1 /* Copyright (c) 2012-2018. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "bittorrent-peer.h"
7 #include "bittorrent-messages.h"
8 #include "connection.h"
10 #include <simgrid/msg.h>
11 #include <xbt/RngStream.h>
14 #include <stdio.h> /* snprintf */
16 XBT_LOG_NEW_DEFAULT_CATEGORY(msg_peers, "Messages specific for the peers");
19 * User parameters for transferred file data. For the test, the default values are :
20 * File size: 10 pieces * 5 blocks/piece * 16384 bytes/block = 819200 bytes
22 #define FILE_PIECES 10UL
23 #define PIECES_BLOCKS 5UL
24 #define BLOCK_SIZE 16384
25 static const unsigned long int FILE_SIZE = FILE_PIECES * PIECES_BLOCKS * BLOCK_SIZE;
27 /** Number of blocks asked by each request */
28 #define BLOCKS_REQUESTED 2
30 #define ENABLE_END_GAME_MODE 1
31 #define SLEEP_DURATION 1
33 int count_pieces(unsigned int bitfield)
36 unsigned int n = bitfield;
44 int peer_has_not_piece(peer_t peer, unsigned int piece)
46 return !(peer->bitfield & 1U << piece);
49 /** Check that a piece is not currently being download by the peer. */
50 int peer_is_not_downloading_piece(peer_t peer, unsigned int piece)
52 return !(peer->current_pieces & 1U << piece);
55 void get_status(char** status, unsigned int bitfield)
57 for (int i = FILE_PIECES - 1; i >= 0; i--)
58 (*status)[i] = (bitfield & (1U << i)) ? '1' : '0';
59 (*status)[FILE_PIECES] = '\0';
62 /** Peer main function */
63 int peer(int argc, char* argv[])
66 xbt_assert(argc == 3 || argc == 4, "Wrong number of arguments");
69 peer_t peer = peer_init(xbt_str_parse_int(argv[1], "Invalid ID: %s"), argc == 4 ? 1 : 0);
72 double deadline = xbt_str_parse_double(argv[2], "Invalid deadline: %s");
73 xbt_assert(deadline > 0, "Wrong deadline supplied");
75 char* status = xbt_malloc0(FILE_PIECES + 1);
76 get_status(&status, peer->bitfield);
77 XBT_INFO("Hi, I'm joining the network with id %d", peer->id);
78 // Getting peer data from the tracker.
79 if (get_peers_data(peer)) {
80 XBT_DEBUG("Got %d peers from the tracker. Current status is: %s", xbt_dict_length(peer->peers), status);
81 peer->begin_receive_time = MSG_get_clock();
82 MSG_mailbox_set_async(peer->mailbox);
83 if (has_finished(peer->bitfield)) {
84 send_handshake_all(peer);
86 leech_loop(peer, deadline);
88 seed_loop(peer, deadline);
90 XBT_INFO("Couldn't contact the tracker.");
93 get_status(&status, peer->bitfield);
94 XBT_INFO("Here is my current status: %s", status);
95 if (peer->comm_received) {
96 MSG_comm_destroy(peer->comm_received);
104 /** @brief Peer main loop when it is leeching.
