1 /* Copyright (c) 2012-2020. 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. */
10 #include "s4u-peer.hpp"
11 #include "s4u-tracker.hpp"
13 XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_bt_peer, "Messages specific for the peers");
16 * User parameters for transferred file data. For the test, the default values are :
17 * File size: 10 pieces * 5 blocks/piece * 16384 bytes/block = 819200 bytes
19 constexpr unsigned long FILE_PIECES = 10UL;
20 constexpr unsigned long PIECES_BLOCKS = 5UL;
21 constexpr int BLOCK_SIZE = 16384;
23 /** Number of blocks asked by each request */
24 constexpr unsigned long BLOCKS_REQUESTED = 2UL;
26 constexpr double SLEEP_DURATION = 1.0;
27 #define BITS_TO_BYTES(x) (((x) / 8 + (x) % 8) ? 1 : 0)
30 * Sizes based on report by A. Legout et al, Understanding BitTorrent: An Experimental Perspective
31 * http://hal.inria.fr/inria-00000156/en
33 constexpr unsigned message_size(MessageType type)
35 constexpr std::array<unsigned, 10> sizes{{/* HANDSHAKE */ 68,
39 /* NOTINTERESTED */ 5,
45 return sizes[static_cast<int>(type)];
48 constexpr const char* message_name(MessageType type)
50 constexpr std::array<const char*, 10> names{{"HANDSHAKE", "CHOKE", "UNCHOKE", "INTERESTED", "NOTINTERESTED", "HAVE",
51 "BITFIELD", "REQUEST", "PIECE", "CANCEL"}};
52 return names[static_cast<int>(type)];
55 Peer::Peer(std::vector<std::string> args)
58 xbt_assert(args.size() == 3 || args.size() == 4, "Wrong number of arguments");
60 id = std::stoi(args[1]);
61 mailbox_ = simgrid::s4u::Mailbox::by_name(std::to_string(id));
62 } catch (const std::invalid_argument&) {
63 throw std::invalid_argument("Invalid ID:" + args[1]);
68 deadline = std::stod(args[2]);
69 } catch (const std::invalid_argument&) {
70 throw std::invalid_argument("Invalid deadline:" + args[2]);
72 xbt_assert(deadline > 0, "Wrong deadline supplied");
74 if (args.size() == 4 && args[3] == "1") {
75 bitfield_ = (1U << FILE_PIECES) - 1U;
76 bitfield_blocks = (1ULL << (FILE_PIECES * PIECES_BLOCKS)) - 1ULL;
78 pieces_count.resize(FILE_PIECES);
80 XBT_INFO("Hi, I'm joining the network with id %d", id);
83 /** Peer main function */
84 void Peer::operator()()
86 // Getting peer data from the tracker.
87 if (getPeersFromTracker()) {
88 XBT_DEBUG("Got %zu peers from the tracker. Current status is: %s", connected_peers.size(), getStatus().c_str());
89 begin_receive_time = simgrid::s4u::Engine::get_clock();
90 mailbox_->set_receiver(simgrid::s4u::Actor::self());
92 sendHandshakeToAllPeers();
98 XBT_INFO("Couldn't contact the tracker.");
101 XBT_INFO("Here is my current status: %s", getStatus().c_str());
104 bool Peer::getPeersFromTracker()
106 simgrid::s4u::Mailbox* tracker_mailbox = simgrid::s4u::Mailbox::by_name(TRACKER_MAILBOX);
107 // Build the task to send to the tracker
108 auto* peer_request = new TrackerQuery(id, mailbox_);
110 XBT_DEBUG("Sending a peer request to the tracker.");
111 tracker_mailbox->put(peer_request, TRACKER_COMM_SIZE, GET_PEERS_TIMEOUT);
112 } catch (const simgrid::TimeoutException&) {
113 XBT_DEBUG("Timeout expired when requesting peers to tracker");
119 auto* answer = static_cast<TrackerAnswer*>(mailbox_->get(GET_PEERS_TIMEOUT));
120 // Add the peers the tracker gave us to our peer list.
