mirror of https://github.com/borgbackup/borg.git
58 lines
1.7 KiB
Python
58 lines
1.7 KiB
Python
sentinel = object()
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class LRUCache:
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def __init__(self, capacity, dispose):
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self._cache = {}
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self._lru = []
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self._capacity = capacity
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self._dispose = dispose
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def __setitem__(self, key, value):
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assert key not in self._cache, (
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"Unexpected attempt to replace a cached item,"
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" without first deleting the old item.")
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self._lru.append(key)
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while len(self._lru) > self._capacity:
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del self[self._lru[0]]
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self._cache[key] = value
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def __getitem__(self, key):
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value = self._cache[key] # raise KeyError if not found
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self._lru.remove(key)
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self._lru.append(key)
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return value
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def __delitem__(self, key):
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value = self._cache.pop(key) # raise KeyError if not found
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self._dispose(value)
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self._lru.remove(key)
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def __contains__(self, key):
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return key in self._cache
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def get(self, key, default=None):
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value = self._cache.get(key, sentinel)
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if value is sentinel:
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return default
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self._lru.remove(key)
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self._lru.append(key)
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return value
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def upd(self, key, value):
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# special use only: update the value for an existing key without having to dispose it first
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# this method complements __setitem__ which should be used for the normal use case.
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assert key in self._cache, "Unexpected attempt to update a non-existing item."
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self._cache[key] = value
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def clear(self):
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for value in self._cache.values():
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self._dispose(value)
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self._cache.clear()
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def items(self):
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return self._cache.items()
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def __len__(self):
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return len(self._cache)
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