105 * @param peer peer data
106 * @param deadline time at which the peer has to leave
108 void leech_loop(peer_t peer, double deadline)
110 double next_choked_update = MSG_get_clock() + UPDATE_CHOKED_INTERVAL;
111 XBT_DEBUG("Start downloading.");
113 /* Send a "handshake" message to all the peers it got (since it couldn't have gotten more than 50 peers) */
114 send_handshake_all(peer);
115 XBT_DEBUG("Starting main leech loop");
117 while (MSG_get_clock() < deadline && count_pieces(peer->bitfield) < FILE_PIECES) {
118 if (peer->comm_received == NULL) {
119 peer->task_received = NULL;
120 peer->comm_received = MSG_task_irecv(&peer->task_received, peer->mailbox);
122 if (MSG_comm_test(peer->comm_received)) {
123 msg_error_t status = MSG_comm_get_status(peer->comm_received);
124 MSG_comm_destroy(peer->comm_received);
125 peer->comm_received = NULL;
126 if (status == MSG_OK) {
127 handle_message(peer, peer->task_received);
130 // We don't execute the choke algorithm if we don't already have a piece
131 if (MSG_get_clock() >= next_choked_update && count_pieces(peer->bitfield) > 0) {
132 update_choked_peers(peer);
133 next_choked_update += UPDATE_CHOKED_INTERVAL;
135 MSG_process_sleep(SLEEP_DURATION);
139 if (has_finished(peer->bitfield))
140 XBT_DEBUG("%d becomes a seeder", peer->id);
143 /** @brief Peer main loop when it is seeding
144 * @param peer peer data
145 * @param deadline time when the peer will leave
147 void seed_loop(peer_t peer, double deadline)
149 double next_choked_update = MSG_get_clock() + UPDATE_CHOKED_INTERVAL;
150 XBT_DEBUG("Start seeding.");
151 // start the main seed loop
152 while (MSG_get_clock() < deadline) {
153 if (peer->comm_received == NULL) {
154 peer->task_received = NULL;
155 peer->comm_received = MSG_task_irecv(&peer->task_received, peer->mailbox);
157 if (MSG_comm_test(peer->comm_received)) {
158 msg_error_t status = MSG_comm_get_status(peer->comm_received);
159 MSG_comm_destroy(peer->comm_received);
160 peer->comm_received = NULL;
161 if (status == MSG_OK) {
162 handle_message(peer, peer->task_received);
165 if (MSG_get_clock() >= next_choked_update) {
166 update_choked_peers(peer);
167 // TODO: Change the choked peer algorithm when seeding.
168 next_choked_update += UPDATE_CHOKED_INTERVAL;
170 MSG_process_sleep(SLEEP_DURATION);
176 /** @brief Retrieves the peer list from the tracker
177 * @param peer current peer data
179 int get_peers_data(peer_t peer)
182 double timeout = MSG_get_clock() + GET_PEERS_TIMEOUT;
184 // Build the task to send to the tracker
185 tracker_task_data_t data =
186 tracker_task_data_new(MSG_host_get_name(MSG_host_self()), peer->mailbox_tracker, peer->id, 0, 0, FILE_SIZE);
187 msg_task_t task_send = MSG_task_create(NULL, 0, TRACKER_COMM_SIZE, data);
188 while ((success == 0) && MSG_get_clock() < timeout) {
189 XBT_DEBUG("Sending a peer request to the tracker.");
190 msg_error_t status = MSG_task_send_with_timeout(task_send, TRACKER_MAILBOX, GET_PEERS_TIMEOUT);
191 if (status == MSG_OK) {
197 msg_task_t task_received = NULL;
198 while ((success == 0) && MSG_get_clock() < timeout) {
199 msg_comm_t comm_received = MSG_task_irecv(&task_received, peer->mailbox_tracker);
200 msg_error_t status = MSG_comm_wait(comm_received, GET_PEERS_TIMEOUT);
201 if (status == MSG_OK) {
202 tracker_task_data_t data = MSG_task_get_data(task_received);
205 // Add the peers the tracker gave us to our peer list.
206 xbt_dynar_foreach (data->peers, i, peer_id) {
207 if (peer_id != peer->id)
208 xbt_dict_set_ext(peer->peers, (char*)&peer_id, sizeof(int), connection_new(peer_id), NULL);
211 // free the communication and the task
212 MSG_comm_destroy(comm_received);
213 tracker_task_data_free(data);
214 MSG_task_destroy(task_received);
221 /** @brief Initialize the peer data.
222 * @param peer peer data
223 * @param id id of the peer to take in the network
224 * @param seed indicates if the peer is a seed.
