examples/msg/bittorrent/tracker.c

   1 /* Copyright (c) 2012. 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 #include "tracker.h"
   7 #include <msg/msg.h>
   8 #include <xbt/RngStream.h>
   9
  10 static void task_free(void *data);
  11
  12 XBT_LOG_NEW_DEFAULT_CATEGORY(msg_tracker,
  13                              "Messages specific for the tracker");
  14 /**
  15  * Tracker main function
  16  * @param argc number of arguments
  17  * @param argv arguments
  18  */
  19 int tracker(int argc, char *argv[]) {
  20         int i, key_elm;
  21         char *key;
  22         void *data_p;
  23
  24         RngStream stream = RngStream_CreateStream("tracker");
  25
  26         //Checking arguments
  27         xbt_assert(argc == 2, "Wrong number of arguments for the tracker.");
  28         //Retrieving end time
  29         double deadline = atof(argv[1]);
  30         xbt_assert(deadline > 0, "Wrong deadline supplied");
  31         //Building peers array
  32         xbt_dynar_t peers_list = xbt_dynar_new(sizeof(int), NULL);
  33
  34         XBT_INFO("Tracker launched.");
  35
  36         msg_comm_t comm_received = NULL;
  37         msg_task_t task_received = NULL;
  38
  39         while (MSG_get_clock() < deadline) {
  40                 if (comm_received == NULL) {
  41                         comm_received = MSG_task_irecv(&task_received,TRACKER_MAILBOX);
  42                 }
  43                 if (MSG_comm_test(comm_received)) {
  44                         //Check for correct status
  45                         if (MSG_comm_get_status(comm_received) == MSG_OK) {
  46                                 //Retrieve the data sent by the peer.
  47                                 tracker_task_data_t data = MSG_task_get_data(task_received);
  48                                 //Add the peer to our peer list.
  49                                 if (!is_in_list(peers_list,data->peer_id)) {
  50                                         xbt_dynar_push_as(peers_list, int, data->peer_id);
  51                                 }
  52                                 //Sending peers to the peer
  53                                 int nb_peers = 0, next_peer;
  54                                 int peers_length = xbt_dynar_length(peers_list);
  55                                 for (i = 0; i < MAXIMUM_PAIRS && i < peers_length; i++) {
  56                                         do {
  57                                                 next_peer = xbt_dynar_get_as(peers_list,RngStream_RandInt(stream, 0, peers_length - 1),int);
  58                                         } while (is_in_list(data->peers, next_peer));
  59                                         xbt_dynar_push_as(data->peers,int,next_peer);
  60                                 }
  61                                 //setting the interval
  62                                 data->interval = TRACKER_QUERY_INTERVAL;
  63                                 //sending the task back to the peer.
  64                                 MSG_task_dsend(task_received,data->mailbox, task_free);
  65                                 //destroy the communication.
  66                         }
  67                         MSG_comm_destroy(comm_received);
  68                         comm_received = NULL;
  69                         task_received = NULL;
  70                 }
  71                 else {
  72                         MSG_process_sleep(1);
  73                 }
  74         }
  75         //Free the remaining communication if any
  76         if (comm_received) {
  77                 MSG_comm_destroy(comm_received);
  78         }
  79         //Free the peers list
  80         xbt_dynar_free(&peers_list);
  81         //Free the RngStream object.
  82         RngStream_DeleteStream(&stream);
  83
  84         XBT_INFO("Tracker is leaving");
  85
  86         return 0;
  87 }
  88 /**
  89  * Build a new task for the tracker.
  90  * @param issuer_host_name Hostname of the issuer. For debugging purposes
  91  */
  92 tracker_task_data_t tracker_task_data_new(const char *issuer_host_name, const char *mailbox, int peer_id, int uploaded, int downloaded, int left) {
  93         tracker_task_data_t task = xbt_new(s_tracker_task_data_t, 1);
  94
  95         task->type = TRACKER_TASK_QUERY;
  96         task->issuer_host_name = issuer_host_name;
  97         task->mailbox = mailbox;
  98         task->peer_id = peer_id;
  99         task->uploaded = uploaded;
 100         task->downloaded = downloaded;
 101         task->left = left;
 102
 103         task->peers = xbt_dynar_new(sizeof(int),NULL);
 104
 105         return task;
 106 }
 107 /**
 108  * Free a tracker task that has not succefully been sent.
 109  * @param data Task to free
 110  */
 111 static void task_free(void *data) {
 112         tracker_task_data_t task_data = MSG_task_get_data(data);
 113         tracker_task_data_free(task_data);
 114         MSG_task_destroy(data);
 115 }
 116 /**
 117  * Free the data structure of a tracker task.
 118  * @param task data to free
 119  */
 120 void tracker_task_data_free(tracker_task_data_t task) {
 121         xbt_dynar_free(&task->peers);
 122         xbt_free(task);
 123 }
 124 /**
 125  * Returns if the given id is in the peers lsit
 126  * @param peers dynar containing the peers
 127  * @param id identifier of the peer to test
 128  */
 129 int is_in_list(xbt_dynar_t peers, int id) {
 130         int i, elm;
 131         xbt_dynar_foreach(peers, i, elm ) {
 132                 if (elm == id) {
 133                         return 1;
 134                 }
 135         }
 136         return 0;
 137 }