121 for (auto const& peer_id : answer->getPeers())
123 connected_peers.emplace(peer_id, Connection(peer_id));
125 } catch (const simgrid::TimeoutException&) {
126 XBT_DEBUG("Timeout expired when requesting peers to tracker");
132 void Peer::sendHandshakeToAllPeers()
134 for (auto const& kv : connected_peers) {
135 const Connection& remote_peer = kv.second;
136 auto* handshake = new Message(MessageType::HANDSHAKE, id, mailbox_);
137 remote_peer.mailbox_->put_init(handshake, message_size(MessageType::HANDSHAKE))->detach();
138 XBT_DEBUG("Sending a HANDSHAKE to %d", remote_peer.id);
142 void Peer::sendMessage(simgrid::s4u::Mailbox* mailbox, MessageType type, uint64_t size)
144 XBT_DEBUG("Sending %s to %s", message_name(type), mailbox->get_cname());
145 mailbox->put_init(new Message(type, id, bitfield_, mailbox_), size)->detach();
148 void Peer::sendBitfield(simgrid::s4u::Mailbox* mailbox)
150 XBT_DEBUG("Sending a BITFIELD to %s", mailbox->get_cname());
152 ->put_init(new Message(MessageType::BITFIELD, id, bitfield_, mailbox_),
153 message_size(MessageType::BITFIELD) + BITS_TO_BYTES(FILE_PIECES))
157 void Peer::sendPiece(simgrid::s4u::Mailbox* mailbox, unsigned int piece, int block_index, int block_length)
159 xbt_assert(not hasNotPiece(piece), "Tried to send a unavailable piece.");
160 XBT_DEBUG("Sending the PIECE %u (%d,%d) to %s", piece, block_index, block_length, mailbox->get_cname());
161 mailbox->put_init(new Message(MessageType::PIECE, id, mailbox_, piece, block_index, block_length), BLOCK_SIZE)
165 void Peer::sendHaveToAllPeers(unsigned int piece)
167 XBT_DEBUG("Sending HAVE message to all my peers");
168 for (auto const& kv : connected_peers) {
169 const Connection& remote_peer = kv.second;
170 remote_peer.mailbox_->put_init(new Message(MessageType::HAVE, id, mailbox_, piece), message_size(MessageType::HAVE))
175 void Peer::sendRequestTo(Connection* remote_peer, unsigned int piece)
177 remote_peer->current_piece = piece;
178 xbt_assert(remote_peer->hasPiece(piece));
179 int block_index = getFirstMissingBlockFrom(piece);
180 if (block_index != -1) {
181 int block_length = static_cast<int>(std::min(BLOCKS_REQUESTED, PIECES_BLOCKS - block_index));
182 XBT_DEBUG("Sending a REQUEST to %s for piece %u (%d,%d)", remote_peer->mailbox_->get_cname(), piece, block_index,
184 remote_peer->mailbox_
185 ->put_init(new Message(MessageType::REQUEST, id, mailbox_, piece, block_index, block_length),
186 message_size(MessageType::REQUEST))
191 std::string Peer::getStatus() const
194 for (unsigned i = 0; i < FILE_PIECES; i++)
195 res += (bitfield_ & (1U << i)) ? '1' : '0';
199 bool Peer::hasFinished() const
201 return bitfield_ == (1U << FILE_PIECES) - 1U;
204 /** Indicates if the remote peer has a piece not stored by the local peer */
205 bool Peer::isInterestedBy(const Connection* remote_peer) const
207 return remote_peer->bitfield & (bitfield_ ^ ((1 << FILE_PIECES) - 1));
210 bool Peer::isInterestedByFree(const Connection* remote_peer) const
212 for (unsigned int i = 0; i < FILE_PIECES; i++)
213 if (hasNotPiece(i) && remote_peer->hasPiece(i) && isNotDownloadingPiece(i))
218 void Peer::updatePiecesCountFromBitfield(unsigned int bitfield)
220 for (unsigned int i = 0; i < FILE_PIECES; i++)
221 if (bitfield & (1U << i))
225 unsigned int Peer::countPieces(unsigned int bitfield) const
227 unsigned int count = 0U;
228 unsigned int n = bitfield;
236 int Peer::nbInterestedPeers() const
