231 lines
10 KiB
Python
231 lines
10 KiB
Python
import logging
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import struct
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from twisted.internet import defer
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from .distance import Distance
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from .error import TimeoutError
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from . import constants
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log = logging.getLogger(__name__)
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def get_contact(contact_list, node_id, address, port):
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for contact in contact_list:
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if contact.id == node_id and contact.address == address and contact.port == port:
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return contact
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raise IndexError(node_id)
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def expand_peer(compact_peer_info):
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host = ".".join([str(ord(d)) for d in compact_peer_info[:4]])
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port, = struct.unpack('>H', compact_peer_info[4:6])
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peer_node_id = compact_peer_info[6:]
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return (peer_node_id, host, port)
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class _IterativeFind:
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# TODO: use polymorphism to search for a value or node
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# instead of using a find_value flag
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def __init__(self, node, shortlist, key, rpc, exclude=None):
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self.exclude = set(exclude or [])
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self.node = node
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self.finished_deferred = defer.Deferred()
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# all distance operations in this class only care about the distance
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# to self.key, so this makes it easier to calculate those
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self.distance = Distance(key)
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# The closest known and active node yet found
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self.closest_node = None if not shortlist else shortlist[0]
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self.prev_closest_node = None
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# Shortlist of contact objects (the k closest known contacts to the key from the routing table)
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self.shortlist = shortlist
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# The search key
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self.key = key
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# The rpc method name (findValue or findNode)
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self.rpc = rpc
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# List of active queries; len() indicates number of active probes
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self.active_probes = []
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# List of contact (address, port) tuples that have already been queried, includes contacts that didn't reply
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self.already_contacted = []
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# A list of found and known-to-be-active remote nodes (Contact objects)
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self.active_contacts = []
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# Ensure only one searchIteration call is running at a time
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self._search_iteration_semaphore = defer.DeferredSemaphore(1)
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self._iteration_count = 0
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self.find_value_result = {}
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self.pending_iteration_calls = []
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@property
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def is_find_node_request(self):
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return self.rpc == "findNode"
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@property
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def is_find_value_request(self):
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return self.rpc == "findValue"
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def is_closer(self, contact):
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if not self.closest_node:
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return True
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return self.distance.is_closer(contact.id, self.closest_node.id)
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def getContactTriples(self, result):
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if self.is_find_value_request:
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contact_triples = result['contacts']
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else:
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contact_triples = result
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for contact_tup in contact_triples:
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if not isinstance(contact_tup, (list, tuple)) or len(contact_tup) != 3:
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raise ValueError("invalid contact triple")
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contact_tup[1] = contact_tup[1].decode() # ips are strings
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return contact_triples
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def sortByDistance(self, contact_list):
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"""Sort the list of contacts in order by distance from key"""
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contact_list.sort(key=lambda c: self.distance(c.id))
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def extendShortlist(self, contact, result):
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# The "raw response" tuple contains the response message and the originating address info
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originAddress = (contact.address, contact.port)
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if self.finished_deferred.called:
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return contact.id
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if self.node.contact_manager.is_ignored(originAddress):
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raise ValueError("contact is ignored")
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if contact.id == self.node.node_id:
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return contact.id
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if contact not in self.active_contacts:
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self.active_contacts.append(contact)
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if contact not in self.shortlist:
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self.shortlist.append(contact)
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# Now grow extend the (unverified) shortlist with the returned contacts
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# TODO: some validation on the result (for guarding against attacks)
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# If we are looking for a value, first see if this result is the value
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# we are looking for before treating it as a list of contact triples
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if self.is_find_value_request and self.key in result:
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# We have found the value
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for peer in result[self.key]:
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_, host, port = expand_peer(peer)
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if (host, port) not in self.exclude:
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self.find_value_result.setdefault(self.key, []).append(peer)
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if self.find_value_result:
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self.finished_deferred.callback(self.find_value_result)
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else:
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if self.is_find_value_request:
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# We are looking for a value, and the remote node didn't have it
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# - mark it as the closest "empty" node, if it is
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# TODO: store to this peer after finding the value as per the kademlia spec
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if 'closestNodeNoValue' in self.find_value_result:
