Move make_key() out of the decorator body. Make keys that only need to be hashed once.
diff --git a/Lib/functools.py b/Lib/functools.py
index 66af5f3..8ef1732 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -142,6 +142,30 @@
_CacheInfo = namedtuple("CacheInfo", ["hits", "misses", "maxsize", "currsize"])
+class _CacheKey(list):
+ 'Make a cache key from optionally typed positional and keyword arguments'
+
+ __slots__ = 'hashvalue'
+
+ def __init__(self, args, kwds, typed,
+ kwd_mark = (object(),),
+ sorted=sorted, tuple=tuple, type=type, hash=hash):
+ key = args
+ if kwds:
+ sorted_items = sorted(kwds.items())
+ key += kwd_mark
+ for item in sorted_items:
+ key += item
+ if typed:
+ key += tuple(type(v) for v in args)
+ if kwds:
+ key += tuple(type(v) for k, v in sorted_items)
+ self[:] = key
+ self.hashvalue = hash(key) # so we only have to hash just once
+
+ def __hash__(self):
+ return self.hashvalue
+
def lru_cache(maxsize=100, typed=False):
"""Least-recently-used cache decorator.
@@ -168,8 +192,8 @@
# to allow the implementation to change (including a possible C version).
# Constants shared by all lru cache instances:
- kwd_mark = (object(),) # separate positional and keyword args
sentinel = object() # unique object used to signal cache misses
+ make_key = _CacheKey # build a key from the function arguments
PREV, NEXT, KEY, RESULT = 0, 1, 2, 3 # names for the link fields
def decorating_function(user_function):
@@ -182,20 +206,6 @@
root = [] # root of the circular doubly linked list
root[:] = [root, root, None, None] # initialize by pointing to self
- def make_key(args, kwds, typed, tuple=tuple, sorted=sorted, type=type):
- # build a cache key from positional and keyword args
- key = args
- if kwds:
- sorted_items = tuple(sorted(kwds.items()))
- key += kwd_mark
- key += tuple(k for k, v in sorted_items)
- key += tuple(v for k, v in sorted_items)
- if typed:
- key += tuple(type(v) for v in args)
- if kwds:
- key += tuple(type(v) for k, v in sorted_items)
- return key
-
if maxsize == 0:
def wrapper(*args, **kwds):
@@ -210,7 +220,7 @@
def wrapper(*args, **kwds):
# simple caching without ordering or size limit
nonlocal hits, misses, currsize
- key = make_key(args, kwds, typed) if kwds or typed else args
+ key = make_key(args, kwds, typed)
result = cache_get(key, sentinel)
if result is not sentinel:
hits += 1
@@ -226,7 +236,7 @@
def wrapper(*args, **kwds):
# size limited caching that tracks accesses by recency
nonlocal root, hits, misses, currsize, full
- key = make_key(args, kwds, typed) if kwds or typed else args
+ key = make_key(args, kwds, typed)
with lock:
link = cache_get(key)
if link is not None: