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# -*- coding: utf-8 -*-
"""
This is a minimal implementation of lru_cache function.
Based on Python 3 functools and backports.functools_lru_cache.
"""
from __future__ import absolute_import
from collections import OrderedDict
from functools import wraps
from threading import RLock
def lru_cache(maxsize=128, typed=False):
if typed is not False:
raise NotImplementedError("typed caching not supported")
def decorating_function(function):
cache = OrderedDict()
stats = [0, 0]
rlock = RLock()
setattr(function, 'cache_info', lambda:
"hits={}, misses={}, maxsize={}, currsize={}".format(
stats[0], stats[1], maxsize, len(cache)))
@wraps(function)
def wrapper(*args, **kwargs):
key = args + tuple(kwargs.items())
with rlock:
if key in cache:
ret = cache[key]
del cache[key]
cache[key] = ret
stats[0] += 1
else:
ret = function(*args, **kwargs)
if len(cache) == maxsize:
cache.popitem(last=False)
cache[key] = ret
stats[1] += 1
return ret
return wrapper
return decorating_function
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