Issue #24483: C implementation of functools.lru_cache() now calculates key's

hash only once.
This commit is contained in:
Serhiy Storchaka 2015-10-02 12:47:11 +03:00
parent c9fda9b903
commit b9d98d532c
4 changed files with 64 additions and 6 deletions

View File

@ -72,6 +72,10 @@ PyAPI_FUNC(int) _PyDict_SetItem_KnownHash(PyObject *mp, PyObject *key,
PyObject *item, Py_hash_t hash);
#endif
PyAPI_FUNC(int) PyDict_DelItem(PyObject *mp, PyObject *key);
#ifndef Py_LIMITED_API
PyAPI_FUNC(int) _PyDict_DelItem_KnownHash(PyObject *mp, PyObject *key,
Py_hash_t hash);
#endif
PyAPI_FUNC(void) PyDict_Clear(PyObject *mp);
PyAPI_FUNC(int) PyDict_Next(
PyObject *mp, Py_ssize_t *pos, PyObject **key, PyObject **value);

View File

@ -32,6 +32,9 @@ Core and Builtins
Library
-------
- Issue #24483: C implementation of functools.lru_cache() now calculates key's
hash only once.
- Issue #22958: Constructor and update method of weakref.WeakValueDictionary
now accept the self and the dict keyword arguments.

View File

@ -601,6 +601,7 @@ struct lru_cache_object;
typedef struct lru_list_elem {
PyObject_HEAD
struct lru_list_elem *prev, *next; /* borrowed links */
Py_hash_t hash;
PyObject *key, *result;
} lru_list_elem;
@ -762,10 +763,14 @@ static PyObject *
infinite_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds)
{
PyObject *result;
Py_hash_t hash;
PyObject *key = lru_cache_make_key(args, kwds, self->typed);
if (!key)
return NULL;
result = PyDict_GetItemWithError(self->cache, key);
hash = PyObject_Hash(key);
if (hash == -1)
return NULL;
result = _PyDict_GetItem_KnownHash(self->cache, key, hash);
if (result) {
Py_INCREF(result);
self->hits++;
@ -781,7 +786,7 @@ infinite_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwd
Py_DECREF(key);
return NULL;
}
if (PyDict_SetItem(self->cache, key, result) < 0) {
if (_PyDict_SetItem_KnownHash(self->cache, key, result, hash) < 0) {
Py_DECREF(result);
Py_DECREF(key);
return NULL;
@ -813,11 +818,15 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
{
lru_list_elem *link;
PyObject *key, *result;
Py_hash_t hash;
key = lru_cache_make_key(args, kwds, self->typed);
if (!key)
return NULL;
link = (lru_list_elem *)PyDict_GetItemWithError(self->cache, key);
hash = PyObject_Hash(key);
if (hash == -1)
return NULL;
link = (lru_list_elem *)_PyDict_GetItem_KnownHash(self->cache, key, hash);
if (link) {
lru_cache_extricate_link(link);
lru_cache_append_link(self, link);
@ -845,7 +854,8 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
/* Remove it from the cache.
The cache dict holds one reference to the link,
and the linked list holds yet one reference to it. */
if (PyDict_DelItem(self->cache, link->key) < 0) {
if (_PyDict_DelItem_KnownHash(self->cache, link->key,
link->hash) < 0) {
lru_cache_append_link(self, link);
Py_DECREF(key);
Py_DECREF(result);
@ -859,9 +869,11 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
oldkey = link->key;
oldresult = link->result;
link->hash = hash;
link->key = key;
link->result = result;
if (PyDict_SetItem(self->cache, key, (PyObject *)link) < 0) {
if (_PyDict_SetItem_KnownHash(self->cache, key, (PyObject *)link,
hash) < 0) {
Py_DECREF(link);
Py_DECREF(oldkey);
Py_DECREF(oldresult);
@ -881,10 +893,12 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
return NULL;
}
link->hash = hash;
link->key = key;
link->result = result;
_PyObject_GC_TRACK(link);
if (PyDict_SetItem(self->cache, key, (PyObject *)link) < 0) {
if (_PyDict_SetItem_KnownHash(self->cache, key, (PyObject *)link,
hash) < 0) {
Py_DECREF(link);
return NULL;
}

View File

@ -1242,6 +1242,7 @@ _PyDict_SetItem_KnownHash(PyObject *op, PyObject *key, PyObject *value,
}
assert(key);
assert(value);
assert(hash != -1);
mp = (PyDictObject *)op;
/* insertdict() handles any resizing that might be necessary */
@ -1290,6 +1291,42 @@ PyDict_DelItem(PyObject *op, PyObject *key)
return 0;
}
int
_PyDict_DelItem_KnownHash(PyObject *op, PyObject *key, Py_hash_t hash)
{
PyDictObject *mp;
PyDictKeyEntry *ep;
PyObject *old_key, *old_value;
PyObject **value_addr;
if (!PyDict_Check(op)) {
PyErr_BadInternalCall();
return -1;
}
assert(key);
assert(hash != -1);
mp = (PyDictObject *)op;
ep = (mp->ma_keys->dk_lookup)(mp, key, hash, &value_addr);
if (ep == NULL)
return -1;
if (*value_addr == NULL) {
_PyErr_SetKeyError(key);
return -1;
}
old_value = *value_addr;
*value_addr = NULL;
mp->ma_used--;
if (!_PyDict_HasSplitTable(mp)) {
ENSURE_ALLOWS_DELETIONS(mp);
old_key = ep->me_key;
Py_INCREF(dummy);
ep->me_key = dummy;
Py_DECREF(old_key);
}
Py_DECREF(old_value);
return 0;
}
void
PyDict_Clear(PyObject *op)
{