8000 gh-112075: _Py_dict_lookup needs to lock shared keys by DinoV · Pull Request #117528 · python/cpython · GitHub
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gh-112075: _Py_dict_lookup needs to lock shared keys #117528

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Merged
merged 8 commits into from
Apr 25, 2024
Merged

gh-112075: _Py_dict_lookup needs to lock shared keys #117528

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7e75eb2
Lock shared keys in `Py_dict_lookup` and use thread-safe lookup in `i…
DinoV Apr 3, 2024
5f498f7
Assert we always have unicode only key in split dict case
DinoV Apr 4, 2024
90fdea3
Re-probe for index with shared keys locked before adding split index
DinoV Apr 5, 2024
1272d68
Refactor to avoid potential to lock keys twice, share impl between in…
DinoV Apr 15, 2024
002ca04
gh-112075: Lock when inserting into shared keys
colesbury Apr 8, 2024
e7d7430
Fix return type
colesbury Apr 15, 2024
a74c0ee
Remove splitdict_lookup_keys_lock_held
DinoV Apr 23, 2024
d5a5403
unicodekeys_lookup_unicode_threadsafe only when gil is disabled
DinoV Apr 25, 2024
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Remove splitdict_lookup_keys_lock_held
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@DinoV
DinoV committed Apr 25, 2024
commit a74c0ee4049343ad81007350f28d8527f6d99ddd
42 changes: 6 additions & 36 deletions Objects/dictobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1188,41 +1188,10 @@ _PyDictKeys_StringLookup(PyDictKeysObject* dk, PyObject *key)
return unicodekeys_lookup_unicode(dk, key, hash);
}


#ifdef Py_GIL_DISABLED

// Version of _Py_dict_lookup specialized for when we have split keys and the
// shared keys are locked.
static Py_ssize_t
splitdict_lookup_keys_lock_held(PyDictObject *mp, PyObject *key, Py_hash_t hash,
PyObject **value_addr)
{
PyDictKeysObject *dk = mp->ma_keys;
Py_ssize_t ix;

_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(mp);
ASSERT_KEYS_LOCKED(dk);
assert(PyUnicode_CheckExact(key));
assert(dk->dk_kind == DICT_KEYS_SPLIT);

ix = unicodekeys_lookup_unicode(dk, key, hash);

if (ix >= 0) {
*value_addr = mp->ma_values->values[ix];
}
else {
*value_addr = NULL;
}

return ix;
}

static Py_ssize_t
unicodekeys_lookup_unicode_threadsafe(PyDictKeysObject* dk, PyObject *key,
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Unused code warning

Py_hash_t hash);

#endif // Py_GIL_DISABLED

/*
The basic lookup function used by all operations.
This is based on Algorithm D from Knuth Vol. 3, Sec. 6.4.
Expand Down Expand Up @@ -1260,15 +1229,16 @@ _Py_dict_lookup(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject **valu
ix = unicodekeys_lookup_unicode_threadsafe(dk, key, hash);
if (ix == DKIX_KEY_CHANGED) {
LOCK_KEYS(dk);
ix = splitdict_lookup_keys_lock_held(mp, key, hash,
value_addr);
ix = unicodekeys_lookup_unicode(dk, key, hash);
UNLOCK_KEYS(dk);
return ix;
}
}
#endif

else {
ix = unicodekeys_lookup_unicode(dk, key, hash);
}
#else
ix = unicodekeys_lookup_unicode(dk, key, hash);
#endif
}
else {
INCREF_KEYS_FT(dk);
Expand Down
0