def __init__(self, id=None, udpPort=4000, dataStore=None, routerTableClass=None, networkProtocol=None):
"""
@param dataStore: The data store to use. This must be class inheriting
from the C{DataStore} interface (or providing the
same API). How the data store manages its data
internally is up to the implementation of that data
store.
@type dataStore: dht.kademlia.datastore.DataStore
@param routerTable: The router table class to use. Since there exists
some ambiguity as to how the router table should be
implemented in Kademlia, a different router table
may be used, as long as the appropriate API is
exposed. This should be a class, not an object,
in order to allow the Peer to pass an
auto-generated peer ID to the routertable object
upon instantiation (if necessary).
@type routerTable: dht.kademlia.routertable.RoutingTable
@param networkProtocol: The network protocol to use. This can be
overridden from the default to (for example)
change the format of the physical RPC messages
being transmitted.
@type networkProtocol: dht.kademlia.protocol.KademliaProtocol
"""
if id != None:
self.id = id
else:
self.id = self._generateID()
self.port = udpPort
self._listeningPort = None # object implementing Twisted IListeningPort
# This will contain a deferred created when joining the network, to enable publishing/retrieving information from
# the DHT as soon as the peer is part of the network (add callbacks to this deferred if scheduling such operations
# before the peer has finished joining the network)
self._joinDeferred = None
# Create k-buckets (for storing neighbors)
#self._buckets = []
#for i in range(160):
# self._buckets.append(kbucket.KBucket())
if routerTableClass == None:
self._routerTable = DefaultRouterTable(self.id)
else:
self._routerTable = routerTableClass(self.id)
# Initialize this peer's network access mechanisms
if networkProtocol == None:
self._protocol = KademliaProtocol(self)
else:
self._protocol = networkProtocol
# Initialize the data storage mechanism used by this peer
if dataStore == None:
#self._dataStore = datastore.DictDataStore()
self._dataStore = DictDataStore()
else:
self._dataStore = dataStore
# Try to restore the peer's state...
if 'peerState' in self._dataStore:
state = self._dataStore['peerState']
self.id = state['id']
for neighborTriple in state['closestPeers']:
neighbor = Neighbor(neighborTriple[0], neighborTriple[1], neighborTriple[2], self._protocol)
self._routerTable.addNeighbor(neighbor)
class Peer(object):
""" Local peer in the Kademlia network
This class represents a single local peer in a Kademlia network; in other
words, this class encapsulates an Entangled-using application's "presence"
in a Kademlia network.
all interactions with the Kademlia network by a client
application is performed via this class (or a subclass).
"""
def __init__(self, id=None, udpPort=4000, dataStore=None, routerTableClass=None, networkProtocol=None):
"""
@param dataStore: The data store to use. This must be class inheriting
from the C{DataStore} interface (or providing the
same API). How the data store manages its data
internally is up to the implementation of that data
store.
@type dataStore: dht.kademlia.datastore.DataStore
@param routerTable: The router table class to use. Since there exists
some ambiguity as to how the router table should be
implemented in Kademlia, a different router table
may be used, as long as the appropriate API is
exposed. This should be a class, not an object,
in order to allow the Peer to pass an
auto-generated peer ID to the routertable object
upon instantiation (if necessary).
@type routerTable: dht.kademlia.routertable.RoutingTable
@param networkProtocol: The network protocol to use. This can be
overridden from the default to (for example)
change the format of the physical RPC messages
being transmitted.
@type networkProtocol: dht.kademlia.protocol.KademliaProtocol
"""
if id != None:
self.id = id
else:
self.id = self._generateID()
self.port = udpPort
self._listeningPort = None # object implementing Twisted IListeningPort
# This will contain a deferred created when joining the network, to enable publishing/retrieving information from
# the DHT as soon as the peer is part of the network (add callbacks to this deferred if scheduling such operations
# before the peer has finished joining the network)
self._joinDeferred = None
# Create k-buckets (for storing neighbors)
#self._buckets = []
#for i in range(160):
# self._buckets.append(kbucket.KBucket())
if routerTableClass == None:
self._routerTable = DefaultRouterTable(self.id)
else:
self._routerTable = routerTableClass(self.id)
# Initialize this peer's network access mechanisms
if networkProtocol == None:
self._protocol = KademliaProtocol(self)
else:
self._protocol = networkProtocol
# Initialize the data storage mechanism used by this peer
if dataStore == None:
#self._dataStore = datastore.DictDataStore()
self._dataStore = DictDataStore()
else:
