42 lines
1.3 KiB
Python
42 lines
1.3 KiB
Python
import time
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import heapq
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def memoize(maxsize):
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"""decorator to 'memoize' a function - caching its results"""
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def decorating_function(f):
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cache = {} # map from key to value
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heap = [] # list of keys, in LRU heap
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cursize = 0 # because len() is slow
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def wrapper(*args):
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key = repr(args)
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# performance crap
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_cache=cache
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_heap=heap
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_heappop = heapq.heappop
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_heappush = heapq.heappush
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_time = time.time
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_cursize = cursize
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_maxsize = maxsize
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if not _cache.has_key(key):
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if _cursize == _maxsize:
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# pop oldest element
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(_,oldkey) = _heappop(_heap)
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_cache.pop(oldkey)
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else:
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_cursize += 1
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# insert this element
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_cache[key] = f(*args)
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_heappush(_heap,(_time(),key))
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wrapper.misses += 1
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else:
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wrapper.hits += 1
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return cache[key]
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wrapper.__doc__ = f.__doc__
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wrapper.__name__ = f.__name__
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wrapper.hits = wrapper.misses = 0
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return wrapper
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return decorating_function
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# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
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