239 for (auto const& kv : connected_peers)
240 if (kv.second.interested)
247 double next_choked_update = simgrid::s4u::Engine::get_clock() + UPDATE_CHOKED_INTERVAL;
248 XBT_DEBUG("Start downloading.");
250 /* Send a "handshake" message to all the peers it got (since it couldn't have gotten more than 50 peers) */
251 sendHandshakeToAllPeers();
252 XBT_DEBUG("Starting main leech loop listening on mailbox: %s", mailbox_->get_cname());
254 void* data = nullptr;
255 while (simgrid::s4u::Engine::get_clock() < deadline && countPieces(bitfield_) < FILE_PIECES) {
256 if (comm_received == nullptr) {
257 comm_received = mailbox_->get_async(&data);
259 if (comm_received->test()) {
260 message = static_cast<Message*>(data);
263 comm_received = nullptr;
265 // We don't execute the choke algorithm if we don't already have a piece
266 if (simgrid::s4u::Engine::get_clock() >= next_choked_update && countPieces(bitfield_) > 0) {
268 next_choked_update += UPDATE_CHOKED_INTERVAL;
270 simgrid::s4u::this_actor::sleep_for(SLEEP_DURATION);
275 XBT_DEBUG("%d becomes a seeder", id);
280 double next_choked_update = simgrid::s4u::Engine::get_clock() + UPDATE_CHOKED_INTERVAL;
281 XBT_DEBUG("Start seeding.");
282 // start the main seed loop
283 void* data = nullptr;
284 while (simgrid::s4u::Engine::get_clock() < deadline) {
285 if (comm_received == nullptr) {
286 comm_received = mailbox_->get_async(&data);
288 if (comm_received->test()) {
289 message = static_cast<Message*>(data);
292 comm_received = nullptr;
294 if (simgrid::s4u::Engine::get_clock() >= next_choked_update) {
296 // TODO: Change the choked peer algorithm when seeding.
297 next_choked_update += UPDATE_CHOKED_INTERVAL;
299 simgrid::s4u::this_actor::sleep_for(SLEEP_DURATION);
305 void Peer::updateActivePeersSet(Connection* remote_peer)
307 if (remote_peer->interested && not remote_peer->choked_upload)
308 active_peers.insert(remote_peer);
310 active_peers.erase(remote_peer);
313 void Peer::handleMessage()
315 XBT_DEBUG("Received a %s message from %s", message_name(message->type), message->return_mailbox->get_cname());
317 auto known_peer = connected_peers.find(message->peer_id);
318 Connection* remote_peer = (known_peer == connected_peers.end()) ? nullptr : &known_peer->second;
319 xbt_assert(remote_peer != nullptr || message->type == MessageType::HANDSHAKE,
320 "The impossible did happened: A not-in-our-list peer sent us a message.");
322 switch (message->type) {
323 case MessageType::HANDSHAKE:
324 // Check if the peer is in our connection list.
325 if (remote_peer == nullptr) {
326 XBT_DEBUG("This peer %d was unknown, answer to its handshake", message->peer_id);
327 connected_peers.emplace(message->peer_id, Connection(message->peer_id));
328 sendMessage(message->return_mailbox, MessageType::HANDSHAKE, message_size(MessageType::HANDSHAKE));
330 // Send our bitfield to the peer
331 sendBitfield(message->return_mailbox);
333 case MessageType::BITFIELD:
334 // Update the pieces list
335 updatePiecesCountFromBitfield(message->bitfield);
336 // Store the bitfield
337 remote_peer->bitfield = message->bitfield;
338 xbt_assert(not remote_peer->am_interested, "Should not be interested at first");
339 if (isInterestedBy(remote_peer)) {
340 remote_peer->am_interested = true;
341 sendMessage(message->return_mailbox, MessageType::INTERESTED, message_size(MessageType::INTERESTED));
344 case MessageType::INTERESTED:
345 // Update the interested state of the peer.