self._dataStore = dataStore
# Try to restore the peer's state...
if 'peerState' in self._dataStore:
state = self._dataStore['peerState']
self.id = state['id']
for neighborTriple in state['closestPeers']:
neighbor = Neighbor(neighborTriple[0], neighborTriple[1], neighborTriple[2], self._protocol)
self._routerTable.addNeighbor(neighbor)
def __del__(self):
self._persistState()
self._listeningPort.stopListening()
def getID(self):
return self.id
def joinNetwork(self, knownPeerAddresses=None):
""" Causes the Peer to join the Kademlia network; normally, this
should be called before any other DHT operations.
@param knownPeerAddresses: A sequence of tuples containing IP address
information for existing peers on the
Kademlia network, in the format:
C{(<ip address>, (udp port>)}
@type knownPeerAddresses: tuple
"""
# Prepare the underlying Kademlia protocol
self._listeningPort = twisted.internet.reactor.listenUDP(self.port, self._protocol)
# Create temporary neighbor information for the list of addresses of known peers
if knownPeerAddresses != None:
bootstrapNeighbors = []
for address, port in knownPeerAddresses:
neighbor = Neighbor(self._generateID(), address, port, self._protocol)
bootstrapNeighbors.append(neighbor)
else:
bootstrapNeighbors = None
# Initiate the Kademlia joining sequence - perform a search for this peer's own ID
print "Short List", bootstrapNeighbors
self._joinDeferred = self._iterativeFind(self.id, bootstrapNeighbors)
self._joinDeferred.addCallback(self._persistState)
# Start refreshing k-buckets periodically, if necessary
twisted.internet.reactor.callLater(constant_variable.checkRefreshInterval, self._refreshPeer)
def printNeighbors(self):
print '\n\nNODE CONTACTS\n==============='
for i in range(len(self._routerTable._buckets)):
for neighbor in self._routerTable._buckets[i]._neighbors:
print neighbor
print '=================================='
def iterativeStore(self, key, value, originalPublisherID=None, age=0):
""" The Kademlia store operation
Call this to store/republish data in the DHT.
@param key: The hashtable key of the data
@type key: str
@param value: The actual data (the value associated with C{key})
@type value: str
@param originalPublisherID: The peer ID of the peer that is the
B{original} publisher of the data
@type originalPublisherID: str
@param age: The relative age of the data (time in seconds since it was
originally published). Note that the original publish time
isn't actually given, to compensate for clock skew between
different peers.
@type age: int
"""
#print ' iterativeStore called'
if originalPublisherID == None:
originalPublisherID = self.id
# Prepare a callback for doing "STORE" RPC calls
def executeStoreRPCs(peers):
#print ' .....execStoreRPCs called'
if len(peers) >= constant_variable.k:
# If this peer itself is closer to the key than the last (furthest) peer in the list,
# we should store the value at ourselves as well
if self._routerTable.distance(key, self.id) < self._routerTable.distance(key, peers[-1].id):
peers.pop()
self.store(key, value, originalPublisherID=originalPublisherID, age=age)
else:
self.store(key, value, originalPublisherID=originalPublisherID, age=age)
for neighbor in peers:
neighbor.store(key, value, originalPublisherID, age)
return peers
# Find k peers closest to the key...
df = self.iterativeFindPeer(key)
# ...and send them STORE RPCs as soon as they've been found
df.addCallback(executeStoreRPCs)
return df
def iterativeFindPeer(self, key):
""" The basic Kademlia peer lookup operation
Call this to find a remote peer in the P2P overlay network.
@param key: the 160-bit key (i.e. the peer or value ID) to search for
@type key: str
@return: This immediately returns a deferred object, which will return
a list of k "closest" neighbors (C{kademlia.neighbor.Neighbor}
objects) to the specified key as soon as the operation is
finished.
@rtype: twisted.internet.defer.Deferred
"""
return self._iterativeFind(key)
def iterativeFindValue(self, key):
""" The Kademlia search operation (deterministic)
Call this to retrieve data from the DHT.
