95 lines
2.4 KiB
Python
95 lines
2.4 KiB
Python
import time
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from itertools import takewhile
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import operator
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from collections import OrderedDict
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from abc import abstractmethod, ABC
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class IStorage(ABC):
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"""
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Local storage for this node.
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IStorage implementations of get must return the same type as put in by set
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"""
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@abstractmethod
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def __setitem__(self, key, value):
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"""
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Set a key to the given value.
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"""
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@abstractmethod
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def __getitem__(self, key):
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"""
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Get the given key. If item doesn't exist, raises C{KeyError}
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"""
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@abstractmethod
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def get(self, key, default=None):
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"""
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Get given key. If not found, return default.
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"""
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@abstractmethod
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def iter_older_than(self, seconds_old):
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"""
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Return the an iterator over (key, value) tuples for items older
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than the given seconds_old.
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"""
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@abstractmethod
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def __iter__(self):
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"""
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Get the iterator for this storage, should yield tuple of (key, value)
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"""
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class ForgetfulStorage(IStorage):
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def __init__(self, ttl=604800):
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"""
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By default, max age is a week.
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"""
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self.data = OrderedDict()
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self.ttl = ttl
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def __setitem__(self, key, value):
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if key in self.data:
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del self.data[key]
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self.data[key] = (time.monotonic(), value)
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self.cull()
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def cull(self):
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for _, _ in self.iter_older_than(self.ttl):
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self.data.popitem(last=False)
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def get(self, key, default=None):
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self.cull()
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if key in self.data:
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return self[key]
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return default
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def __getitem__(self, key):
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self.cull()
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return self.data[key][1]
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def __repr__(self):
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self.cull()
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return repr(self.data)
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def iter_older_than(self, seconds_old):
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min_birthday = time.monotonic() - seconds_old
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zipped = self._triple_iter()
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matches = takewhile(lambda r: min_birthday >= r[1], zipped)
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return list(map(operator.itemgetter(0, 2), matches))
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def _triple_iter(self):
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ikeys = self.data.keys()
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ibirthday = map(operator.itemgetter(0), self.data.values())
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ivalues = map(operator.itemgetter(1), self.data.values())
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return zip(ikeys, ibirthday, ivalues)
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def __iter__(self):
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self.cull()
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ikeys = self.data.keys()
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ivalues = map(operator.itemgetter(1), self.data.values())
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return zip(ikeys, ivalues)
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