226 peer_t peer_init(int id, int seed)
228 peer_t peer = xbt_new(s_peer_t, 1);
230 peer->hostname = MSG_host_get_name(MSG_host_self());
232 snprintf(peer->mailbox, MAILBOX_SIZE - 1, "%d", id);
233 snprintf(peer->mailbox_tracker, MAILBOX_SIZE - 1, "tracker_%d", id);
234 peer->peers = xbt_dict_new_homogeneous(NULL);
235 peer->active_peers = xbt_dict_new_homogeneous(NULL);
238 peer->bitfield = (1U << FILE_PIECES) - 1U;
239 peer->bitfield_blocks = (1ULL << (FILE_PIECES * PIECES_BLOCKS)) - 1ULL;
242 peer->bitfield_blocks = 0;
245 peer->current_pieces = 0;
247 peer->pieces_count = xbt_new0(short, FILE_PIECES);
249 peer->stream = (RngStream)MSG_host_get_data(MSG_host_self());
250 peer->comm_received = NULL;
257 /** Destroys a poor peer object. */
258 void peer_free(peer_t peer)
261 connection_t connection;
262 xbt_dict_cursor_t cursor;
263 xbt_dict_foreach (peer->peers, cursor, key, connection) {
264 connection_free(connection);
266 xbt_dict_free(&peer->peers);
267 xbt_dict_free(&peer->active_peers);
268 xbt_free(peer->pieces_count);
272 /** @brief Returns if a peer has finished downloading the file
273 * @param bitfield peer bitfield
275 int has_finished(unsigned int bitfield)
277 return bitfield == (1U << FILE_PIECES) - 1U;
280 int nb_interested_peers(peer_t peer)
282 xbt_dict_cursor_t cursor = NULL;
284 connection_t connection;
286 xbt_dict_foreach (peer->peers, cursor, key, connection) {
287 if (connection->interested)
293 void update_active_peers_set(peer_t peer, connection_t remote_peer)
295 if ((remote_peer->interested != 0) && (remote_peer->choked_upload == 0)) {
296 // add in the active peers set
297 xbt_dict_set_ext(peer->active_peers, (char*)&remote_peer->id, sizeof(int), remote_peer, NULL);
298 } else if (xbt_dict_get_or_null_ext(peer->active_peers, (char*)&remote_peer->id, sizeof(int))) {
299 xbt_dict_remove_ext(peer->active_peers, (char*)&remote_peer->id, sizeof(int));
303 /** @brief Handle a received message sent by another peer
304 * @param peer Peer data
305 * @param task task received.
307 void handle_message(peer_t peer, msg_task_t task)
309 const char* type_names[10] = {"HANDSHAKE", "CHOKE", "UNCHOKE", "INTERESTED", "NOTINTERESTED",
310 "HAVE", "BITFIELD", "REQUEST", "PIECE", "CANCEL"};
311 message_t message = MSG_task_get_data(task);
312 XBT_DEBUG("Received a %s message from %s (%s)", type_names[message->type], message->mailbox,
313 message->issuer_host_name);
315 connection_t remote_peer;
316 remote_peer = xbt_dict_get_or_null_ext(peer->peers, (char*)&message->peer_id, sizeof(int));
318 switch (message->type) {
319 case MESSAGE_HANDSHAKE:
320 // Check if the peer is in our connection list.
321 if (remote_peer == 0) {
322 xbt_dict_set_ext(peer->peers, (char*)&message->peer_id, sizeof(int), connection_new(message->peer_id), NULL);
323 send_handshake(peer, message->mailbox);
325 // Send our bitfield to the peer
326 send_bitfield(peer, message->mailbox);
328 case MESSAGE_BITFIELD:
329 // Update the pieces list
330 update_pieces_count_from_bitfield(peer, message->bitfield);
331 // Store the bitfield
332 remote_peer->bitfield = message->bitfield;
333 xbt_assert(!remote_peer->am_interested, "Should not be interested at first");
334 if (is_interested(peer, remote_peer)) {
335 remote_peer->am_interested = 1;
336 send_interested(peer, message->mailbox);
339 case MESSAGE_INTERESTED:
340 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
341 // Update the interested state of the peer.
342 remote_peer->interested = 1;
343 update_active_peers_set(peer, remote_peer);
345 case MESSAGE_NOTINTERESTED:
346 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
347 remote_peer->interested = 0;
348 update_active_peers_set(peer, remote_peer);
350 case MESSAGE_UNCHOKE:
351 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
352 xbt_assert(remote_peer->choked_download);
353 remote_peer->choked_download = 0;
354 // Send requests to the peer, since it has unchoked us
355 if (remote_peer->am_interested)
356 request_new_piece_to_peer(peer, remote_peer);
359 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
360 xbt_assert(!remote_peer->choked_download);
361 remote_peer->choked_download = 1;
362 if (remote_peer->current_piece != -1)
363 remove_current_piece(peer, remote_peer, remote_peer->current_piece);
366 XBT_DEBUG("\t for piece %d", message->index);
367 xbt_assert((message->index >= 0 && message->index < FILE_PIECES), "Wrong HAVE message received");
368 remote_peer->bitfield = remote_peer->bitfield | (1U << message->index);
369 peer->pieces_count[message->index]++;
370 // If the piece is in our pieces, we tell the peer that we are interested.
