propagation.py

   1 #!/usr/bin/env python
   2 import socket, uuid
   3 import log
   4
   5 # create an upd socket
   6 # listen on it for incoming messages and forward them
   7 # manage the forwarding routing table
   8 # the peudo-code can be found here http://en.wikipedia.org/wiki/Chord_%28peer-to-peer%29
   9
  10 class RingMember:
  11
  12     def __init__(self, id, ip, port):
  13         self.port = port
  14         self.ip = ip
  15         self.id = id
  16
  17     def toString(self):
  18         return str(self.id) + ' ' + self.ip + ' ' + str(self.port)
  19
  20 class Ring:
  21
  22     def __init__(self, entryPoint):
  23         # initialize the connection
  24         self.sock = socket.socket( socket.AF_INET6, socket.SOCK_DGRAM )
  25         self.sock.bind(('', 0))
  26         self.me = RingMember(uuid.uuid1().int ,'',  self.sock.getsockname()[1]) # TODO : get the address
  27         # to enter the ring
  28         self.predecessor = None
  29         if entryPoint == None:
  30             self.successor = self.me
  31         else:
  32             self.send('FIND_SUCCESSOR ' + str(self.me.id) + ' ' + self.me.toString(), entryPoint)
  33         log.log('Init the ring with me = ' + self.me.toString(), 3)
  34
  35     # TODO :
  36     def handleMessages(self):
  37         # TODO : switch to log
  38         log.log('Handling messages ...', 3)
  39         pass
  40
  41     def send(self, message, target):
  42         # TODO : switch to log
  43         log.log('Sending : ' + message + ' to ' + target.toString(), 5)
  44         self.sock.sendto(message, (target.ip, target.port))
  45
  46     def findSuccessor(self, id, sender):
  47         if self.id < id and id <= self.successor:
  48             self.send('SUCCESSOR_IS ' + self.successor.toString(), sender)
  49         else:
  50             self.send('FIND_SUCCESSOR ' + str(id) + ' ' + sender.toString(), successor) # TODO : use the fingers
  51
  52 # Just copying the pseudocode from wikipedia, I will make it work later
  53 # Possible messages (just for the creation of the ring) :
  54 #
  55 # find_successor $id $sender : $sender whants the IP of the successor of $id
  56 # successor_is $ip $successor
  57 # get_predecessor
  58 # notify $sender_ip $sender_id
  59 # PING
  60
  61     # called periodically
  62     # pb : how to fix successor
  63 #    def stabilize(self):
  64 #        x = SEND get_predecessor TO self.successor
  65 #        if n < x && x < self.successor:
  66 #            self.successor = x
  67 #            SEND notify self.ip, self.id TO self.successor
  68
  69 #    def notify(self, n2)
  70 #        if self.predecessor == None || (predecessor < n2 && n2 < n):
  71 #            self.predecessor = n2
  72
  73     # to be called periodically
  74 #    def fixFingers(self)
  75 #        next = (next + 1) mod (nFingers) # Or Random, cf google
  76 #        finger[next] = find_successor(n+2^{next-1});
  77
  78     # to be called periodically
  79 #    def checkPredecessor(self)
  80 #        if NO PING from self.predecessor:
  81 #            self.predecessor = None