Refactor dht.node.iterativeFind
Move nested functions into a helper class. Add new, smaller functions to increase readability
This commit is contained in:
Job Evers-Meltzer
parent
fa8190356a
commit
740fad5cbe
1 changed files with 210 additions and 168 deletions
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@ -34,6 +34,7 @@ def rpcmethod(func):
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func.rpcmethod = True
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return func
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class Node(object):
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""" Local node in the Kademlia network
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@ -591,176 +592,11 @@ class Node(object):
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# This is used during the bootstrap process; node ID's are most probably fake
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shortlist = startupShortlist
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# List of active queries; len() indicates number of active probes
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#
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# n.b: using lists for these variables, because Python doesn't
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# allow binding a new value to a name in an enclosing
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# (non-global) scope
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activeProbes = []
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# List of contact IDs that have already been queried
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alreadyContacted = []
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# Probes that were active during the previous iteration
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# A list of found and known-to-be-active remote nodes
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activeContacts = []
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# This should only contain one entry; the next scheduled iteration call
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pendingIterationCalls = []
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prevClosestNode = [None]
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findValueResult = {}
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slowNodeCount = [0]
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def extendShortlist(responseTuple):
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""" @type responseMsg: kademlia.msgtypes.ResponseMessage """
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# The "raw response" tuple contains the response message,
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# and the originating address info
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responseMsg = responseTuple[0]
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originAddress = responseTuple[1] # tuple: (ip adress, udp port)
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# Make sure the responding node is valid, and abort the operation if it isn't
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if responseMsg.nodeID in activeContacts or responseMsg.nodeID == self.id:
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return responseMsg.nodeID
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# Mark this node as active
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if responseMsg.nodeID in shortlist:
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# Get the contact information from the shortlist...
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aContact = shortlist[shortlist.index(responseMsg.nodeID)]
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else:
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# If it's not in the shortlist; we probably used a fake ID to reach it
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# - reconstruct the contact, using the real node ID this time
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aContact = Contact(
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responseMsg.nodeID, originAddress[0], originAddress[1], self._protocol)
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activeContacts.append(aContact)
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# This makes sure "bootstrap"-nodes with "fake" IDs don't get queried twice
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if responseMsg.nodeID not in alreadyContacted:
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alreadyContacted.append(responseMsg.nodeID)
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# Now grow extend the (unverified) shortlist with the returned contacts
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result = responseMsg.response
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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 findValue is True and key in result and not 'contacts' in result:
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# We have found the value
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findValueResult[key] = result[key]
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findValueResult['from_peer'] = aContact.address
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else:
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if findValue is True:
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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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if 'closestNodeNoValue' in findValueResult:
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is_closer = (
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self._routingTable.distance(key, responseMsg.nodeID) <
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self._routingTable.distance(key, activeContacts[0].id))
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if is_closer:
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findValueResult['closestNodeNoValue'] = aContact
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else:
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findValueResult['closestNodeNoValue'] = aContact
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contactTriples = result['contacts']
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else:
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contactTriples = result
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for contactTriple in contactTriples:
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if isinstance(contactTriple, (list, tuple)) and len(contactTriple) == 3:
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testContact = Contact(
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contactTriple[0], contactTriple[1], contactTriple[2], self._protocol)
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if testContact not in shortlist:
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shortlist.append(testContact)
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return responseMsg.nodeID
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def removeFromShortlist(failure):
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""" @type failure: twisted.python.failure.Failure """
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failure.trap(protocol.TimeoutError)
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deadContactID = failure.getErrorMessage()
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if deadContactID in shortlist:
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shortlist.remove(deadContactID)
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return deadContactID
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def cancelActiveProbe(contactID):
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activeProbes.pop()
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if len(activeProbes) <= constants.alpha/2 and len(pendingIterationCalls):
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# Force the iteration
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pendingIterationCalls[0].cancel()
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del pendingIterationCalls[0]
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searchIteration()
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def log_error(err):
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log.error(err.getErrorMessage())
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# Send parallel, asynchronous FIND_NODE RPCs to the shortlist of contacts
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def searchIteration():
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slowNodeCount[0] = len(activeProbes)
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# TODO: move sort_key to be a method on the class
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def sort_key(firstContact, secondContact, targetKey=key):
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return cmp(
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self._routingTable.distance(firstContact.id, targetKey),
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self._routingTable.distance(secondContact.id, targetKey)
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)
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# Sort the discovered active nodes from closest to furthest
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activeContacts.sort(sort_key)
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# This makes sure a returning probe doesn't force calling this function by mistake
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while len(pendingIterationCalls):
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del pendingIterationCalls[0]
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# See if should continue the search
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if key in findValueResult:
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outerDf.callback(findValueResult)
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return
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elif len(activeContacts) and findValue == False:
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is_all_done = (
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len(activeContacts) >= constants.k or
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(
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activeContacts[0] == prevClosestNode[0] and
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len(activeProbes) == slowNodeCount[0]
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)
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)
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if is_all_done:
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# TODO: Re-send the FIND_NODEs to all of the k closest nodes not already queried
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#
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# Ok, we're done; either we have accumulated k
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# active contacts or no improvement in closestNode
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# has been noted
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outerDf.callback(activeContacts)
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return
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# The search continues...