346 remote_peer->interested = true;
347 updateActivePeersSet(remote_peer);
349 case MessageType::NOTINTERESTED:
350 remote_peer->interested = false;
351 updateActivePeersSet(remote_peer);
353 case MessageType::UNCHOKE:
354 xbt_assert(remote_peer->choked_download);
355 remote_peer->choked_download = false;
356 // Send requests to the peer, since it has unchoked us
357 if (remote_peer->am_interested)
358 requestNewPieceTo(remote_peer);
360 case MessageType::CHOKE:
361 xbt_assert(not remote_peer->choked_download);
362 remote_peer->choked_download = true;
363 if (remote_peer->current_piece != -1)
364 removeCurrentPiece(remote_peer, remote_peer->current_piece);
366 case MessageType::HAVE:
367 XBT_DEBUG("\t for piece %d", message->piece);
368 xbt_assert((message->piece >= 0 && static_cast<unsigned int>(message->piece) < FILE_PIECES),
369 "Wrong HAVE message received");
370 remote_peer->bitfield = remote_peer->bitfield | (1U << static_cast<unsigned int>(message->piece));
371 pieces_count[message->piece]++;
372 // If the piece is in our pieces, we tell the peer that we are interested.
373 if (not remote_peer->am_interested && hasNotPiece(message->piece)) {
374 remote_peer->am_interested = true;
375 sendMessage(message->return_mailbox, MessageType::INTERESTED, message_size(MessageType::INTERESTED));
376 if (not remote_peer->choked_download)
377 requestNewPieceTo(remote_peer);
380 case MessageType::REQUEST:
381 xbt_assert(remote_peer->interested);
382 xbt_assert((message->piece >= 0 && static_cast<unsigned int>(message->piece) < FILE_PIECES),
383 "Wrong HAVE message received");
384 if (not remote_peer->choked_upload) {
385 XBT_DEBUG("\t for piece %d (%d,%d)", message->piece, message->block_index,
386 message->block_index + message->block_length);
387 if (not hasNotPiece(message->piece)) {
388 sendPiece(message->return_mailbox, message->piece, message->block_index, message->block_length);
391 XBT_DEBUG("\t for piece %d but he is choked.", message->peer_id);
394 case MessageType::PIECE:
395 XBT_DEBUG(" \t for piece %d (%d,%d)", message->piece, message->block_index,
396 message->block_index + message->block_length);
397 xbt_assert(not remote_peer->choked_download);
398 xbt_assert(not remote_peer->choked_download, "Can't received a piece if I'm choked !");
399 xbt_assert((message->piece >= 0 && static_cast<unsigned int>(message->piece) < FILE_PIECES),
400 "Wrong piece received");
401 // TODO: Execute a computation.
402 if (hasNotPiece(static_cast<unsigned int>(message->piece))) {
403 updateBitfieldBlocks(message->piece, message->block_index, message->block_length);
404 if (hasCompletedPiece(static_cast<unsigned int>(message->piece))) {
405 // Removing the piece from our piece list
406 removeCurrentPiece(remote_peer, message->piece);
407 // Setting the fact that we have the piece
408 bitfield_ = bitfield_ | (1U << static_cast<unsigned int>(message->piece));
409 XBT_DEBUG("My status is now %s", getStatus().c_str());
410 // Sending the information to all the peers we are connected to
411 sendHaveToAllPeers(message->piece);
412 // sending UNINTERESTED to peers that do not have what we want.
413 updateInterestedAfterReceive();
414 } else { // piece not completed
415 sendRequestTo(remote_peer, message->piece); // ask for the next block
418 XBT_DEBUG("However, we already have it");
419 requestNewPieceTo(remote_peer);
422 case MessageType::CANCEL:
427 // Update the peer speed.
