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bpo-45219: Factor dictkey indexing (GH-28389)

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Mark Shannon 2021-09-17 12:20:51 +01:00 • committed by GitHub
parent cb07838ab7
commit 064464fc38
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3 changed files with 106 additions and 63 deletions
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126
Objects/dictobject.c
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@ -734,6 +734,73 @@ lookdict_index(PyDictKeysObject *k, Py_hash_t hash, Py_ssize_t index)
Py_UNREACHABLE();
}
static Py_ssize_t
dictkeys_stringlookup(PyDictKeysObject* dk, PyObject *key, Py_hash_t hash)
{
PyDictKeyEntry *ep0 = DK_ENTRIES(dk);
size_t mask = DK_MASK(dk);
size_t perturb = hash;
size_t i = (size_t)hash & mask;
Py_ssize_t ix;
for (;;) {
ix = dictkeys_get_index(dk, i);
if (ix >= 0) {
PyDictKeyEntry *ep = &ep0[ix];
assert(ep->me_key != NULL);
assert(PyUnicode_CheckExact(ep->me_key));
if (ep->me_key == key ||
(ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
return ix;
}
}
else if (ix == DKIX_EMPTY) {
return DKIX_EMPTY;
}
perturb >>= PERTURB_SHIFT;
i = mask & (i*5 + perturb + 1);
ix = dictkeys_get_index(dk, i);
if (ix >= 0) {
PyDictKeyEntry *ep = &ep0[ix];
assert(ep->me_key != NULL);
assert(PyUnicode_CheckExact(ep->me_key));
if (ep->me_key == key ||
(ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
return ix;
}
}
else if (ix == DKIX_EMPTY) {
return DKIX_EMPTY;
}
perturb >>= PERTURB_SHIFT;
i = mask & (i*5 + perturb + 1);
}
Py_UNREACHABLE();
}
/* Lookup a string in a (all unicode) dict keys.
* Returns DKIX_ERROR if key is not a string,
* or if the dict keys is not all strings.
* If the keys is present then return the index of key.
* If the key is not present then return DKIX_EMPTY.
*/
Py_ssize_t
_PyDictKeys_StringLookup(PyDictKeysObject* dk, PyObject *key)
{
DictKeysKind kind = dk->dk_kind;
if (!PyUnicode_CheckExact(key) || kind == DICT_KEYS_GENERAL) {
return DKIX_ERROR;
}
Py_hash_t hash = ((PyASCIIObject *)key)->hash;
if (hash == -1) {
hash = PyUnicode_Type.tp_hash(key);
if (hash == -1) {
PyErr_Clear();
return DKIX_ERROR;
}
}
return dictkeys_stringlookup(dk, key, hash);
}
/*
The basic lookup function used by all operations.
This is based on Algorithm D from Knuth Vol. 3, Sec. 6.4.
@ -756,49 +823,24 @@ _Py_dict_lookup(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject **valu
start:
dk = mp->ma_keys;
DictKeysKind kind = dk->dk_kind;
if (PyUnicode_CheckExact(key) && kind != DICT_KEYS_GENERAL) {
Py_ssize_t ix = dictkeys_stringlookup(dk, key, hash);
if (ix == DKIX_EMPTY) {
*value_addr = NULL;
}
else if (kind == DICT_KEYS_SPLIT) {
*value_addr = mp->ma_values[ix];
}
else {
*value_addr = DK_ENTRIES(dk)[ix].me_value;
}
return ix;
}
PyDictKeyEntry *ep0 = DK_ENTRIES(dk);
size_t mask = DK_MASK(dk);
size_t perturb = hash;
size_t i = (size_t)hash & mask;
Py_ssize_t ix;
if (PyUnicode_CheckExact(key) && kind != DICT_KEYS_GENERAL) {
/* Strings only */
for (;;) {
ix = dictkeys_get_index(mp->ma_keys, i);
if (ix >= 0) {
PyDictKeyEntry *ep = &ep0[ix];
assert(ep->me_key != NULL);
assert(PyUnicode_CheckExact(ep->me_key));
if (ep->me_key == key ||
(ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
goto found;
}
}
else if (ix == DKIX_EMPTY) {
*value_addr = NULL;
return DKIX_EMPTY;
}
perturb >>= PERTURB_SHIFT;
i = mask & (i*5 + perturb + 1);
ix = dictkeys_get_index(mp->ma_keys, i);
if (ix >= 0) {
PyDictKeyEntry *ep = &ep0[ix];
assert(ep->me_key != NULL);
assert(PyUnicode_CheckExact(ep->me_key));
if (ep->me_key == key ||
(ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
goto found;
}
}
else if (ix == DKIX_EMPTY) {
*value_addr = NULL;
return DKIX_EMPTY;
}
perturb >>= PERTURB_SHIFT;
i = mask & (i*5 + perturb + 1);
}
Py_UNREACHABLE();
}
for (;;) {
ix = dictkeys_get_index(dk, i);
if (ix == DKIX_EMPTY) {
@ -4997,15 +5039,15 @@ _PyDictKeys_DecRef(PyDictKeysObject *keys)
static uint32_t next_dict_keys_version = 2;
uint32_t _PyDictKeys_GetVersionForCurrentState(PyDictObject *dict)
uint32_t _PyDictKeys_GetVersionForCurrentState(PyDictKeysObject *dictkeys)
{
if (dict->ma_keys->dk_version != 0) {
return dict->ma_keys->dk_version;
if (dictkeys->dk_version != 0) {
return dictkeys->dk_version;
}
if (next_dict_keys_version == 0) {
return 0;
}
uint32_t v = next_dict_keys_version++;
dict->ma_keys->dk_version = v;
dictkeys->dk_version = v;
return v;
}