Factor out shared variables.

This commit is contained in:
Raymond Hettinger 2012-04-29 14:55:27 -07:00
parent 678e7f3be6
commit 9f0ab9f564
1 changed files with 6 additions and 4 deletions

View File

@ -167,18 +167,20 @@ def lru_cache(maxsize=100, typed=False):
# The internals of the lru_cache are encapsulated for thread safety and
# 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
_len = len # localize the global len() function
PREV, NEXT, KEY, RESULT = 0, 1, 2, 3 # names for the link fields
def decorating_function(user_function):
cache = {}
hits = misses = 0
kwd_mark = (object(),) # separate positional and keyword args
cache_get = cache.get # bound method to lookup a key or return None
sentinel = object() # unique object used with cache_get
_len = len # localize the global len() function
lock = Lock() # because linkedlist updates aren't threadsafe
root = [] # root of the circular doubly linked list
root[:] = [root, root, None, None] # initialize by pointing to self
PREV, NEXT, KEY, RESULT = 0, 1, 2, 3 # names for the link fields
def make_key(args, kwds, typed, tuple=tuple, sorted=sorted, type=type):
# build a cache key from positional and keyword args