371 if ((remote_peer->am_interested == 0) && peer_has_not_piece(peer, message->index)) {
372 remote_peer->am_interested = 1;
373 send_interested(peer, message->mailbox);
374 if (remote_peer->choked_download == 0)
375 request_new_piece_to_peer(peer, remote_peer);
378 case MESSAGE_REQUEST:
379 xbt_assert(remote_peer->interested);
380 xbt_assert((message->index >= 0 && message->index < FILE_PIECES), "Wrong request received");
381 if (remote_peer->choked_upload == 0) {
382 XBT_DEBUG("\t for piece %d (%d,%d)", message->index, message->block_index,
383 message->block_index + message->block_length);
384 if (!peer_has_not_piece(peer, message->index)) {
385 send_piece(peer, message->mailbox, message->index, message->block_index, message->block_length);
388 XBT_DEBUG("\t for piece %d but he is choked.", message->peer_id);
392 XBT_DEBUG(" \t for piece %d (%d,%d)", message->index, message->block_index,
393 message->block_index + message->block_length);
394 xbt_assert(!remote_peer->choked_download);
395 xbt_assert(remote_peer->am_interested || ENABLE_END_GAME_MODE,
396 "Can't received a piece if I'm not interested wihtout end-game mode!"
397 "piece (%d) bitfield(%u) remote bitfield(%u)",
398 message->index, peer->bitfield, remote_peer->bitfield);
399 xbt_assert(remote_peer->choked_download != 1, "Can't received a piece if I'm choked !");
400 xbt_assert((message->index >= 0 && message->index < FILE_PIECES), "Wrong piece received");
401 // TODO: Execute à computation.
402 if (peer_has_not_piece(peer, message->index)) {
403 update_bitfield_blocks(peer, message->index, message->block_index, message->block_length);
404 if (piece_complete(peer, message->index)) {
405 // Removing the piece from our piece list
406 remove_current_piece(peer, remote_peer, message->index);
407 // Setting the fact that we have the piece
408 peer->bitfield = peer->bitfield | (1U << message->index);
409 char* status = xbt_malloc0(FILE_PIECES + 1);
410 get_status(&status, peer->bitfield);
411 XBT_DEBUG("My status is now %s", status);
413 // Sending the information to all the peers we are connected to
414 send_have(peer, message->index);
415 // sending UNINTERESTED to peers that do not have what we want.
416 update_interested_after_receive(peer);
417 } else { // piece not completed
418 send_request_to_peer(peer, remote_peer, message->index); // ask for the next block
421 XBT_DEBUG("However, we already have it");
422 xbt_assert(ENABLE_END_GAME_MODE, "Should not happen because we don't use end game mode !");
423 request_new_piece_to_peer(peer, remote_peer);
431 // Update the peer speed.
433 connection_add_speed_value(remote_peer, 1.0 / (MSG_get_clock() - peer->begin_receive_time));
435 peer->begin_receive_time = MSG_get_clock();
437 task_message_free(task);
440 /** Selects the appropriate piece to download and requests it to the remote_peer */
441 void request_new_piece_to_peer(peer_t peer, connection_t remote_peer)
443 int piece = select_piece_to_download(peer, remote_peer);
445 peer->current_pieces |= (1U << (unsigned int)piece);
446 send_request_to_peer(peer, remote_peer, piece);
450 /** remove current_piece from the list of currently downloaded pieces. */
451 void remove_current_piece(peer_t peer, connection_t remote_peer, unsigned int current_piece)
453 peer->current_pieces &= ~(1U << current_piece);
454 remote_peer->current_piece = -1;
457 /** @brief Updates the list of who has a piece from a bitfield
458 * @param peer peer we want to update the list
459 * @param bitfield bitfield
461 void update_pieces_count_from_bitfield(peer_t peer, unsigned int bitfield)
463 for (int i = 0; i < FILE_PIECES; i++) {
464 if (bitfield & (1U << i)) {
465 peer->pieces_count[i]++;
470 /** @brief Return the piece to be downloaded
471 * There are two cases (as described in "Bittorrent Architecture Protocol", Ryan Toole :
472 * If a piece is partially downloaded, this piece will be selected prioritarily
473 * If the peer has strictly less than 4 pieces, he chooses a piece at random.
