examples/lua/bittorrent/tracker.lua

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