429 remote_peer->addSpeedValue(1.0 / (simgrid::s4u::Engine::get_clock() - begin_receive_time));
431 begin_receive_time = simgrid::s4u::Engine::get_clock();
434 /** Selects the appropriate piece to download and requests it to the remote_peer */
435 void Peer::requestNewPieceTo(Connection* remote_peer)
437 int piece = selectPieceToDownload(remote_peer);
439 current_pieces |= (1U << (unsigned int)piece);
440 sendRequestTo(remote_peer, piece);
444 void Peer::removeCurrentPiece(Connection* remote_peer, unsigned int current_piece)
446 current_pieces &= ~(1U << current_piece);
447 remote_peer->current_piece = -1;
450 /** @brief Return the piece to be downloaded
451 * There are two cases (as described in "Bittorrent Architecture Protocol", Ryan Toole :
452 * If a piece is partially downloaded, this piece will be selected prioritarily
453 * If the peer has strictly less than 4 pieces, he chooses a piece at random.
454 * If the peer has more than pieces, he downloads the pieces that are the less replicated (rarest policy).
455 * If all pieces have been downloaded or requested, we select a random requested piece (endgame mode).
456 * @param remote_peer: information about the connection
457 * @return the piece to download if possible. -1 otherwise
459 int Peer::selectPieceToDownload(const Connection* remote_peer)
461 int piece = partiallyDownloadedPiece(remote_peer);
462 // strict priority policy
467 if (countPieces(current_pieces) >= (FILE_PIECES - countPieces(bitfield_)) && isInterestedBy(remote_peer)) {
468 int nb_interesting_pieces = 0;
469 // compute the number of interesting pieces
470 for (unsigned int i = 0; i < FILE_PIECES; i++)
471 if (remotePeerHasMissingPiece(remote_peer, i))
472 nb_interesting_pieces++;
474 xbt_assert(nb_interesting_pieces != 0);
475 // get a random interesting piece
476 int random_piece_index = random.uniform_int(0, nb_interesting_pieces - 1);
477 int current_index = 0;
478 for (unsigned int i = 0; i < FILE_PIECES; i++) {
479 if (remotePeerHasMissingPiece(remote_peer, i)) {
480 if (random_piece_index == current_index) {
487 xbt_assert(piece != -1);
490 // Random first policy
491 if (countPieces(bitfield_) < 4 && isInterestedByFree(remote_peer)) {
492 int nb_interesting_pieces = 0;
493 // compute the number of interesting pieces
494 for (unsigned int i = 0; i < FILE_PIECES; i++)
495 if (remotePeerHasMissingPiece(remote_peer, i) && isNotDownloadingPiece(i))
496 nb_interesting_pieces++;
497 xbt_assert(nb_interesting_pieces != 0);
498 // get a random interesting piece
499 int random_piece_index = random.uniform_int(0, nb_interesting_pieces - 1);
500 int current_index = 0;
501 for (unsigned int i = 0; i < FILE_PIECES; i++) {
502 if (remotePeerHasMissingPiece(remote_peer, i) && isNotDownloadingPiece(i)) {
503 if (random_piece_index == current_index) {
510 xbt_assert(piece != -1);
512 } else { // Rarest first policy
513 short min = SHRT_MAX;
514 int nb_min_pieces = 0;
515 int current_index = 0;
516 // compute the smallest number of copies of available pieces
517 for (unsigned int i = 0; i < FILE_PIECES; i++) {
518 if (pieces_count[i] < min && remotePeerHasMissingPiece(remote_peer, i) && isNotDownloadingPiece(i))
519 min = pieces_count[i];
522 xbt_assert(min != SHRT_MAX || not isInterestedByFree(remote_peer));
523 // compute the number of rarest pieces
524 for (unsigned int i = 0; i < FILE_PIECES; i++)
525 if (pieces_count[i] == min && remotePeerHasMissingPiece(remote_peer, i) && isNotDownloadingPiece(i))
