj;
+ if (!PyType_Check(obj) || !PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE)) {
+ PyErr_Format(PyExc_TypeError,
+ "heap type expected, got %R", obj);
+ return NULL;
+ }
+ tp->tp_del = slot_tp_del;
+ Py_INCREF(obj);
+ return obj;
+}
+
static PyObject *
_test_incref(PyObject *ob)
{
@@ -2789,6 +2868,7 @@
{"pytime_object_to_time_t", test_pytime_object_to_time_t, METH_VARARGS},
{"pytime_object_to_timeval", test_pytime_object_to_timeval, METH_VARARGS},
{"pytime_object_to_timespec", test_pytime_object_to_timespec, METH_VARARGS},
+ {"with_tp_del", with_tp_del, METH_VARARGS},
{"test_pymem",
(PyCFunction)test_pymem_alloc0, METH_NOARGS},
{"test_pymem_alloc0",
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index d96d2c7..dac7feb 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -223,10 +223,10 @@
#define GC_REACHABLE _PyGC_REFS_REACHABLE
#define GC_TENTATIVELY_UNREACHABLE _PyGC_REFS_TENTATIVELY_UNREACHABLE
-#define IS_TRACKED(o) ((AS_GC(o))->gc.gc_refs != GC_UNTRACKED)
-#define IS_REACHABLE(o) ((AS_GC(o))->gc.gc_refs == GC_REACHABLE)
+#define IS_TRACKED(o) (_PyGC_REFS(o) != GC_UNTRACKED)
+#define IS_REACHABLE(o) (_PyGC_REFS(o) == GC_REACHABLE)
#define IS_TENTATIVELY_UNREACHABLE(o) ( \
- (AS_GC(o))->gc.gc_refs == GC_TENTATIVELY_UNREACHABLE)
+ _PyGC_REFS(o) == GC_TENTATIVELY_UNREACHABLE)
/*** list functions ***/
@@ -341,8 +341,8 @@
{
PyGC_Head *gc = containers->gc.gc_next;
for (; gc != containers; gc = gc->gc.gc_next) {
- assert(gc->gc.gc_refs == GC_REACHABLE);
- gc->gc.gc_refs = Py_REFCNT(FROM_GC(gc));
+ assert(_PyGCHead_REFS(gc) == GC_REACHABLE);
+ _PyGCHead_SET_REFS(gc, Py_REFCNT(FROM_GC(gc)));
/* Python's cyclic gc should never see an incoming refcount
* of 0: if something decref'ed to 0, it should have been
* deallocated immediately at that time.
@@ -361,7 +361,7 @@
* so serious that maybe this should be a release-build
* check instead of an assert?
*/
- assert(gc->gc.gc_refs != 0);
+ assert(_PyGCHead_REFS(gc) != 0);
}
}
@@ -376,9 +376,9 @@
* generation being collected, which can be recognized
* because only they have positive gc_refs.
*/
- assert(gc->gc.gc_refs != 0); /* else refcount was too small */
- if (gc->gc.gc_refs > 0)
- gc->gc.gc_refs--;
+ assert(_PyGCHead_REFS(gc) != 0); /* else refcount was too small */
+ if (_PyGCHead_REFS(gc) > 0)
+ _PyGCHead_DECREF(gc);
}
return 0;
}
@@ -407,7 +407,7 @@
{
if (PyObject_IS_GC(op)) {
PyGC_Head *gc = AS_GC(op);
- const Py_ssize_t gc_refs = gc->gc.gc_refs;
+ const Py_ssize_t gc_refs = _PyGCHead_REFS(gc);
if (gc_refs == 0) {
/* This is in move_unreachable's 'young' list, but
@@ -415,7 +415,7 @@
* we need to do is tell move_unreachable that it's
* reachable.
*/
- gc->gc.gc_refs = 1;
+ _PyGCHead_SET_REFS(gc, 1);
}
else if (gc_refs == GC_TENTATIVELY_UNREACHABLE) {
/* This had gc_refs = 0 when move_unreachable got
@@ -425,7 +425,7 @@
* again.
*/
gc_list_move(gc, reachable);
- gc->gc.gc_refs = 1;
+ _PyGCHead_SET_REFS(gc, 1);
}
/* Else there's nothing to do.