474 * If the peer has more than pieces, he downloads the pieces that are the less replicated (rarest policy).
475 * If all pieces have been downloaded or requested, we select a random requested piece (endgame mode).
476 * @param peer: local peer
477 * @param remote_peer: information about the connection
478 * @return the piece to download if possible. -1 otherwise
480 int select_piece_to_download(peer_t peer, connection_t remote_peer)
482 int piece = partially_downloaded_piece(peer, remote_peer);
483 // strict priority policy
488 if (count_pieces(peer->current_pieces) >= (FILE_PIECES - count_pieces(peer->bitfield)) &&
489 (is_interested(peer, remote_peer) != 0)) {
490 #if ENABLE_END_GAME_MODE == 0
493 int nb_interesting_pieces = 0;
494 // compute the number of interesting pieces
495 for (int i = 0; i < FILE_PIECES; i++) {
496 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i)) {
497 nb_interesting_pieces++;
500 xbt_assert(nb_interesting_pieces != 0);
501 // get a random interesting piece
502 int random_piece_index = RngStream_RandInt(peer->stream, 0, nb_interesting_pieces - 1);
503 int current_index = 0;
504 for (int i = 0; i < FILE_PIECES; i++) {
505 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i)) {
506 if (random_piece_index == current_index) {
513 xbt_assert(piece != -1);
516 // Random first policy
517 if (count_pieces(peer->bitfield) < 4 && (is_interested_and_free(peer, remote_peer) != 0)) {
518 int nb_interesting_pieces = 0;
519 // compute the number of interesting pieces
520 for (int i = 0; i < FILE_PIECES; i++) {
521 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
522 peer_is_not_downloading_piece(peer, i)) {
523 nb_interesting_pieces++;
526 xbt_assert(nb_interesting_pieces != 0);
527 // get a random interesting piece
528 int random_piece_index = RngStream_RandInt(peer->stream, 0, nb_interesting_pieces - 1);
529 int current_index = 0;
530 for (int i = 0; i < FILE_PIECES; i++) {
531 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
532 peer_is_not_downloading_piece(peer, i)) {
533 if (random_piece_index == current_index) {
540 xbt_assert(piece != -1);
542 } else { // Rarest first policy
543 short min = SHRT_MAX;
544 int nb_min_pieces = 0;
545 int current_index = 0;
546 // compute the smallest number of copies of available pieces
547 for (int i = 0; i < FILE_PIECES; i++) {
548 if (peer->pieces_count[i] < min && peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
549 peer_is_not_downloading_piece(peer, i))
550 min = peer->pieces_count[i];
552 xbt_assert(min != SHRT_MAX || (is_interested_and_free(peer, remote_peer) == 0));
553 // compute the number of rarest pieces
554 for (int i = 0; i < FILE_PIECES; i++) {
555 if (peer->pieces_count[i] == min && peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
556 peer_is_not_downloading_piece(peer, i))
559 xbt_assert(nb_min_pieces != 0 || (is_interested_and_free(peer, remote_peer) == 0));
560 // get a random rarest piece
561 int random_rarest_index = RngStream_RandInt(peer->stream, 0, nb_min_pieces - 1);
562 for (int i = 0; i < FILE_PIECES; i++) {
563 if (peer->pieces_count[i] == min && peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
564 peer_is_not_downloading_piece(peer, i)) {
565 if (random_rarest_index == current_index) {
572 xbt_assert(piece != -1 || (is_interested_and_free(peer, remote_peer) == 0));
577 /** @brief Update the list of current choked and unchoked peers, using the choke algorithm
578 * @param peer the current peer
580 void update_choked_peers(peer_t peer)
582 if (nb_interested_peers(peer) == 0)
