py-libp2p/kademlia/storage.py

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2018-10-14 22:32:27 +08:00
import time
from itertools import takewhile
import operator
from collections import OrderedDict
class IStorage:
"""
Local storage for this node.
IStorage implementations of get must return the same type as put in by set
"""
def __setitem__(self, key, value):
"""
Set a key to the given value.
"""
raise NotImplementedError
def __getitem__(self, key):
"""
Get the given key. If item doesn't exist, raises C{KeyError}
"""
raise NotImplementedError
def get(self, key, default=None):
"""
Get given key. If not found, return default.
"""
raise NotImplementedError
def iteritemsOlderThan(self, secondsOld):
"""
Return the an iterator over (key, value) tuples for items older
than the given secondsOld.
"""
raise NotImplementedError
def __iter__(self):
"""
Get the iterator for this storage, should yield tuple of (key, value)
"""
raise NotImplementedError
class ForgetfulStorage(IStorage):
def __init__(self, ttl=604800):
"""
By default, max age is a week.
"""
self.data = OrderedDict()
self.ttl = ttl
def __setitem__(self, key, value):
if key in self.data:
del self.data[key]
self.data[key] = (time.monotonic(), value)
self.cull()
def cull(self):
for _, _ in self.iteritemsOlderThan(self.ttl):
self.data.popitem(last=False)
def get(self, key, default=None):
self.cull()
if key in self.data:
return self[key]
return default
def __getitem__(self, key):
self.cull()
return self.data[key][1]
def __iter__(self):
self.cull()
return iter(self.data)
def __repr__(self):
self.cull()
return repr(self.data)
def iteritemsOlderThan(self, secondsOld):
minBirthday = time.monotonic() - secondsOld
zipped = self._tripleIterable()
matches = takewhile(lambda r: minBirthday >= r[1], zipped)
return list(map(operator.itemgetter(0, 2), matches))
def _tripleIterable(self):
ikeys = self.data.keys()
ibirthday = map(operator.itemgetter(0), self.data.values())
ivalues = map(operator.itemgetter(1), self.data.values())
return zip(ikeys, ibirthday, ivalues)
def items(self):
self.cull()
ikeys = self.data.keys()
ivalues = map(operator.itemgetter(1), self.data.values())
return zip(ikeys, ivalues)