* If gc_refs > 0, it must be in move_unreachable's 'young'
@@ -469,7 +469,7 @@
while (gc != young) {
PyGC_Head *next;
- if (gc->gc.gc_refs) {
+ if (_PyGCHead_REFS(gc)) {
/* gc is definitely reachable from outside the
* original 'young'. Mark it as such, and traverse
* its pointers to find any other objects that may
@@ -480,8 +480,8 @@
*/
PyObject *op = FROM_GC(gc);
traverseproc traverse = Py_TYPE(op)->tp_traverse;
- assert(gc->gc.gc_refs > 0);
- gc->gc.gc_refs = GC_REACHABLE;
+ assert(_PyGCHead_REFS(gc) > 0);
+ _PyGCHead_SET_REFS(gc, GC_REACHABLE);
(void) traverse(op,
(visitproc)visit_reachable,
(void *)young);
@@ -500,7 +500,7 @@
*/
next = gc->gc.gc_next;
gc_list_move(gc, unreachable);
- gc->gc.gc_refs = GC_TENTATIVELY_UNREACHABLE;
+ _PyGCHead_SET_REFS(gc, GC_TENTATIVELY_UNREACHABLE);
}
gc = next;
}
@@ -520,22 +520,19 @@
}
}
-/* Return true if object has a finalization method. */
+/* Return true if object has a pre-PEP 442 finalization method. */
static int
-has_finalizer(PyObject *op)
+has_legacy_finalizer(PyObject *op)
{
- if (PyGen_CheckExact(op))
- return PyGen_NeedsFinalizing((PyGenObject *)op);
- else
- return op->ob_type->tp_del != NULL;
+ return op->ob_type->tp_del != NULL;
}
-/* Move the objects in unreachable with __del__ methods into `finalizers`.
+/* Move the objects in unreachable with tp_del slots into `finalizers`.
* Objects moved into `finalizers` have gc_refs set to GC_REACHABLE; the
* objects remaining in unreachable are left at GC_TENTATIVELY_UNREACHABLE.
*/
static void
-move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
+move_legacy_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
{
PyGC_Head *gc;
PyGC_Head *next;
@@ -549,14 +546,14 @@
assert(IS_TENTATIVELY_UNREACHABLE(op));
next = gc->gc.gc_next;
- if (has_finalizer(op)) {
+ if (has_legacy_finalizer(op)) {
gc_list_move(gc, finalizers);
- gc->gc.gc_refs = GC_REACHABLE;
+ _PyGCHead_SET_REFS(gc, GC_REACHABLE);
}
}
}
-/* A traversal callback for move_finalizer_reachable. */
+/* A traversal callback for move_legacy_finalizer_reachable. */
static int
visit_move(PyObject *op, PyGC_Head *tolist)
{
@@ -564,7 +561,7 @@
if (IS_TENTATIVELY_UNREACHABLE(op)) {
PyGC_Head *gc = AS_GC(op);
gc_list_move(gc, tolist);
- gc->gc.gc_refs = GC_REACHABLE;
+ _PyGCHead_SET_REFS(gc, GC_REACHABLE);
}
}
return 0;
@@ -574,7 +571,7 @@
* into finalizers set.
*/
static void
-move_finalizer_reachable(PyGC_Head *finalizers)
+move_legacy_finalizer_reachable(PyGC_Head *finalizers)
{
traverseproc traverse;
PyGC_Head *gc = finalizers->gc.gc_next;
@@ -747,7 +744,7 @@
msg, Py_TYPE(op)->tp_name, op);
}
-/* Handle uncollectable garbage (cycles with finalizers, and stuff reachable
+/* Handle uncollectable garbage (cycles with tp_del slots, and stuff reachable
* only from such cycles).
* If DEBUG_SAVEALL, all objects in finalizers are appended to the module
* garbage list (a Python list), else only the objects in finalizers with
@@ -757,7 +754,7 @@
* The finalizers list is made empty on a successful return.
*/
static int
-handle_finalizers(PyGC_Head *finalizers, PyGC_Head *old)
+handle_legacy_finalizers(PyGC_Head *finalizers, PyGC_Head *old)
{
PyGC_Head *gc = finalizers->gc.gc_next;
@@ -769,7 +766,7 @@
for (; gc != finalizers; gc = gc->gc.gc_next) {
PyObject *op = FROM_GC(gc);
- if ((debug & DEBUG_SAVEALL) || has_finalizer(op)) {
+ if ((debug & DEBUG_SAVEALL) || has_legacy_finalizer(op)) {
if (PyList_Append(garbage, op) < 0)
return -1;
}
@@ -779,6 +776,62 @@
return 0;
}
+static void
+finalize_garbage(PyGC_Head *collectable, PyGC_Head *old)
+{
+ destructor finalize;
+ PyGC_Head *gc = collectable->gc.gc_next;
+
+ for (; gc != collectable; gc = gc->gc.gc_next) {
+ PyObject *op = FROM_GC(gc);
+
+ if (!_PyGCHead_FINALIZED(gc) &&
+ PyType_HasFeature(Py_TYPE(op), Py_TPFLAGS_HAVE_FINALIZE) &&
+ (finalize = Py_TYPE(op)->tp_finalize) != NULL) {
+ _PyGCHead_SET_FINALIZED(gc, 1);
+ Py_INCREF(op);
+ finalize(op);
+ if (Py_REFCNT(op) == 1) {
+ /* op will be destroyed */
