examples/lua/bittorrent/tracker.lua

   1 -- Copyright (c) 2012, 2014. The SimGrid Team.
   2 -- All rights reserved.
   3
   4 -- This program is free software; you can redistribute it and/or modify it
   5 -- under the terms of the license (GNU LGPL) which comes with this package.
   6
   7 -- A SimGrid Lua implementation of the Bittorrent protocol.
   8
   9 require("simgrid")
  10
  11 common_tracker = {
  12         MAXIMUM_PEERS = 50
  13 }
  14
  15
  16
  17 function tracker(...)
  18         tracker_data = {
  19                 peers_list = {},
  20                 deadline = 0,
  21                 comm_received = nil
  22         }
  23   -- Check the arguments
  24   local args = {...}
  25   if #args ~= 1 then
  26         simgrid.info("Wrong number of arguments for the tracker")
  27   end
  28   -- Initialization of the random generator
  29   math.randomseed(42)
  30   -- Retrieve the end time
  31   tracker_data.deadline = tonumber(args[1])
  32
  33   simgrid.info("Tracker launched")
  34
  35   local now = simgrid.get_clock()
  36
  37   tracker_data.comm_received = simgrid.task.irecv("tracker")
  38   while now < tracker_data.deadline do
  39         task, err = tracker_data.comm_received:test()
  40         if task then
  41                 simgrid.debug("Received a request from " .. task.mailbox)
  42                 tracker_data.comm_received = simgrid.task.irecv("tracker")
  43                 -- Sending peers to the peer
  44                 local peers = {}
  45                 local i = 0
  46                 if #tracker_data.peers_list > 0 then
  47                         i = math.random(1,#tracker_data.peers_list)
  48                 end
  49                 while #peers < #tracker_data.peers_list and #peers < common_tracker.MAXIMUM_PEERS do
  50                         table.insert(peers,tracker_data.peers_list[i])
  51                         i = (i % #tracker_data.peers_list) +1
  52                 end
  53                 task.type = "ANSWER"
  54                 task.peers = peers
  55                 -- Add the peer to our peer list
  56                 table.insert(tracker_data.peers_list,task.peer_id)
  57                 -- Setting the interval
  58                 task.interval = TRACKER_QUERY_INTERVAL
  59                 -- Sending the task back to the peer
  60                 task:dsend(task.mailbox)
  61         else
  62                 simgrid.process.sleep(1)
  63                 now = simgrid.get_clock()
  64         end
  65   end
  66
  67   simgrid.info("Tracker is leaving")
  68 end