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if len(activeContacts):
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prevClosestNode[0] = activeContacts[0]
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contactedNow = 0
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shortlist.sort(sort_key)
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# Store the current shortList length before contacting other nodes
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prevShortlistLength = len(shortlist)
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for contact in shortlist:
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if contact.id not in alreadyContacted:
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activeProbes.append(contact.id)
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rpcMethod = getattr(contact, rpc)
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df = rpcMethod(key, rawResponse=True)
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df.addCallback(extendShortlist)
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df.addErrback(removeFromShortlist)
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df.addCallback(cancelActiveProbe)
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df.addErrback(log_error)
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alreadyContacted.append(contact.id)
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contactedNow += 1
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if contactedNow == constants.alpha:
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break
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should_lookup_active_calls = (
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len(activeProbes) > slowNodeCount[0] or
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(
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len(shortlist) < constants.k and
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len(activeContacts) < len(shortlist) and
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len(activeProbes) > 0
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)
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)
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if should_lookup_active_calls:
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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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call = twisted.internet.reactor.callLater(
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constants.iterativeLookupDelay, searchIteration) #IGNORE:E1101
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pendingIterationCalls.append(call)
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# Check for a quick contact response that made an update to the shortList
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elif prevShortlistLength < len(shortlist):
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# Ensure that the closest contacts are taken from the updated shortList
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searchIteration()
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else:
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# If no probes were sent, there will not be any improvement, so we're done
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outerDf.callback(activeContacts)
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outerDf = defer.Deferred()
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helper = _IterativeFindHelper(self, outerDf, shortlist, key, findValue, rpc)
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# Start the iterations
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searchIteration()
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helper.searchIteration()
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return outerDf
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def _refreshNode(self):
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@ -796,6 +632,212 @@ class Node(object):
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return df
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# This was originally a set of nested methods in _iterativeFind
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# but they have been moved into this helper class in-order to
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# have better scoping and readability
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class _IterativeFindHelper(object):
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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, outer_d, shortlist, key, find_value, rpc):
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self.node = node
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self.outer_d = outer_d
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self.shortlist = shortlist
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self.key = key
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self.find_value = find_value
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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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#
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# n.b: using lists for these variables, because Python doesn't
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# allow binding a new value to a name in an enclosing
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# (non-global) scope
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self.active_probes = []
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# List of contact IDs that have already been queried
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self.already_contacted = []
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# Probes that were active during the previous iteration
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# A list of found and known-to-be-active remote nodes
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self.active_contacts = []
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# This should only contain one entry; the next scheduled iteration call
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self.pending_iteration_calls = []
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self.prev_closest_node = [None]
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self.find_value_result = {}
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self.slow_node_count = [0]
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def extendShortlist(self, responseTuple):
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""" @type responseMsg: kademlia.msgtypes.ResponseMessage """
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# The "raw response" tuple contains the response message,
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# and the originating address info
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responseMsg = responseTuple[0]
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originAddress = responseTuple[1] # tuple: (ip adress, udp port)
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# Make sure the responding node is valid, and abort the operation if it isn't
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if responseMsg.nodeID in self.active_contacts or responseMsg.nodeID == self.node.id:
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return responseMsg.nodeID
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# Mark this node as active
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aContact = self._getActiveContact(responseMsg, originAddress)
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self.active_contacts.append(aContact)
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# This makes sure "bootstrap"-nodes with "fake" IDs don't get queried twice
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if responseMsg.nodeID not in self.already_contacted:
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self.already_contacted.append(responseMsg.nodeID)
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# Now grow extend the (unverified) shortlist with the returned contacts
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result = responseMsg.response
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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.find_value is True and self.key in result and not 'contacts' in result:
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# We have found the value
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self.find_value_result[self.key] = result[self.key]
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self.find_value_result['from_peer'] = aContact.address
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else:
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if self.find_value is True:
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self._setClosestNodeValue(responseMsg, aContact)
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self._keepSearching(result)
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return responseMsg.nodeID
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def _getActiveContact(self, responseMsg, originAddress):
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if responseMsg.nodeID in self.shortlist:
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# Get the contact information from the shortlist...