+ gc = gc->gc.gc_prev;
+ }
+ Py_DECREF(op);
+ }
+ }
+}
+
+/* Walk the collectable list and check that they are really unreachable
+ from the outside (some objects could have been resurrected by a
+ finalizer). */
+static int
+check_garbage(PyGC_Head *collectable)
+{
+ PyGC_Head *gc;
+ for (gc = collectable->gc.gc_next; gc != collectable;
+ gc = gc->gc.gc_next) {
+ _PyGCHead_SET_REFS(gc, Py_REFCNT(FROM_GC(gc)));
+ assert(_PyGCHead_REFS(gc) != 0);
+ }
+ subtract_refs(collectable);
+ for (gc = collectable->gc.gc_next; gc != collectable;
+ gc = gc->gc.gc_next) {
+ assert(_PyGCHead_REFS(gc) >= 0);
+ if (_PyGCHead_REFS(gc) != 0)
+ return -1;
+ }
+ return 0;
+}
+
+static void
+revive_garbage(PyGC_Head *collectable)
+{
+ PyGC_Head *gc;
+ for (gc = collectable->gc.gc_next; gc != collectable;
+ gc = gc->gc.gc_next) {
+ _PyGCHead_SET_REFS(gc, GC_REACHABLE);
+ }
+}
+
/* Break reference cycles by clearing the containers involved. This is
* tricky business as the lists can be changing and we don't know which
* objects may be freed. It is possible I screwed something up here.
@@ -792,7 +845,6 @@
PyGC_Head *gc = collectable->gc.gc_next;
PyObject *op = FROM_GC(gc);
- assert(IS_TENTATIVELY_UNREACHABLE(op));
if (debug & DEBUG_SAVEALL) {
PyList_Append(garbage, op);
}
@@ -806,7 +858,7 @@
if (collectable->gc.gc_next == gc) {
/* object is still alive, move it, it may die later */
gc_list_move(gc, old);
- gc->gc.gc_refs = GC_REACHABLE;
+ _PyGCHead_SET_REFS(gc, GC_REACHABLE);
}
}
}
@@ -929,19 +981,15 @@
}
/* All objects in unreachable are trash, but objects reachable from
- * finalizers can't safely be deleted. Python programmers should take
- * care not to create such things. For Python, finalizers means
- * instance objects with __del__ methods. Weakrefs with callbacks
- * can also call arbitrary Python code but they will be dealt with by
- * handle_weakrefs().
+ * legacy finalizers (e.g. tp_del) can't safely be deleted.
*/
gc_list_init(&finalizers);
- move_finalizers(&unreachable, &finalizers);
- /* finalizers contains the unreachable objects with a finalizer;
+ move_legacy_finalizers(&unreachable, &finalizers);
+ /* finalizers contains the unreachable objects with a legacy finalizer;
* unreachable objects reachable *from* those are also uncollectable,
* and we move those into the finalizers list too.
*/
- move_finalizer_reachable(&finalizers);
+ move_legacy_finalizer_reachable(&finalizers);
/* Collect statistics on collectable objects found and print
* debugging information.
@@ -957,11 +1005,20 @@
/* Clear weakrefs and invoke callbacks as necessary. */
m += handle_weakrefs(&unreachable, old);
- /* Call tp_clear on objects in the unreachable set. This will cause
- * the reference cycles to be broken. It may also cause some objects
- * in finalizers to be freed.
- */
- delete_garbage(&unreachable, old);
+ /* Call tp_finalize on objects which have one. */
+ finalize_garbage(&unreachable, old);
+
+ if (check_garbage(&unreachable)) {
+ revive_garbage(&unreachable);
+ gc_list_merge(&unreachable, old);
+ }
+ else {
+ /* Call tp_clear on objects in the unreachable set. This will cause
+ * the reference cycles to be broken. It may also cause some objects
+ * in finalizers to be freed.
+ */
+ delete_garbage(&unreachable, old);
+ }
/* Collect statistics on uncollectable objects found and print
* debugging information. */
@@ -992,7 +1049,7 @@
* reachable list of garbage. The programmer has to deal with
* this if they insist on creating this type of structure.
*/
- (void)handle_finalizers(&finalizers, old);
+ (void)handle_legacy_finalizers(&finalizers, old);
/* Clear free list only during the collection of the highest
* generation */
@@ -1662,7 +1719,8 @@
sizeof(PyGC_Head) + basicsize);
if (g == NULL)
return PyErr_NoMemory();
- g->gc.gc_refs = GC_UNTRACKED;
+ g->gc.gc_refs = 0;
+ _PyGCHead_SET_REFS(g, GC_UNTRACKED);
generations[0].count++; /* number of allocated GC objects */
if (generations[0].count > generations[0].threshold &&
enabled &&