@param key: the 160-bit key (i.e. the value ID) to search for
@type key: str
@return: This immediately returns a deferred object, which will return
either one of two things:
- If the value was found, it will return a Python
dictionary containing the searched-for key (the C{key}
parameter passed to this method), and its associated
value, in the format:
C{<str>key: <str>data_value}
- If the value was not found, it will return a list of k
"closest" neighbors (C{kademlia.neighbor.Neighbor} objects)
to the specified key
@rtype: twisted.internet.defer.Deferred
"""
# Prepare a callback for this operation
outerDf = defer.Deferred()
def checkResult(result):
if type(result) == dict:
# We have found the value; now see who was the closest neighbor without it...
if 'closestPeerNoValue' in result:
# ...and store the key/value pair
neighbor = result['closestPeerNoValue']
neighbor.store(key, result[key])
outerDf.callback(result)
else:
# The value wasn't found, but a list of neighbors was returned
# Now, see if we have the value (it might seem wasteful to search on the network
# first, but it ensures that all values are properly propagated through the
# network
if key in self._dataStore:
# Ok, we have the value locally, so use that
value = self._dataStore[key]
# Send this value to the closest peer without it
if len(result) > 0:
neighbor = result[0]
neighbor.store(key, value)
outerDf.callback({key: value})
else:
# Ok, value does not exist in DHT at all
outerDf.callback(result)
# Execute the search
df = self._iterativeFind(key, rpc='findValue')
df.addCallback(checkResult)
return outerDf
def addNeighbor(self, neighbor):
""" Add/update the given neighbor; simple wrapper for the same method
in this object's RoutingTable object
@param neighbor: The neighbor to add to this peer's k-buckets
@type neighbor: kademlia.neighbor.Neighbor
"""
self._routerTable.addNeighbor(neighbor)
def removeNeighbor(self, neighborID):
""" Remove the neighbor with the specified peer ID from this peer's
table of known peers. This is a simple wrapper for the same method
in this object's RoutingTable object
@param neighborID: The peer ID of the neighbor to remove
@type neighborID: str
"""
self._routerTable.removeNeighbor(neighborID)
def findNeighbor(self, neighborID):
""" Find a dht.kademlia.neighbor.Neighbor object for the specified
cotact ID
@param neighborID: The neighbor ID of the required Neighbor object
@type neighborID: str
@return: Neighbor object of remote peer with the specified peer ID,
or None if the neighbor was not found
@rtype: twisted.internet.defer.Deferred
"""
try:
neighbor = self._routerTable.getNeighbor(neighborID)
df = defer.Deferred()
df.callback(neighbor)
except ValueError:
def parseResults(peers):
if neighborID in peers:
neighbor = peers[peers.index(neighborID)]
return neighbor
else:
return None
df = self.iterativeFindPeer(neighborID)
df.addCallback(parseResults)
return df
@rpcmethod
def ping(self):
""" Used to verify neighbor between two Kademlia peers
@rtype: str
"""
return 'pong'
@rpcmethod
def store(self, key, value, originalPublisherID=None, age=0, **kwargs):
""" Store the received data in this peer's local hash table
@param key: The hashtable key of the data
@type key: str
@param value: The actual data (the value associated with C{key})
@type value: str
@param originalPublisherID: The peer ID of the peer that is the
B{original} publisher of the data
@type originalPublisherID: str
@param age: The relative age of the data (time in seconds since it was
originally published). Note that the original publish time
isn't actually given, to compensate for clock skew between
different peers.
@type age: int
@rtype: str
@todo: Since the data (value) may be large, passing it around as a buffer
(which is the case currently) might not be a good idea... will have
to fix this (perhaps use a stream from the Protocol class?)
"""
# Get the sender's ID (if any)
if '_rpcPeerID' in kwargs:
rpcSenderID = kwargs['_rpcPeerID']
else:
rpcSenderID = None
if originalPublisherID == None:
if rpcSenderID != None:
originalPublisherID = rpcSenderID
else:
raise TypeError, 'No publisher specifed, and RPC caller ID not available. Data requires an original publisher.'
now = int(time.time())
originallyPublished = now - age
self._dataStore.setItem(key, value, now, originallyPublished, originalPublisherID)
return 'OK'
@rpcmethod
def findPeer(self, key, **kwargs):
""" Finds a number of known peers closest to the peer/value with the
specified key.
@param key: the 160-bit key (i.e. the peer or value ID) to search for
@type key: str
@return: A list of neighbor triples closest to the specified key.
