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
  40
  41 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4: