Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

Appearance settings

gh-103743: Add PyUnstable_Object_GC_NewWithExtraData #103744

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 9 commits into from
May 2, 2023
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 20 additions & 1 deletion 21 Doc/c-api/gcsupport.rst
Original file line number Diff line number Diff line change
Expand Up @@ -59,12 +59,31 @@ rules:
Analogous to :c:func:`PyObject_New` but for container objects with the
:const:`Py_TPFLAGS_HAVE_GC` flag set.


.. c:function:: TYPE* PyObject_GC_NewVar(TYPE, PyTypeObject *type, Py_ssize_t size)

Analogous to :c:func:`PyObject_NewVar` but for container objects with the
:const:`Py_TPFLAGS_HAVE_GC` flag set.

.. c:function:: PyObject* PyUnstable_Object_GC_NewWithExtraData(PyTypeObject *type, size_t extra_size)

Analogous to :c:func:`PyObject_GC_New` but allocates *extra_size*
bytes at the end of the object (at offset
:c:member:`~PyTypeObject.tp_basicsize`).
The allocated memory is initialized to zeros,
except for the :c:type:`Python object header <PyObject>`.

The extra data will be deallocated with the object, but otherwise it is
not managed by Python.

.. warning::
The function is marked as unstable because the final mechanism
for reserving extra data after an instance is not yet decided.
For allocating a variable number of fields, prefer using
:c:type:`PyVarObject` and :c:member:`~PyTypeObject.tp_itemsize`
instead.

.. versionadded:: 3.12


.. c:function:: TYPE* PyObject_GC_Resize(TYPE, PyVarObject *op, Py_ssize_t newsize)

Expand Down
3 changes: 3 additions & 0 deletions 3 Include/cpython/objimpl.h
Original file line number Diff line number Diff line change
Expand Up @@ -90,3 +90,6 @@ PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
PyAPI_FUNC(int) PyType_SUPPORTS_WEAKREFS(PyTypeObject *type);

PyAPI_FUNC(PyObject **) PyObject_GET_WEAKREFS_LISTPTR(PyObject *op);

PyAPI_FUNC(PyObject *) PyUnstable_Object_GC_NewWithExtraData(PyTypeObject *,
size_t);
14 changes: 14 additions & 0 deletions 14 Lib/test/test_capi/test_misc.py
Original file line number Diff line number Diff line change
Expand Up @@ -1043,6 +1043,20 @@ class dictsub(dict): ... # dict subclasses must work
self.assertEqual(_testcapi.function_get_kw_defaults(some), None)
self.assertEqual(some.__kwdefaults__, None)

def test_unstable_gc_new_with_extra_data(self):
class Data(_testcapi.ObjExtraData):
__slots__ = ('x', 'y')

d = Data()
d.x = 10
d.y = 20
d.extra = 30
self.assertEqual(d.x, 10)
self.assertEqual(d.y, 20)
self.assertEqual(d.extra, 30)
del d.extra
self.assertIsNone(d.extra)


class TestPendingCalls(unittest.TestCase):

Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Add :c:func:`PyUnstable_Object_GC_NewWithExtraData` function that can be used to
allocate additional memory after an object for data not managed by Python.
105 changes: 104 additions & 1 deletion 105 Modules/_testcapimodule.c
Original file line number Diff line number Diff line change
Expand Up @@ -3363,7 +3363,7 @@ test_gc_visit_objects_basic(PyObject *Py_UNUSED(self),
}
state.target = obj;
state.found = 0;

PyUnstable_GC_VisitObjects(gc_visit_callback_basic, &state);
Py_DECREF(obj);
if (!state.found) {
Expand Down Expand Up @@ -3400,6 +3400,98 @@ test_gc_visit_objects_exit_early(PyObject *Py_UNUSED(self),
Py_RETURN_NONE;
}

typedef struct {
PyObject_HEAD
} ObjExtraData;

static PyObject *
obj_extra_data_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
size_t extra_size = sizeof(PyObject *);
PyObject *obj = PyUnstable_Object_GC_NewWithExtraData(type, extra_size);
if (obj == NULL) {
return PyErr_NoMemory();
}
PyObject_GC_Track(obj);
return obj;
}