584 XBT_DEBUG("(%d) update_choked peers %u active peers", peer->id, xbt_dict_size(peer->active_peers));
585 // update the current round
586 peer->round = (peer->round + 1) % 3;
588 char* key_choked = NULL;
589 connection_t peer_choosed = NULL;
590 connection_t peer_choked = NULL;
591 // remove a peer from the list
592 xbt_dict_cursor_t cursor = NULL;
593 xbt_dict_cursor_first(peer->active_peers, &cursor);
594 if (!xbt_dict_is_empty(peer->active_peers)) {
595 key_choked = xbt_dict_cursor_get_key(cursor);
596 peer_choked = xbt_dict_cursor_get_data(cursor);
598 xbt_dict_cursor_free(&cursor);
600 /**If we are currently seeding, we unchoke the peer which has been unchoked the last time.*/
601 if (has_finished(peer->bitfield)) {
602 connection_t connection;
603 double unchoke_time = MSG_get_clock() + 1;
605 xbt_dict_foreach (peer->peers, cursor, key, connection) {
606 if (connection->last_unchoke < unchoke_time && (connection->interested != 0) &&
607 (connection->choked_upload != 0)) {
608 unchoke_time = connection->last_unchoke;
609 peer_choosed = connection;
613 // Random optimistic unchoking
614 if (peer->round == 0) {
617 // We choose a random peer to unchoke.
618 int id_chosen = RngStream_RandInt(peer->stream, 0, xbt_dict_length(peer->peers) - 1);
620 connection_t connection;
621 xbt_dict_foreach (peer->peers, cursor, key, connection) {
622 if (i == id_chosen) {
623 peer_choosed = connection;
628 xbt_dict_cursor_free(&cursor);
629 if (peer_choosed == NULL)
630 THROWF(unknown_error, 0, "A peer should have be selected at this point");
631 else if ((peer_choosed->interested == 0) || (peer_choosed->choked_upload == 0))
634 XBT_DEBUG("Nothing to do, keep going");
636 } while (peer_choosed == NULL && j < MAXIMUM_PEERS);
638 // Use the "fastest download" policy.
639 connection_t connection;
640 double fastest_speed = 0.0;
641 xbt_dict_foreach (peer->peers, cursor, key, connection) {
642 if (connection->peer_speed > fastest_speed && (connection->choked_upload != 0) &&
643 (connection->interested != 0)) {
644 peer_choosed = connection;
645 fastest_speed = connection->peer_speed;
651 if (peer_choosed != NULL)
652 XBT_DEBUG("(%d) update_choked peers unchoked (%d) ; int (%d) ; choked (%d) ", peer->id, peer_choosed->id,
653 peer_choosed->interested, peer_choosed->choked_upload);
655 if (peer_choked != peer_choosed) {
656 if (peer_choked != NULL) {
657 xbt_assert((!peer_choked->choked_upload), "Tries to choked a choked peer");
658 peer_choked->choked_upload = 1;
659 xbt_assert((*((int*)key_choked) == peer_choked->id));
660 update_active_peers_set(peer, peer_choked);
661 XBT_DEBUG("(%d) Sending a CHOKE to %d", peer->id, peer_choked->id);
662 send_choked(peer, peer_choked->mailbox);
664 if (peer_choosed != NULL) {
665 xbt_assert((peer_choosed->choked_upload), "Tries to unchoked an unchoked peer");
666 peer_choosed->choked_upload = 0;
667 xbt_dict_set_ext(peer->active_peers, (char*)&peer_choosed->id, sizeof(int), peer_choosed, NULL);
668 peer_choosed->last_unchoke = MSG_get_clock();
669 XBT_DEBUG("(%d) Sending a UNCHOKE to %d", peer->id, peer_choosed->id);
670 update_active_peers_set(peer, peer_choosed);
671 send_unchoked(peer, peer_choosed->mailbox);
676 /** @brief Update "interested" state of peers: send "not interested" to peers that don't have any more pieces we want.
677 * @param peer our peer data
679 void update_interested_after_receive(peer_t peer)
682 xbt_dict_cursor_t cursor;
683 connection_t connection;
684 xbt_dict_foreach (peer->peers, cursor, key, connection) {
685 if (connection->am_interested != 0) {
687 // Check if the peer still has a piece we want.
