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https://github.com/ltcptgeneral/cs239-caching.git
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60 lines
1.6 KiB
Python
60 lines
1.6 KiB
Python
from .cache import Cache
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from database import get_user_profile
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from collections import OrderedDict
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import math
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class PrefetchCache(Cache):
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limit = None
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cache = None
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def __init__(self, limit):
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super()
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self.limit = limit
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self.cache = OrderedDict()
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def __eq__(self, other):
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return self.cache == other
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def __len__(self):
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return len(self.cache)
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def get(self, key: str) -> str:
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if key in self.cache:
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self.cache.move_to_end(key)
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return self.cache[key]
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else:
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return None
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def put(self, key: str, val: str) -> bool:
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# LRU evict
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evict = False
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if len(self.cache) >= self.limit:
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self.cache.popitem(last = False)
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evict = True
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self.cache[key] = val
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if self.prefetch(val):
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evict = True
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return evict
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def prefetch(self, profile) -> bool:
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evict = False
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for i in range(math.ceil(self.limit*0.1)):
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if i < len(profile["friends"]):
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data = get_user_profile(profile["friends"][i])
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if len(self.cache) >= self.limit:
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self.cache.popitem(last = False)
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evict = True
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self.cache[profile["friends"][i]] = data
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else:
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break
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return evict
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def invalidate(self, key: str) -> bool:
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# basic delete invalidation, no (p)refetching
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if key in self.cache:
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del self.cache[key]
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return True
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else:
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return False
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