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memoized.py
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memoized.py
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# -*- coding: utf-8 -*-
from __future__ import division
import atexit
import functools
import sys
from utils import flatten, makehash
__author__ = "Aijun Bai"
__copyright__ = "Copyright 2015, Alibaba Inc."
__email__ = "aijunbai@gmail.com"
class memoized(object):
"""A memoized decorator with reset functionality for instance methods
"""
memo = makehash()
n_call = 0
n_hit = 0
n_reset = 0
def __init__(self, f):
self.f = f
functools.update_wrapper(self, f)
@staticmethod
def key(*args, **kwargs):
args = flatten(list(args))
return tuple(args), frozenset(kwargs.items())
def __call__(self, obj, *args, **kwargs):
memoized.n_call += 1
key = memoized.key(*args, **kwargs)
fn = self.f.__name__
if key not in memoized.memo[obj][fn]:
memoized.memo[obj][fn][key] = self.f(obj, *args, **kwargs)
else:
memoized.n_hit += 1
return memoized.memo[obj][fn][key]
def __get__(self, obj, objtype):
return functools.partial(self.__call__, obj)
@staticmethod
def reset(name=None):
def wrapper(f):
@functools.wraps(f)
def helper(obj, *args, **kwargs):
if name and name in memoized.memo[obj]:
del memoized.memo[obj][name]
elif obj in memoized.memo:
del memoized.memo[obj]
memoized.n_reset += 1
return f(obj, *args, **kwargs)
return helper
return wrapper
@classmethod
def statistics(cls):
if cls.n_call:
print >> sys.stderr, 'memoized hitting rate: %d/%d=%f' % \
(cls.n_hit, cls.n_call,
cls.n_hit / cls.n_call)
if cls.n_reset:
print >> sys.stderr, 'memoized reset times: %d' % cls.n_reset
if __debug__:
atexit.register(memoized.statistics)