This method will return C{k} (or C{count}, if specified)
neighbors if at all possible; it will only return fewer if the
peer is returning all of the neighbors that it knows of.
@rtype: list
"""
# Get the sender's ID (if any)
if '_rpcPeerID' in kwargs:
rpcSenderID = kwargs['_rpcPeerID']
else:
rpcSenderID = None
neighbors = self._routerTable.findClosePeers(key, constant_variable.k, rpcSenderID)
neighborTriples = []
for neighbor in neighbors:
neighborTriples.append( (neighbor.id, neighbor.address, neighbor.port) )
return neighborTriples
@rpcmethod
def findValue(self, key, **kwargs):
""" Return the value associated with the specified key if present in
this peer's data, otherwise execute FIND_NODE for the key
@param key: The hashtable key of the data to return
@type key: str
@return: A dictionary containing the requested key/value pair,
or a list of neighbor triples closest to the requested key.
@rtype: dict or list
"""
if key in self._dataStore:
return {key: self._dataStore[key]}
else:
return self.findPeer(key, **kwargs)
def _generateID(self):
""" Generates a 160-bit pseudo-random identifier
@return: A globally unique 160-bit pseudo-random identifier
@rtype: str
"""
hash = hashlib.sha1()
hash.update(str(random.getrandbits(255)))
return hash.digest()
def _iterativeFind(self, key, startupShortlist=None, rpc='findPeer'):
""" The basic Kademlia iterative lookup operation (for peers/values)
This builds a list of k "closest" neighbors through iterative use of
the "FIND_NODE" RPC, or if C{findValue} is set to C{True}, using the
"FIND_VALUE" RPC, in which case the value (if found) may be returned
instead of a list of neighbors
@param key: the 160-bit key (i.e. the peer or value ID) to search for
@type key: str
@param startupShortlist: A list of neighbors to use as the starting
shortlist for this search; this is normally
only used when the peer joins the network
@type startupShortlist: list
@param rpc: The name of the RPC to issue to remote peers during the
Kademlia lookup operation (e.g. this sets whether this
algorithm should search for a data value (if
rpc='findValue') or not. It can thus be used to perform
other operations that piggy-back on the basic Kademlia
lookup operation (Entangled's "delete" RPC, for instance).
@type rpc: str
@return: If C{findValue} is C{True}, the algorithm will stop as soon
as a data value for C{key} is found, and return a dictionary
containing the key and the found value. Otherwise, it will
return a list of the k closest peers to the specified key
@rtype: twisted.internet.defer.Deferred
"""
if rpc != 'findPeer':
findValue = True
else:
findValue = False
shortlist = []
if startupShortlist == None:
shortlist = self._routerTable.findClosePeers(key, constant_variable.alpha)
if key != self.id:
# Update the "last accessed" timestamp for the appropriate k-bucket
self._routerTable.touchKBucket(key)
if len(shortlist) == 0:
# This peer doesn't know of any other peers
fakeDf = defer.Deferred()
fakeDf.callback([])
return fakeDf
else:
# This is used during the bootstrap process; peer ID's are most probably fake
shortlist = startupShortlist
# List of active queries; len() indicates number of active probes
# - using lists for these variables, because Python doesn't allow binding a new value to a name in an enclosing (non-global) scope
activeProbes = []
# List of neighbor IDs that have already been queried
alreadyNeighbored = []
# Probes that were active during the previous iteration
# A list of found and known-to-be-active remote peers
activeNeighbors = []
# This should only contain one entry; the next scheduled iteration call
pendingIterationCalls = []
prevClosestPeer = [None]
findValueResult = {}
slowPeerCount = [0]
def extendShortlist(responseTuple):
""" @type responseMsg: kademlia.msgtypes.ResponseMessage """
# The "raw response" tuple contains the response message, and the originating address info
responseMsg = responseTuple[0]
originAddress = responseTuple[1] # tuple: (ip adress, udp port)
# Make sure the responding peer is valid, and abort the operation if it isn't
if responseMsg.peerID in activeNeighbors or responseMsg.peerID == self.id:
return responseMsg.peerID
# Mark this peer as active
if responseMsg.peerID in shortlist:
