ceph/src/pybind/mgr/dashboard/plugins/lru_cache.py

   1 # -*- coding: utf-8 -*-
   2 """
   3 This is a minimal implementation of lru_cache function.
   4
   5 Based on Python 3 functools and backports.functools_lru_cache.
   6 """
   7
   8 from collections import OrderedDict
   9 from functools import wraps
  10 from threading import RLock
  11
  12
  13 def lru_cache(maxsize=128, typed=False):
  14     if typed is not False:
  15         raise NotImplementedError("typed caching not supported")
  16
  17     def decorating_function(function):
  18         cache = OrderedDict()
  19         stats = [0, 0]
  20         rlock = RLock()
  21         setattr(function, 'cache_info', lambda:
  22                 "hits={}, misses={}, maxsize={}, currsize={}".format(
  23                     stats[0], stats[1], maxsize, len(cache)))
  24
  25         @wraps(function)
  26         def wrapper(*args, **kwargs):
  27             key = args + tuple(kwargs.items())
  28             with rlock:
  29                 if key in cache:
  30                     ret = cache[key]
  31                     del cache[key]
  32                     cache[key] = ret
  33                     stats[0] += 1
  34                 else:
  35                     ret = function(*args, **kwargs)
  36                     if len(cache) == maxsize:
  37                         cache.popitem(last=False)
  38                     cache[key] = ret
  39                     stats[1] += 1
  40             return ret
  41
  42         return wrapper
  43     return decorating_function