688 for (int i = 0; i < FILE_PIECES; i++) {
689 if (peer_has_not_piece(peer, i) && connection_has_piece(connection, i)) {
694 if (!interested) { // no more piece to download from connection
695 connection->am_interested = 0;
696 send_notinterested(peer, connection->mailbox);
702 void update_bitfield_blocks(peer_t peer, int index, int block_index, int block_length)
704 xbt_assert((index >= 0 && index <= FILE_PIECES), "Wrong piece.");
705 xbt_assert((block_index >= 0 && block_index <= PIECES_BLOCKS), "Wrong block : %d.", block_index);
706 for (int i = block_index; i < (block_index + block_length); i++) {
707 peer->bitfield_blocks |= (1ULL << (unsigned int)(index * PIECES_BLOCKS + i));
711 /** Returns if a peer has completed the download of a piece */
712 int piece_complete(peer_t peer, int index)
714 for (int i = 0; i < PIECES_BLOCKS; i++) {
715 if (!(peer->bitfield_blocks & 1ULL << (index * PIECES_BLOCKS + i))) {
722 /** Returns the first block that a peer doesn't have in a piece. If the peer has all blocks of the piece, returns -1. */
723 int get_first_block(peer_t peer, int piece)
725 for (int i = 0; i < PIECES_BLOCKS; i++) {
726 if (!(peer->bitfield_blocks & 1ULL << (piece * PIECES_BLOCKS + i))) {
733 /** Indicates if the remote peer has a piece not stored by the local peer */
734 int is_interested(peer_t peer, connection_t remote_peer)
736 return remote_peer->bitfield & (peer->bitfield ^ ((1 << FILE_PIECES) - 1));
739 /** Indicates if the remote peer has a piece not stored by the local peer nor requested by the local peer */
740 int is_interested_and_free(peer_t peer, connection_t remote_peer)
742 for (int i = 0; i < FILE_PIECES; i++) {
743 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) && peer_is_not_downloading_piece(peer, i)) {
750 /** Returns a piece that is partially downloaded and stored by the remote peer if any -1 otherwise. */
751 int partially_downloaded_piece(peer_t peer, connection_t remote_peer)
753 for (int i = 0; i < FILE_PIECES; i++) {
754 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) && peer_is_not_downloading_piece(peer, i) &&
755 get_first_block(peer, i) > 0)
761 /** @brief Send request messages to a peer that have unchoked us
763 * @param remote_peer peer data to the peer we want to send the request
765 void send_request_to_peer(peer_t peer, connection_t remote_peer, int piece)
767 remote_peer->current_piece = piece;
768 xbt_assert(connection_has_piece(remote_peer, piece));
769 int block_index = get_first_block(peer, piece);
770 if (block_index != -1) {
771 int block_length = MIN(BLOCKS_REQUESTED, PIECES_BLOCKS - block_index);
772 send_request(peer, remote_peer->mailbox, piece, block_index, block_length);
776 /***********************************************************
778 * Low level message functions
780 ***********************************************************/
782 /** @brief Send a "interested" message to a peer
783 * @param peer peer data
784 * @param mailbox destination mailbox
786 void send_interested(peer_t peer, const char* mailbox)
788 msg_task_t task = task_message_new(MESSAGE_INTERESTED, peer->hostname, peer->mailbox, peer->id,
789 task_message_size(MESSAGE_INTERESTED));
790 MSG_task_dsend(task, mailbox, task_message_free);
791 XBT_DEBUG("Sending INTERESTED to %s", mailbox);
794 /** @brief Send a "not interested" message to a peer
795 * @param peer peer data
796 * @param mailbox destination mailbox
798 void send_notinterested(peer_t peer, const char* mailbox)
800 msg_task_t task = task_message_new(MESSAGE_NOTINTERESTED, peer->hostname, peer->mailbox, peer->id,
801 task_message_size(MESSAGE_NOTINTERESTED));
802 MSG_task_dsend(task, mailbox, task_message_free);
803 XBT_DEBUG("Sending NOTINTERESTED to %s", mailbox);
806 /** @brief Send a handshake message to all the peers the peer has.
