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bpo-44206: Add a version number to dictionary keys (GH-26333)

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* Store log2(size) instead of size in dict-keys.

* Use enum instead of function pointer to record kind of keys.

* Add version number to dict keys.
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Mark Shannon 2021-05-28 09:54:10 +01:00 • committed by GitHub
parent 8994e9c2cd
commit f8a95df84b
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7 changed files with 223 additions and 317 deletions
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12
Objects/odictobject.c
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@ -40,9 +40,9 @@ we've considered:
The approach with the least performance impact (time and space) is #2,
mirroring the key order of dict's dk_entries with an array of node pointers.
While lookdict() and friends (dk_lookup) don't give us the index into the
array, we make use of pointer arithmetic to get that index. An alternative
would be to refactor lookdict() to provide the index, explicitly exposing
While _Py_dict_lookup() does not give us the index into the array,
we make use of pointer arithmetic to get that index. An alternative would
be to refactor _Py_dict_lookup() to provide the index, explicitly exposing
the implementation detail. We could even just use a custom lookup function
for OrderedDict that facilitates our need. However, both approaches are
significantly more complicated than just using pointer arithmetic.
@ -535,7 +535,7 @@ _odict_get_index_raw(PyODictObject *od, PyObject *key, Py_hash_t hash)
PyDictKeysObject *keys = ((PyDictObject *)od)->ma_keys;
Py_ssize_t ix;
ix = (keys->dk_lookup)((PyDictObject *)od, key, hash, &value);
ix = _Py_dict_lookup((PyDictObject *)od, key, hash, &value);
if (ix == DKIX_EMPTY) {
return keys->dk_nentries; /* index of new entry */
}
@ -553,7 +553,7 @@ _odict_resize(PyODictObject *od)
_ODictNode **fast_nodes, *node;
/* Initialize a new "fast nodes" table. */
size = ((PyDictObject *)od)->ma_keys->dk_size;
size = 1 << (((PyDictObject *)od)->ma_keys->dk_log2_size);
fast_nodes = PyMem_NEW(_ODictNode *, size);
if (fast_nodes == NULL) {
PyErr_NoMemory();
@ -592,7 +592,7 @@ _odict_get_index(PyODictObject *od, PyObject *key, Py_hash_t hash)
/* Ensure od_fast_nodes and dk_entries are in sync. */
if (od->od_resize_sentinel != keys ||
od->od_fast_nodes_size != keys->dk_size) {
od->od_fast_nodes_size != (1 << (keys->dk_log2_size))) {
int resize_res = _odict_resize(od);
if (resize_res < 0)
return -1;