30 lines
971 B
Python
30 lines
971 B
Python
from time import monotonic
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class LRUCache:
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def __init__(self, open: callable, *, capacity: int, maxage: float):
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self.open = open
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self.capacity = capacity
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self.maxage = maxage
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self.cache = [] # Each item is a tuple: (key, handle, timestamp), recent items first
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def __contains__(self, key):
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return any(rec[0] == key for rec in self.cache)
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def __getitem__(self, key):
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# Take from cache or open a new one
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for i, (k, f, ts) in enumerate(self.cache):
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if k == key:
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self.cache.pop(i)
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break
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else:
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f = self.open(key)
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# Add/restore to end of cache
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self.cache.append((key, f, monotonic()))
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self.expire_items()
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return f
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def expire_items(self):
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ts = monotonic() - self.maxage
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while len(self.cache) > self.capacity or self.cache and self.cache[-1][2] < ts:
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self.cache.pop()[1].close()
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