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[3.11] pythonGH-92678: Expose managed dict clear and visit functions (p…
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…ythonGH-95246).

(cherry picked from commit 27055d7)

Co-authored-by: Mark Shannon <[email protected]>
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markshannon authored and pablogsal committed Jul 25, 2022
1 parent 4c10dba commit 2424e69
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Showing 5 changed files with 58 additions and 0 deletions.
3 changes: 3 additions & 0 deletions Include/cpython/dictobject.h
Original file line number Diff line number Diff line change
Expand Up @@ -76,3 +76,6 @@ typedef struct {

PyAPI_FUNC(PyObject *) _PyDictView_New(PyObject *, PyTypeObject *);
PyAPI_FUNC(PyObject *) _PyDictView_Intersect(PyObject* self, PyObject *other);

PyAPI_FUNC(int) _PyObject_VisitManagedDict(PyObject *self, visitproc visit, void *arg);
PyAPI_FUNC(void) _PyObject_ClearManagedDict(PyObject *self);
14 changes: 14 additions & 0 deletions Lib/test/test_capi.py
Original file line number Diff line number Diff line change
Expand Up @@ -705,6 +705,20 @@ def test_export_symbols(self):
with self.subTest(name=name):
self.assertTrue(hasattr(ctypes.pythonapi, name))

def test_clear_managed_dict(self):

class C:
def __init__(self):
self.a = 1

c = C()
_testcapi.clear_managed_dict(c)
self.assertEqual(c.__dict__, {})
c = C()
self.assertEqual(c.__dict__, {'a':1})
_testcapi.clear_managed_dict(c)
self.assertEqual(c.__dict__, {})


class TestPendingCalls(unittest.TestCase):

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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Adds unstable C-API functions ``_PyObject_VisitManagedDict`` and
``_PyObject_ClearManagedDict`` to allow C extensions to allow the VM to
manage their object's dictionaries.
9 changes: 9 additions & 0 deletions Modules/_testcapimodule.c
Original file line number Diff line number Diff line change
Expand Up @@ -6014,6 +6014,14 @@ settrace_to_record(PyObject *self, PyObject *list)
Py_RETURN_NONE;
}

static PyObject *
clear_managed_dict(PyObject *self, PyObject *obj)
{
_PyObject_ClearManagedDict(obj);
Py_RETURN_NONE;
}


static PyObject *negative_dictoffset(PyObject *, PyObject *);
static PyObject *test_buildvalue_issue38913(PyObject *, PyObject *);
static PyObject *getargs_s_hash_int(PyObject *, PyObject *, PyObject*);
Expand Down Expand Up @@ -6315,6 +6323,7 @@ static PyMethodDef TestMethods[] = {
{"get_feature_macros", get_feature_macros, METH_NOARGS, NULL},
{"test_code_api", test_code_api, METH_NOARGS, NULL},
{"settrace_to_record", settrace_to_record, METH_O, NULL},
{"clear_managed_dict", clear_managed_dict, METH_O, NULL},
{NULL, NULL} /* sentinel */
};

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29 changes: 29 additions & 0 deletions Objects/dictobject.c
Original file line number Diff line number Diff line change
Expand Up @@ -5583,6 +5583,35 @@ _PyObject_FreeInstanceAttributes(PyObject *self)
free_values(*values_ptr);
}

int
_PyObject_VisitManagedDict(PyObject *self, visitproc visit, void *arg)
{
PyTypeObject *tp = Py_TYPE(self);
if((tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0) {
return 0;
}
assert(tp->tp_dictoffset);
int err = _PyObject_VisitInstanceAttributes(self, visit, arg);
if (err) {
return err;
}
Py_VISIT(*_PyObject_ManagedDictPointer(self));
return 0;
}


void
_PyObject_ClearManagedDict(PyObject *self)
{
PyTypeObject *tp = Py_TYPE(self);
if((tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0) {
return;
}
_PyObject_FreeInstanceAttributes(self);
*_PyObject_ValuesPointer(self) = NULL;
Py_CLEAR(*_PyObject_ManagedDictPointer(self));
}

PyObject *
PyObject_GenericGetDict(PyObject *obj, void *context)
{
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