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return self.shortlist[self.shortlist.index(responseMsg.nodeID)]
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else:
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# If it's not in the shortlist; we probably used a fake ID to reach it
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# - reconstruct the contact, using the real node ID this time
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return Contact(
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responseMsg.nodeID, originAddress[0], originAddress[1], self.node._protocol)
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def _keepSearching(self, result):
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contactTriples = self._getContactTriples(result)
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for contactTriple in contactTriples:
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self._addIfValid(contactTriple)
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def _getContactTriples(self, result):
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if self.find_value is True:
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return result['contacts']
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else:
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return result
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def _setClosestNodeValue(self, responseMsg, aContact):
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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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if 'closestNodeNoValue' in self.find_value_result:
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if self._is_closer(responseMsg):
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self.find_value_result['closestNodeNoValue'] = aContact
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else:
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self.find_value_result['closestNodeNoValue'] = aContact
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def _is_closer(self, responseMsg):
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return (
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self.node._routingTable.distance(self.key, responseMsg.nodeID) <
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self.node._routingTable.distance(self.key, self.active_contacts[0].id)
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)
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def _addIfValid(self, contactTriple):
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if isinstance(contactTriple, (list, tuple)) and len(contactTriple) == 3:
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testContact = Contact(
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contactTriple[0], contactTriple[1], contactTriple[2], self.node._protocol)
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if testContact not in self.shortlist:
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self.shortlist.append(testContact)
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def removeFromShortlist(self, failure):
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""" @type failure: twisted.python.failure.Failure """
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failure.trap(protocol.TimeoutError)
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deadContactID = failure.getErrorMessage()
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if deadContactID in self.shortlist:
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self.shortlist.remove(deadContactID)
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return deadContactID
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def cancelActiveProbe(self, contactID):
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self.active_probes.pop()
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if len(self.active_probes) <= constants.alpha/2 and len(self.pending_iteration_calls):
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# Force the iteration
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self.pending_iteration_calls[0].cancel()
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del self.pending_iteration_calls[0]
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self.searchIteration()
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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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self.slow_node_count[0] = len(self.active_probes)
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# TODO: move sort_key to be a method on the class
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def sort_key(firstContact, secondContact, targetKey=self.key):
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return cmp(
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self.node._routingTable.distance(firstContact.id, targetKey),
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self.node._routingTable.distance(secondContact.id, targetKey)
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)
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# Sort the discovered active nodes from closest to furthest
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self.active_contacts.sort(sort_key)
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# This makes sure a returning probe doesn't force calling this function by mistake
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while len(self.pending_iteration_calls):
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del self.pending_iteration_calls[0]
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# See if should continue the search
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if self.key in self.find_value_result:
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self.outer_d.callback(self.find_value_result)
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return
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elif len(self.active_contacts) and self.find_value == False:
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if self._is_all_done():
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# TODO: Re-send the FIND_NODEs to all of the k closest nodes not already queried
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#
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# Ok, we're done; either we have accumulated k active
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# contacts or no improvement in closestNode has been
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# noted
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self.outer_d.callback(self.active_contacts)
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return
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# The search continues...
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if len(self.active_contacts):
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self.prev_closest_node[0] = self.active_contacts[0]
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contactedNow = 0
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self.shortlist.sort(sort_key)
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# Store the current shortList length before contacting other nodes
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prevShortlistLength = len(self.shortlist)
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for contact in self.shortlist:
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if contact.id not in self.already_contacted:
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self._probeContact(contact)
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contactedNow += 1
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if contactedNow == constants.alpha:
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break
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if self._should_lookup_active_calls():
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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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call = twisted.internet.reactor.callLater(
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constants.iterativeLookupDelay, self.searchIteration) #IGNORE:E1101
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self.pending_iteration_calls.append(call)
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# Check for a quick contact response that made an update to the shortList
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elif prevShortlistLength < len(self.shortlist):
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# Ensure that the closest contacts are taken from the updated shortList
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self.searchIteration()
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else:
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# If no probes were sent, there will not be any improvement, so we're done
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self.outer_d.callback(self.active_contacts)
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def _probeContact(self, contact):
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self.active_probes.append(contact.id)
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rpcMethod = getattr(contact, self.rpc)
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df = rpcMethod(self.key, rawResponse=True)
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df.addCallback(self.extendShortlist)
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df.addErrback(self.removeFromShortlist)
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df.addCallback(self.cancelActiveProbe)
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df.addErrback(log.fail(), 'Failed to contact %s', contact)
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self.already_contacted.append(contact.id)
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def _should_lookup_active_calls(self):
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return (
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len(self.active_probes) > self.slow_node_count[0] or
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(
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len(self.shortlist) < constants.k and
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len(self.active_contacts) < len(self.shortlist) and
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len(self.active_probes) > 0
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)
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)
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def _is_all_done(self):
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return (
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len(self.active_contacts) >= constants.k or
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(
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self.active_contacts[0] == self.prev_closest_node[0] and
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len(self.active_probes) == self.slow_node_count[0]
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)
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)
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def main():
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parser = argparse.ArgumentParser(description="Launch a dht node")
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parser.add_argument("udp_port", help="The UDP port on which the node will listen",
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