addons/document_webdav/cache.py

   1 import time
   2 import heapq
   3
   4 def memoize(maxsize):
   5         """decorator to 'memoize' a function - caching its results"""
   6         def decorating_function(f):
   7                 cache = {}  # map from key to value
   8                 heap = []   # list of keys, in LRU heap
   9                 cursize = 0 # because len() is slow
  10                 def wrapper(*args):
  11                         key = repr(args)
  12                         # performance crap
  13                         _cache=cache
  14                         _heap=heap
  15                         _heappop = heapq.heappop
  16                         _heappush = heapq.heappush
  17                         _time = time.time
  18                         _cursize = cursize
  19                         _maxsize = maxsize
  20                         if not _cache.has_key(key):
  21                                 if _cursize == _maxsize:
  22                                         # pop oldest element
  23                                         (_,oldkey) = _heappop(_heap)
  24                                         _cache.pop(oldkey)
  25                                 else:
  26                                         _cursize += 1
  27                                 # insert this element
  28                                 _cache[key] = f(*args)
  29                                 _heappush(_heap,(_time(),key))
  30                                 wrapper.misses += 1
  31                         else:
  32                                 wrapper.hits += 1
  33                         return cache[key]
  34                 wrapper.__doc__ = f.__doc__
  35                 wrapper.__name__ = f.__name__
  36                 wrapper.hits = wrapper.misses = 0
  37                 return wrapper
  38         return decorating_function
  39