# Get the neighbor information from the shortlist...
aNeighbor = shortlist[shortlist.index(responseMsg.peerID)]
else:
# If it's not in the shortlist; we probably used a fake ID to reach it
# - reconstruct the neighbor, using the real peer ID this time
aNeighbor = Neighbor(responseMsg.peerID, originAddress[0], originAddress[1], self._protocol)
activeNeighbors.append(aNeighbor)
# This makes sure "bootstrap"-peers with "fake" IDs don't get queried twice
if responseMsg.peerID not in alreadyNeighbored:
alreadyNeighbored.append(responseMsg.peerID)
# Now grow extend the (unverified) shortlist with the returned neighbors
result = responseMsg.response
#TODO: some validation on the result (for guarding against attacks)
# If we are looking for a value, first see if this result is the value
# we are looking for before treating it as a list of neighbor triples
if findValue == True and type(result) == dict:
# We have found the value
findValueResult[key] = result[key]
else:
if findValue == True:
# We are looking for a value, and the remote peer didn't have it
# - mark it as the closest "empty" peer, if it is
if 'closestPeerNoValue' in findValueResult:
if self._routerTable.distance(key, responseMsg.peerID) < self._routerTable.distance(key, activeNeighbors[0].id):
findValueResult['closestPeerNoValue'] = aNeighbor
else:
findValueResult['closestPeerNoValue'] = aNeighbor
for neighborTriple in result:
if isinstance(neighborTriple, (list, tuple)) and len(neighborTriple) == 3:
testNeighbor = Neighbor(neighborTriple[0], neighborTriple[1], neighborTriple[2], self._protocol)
if testNeighbor not in shortlist:
shortlist.append(testNeighbor)
return responseMsg.peerID
def removeFromShortlist(failure):
""" @type failure: twisted.python.failure.Failure """
failure.trap(TimeoutErrorProtocol)
deadNeighborID = failure.getErrorMessage()
if deadNeighborID in shortlist:
shortlist.remove(deadNeighborID)
return deadNeighborID
def cancelActiveProbe(neighborID):
activeProbes.pop()
if len(activeProbes) <= constant_variable.alpha/2 and len(pendingIterationCalls):
# Force the iteration
pendingIterationCalls[0].cancel()
del pendingIterationCalls[0]
#print 'forcing iteration ================='
searchIteration()
# Send parallel, asynchronous FIND_NODE RPCs to the shortlist of neighbors
def searchIteration():
#print '==> searchiteration'
slowPeerCount[0] = len(activeProbes)
# Sort the discovered active peers from closest to furthest
activeNeighbors.sort(lambda firstNeighbor, secondNeighbor, targetKey=key: cmp(self._routerTable.distance(firstNeighbor.id, targetKey), self._routerTable.distance(secondNeighbor.id, targetKey)))
# This makes sure a returning probe doesn't force calling this function by mistake
while len(pendingIterationCalls):
del pendingIterationCalls[0]
# See if should continue the search
if key in findValueResult:
#print '++++++++++++++ DONE (findValue found) +++++++++++++++\n\n'
outerDf.callback(findValueResult)
return
elif len(activeNeighbors) and findValue == False:
if (len(activeNeighbors) >= constant_variable.k) or (activeNeighbors[0] == prevClosestPeer[0] and len(activeProbes) == slowPeerCount[0]):
# TODO: Re-send the FIND_NODEs to all of the k closest peers not already queried
# Ok, we're done; either we have accumulated k active neighbors or no improvement in closestPeer has been noted
#if len(activeNeighbors) >= constants.k:
# print '++++++++++++++ DONE (test for k active neighbors) +++++++++++++++\n\n'
#else:
# print '++++++++++++++ DONE (test for closest peer) +++++++++++++++\n\n'
outerDf.callback(activeNeighbors)