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if self.is_closer(contact):
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self.find_value_result['closestNodeNoValue'] = contact
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else:
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self.find_value_result['closestNodeNoValue'] = contact
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contactTriples = self.getContactTriples(result)
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for contactTriple in contactTriples:
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if (contactTriple[1], contactTriple[2]) in ((c.address, c.port) for c in self.already_contacted):
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continue
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elif self.node.contact_manager.is_ignored((contactTriple[1], contactTriple[2])):
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continue
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else:
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found_contact = self.node.contact_manager.make_contact(contactTriple[0], contactTriple[1],
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contactTriple[2], self.node._protocol)
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if found_contact not in self.shortlist:
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self.shortlist.append(found_contact)
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if not self.finished_deferred.called and self.should_stop():
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self.sortByDistance(self.active_contacts)
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self.finished_deferred.callback(self.active_contacts[:min(constants.k, len(self.active_contacts))])
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return contact.id
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@defer.inlineCallbacks
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def probeContact(self, contact):
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fn = getattr(contact, self.rpc)
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try:
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response = yield fn(self.key)
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result = self.extendShortlist(contact, response)
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defer.returnValue(result)
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except (TimeoutError, defer.CancelledError, ValueError, IndexError):
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defer.returnValue(contact.id)
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def should_stop(self):
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if self.is_find_value_request:
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# search stops when it finds a value, let it run
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return False
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if self.prev_closest_node and self.closest_node and self.distance.is_closer(self.prev_closest_node.id,
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self.closest_node.id):
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# we're getting further away
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return True
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if len(self.active_contacts) >= constants.k:
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# we have enough results
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return True
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return False
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# Send parallel, asynchronous FIND_NODE RPCs to the shortlist of contacts
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def _searchIteration(self):
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# Sort the discovered active nodes from closest to furthest
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if len(self.active_contacts):
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self.sortByDistance(self.active_contacts)
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self.prev_closest_node = self.closest_node
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self.closest_node = self.active_contacts[0]
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# Sort the current shortList before contacting other nodes
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self.sortByDistance(self.shortlist)
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probes = []
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already_contacted_addresses = {(c.address, c.port) for c in self.already_contacted}
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to_remove = []
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for contact in self.shortlist:
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if self.node.contact_manager.is_ignored((contact.address, contact.port)):
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to_remove.append(contact) # a contact became bad during iteration
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continue
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if (contact.address, contact.port) not in already_contacted_addresses:
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self.already_contacted.append(contact)
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to_remove.append(contact)
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probe = self.probeContact(contact)
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probes.append(probe)
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self.active_probes.append(probe)
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if len(probes) == constants.alpha:
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break
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for contact in to_remove: # these contacts will be re-added to the shortlist when they reply successfully
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self.shortlist.remove(contact)
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# run the probes
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if probes:
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# Schedule the next iteration if there are any active
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# calls (Kademlia uses loose parallelism)
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self.searchIteration()
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d = defer.DeferredList(probes, consumeErrors=True)
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def _remove_probes(results):
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for probe in probes:
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self.active_probes.remove(probe)
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return results
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d.addCallback(_remove_probes)
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elif not self.finished_deferred.called and not self.active_probes or self.should_stop():
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# If no probes were sent, there will not be any improvement, so we're done
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if self.is_find_value_request:
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self.finished_deferred.callback(self.find_value_result)
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else:
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self.sortByDistance(self.active_contacts)
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self.finished_deferred.callback(self.active_contacts[:min(constants.k, len(self.active_contacts))])
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elif not self.finished_deferred.called:
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# Force the next iteration
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self.searchIteration()
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def searchIteration(self, delay=constants.iterativeLookupDelay):
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def _cancel_pending_iterations(result):
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while self.pending_iteration_calls:
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canceller = self.pending_iteration_calls.pop()
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canceller()
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return result
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self.finished_deferred.addBoth(_cancel_pending_iterations)
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self._iteration_count += 1
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call, cancel = self.node.reactor_callLater(delay, self._search_iteration_semaphore.run, self._searchIteration)
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self.pending_iteration_calls.append(cancel)
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def iterativeFind(node, shortlist, key, rpc, exclude=None):
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helper = _IterativeFind(node, shortlist, key, rpc, exclude)
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helper.searchIteration(0)
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return helper.finished_deferred
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