258 lines
8.9 KiB
Python
258 lines
8.9 KiB
Python
"""
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Package for interacting on the network at a high level.
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"""
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import random
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import pickle
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import asyncio
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import logging
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from .protocol import KademliaProtocol
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from .utils import digest
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from .storage import ForgetfulStorage
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from .node import Node
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from .crawling import ValueSpiderCrawl
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from .crawling import NodeSpiderCrawl
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log = logging.getLogger(__name__) # pylint: disable=invalid-name
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# pylint: disable=too-many-instance-attributes
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class Server:
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"""
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High level view of a node instance. This is the object that should be
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created to start listening as an active node on the network.
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"""
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protocol_class = KademliaProtocol
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def __init__(self, ksize=20, alpha=3, node_id=None, storage=None):
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"""
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Create a server instance. This will start listening on the given port.
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Args:
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ksize (int): The k parameter from the paper
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alpha (int): The alpha parameter from the paper
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node_id: The id for this node on the network.
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storage: An instance that implements
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:interface:`~kademlia.storage.IStorage`
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"""
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self.ksize = ksize
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self.alpha = alpha
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self.storage = storage or ForgetfulStorage()
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self.node = Node(node_id or digest(random.getrandbits(255)))
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self.transport = None
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self.protocol = None
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self.refresh_loop = None
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self.save_state_loop = None
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def stop(self):
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if self.transport is not None:
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self.transport.close()
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if self.refresh_loop:
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self.refresh_loop.cancel()
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if self.save_state_loop:
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self.save_state_loop.cancel()
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def _create_protocol(self):
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return self.protocol_class(self.node, self.storage, self.ksize)
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async def listen(self, port, interface='0.0.0.0'):
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"""
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Start listening on the given port.
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Provide interface="::" to accept ipv6 address
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"""
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loop = asyncio.get_event_loop()
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listen = loop.create_datagram_endpoint(self._create_protocol,
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local_addr=(interface, port))
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log.info("Node %i listening on %s:%i",
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self.node.long_id, interface, port)
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self.transport, self.protocol = await listen
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# finally, schedule refreshing table
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self.refresh_table()
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def refresh_table(self):
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log.debug("Refreshing routing table")
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asyncio.ensure_future(self._refresh_table())
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loop = asyncio.get_event_loop()
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self.refresh_loop = loop.call_later(3600, self.refresh_table)
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async def _refresh_table(self):
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"""
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Refresh buckets that haven't had any lookups in the last hour
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(per section 2.3 of the paper).
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"""
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results = []
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for node_id in self.protocol.get_refresh_ids():
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node = Node(node_id)
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nearest = self.protocol.router.find_neighbors(node, self.alpha)
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spider = NodeSpiderCrawl(self.protocol, node, nearest,
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self.ksize, self.alpha)
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results.append(spider.find())
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# do our crawling
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await asyncio.gather(*results)
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# now republish keys older than one hour
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for dkey, value in self.storage.iter_older_than(3600):
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await self.set_digest(dkey, value)
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def bootstrappable_neighbors(self):
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"""
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Get a :class:`list` of (ip, port) :class:`tuple` pairs suitable for
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use as an argument to the bootstrap method.
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The server should have been bootstrapped
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already - this is just a utility for getting some neighbors and then
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storing them if this server is going down for a while. When it comes
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back up, the list of nodes can be used to bootstrap.
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"""
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neighbors = self.protocol.router.find_neighbors(self.node)
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return [tuple(n)[-2:] for n in neighbors]
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async def bootstrap(self, addrs):
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"""
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Bootstrap the server by connecting to other known nodes in the network.
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Args:
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addrs: A `list` of (ip, port) `tuple` pairs. Note that only IP
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addresses are acceptable - hostnames will cause an error.