static PyObject **
obj_extra_data_get_extra_storage(PyObject *self)
{
return (PyObject **)((char *)self + Py_TYPE(self)->tp_basicsize);
}

static PyObject *
obj_extra_data_get(PyObject *self, void *Py_UNUSED(ignored))
{
PyObject **extra_storage = obj_extra_data_get_extra_storage(self);
PyObject *value = *extra_storage;
if (!value) {
Py_RETURN_NONE;
}
return Py_NewRef(value);
}

static int
obj_extra_data_set(PyObject *self, PyObject *newval, void *Py_UNUSED(ignored))
{
PyObject **extra_storage = obj_extra_data_get_extra_storage(self);
Py_CLEAR(*extra_storage);
if (newval) {
*extra_storage = Py_NewRef(newval);
}
return 0;
}

static PyGetSetDef obj_extra_data_getset[] = {
{"extra", (getter)obj_extra_data_get, (setter)obj_extra_data_set, NULL},
{NULL}
};

static int
obj_extra_data_traverse(PyObject *self, visitproc visit, void *arg)
{
PyObject **extra_storage = obj_extra_data_get_extra_storage(self);
PyObject *value = *extra_storage;
Py_VISIT(value);
return 0;
}

static int
obj_extra_data_clear(PyObject *self)
{
PyObject **extra_storage = obj_extra_data_get_extra_storage(self);
Py_CLEAR(*extra_storage);
return 0;
}

static void
obj_extra_data_dealloc(PyObject *self)
{
PyTypeObject *tp = Py_TYPE(self);
PyObject_GC_UnTrack(self);
obj_extra_data_clear(self);
tp->tp_free(self);
Py_DECREF(tp);
}

static PyType_Slot ObjExtraData_Slots[] = {
{Py_tp_getset, obj_extra_data_getset},
{Py_tp_dealloc, obj_extra_data_dealloc},
{Py_tp_traverse, obj_extra_data_traverse},
{Py_tp_clear, obj_extra_data_clear},
{Py_tp_new, obj_extra_data_new},
{Py_tp_free, PyObject_GC_Del},
{0, NULL},
};

static PyType_Spec ObjExtraData_TypeSpec = {
.name = "_testcapi.ObjExtraData",
.basicsize = sizeof(ObjExtraData),
.flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
.slots = ObjExtraData_Slots,
};

struct atexit_data {
int called;
Expand Down Expand Up @@ -4124,6 +4216,17 @@ PyInit__testcapi(void)
Py_INCREF(&MethStatic_Type);
PyModule_AddObject(m, "MethStatic", (PyObject *)&MethStatic_Type);

PyObject *ObjExtraData_Type = PyType_FromModuleAndSpec(
m, &ObjExtraData_TypeSpec, NULL);
if (ObjExtraData_Type == 0) {
return NULL;
}
int ret = PyModule_AddType(m, (PyTypeObject*)ObjExtraData_Type);
Py_DECREF(&ObjExtraData_Type);
if (ret < 0) {
return NULL;
}

PyModule_AddObject(m, "CHAR_MAX", PyLong_FromLong(CHAR_MAX));
PyModule_AddObject(m, "CHAR_MIN", PyLong_FromLong(CHAR_MIN));
PyModule_AddObject(m, "UCHAR_MAX", PyLong_FromLong(UCHAR_MAX));
Expand Down
13 changes: 13 additions & 0 deletions 13 Modules/gcmodule.c
Original file line number Diff line number Diff line change
Expand Up @@ -2357,6 +2357,19 @@ _PyObject_GC_NewVar(PyTypeObject *tp, Py_ssize_t nitems)
return op;
}

PyObject *
PyUnstable_Object_GC_NewWithExtraData(PyTypeObject *tp, size_t extra_size)
{
size_t presize = _PyType_PreHeaderSize(tp);
PyObject *op = gc_alloc(_PyObject_SIZE(tp) + extra_size, presize);
if (op == NULL) {
return NULL;
}
memset(op, 0, _PyObject_SIZE(tp) + extra_size);
_PyObject_Init(op, tp);
return op;
}

PyVarObject *
_PyObject_GC_Resize(PyVarObject *op, Py_ssize_t nitems)
{
Expand Down
Morty Proxy This is a proxified and sanitized view of the page, visit original site.