[Python]使用Decorator设计Cache

直接上源码：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Created on 4/20/16

@author: Jiezhi.G@gmail.com

My Blog: jiezhi.github.io

Reference: <Expert Python Programming> Chapter 2--Decorators_Proxy Page.53
"""
import time
import hashlib
import pickle

cache = {}

def is_obsolete(entry, duration):
return time.time() - entry['time'] > duration

def compute_key(function, args, kw):
key = pickle.dumps((function.func_name, args, kw))
return hashlib.sha1(key).hexdigest()

def memoize(duration=10):
def _memoize(function):
def __memoize(*args, **kw):
key = compute_key(function, args, kw)

# do we have it already?
if key in cache and not is_obsolete(cache[key], duration):
print 'we got a winner'
return cache[key]['value']

# computing
result = function(*args, **kw)

# storing the result
cache[key] = {'value': result, 'time': time.time()}
return result

return __memoize
return _memoize

@memoize()
def very_very_very_complex_stuff(a, b):
return a + b

if __name__ == '__main__':
print very_very_very_complex_stuff(2, 2)
print cache
print very_very_very_complex_stuff(2, 2)


运行后可以看到结果：

4
{'dedfca39c250ca2047c5d66a13c5df2e9ac90181': {'value': 4, 'time': 1461155366.249486}}
we got a winner
4