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gh-122208: Don't delivery PyDict_EVENT_ADDED until it can't fail #122207

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merged 3 commits into from
Jul 24, 2024
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gh-122208: Don't delivery PyDict_EVENT_ADDED until it can't fail #122207

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991098e
Don't delivery PyDict_EVENT_ADDED until it can't fail
DinoV Jul 23, 2024
d3ac46e
📜🤖 Added by blurb_it.
blurb-it[bot] Jul 23, 2024
e9ceec0
Add back accidently removed assertion
DinoV Jul 24, 2024
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2024-07-23-23-59-04.gh-issue-122208.z8KHsY.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Dictionary watchers now only deliver the PyDict_EVENT_ADDED event when the insertion is in a known good state to succeed.
19 changes: 8 additions & 11 deletions Objects/dictobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1627,6 +1627,10 @@ insert_combined_dict(PyInterpreterState *interp, PyDictObject *mp,
}
}

uint64_t new_version = _PyDict_NotifyEvent(
interp, PyDict_EVENT_ADDED, mp, key, value);
mp->ma_keys->dk_version = 0;

Py_ssize_t hashpos = find_empty_slot(mp->ma_keys, hash);
dictkeys_set_index(mp->ma_keys, hashpos, mp->ma_keys->dk_nentries);

Expand All @@ -1643,6 +1647,7 @@ insert_combined_dict(PyInterpreterState *interp, PyDictObject *mp,
STORE_VALUE(ep, value);
STORE_HASH(ep, hash);
}
mp->ma_version_tag = new_version;
STORE_KEYS_USABLE(mp->ma_keys, mp->ma_keys->dk_usable - 1);
STORE_KEYS_NENTRIES(mp->ma_keys, mp->ma_keys->dk_nentries + 1);
assert(mp->ma_keys->dk_usable >= 0);
Expand Down Expand Up @@ -1746,15 +1751,11 @@ insertdict(PyInterpreterState *interp, PyDictObject *mp,

if (ix == DKIX_EMPTY) {
assert(!_PyDict_HasSplitTable(mp));
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Was it intentional to remove this assertion? Doesn't seem related to the dict watcher stuff.

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No, thanks for catching that, I'll remove it.

Luckily there was no debugging involved! Just trying to re-factor some existing code to use dict watchers and I was worried about what would happen when the updates would fail (as the existing code handled it). So this will actually make that somewhat cleaner!

uint64_t new_version = _PyDict_NotifyEvent(
interp, PyDict_EVENT_ADDED, mp, key, value);
/* Insert into new slot. */
mp->ma_keys->dk_version = 0;
assert(old_value == NULL);
if (insert_combined_dict(interp, mp, hash, key, value) < 0) {
goto Fail;
}
mp->ma_version_tag = new_version;
STORE_USED(mp, mp->ma_used + 1);
ASSERT_CONSISTENT(mp);
return 0;
Expand Down Expand Up @@ -1795,9 +1796,6 @@ insert_to_emptydict(PyInterpreterState *interp, PyDictObject *mp,
assert(mp->ma_keys == Py_EMPTY_KEYS);
ASSERT_DICT_LOCKED(mp);

uint64_t new_version = _PyDict_NotifyEvent(
interp, PyDict_EVENT_ADDED, mp, key, value);

int unicode = PyUnicode_CheckExact(key);
PyDictKeysObject *newkeys = new_keys_object(
interp, PyDict_LOG_MINSIZE, unicode);
Expand All @@ -1806,6 +1804,9 @@ insert_to_emptydict(PyInterpreterState *interp, PyDictObject *mp,
Py_DECREF(value);
return -1;
}
uint64_t new_version = _PyDict_NotifyEvent(
interp, PyDict_EVENT_ADDED, mp, key, value);

/* We don't decref Py_EMPTY_KEYS here because it is immortal. */
assert(mp->ma_values == NULL);

Expand Down Expand Up @@ -4199,9 +4200,6 @@ dict_setdefault_ref_lock_held(PyObject *d, PyObject *key, PyObject *default_valu

if (ix == DKIX_EMPTY) {
assert(!_PyDict_HasSplitTable(mp));
uint64_t new_version = _PyDict_NotifyEvent(
interp, PyDict_EVENT_ADDED, mp, key, default_value);
mp->ma_keys->dk_version = 0;
value = default_value;

if (insert_combined_dict(interp, mp, hash, Py_NewRef(key), Py_NewRef(value)) < 0) {
Expand All @@ -4214,7 +4212,6 @@ dict_setdefault_ref_lock_held(PyObject *d, PyObject *key, PyObject *default_valu

MAINTAIN_TRACKING(mp, key, value);
STORE_USED(mp, mp->ma_used + 1);
mp->ma_version_tag = new_version;
assert(mp->ma_keys->dk_usable >= 0);
ASSERT_CONSISTENT(mp);
if (result) {
Expand Down
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