return
# The search continues...
if len(activeNeighbors):
prevClosestPeer[0] = activeNeighbors[0]
neighboredNow = 0
shortlist.sort(lambda firstNeighbor, secondNeighbor, targetKey=key: cmp(self._routerTable.distance(firstNeighbor.id, targetKey), self._routerTable.distance(secondNeighbor.id, targetKey)))
# Store the current shortList length before neighboring other peers
prevShortlistLength = len(shortlist)
for neighbor in shortlist:
if neighbor.id not in alreadyNeighbored:
activeProbes.append(neighbor.id)
rpcMethod = getattr(neighbor, rpc)
df = rpcMethod(key, rawResponse=True)
df.addCallback(extendShortlist)
df.addErrback(removeFromShortlist)
df.addCallback(cancelActiveProbe)
alreadyNeighbored.append(neighbor.id)
neighboredNow += 1
if neighboredNow == constant_variable.alpha:
break
if len(activeProbes) > slowPeerCount[0] \
or (len(shortlist) < constant_variable.k and len(activeNeighbors) < len(shortlist) and len(activeProbes) > 0):
#print '----------- scheduling next call -------------'
# Schedule the next iteration if there are any active calls (Kademlia uses loose parallelism)
call = twisted.internet.reactor.callLater(constant_variable.iterativeLookupDelay, searchIteration) #IGNORE:E1101
pendingIterationCalls.append(call)
# Check for a quick neighbor response that made an update to the shortList
elif prevShortlistLength < len(shortlist):
# Ensure that the closest neighbors are taken from the updated shortList
searchIteration()
else:
#print '++++++++++++++ DONE (logically) +++++++++++++\n\n'
# If no probes were sent, there will not be any improvement, so we're done
outerDf.callback(activeNeighbors)
outerDf = defer.Deferred()
# Start the iterations
searchIteration()
return outerDf
def _persistState(self, *args):
state = {'id': self.id,
'closestPeers': self.findPeer(self.id)}
now = int(time.time())
self._dataStore.setItem('peerState', state, now, now, self.id)
def _refreshPeer(self):
""" Periodically called to perform k-bucket refreshes and data
replication/republishing as necessary """
#print 'refreshPeer called'
df = self._refreshRoutingTable()
df.addCallback(self._republishData)
df.addCallback(self._scheduleNextPeerRefresh)
def _refreshRoutingTable(self):
peerIDs = self._routerTable.getRefreshList(0, False)
outerDf = defer.Deferred()
def searchForNextPeerID(dfResult=None):
if len(peerIDs) > 0:
searchID = peerIDs.pop()
df = self.iterativeFindPeer(searchID)
df.addCallback(searchForNextPeerID)
else:
# If this is reached, we have finished refreshing the router table
outerDf.callback(None)
# Start the refreshing cycle
searchForNextPeerID()
return outerDf
def _republishData(self, *args):
#print '---republishData() called'
df = twisted.internet.threads.deferToThread(self._threadedRepublishData)
return df
def _scheduleNextPeerRefresh(self, *args):
#print '==== sheduling next refresh'
twisted.internet.reactor.callLater(constants.checkRefreshInterval, self._refreshPeer)
def _threadedRepublishData(self, *args):
""" Republishes and expires any stored data (i.e. stored
C{(key, value pairs)} that need to be republished/expired
This method should run in a deferred thread
"""
#print '== republishData called, peer:',ord(self.id[0])
expiredKeys = []
for key in self._dataStore:
# Filter internal variables stored in the datastore
if key == 'peerState':
continue
now = int(time.time())
originalPublisherID = self._dataStore.originalPublisherID(key)
age = now - self._dataStore.originalPublishTime(key)
#print ' peer:',ord(self.id[0]),'key:',ord(key[0]),'orig publishing time:',self._dataStore.originalPublishTime(key),'now:',now,'age:',age,'lastPublished age:',now - self._dataStore.lastPublished(key),'original pubID:', ord(originalPublisherID[0])
if originalPublisherID == self.id:
# This peer is the original publisher; it has to republish
# the data before it expires (24 hours in basic Kademlia)
if age >= constants.dataExpireTimeout:
#print ' REPUBLISHING key:', key
#self.iterativeStore(key, self._dataStore[key])
twisted.internet.reactor.callFromThread(self.iterativeStore, key, self._dataStore[key])
else:
# This peer needs to replicate the data at set intervals,
# until it expires, without changing the metadata associated with it
# First, check if the data has expired
if age >= constants.dataExpireTimeout:
# This key/value pair has expired (and it has not been republished by the original publishing peer
# - remove it
expiredKeys.append(key)
elif now - self._dataStore.lastPublished(key) >= constants.replicateInterval:
# ...data has not yet expired, and we need to replicate it
#print ' replicating key:', key,'age:',age
#self.iterativeStore(key=key, value=self._dataStore[key], originalPublisherID=originalPublisherID, age=age)
twisted.internet.reactor.callFromThread(self.iterativeStore, key=key, value=self._dataStore[key], originalPublisherID=originalPublisherID, age=age)
for key in expiredKeys:
#print ' expiring key:', key
del self._dataStore[key]
