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Remove the lfu_cache. Add more tests.

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This commit is contained in:
Raymond Hettinger 2010-08-15 03:30:45 +00:00
parent 0f56e90f05
commit f309828175
3 changed files with 29 additions and 129 deletions
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52
Lib/functools.py
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@ -110,58 +110,6 @@ def cmp_to_key(mycmp):
raise TypeError('hash not implemented')
return K
def lfu_cache(maxsize=100):
"""Least-frequently-used cache decorator.
Arguments to the cached function must be hashable.
Cache performance statistics stored in f.hits and f.misses.
Clear the cache using f.clear().
http://en.wikipedia.org/wiki/Cache_algorithms#Least-Frequently_Used
"""
def decorating_function(user_function, tuple=tuple, sorted=sorted,
len=len, KeyError=KeyError):
cache = {} # mapping of args to results
use_count = Counter() # times each key has been accessed
kwd_mark = object() # separate positional and keyword args
lock = Lock()
@wraps(user_function)
def wrapper(*args, **kwds):
key = args
if kwds:
key += (kwd_mark,) + tuple(sorted(kwds.items()))
try:
with lock:
use_count[key] += 1 # count a use of this key
result = cache[key]
wrapper.hits += 1
except KeyError:
result = user_function(*args, **kwds)
with lock:
use_count[key] += 1 # count a use of this key
cache[key] = result
wrapper.misses += 1
if len(cache) > maxsize:
# purge the 10% least frequently used entries
for key, _ in nsmallest(maxsize // 10 or 1,
use_count.items(),
key=itemgetter(1)):
del cache[key], use_count[key]
return result
def clear():
"""Clear the cache and cache statistics"""
with lock:
cache.clear()
use_count.clear()
wrapper.hits = wrapper.misses = 0
wrapper.hits = wrapper.misses = 0
wrapper.clear = clear
return wrapper
return decorating_function
def lru_cache(maxsize=100):
"""Least-recently-used cache decorator.