diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-03-20-01-21-37.bpo-43452.tDVJkc.rst b/Misc/NEWS.d/next/Core and Builtins/2021-03-20-01-21-37.bpo-43452.tDVJkc.rst
new file mode 100644
index 00000000000000..c2fe10afdee8c4
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-03-20-01-21-37.bpo-43452.tDVJkc.rst
@@ -0,0 +1 @@
+Added micro-optimizations to ``_PyType_Lookup()`` to improve cache lookup performance in the common case of cache hits.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 9e7121448f87df..51b60623877bc3 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -32,8 +32,7 @@ class object "PyObject *" "&PyBaseObject_Type"
& ((1 << MCACHE_SIZE_EXP) - 1))
#define MCACHE_HASH_METHOD(type, name) \
- MCACHE_HASH((type)->tp_version_tag, \
- ((PyASCIIObject *)(name))->hash)
+ MCACHE_HASH((type)->tp_version_tag, ((Py_ssize_t)(name)) >> 3)
#define MCACHE_CACHEABLE_NAME(name) \
PyUnicode_CheckExact(name) && \
PyUnicode_IS_READY(name) && \
@@ -333,6 +332,7 @@ PyType_Modified(PyTypeObject *type)
}
}
type->tp_flags &= ~Py_TPFLAGS_VALID_VERSION_TAG;
+ type->tp_version_tag = 0; /* 0 is not a valid version tag */
}
static void
@@ -391,6 +391,7 @@ type_mro_modified(PyTypeObject *type, PyObject *bases) {
Py_XDECREF(type_mro_meth);
type->tp_flags &= ~(Py_TPFLAGS_HAVE_VERSION_TAG|
Py_TPFLAGS_VALID_VERSION_TAG);
+ type->tp_version_tag = 0; /* 0 is not a valid version tag */
}
static int
@@ -3346,18 +3347,15 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
PyObject *res;
int error;
- if (MCACHE_CACHEABLE_NAME(name) &&
- _PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG)) {
- /* fast path */
- unsigned int h = MCACHE_HASH_METHOD(type, name);
- struct type_cache *cache = get_type_cache();
- struct type_cache_entry *entry = &cache->hashtable[h];
- if (entry->version == type->tp_version_tag && entry->name == name) {
+ unsigned int h = MCACHE_HASH_METHOD(type, name);
+ struct type_cache *cache = get_type_cache();
+ struct type_cache_entry *entry = &cache->hashtable[h];
+ if (entry->version == type->tp_version_tag &&
+ entry->name == name) {
#if MCACHE_STATS
- cache->hits++;
+ cache->hits++;
#endif
- return entry->value;
- }
+ return entry->value;
}
/* We may end up clearing live exceptions below, so make sure it's ours. */
@@ -3380,24 +3378,21 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
return NULL;
}
- if (MCACHE_CACHEABLE_NAME(name)) {
- struct type_cache *cache = get_type_cache();
- if (assign_version_tag(cache, type)) {
- unsigned int h = MCACHE_HASH_METHOD(type, name);
- struct type_cache_entry *entry = &cache->hashtable[h];
- entry->version = type->tp_version_tag;
- entry->value = res; /* borrowed */
- assert(((PyASCIIObject *)(name))->hash != -1);
+ if (MCACHE_CACHEABLE_NAME(name) && assign_version_tag(cache, type)) {
+ h = MCACHE_HASH_METHOD(type, name);
+ struct type_cache_entry *entry = &cache->hashtable[h];
+ entry->version = type->tp_version_tag;
+ entry->value = res; /* borrowed */
+ assert(((PyASCIIObject *)(name))->hash != -1);
#if MCACHE_STATS
- if (entry->name != Py_None && entry->name != name) {
- cache->collisions++;
- }
- else {
- cache->misses++;
- }
-#endif
- Py_SETREF(entry->name, Py_NewRef(name));
+ if (entry->name != Py_None && entry->name != name) {
+ cache->collisions++;
}
+ else {
+ cache->misses++;
+ }
+#endif
+ Py_SETREF(entry->name, Py_NewRef(name));
}
return res;
}
pFad - Phonifier reborn
Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.
Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
Alternative Proxies:
Alternative Proxy
pFad Proxy
pFad v3 Proxy
pFad v4 Proxy