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"""
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log.debug("Attempting to bootstrap node with %i initial contacts",
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len(addrs))
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cos = list(map(self.bootstrap_node, addrs))
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gathered = await asyncio.gather(*cos)
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nodes = [node for node in gathered if node is not None]
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spider = NodeSpiderCrawl(self.protocol, self.node, nodes,
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self.ksize, self.alpha)
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return await spider.find()
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async def bootstrap_node(self, addr):
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result = await self.protocol.ping(addr, self.node.id)
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return Node(result[1], addr[0], addr[1]) if result[0] else None
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async def get(self, key):
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"""
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Get a key if the network has it.
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Returns:
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:class:`None` if not found, the value otherwise.
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"""
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log.info("Looking up key %s", key)
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dkey = digest(key)
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# if this node has it, return it
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if self.storage.get(dkey) is not None:
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return self.storage.get(dkey)
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node = Node(dkey)
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nearest = self.protocol.router.find_neighbors(node)
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if not nearest:
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log.warning("There are no known neighbors to get key %s", key)
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return None
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spider = ValueSpiderCrawl(self.protocol, node, nearest,
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self.ksize, self.alpha)
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return await spider.find()
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async def set(self, key, value):
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"""
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Set the given string key to the given value in the network.
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"""
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if not check_dht_value_type(value):
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raise TypeError(
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"Value must be of type int, float, bool, str, or bytes"
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)
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log.info("setting '%s' = '%s' on network", key, value)
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dkey = digest(key)
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return await self.set_digest(dkey, value)
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async def set_digest(self, dkey, value):
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"""
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Set the given SHA1 digest key (bytes) to the given value in the
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network.
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"""
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node = Node(dkey)
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nearest = self.protocol.router.find_neighbors(node)
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if not nearest:
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log.warning("There are no known neighbors to set key %s",
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dkey.hex())
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return False
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spider = NodeSpiderCrawl(self.protocol, node, nearest,
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self.ksize, self.alpha)
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nodes = await spider.find()
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log.info("setting '%s' on %s", dkey.hex(), list(map(str, nodes)))
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# if this node is close too, then store here as well
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biggest = max([n.distance_to(node) for n in nodes])
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if self.node.distance_to(node) < biggest:
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self.storage[dkey] = value
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results = [self.protocol.call_store(n, dkey, value) for n in nodes]
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# return true only if at least one store call succeeded
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return any(await asyncio.gather(*results))
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def save_state(self, fname):
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"""
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Save the state of this node (the alpha/ksize/id/immediate neighbors)
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to a cache file with the given fname.
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"""
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log.info("Saving state to %s", fname)
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data = {
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'ksize': self.ksize,
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'alpha': self.alpha,
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'id': self.node.id,
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'neighbors': self.bootstrappable_neighbors()
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}
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if not data['neighbors']:
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log.warning("No known neighbors, so not writing to cache.")
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return
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with open(fname, 'wb') as file:
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pickle.dump(data, file)
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@classmethod
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def load_state(cls, fname):
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"""
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Load the state of this node (the alpha/ksize/id/immediate neighbors)
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from a cache file with the given fname.
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"""
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log.info("Loading state from %s", fname)
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with open(fname, 'rb') as file:
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data = pickle.load(file)
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svr = Server(data['ksize'], data['alpha'], data['id'])
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if data['neighbors']:
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svr.bootstrap(data['neighbors'])
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return svr
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def save_state_regularly(self, fname, frequency=600):
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"""
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Save the state of node with a given regularity to the given
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filename.
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Args:
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fname: File name to save retularly to
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frequency: Frequency in seconds that the state should be saved.
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By default, 10 minutes.
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"""
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self.save_state(fname)
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loop = asyncio.get_event_loop()
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self.save_state_loop = loop.call_later(frequency,
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self.save_state_regularly,
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fname,
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frequency)
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def check_dht_value_type(value):
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"""
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Checks to see if the type of the value is a valid type for
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placing in the dht.
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"""
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typeset = [
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int,
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float,
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bool,
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str,
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bytes
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]
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return type(value) in typeset # pylint: disable=unidiomatic-typecheck
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