examples/c/app-bittorrent/tracker.c

   1 /* Copyright (c) 2012-2020. 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 #include "tracker.h"
   8
   9 #include "simgrid/actor.h"
  10 #include "simgrid/comm.h"
  11 #include "simgrid/engine.h"
  12 #include "xbt/log.h"
  13
  14 XBT_LOG_NEW_DEFAULT_CATEGORY(bittorrent_tracker, "Messages specific for the tracker");
  15
  16 void tracker_answer_free(void* data)
  17 {
  18   tracker_answer_t a = (tracker_answer_t)data;
  19   xbt_dynar_free(&a->peers);
  20   free(a);
  21 }
  22
  23 static int is_in_list(const_xbt_dynar_t peers, int id)
  24 {
  25   return xbt_dynar_member(peers, &id);
  26 }
  27
  28 /**
  29  * Tracker main function
  30  * @param argc number of arguments
  31  * @param argv arguments
  32  */
  33 void tracker(int argc, char* argv[])
  34 {
  35   // Checking arguments
  36   xbt_assert(argc == 2, "Wrong number of arguments for the tracker.");
  37   // Retrieving end time
  38   double deadline = xbt_str_parse_double(argv[1], "Invalid deadline: %s");
  39   xbt_assert(deadline > 0, "Wrong deadline supplied");
  40
  41   // Building peers array
  42   xbt_dynar_t peers_list = xbt_dynar_new(sizeof(int), NULL);
  43
  44   sg_mailbox_t mailbox = sg_mailbox_by_name(TRACKER_MAILBOX);
  45
  46   XBT_INFO("Tracker launched.");
  47   sg_comm_t comm_received = NULL;
  48   void* received          = NULL;
  49
  50   while (simgrid_get_clock() < deadline) {
  51     if (comm_received == NULL)
  52       comm_received = sg_mailbox_get_async(mailbox, &received);
  53
  54     if (sg_comm_test(comm_received)) {
  55       // Retrieve the data sent by the peer.
  56       xbt_assert(received != NULL);
  57       tracker_query_t tq = (tracker_query_t)received;
  58
  59       // Add the peer to our peer list.
  60       if (!is_in_list(peers_list, tq->peer_id))
  61         xbt_dynar_push_as(peers_list, int, tq->peer_id);
  62
  63       // Sending peers to the requesting peer
  64       tracker_answer_t ta = tracker_answer_new(TRACKER_QUERY_INTERVAL);
  65       int next_peer;
  66       int peers_length = xbt_dynar_length(peers_list);
  67       for (int i = 0; i < MAXIMUM_PEERS && i < peers_length; i++) {
  68         do {
  69           next_peer = xbt_dynar_get_as(peers_list, rand() % peers_length, int);
  70         } while (is_in_list(ta->peers, next_peer));
  71         xbt_dynar_push_as(ta->peers, int, next_peer);
  72       }
  73       // sending the task back to the peer.
  74       sg_comm_t answer = sg_mailbox_put_init(tq->return_mailbox, ta, TRACKER_COMM_SIZE);
  75       sg_comm_detach(answer, tracker_answer_free);
  76
  77       xbt_free(tq);
  78       comm_received = NULL;
  79       received      = NULL;
  80     } else {
  81       sg_actor_sleep_for(1);
  82     }
  83   }
  84   // Free the remaining communication if any
  85   if (comm_received)
  86     sg_comm_unref(comm_received);
  87   // Free the peers list
  88   xbt_dynar_free(&peers_list);
  89
  90   XBT_INFO("Tracker is leaving");
  91 }
  92
  93 tracker_query_t tracker_query_new(int peer_id, sg_mailbox_t return_mailbox)
  94 {
  95   tracker_query_t tq = xbt_new(s_tracker_query_t, 1);
  96   tq->peer_id        = peer_id;
  97   tq->return_mailbox = return_mailbox;
  98   return tq;
  99 }
 100
 101 tracker_answer_t tracker_answer_new(int interval)
 102 {
 103   tracker_answer_t ta = xbt_new(s_tracker_answer_t, 1);
 104   ta->interval        = interval;
 105   ta->peers           = xbt_dynar_new(sizeof(int), NULL);
 106   ;
 107   return ta;
 108 }
 109
 110 /**
 111  * Build a new task for the tracker.
 112  * @param issuer_host_name Hostname of the issuer. For debugging purposes
 113  */
 114 // tracker_task_data_t tracker_task_data_new(const char* issuer_host_name, sg_mailbox_t mailbox, int peer_id, int
 115 // uploaded,
 116 //                                          int downloaded, int left)
 117 //{
 118 //  tracker_task_data_t task = xbt_new(s_tracker_task_data_t, 1);
 119 //
 120 //  task->type             = TRACKER_TASK_QUERY;
 121 //  task->issuer_host_name = issuer_host_name;
 122 //  task->mailbox          = mailbox;
 123 //  task->peer_id          = peer_id;
 124 //  task->uploaded         = uploaded;
 125 //  task->downloaded       = downloaded;
 126 //  task->left             = left;
 127 //
 128 //  task->peers = xbt_dynar_new(sizeof(int), NULL);
 129 //
 130 //  return task;
 131 //}
 132 //
 133 ///**
 134 // * Free the data structure of a tracker task.
 135 // * @param task data to free
 136 // */
 137 // void tracker_task_data_free(tracker_task_data_t task)
 138 //{
 139 //  xbt_dynar_free(&task->peers);
 140 //  xbt_free(task);
 141 //}
 142 //