807 * @param peer peer data
809 void send_handshake_all(peer_t peer)
811 connection_t remote_peer;
812 xbt_dict_cursor_t cursor = NULL;
814 xbt_dict_foreach (peer->peers, cursor, key, remote_peer) {
815 msg_task_t task = task_message_new(MESSAGE_HANDSHAKE, peer->hostname, peer->mailbox, peer->id,
816 task_message_size(MESSAGE_HANDSHAKE));
817 MSG_task_dsend(task, remote_peer->mailbox, task_message_free);
818 XBT_DEBUG("Sending a HANDSHAKE to %s", remote_peer->mailbox);
822 /** @brief Send a "handshake" message to an user
823 * @param peer peer data
824 * @param mailbox mailbox where to we send the message
826 void send_handshake(peer_t peer, const char* mailbox)
828 XBT_DEBUG("Sending a HANDSHAKE to %s", mailbox);
829 msg_task_t task = task_message_new(MESSAGE_HANDSHAKE, peer->hostname, peer->mailbox, peer->id,
830 task_message_size(MESSAGE_HANDSHAKE));
831 MSG_task_dsend(task, mailbox, task_message_free);
834 /** Send a "choked" message to a peer. */
835 void send_choked(peer_t peer, const char* mailbox)
837 XBT_DEBUG("Sending a CHOKE to %s", mailbox);
839 task_message_new(MESSAGE_CHOKE, peer->hostname, peer->mailbox, peer->id, task_message_size(MESSAGE_CHOKE));
840 MSG_task_dsend(task, mailbox, task_message_free);
843 /** Send a "unchoked" message to a peer */
844 void send_unchoked(peer_t peer, const char* mailbox)
846 XBT_DEBUG("Sending a UNCHOKE to %s", mailbox);
848 task_message_new(MESSAGE_UNCHOKE, peer->hostname, peer->mailbox, peer->id, task_message_size(MESSAGE_UNCHOKE));
849 MSG_task_dsend(task, mailbox, task_message_free);
852 /** Send a "HAVE" message to all peers we are connected to */
853 void send_have(peer_t peer, int piece)
855 XBT_DEBUG("Sending HAVE message to all my peers");
856 connection_t remote_peer;
857 xbt_dict_cursor_t cursor = NULL;
859 xbt_dict_foreach (peer->peers, cursor, key, remote_peer) {
860 msg_task_t task = task_message_index_new(MESSAGE_HAVE, peer->hostname, peer->mailbox, peer->id, piece,
861 task_message_size(MESSAGE_HAVE));
862 MSG_task_dsend(task, remote_peer->mailbox, task_message_free);
866 /** @brief Send a bitfield message to all the peers the peer has.
867 * @param peer peer data
869 void send_bitfield(peer_t peer, const char* mailbox)
871 XBT_DEBUG("Sending a BITFIELD to %s", mailbox);
872 msg_task_t task = task_message_bitfield_new(peer->hostname, peer->mailbox, peer->id, peer->bitfield, FILE_PIECES);
873 MSG_task_dsend(task, mailbox, task_message_free);
876 /** Send a "request" message to a pair, containing a request for a piece */
877 void send_request(peer_t peer, const char* mailbox, int piece, int block_index, int block_length)
879 XBT_DEBUG("Sending a REQUEST to %s for piece %d (%d,%d)", mailbox, piece, block_index, block_length);
880 msg_task_t task = task_message_request_new(peer->hostname, peer->mailbox, peer->id, piece, block_index, block_length);
881 MSG_task_dsend(task, mailbox, task_message_free);
884 /** Send a "piece" message to a pair, containing a piece of the file */
885 void send_piece(peer_t peer, const char* mailbox, int piece, int block_index, int block_length)
887 XBT_DEBUG("Sending the PIECE %d (%d,%d) to %s", piece, block_index, block_length, mailbox);
888 xbt_assert(piece >= 0, "Tried to send a piece that doesn't exist.");
889 xbt_assert(!peer_has_not_piece(peer, piece), "Tried to send a piece that we doesn't have.");
891 task_message_piece_new(peer->hostname, peer->mailbox, peer->id, piece, block_index, block_length, BLOCK_SIZE);
892 MSG_task_dsend(task, mailbox, task_message_free);