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bpo-32623: Resize dict after del/pop #5297

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bpo-32623: Resize dict after del/pop #5297

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4 changes: 3 additions & 1 deletion Lib/test/test_dict.py
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Original file line number Diff line number Diff line change
Expand Up @@ -996,6 +996,7 @@ class C:
a = C()

a.a = 1
a.b = 2
self.assertTrue(_testcapi.dict_hassplittable(a.__dict__))

# dict.pop() convert it to combined table
Expand All @@ -1009,10 +1010,11 @@ class C:
# Same for popitem()
a = C()
a.a = 2
a.b = 3
self.assertTrue(_testcapi.dict_hassplittable(a.__dict__))
a.__dict__.popitem()
self.assertFalse(_testcapi.dict_hassplittable(a.__dict__))
a.a = 3
a.a = 4
self.assertFalse(_testcapi.dict_hassplittable(a.__dict__))

def test_iterator_pickling(self):
Expand Down
22 changes: 21 additions & 1 deletion Objects/dictobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1475,6 +1475,18 @@ _PyDict_SetItem_KnownHash(PyObject *op, PyObject *key, PyObject *value,
return insertdict(mp, key, hash, value);
}

// Resize dict if dk_size is too large.
static int
after_removed(PyDictObject *mp)
{
if (mp->ma_used == 0) {
PyDict_Clear((PyObject *)mp);
} else if (mp->ma_used < mp->ma_keys->dk_size/8) {
return insertion_resize(mp);
}
return 0;
}

static int
delitem_common(PyDictObject *mp, Py_hash_t hash, Py_ssize_t ix,
PyObject *old_value)
Expand All @@ -1497,7 +1509,7 @@ delitem_common(PyDictObject *mp, Py_hash_t hash, Py_ssize_t ix,
Py_DECREF(old_value);

assert(_PyDict_CheckConsistency(mp));
return 0;
return after_removed(mp);
}

int
Expand Down Expand Up @@ -1767,6 +1779,10 @@ _PyDict_Pop_KnownHash(PyObject *dict, PyObject *key, Py_hash_t hash, PyObject *d
Py_DECREF(old_key);

assert(_PyDict_CheckConsistency(mp));
if (after_removed(mp) < 0) {
Py_DECREF(old_value);
return NULL;
}
return old_value;
}

Expand Down Expand Up @@ -2950,6 +2966,10 @@ dict_popitem(PyDictObject *mp)
mp->ma_used--;
mp->ma_version_tag = DICT_NEXT_VERSION();
assert(_PyDict_CheckConsistency(mp));
if (after_removed(mp) < 0) {
Py_DECREF(res);
return NULL;
}
return res;
}

Expand Down