528 xbt_assert(nb_min_pieces != 0 || not isInterestedByFree(remote_peer));
529 // get a random rarest piece
530 int random_rarest_index = 0;
531 if (nb_min_pieces > 0) {
532 random_rarest_index = random.uniform_int(0, nb_min_pieces - 1);
534 for (unsigned int i = 0; i < FILE_PIECES; i++)
535 if (pieces_count[i] == min && remotePeerHasMissingPiece(remote_peer, i) && isNotDownloadingPiece(i)) {
536 if (random_rarest_index == current_index) {
543 xbt_assert(piece != -1 || not isInterestedByFree(remote_peer));
548 void Peer::updateChokedPeers()
550 if (nbInterestedPeers() == 0)
552 XBT_DEBUG("(%d) update_choked peers %zu active peers", id, active_peers.size());
553 // update the current round
554 round_ = (round_ + 1) % 3;
555 Connection* chosen_peer = nullptr;
556 // select first active peer and remove it from the set
557 Connection* choked_peer;
558 if (active_peers.empty()) {
559 choked_peer = nullptr;
561 choked_peer = *active_peers.begin();
562 active_peers.erase(choked_peer);
565 /**If we are currently seeding, we unchoke the peer which has been unchoked the last time.*/
567 double unchoke_time = simgrid::s4u::Engine::get_clock() + 1;
568 for (auto& kv : connected_peers) {
569 Connection& remote_peer = kv.second;
570 if (remote_peer.last_unchoke < unchoke_time && remote_peer.interested && remote_peer.choked_upload) {
571 unchoke_time = remote_peer.last_unchoke;
572 chosen_peer = &remote_peer;
576 // Random optimistic unchoking
580 // We choose a random peer to unchoke.
581 auto chosen_peer_it = connected_peers.begin();
582 std::advance(chosen_peer_it, random.uniform_int(0, static_cast<int>(connected_peers.size() - 1)));
583 chosen_peer = &chosen_peer_it->second;
584 if (not chosen_peer->interested || not chosen_peer->choked_upload)
585 chosen_peer = nullptr;
587 XBT_DEBUG("Nothing to do, keep going");
589 } while (chosen_peer == nullptr && j < MAXIMUM_PEERS);
591 // Use the "fastest download" policy.
592 double fastest_speed = 0.0;
593 for (auto& kv : connected_peers) {
594 Connection& remote_peer = kv.second;
595 if (remote_peer.peer_speed > fastest_speed && remote_peer.choked_upload && remote_peer.interested) {
596 fastest_speed = remote_peer.peer_speed;
597 chosen_peer = &remote_peer;
603 if (chosen_peer != nullptr)
604 XBT_DEBUG("(%d) update_choked peers unchoked (%d) ; int (%d) ; choked (%d) ", id, chosen_peer->id,
605 chosen_peer->interested, chosen_peer->choked_upload);
607 if (choked_peer != chosen_peer) {
608 if (choked_peer != nullptr) {
609 xbt_assert(not choked_peer->choked_upload, "Tries to choked a choked peer");
610 choked_peer->choked_upload = true;
611 updateActivePeersSet(choked_peer);
612 XBT_DEBUG("(%d) Sending a CHOKE to %d", id, choked_peer->id);
613 sendMessage(choked_peer->mailbox_, MessageType::CHOKE, message_size(MessageType::CHOKE));
615 if (chosen_peer != nullptr) {
616 xbt_assert((chosen_peer->choked_upload), "Tries to unchoked an unchoked peer");
617 chosen_peer->choked_upload = false;
618 active_peers.insert(chosen_peer);
619 chosen_peer->last_unchoke = simgrid::s4u::Engine::get_clock();
620 XBT_DEBUG("(%d) Sending a UNCHOKE to %d", id, chosen_peer->id);
621 updateActivePeersSet(chosen_peer);
622 sendMessage(chosen_peer->mailbox_, MessageType::UNCHOKE, message_size(MessageType::UNCHOKE));
627 /** @brief Update "interested" state of peers: send "not interested" to peers that don't have any more pieces we want.*/
628 void Peer::updateInterestedAfterReceive()
630 for (auto& kv : connected_peers) {
631 Connection& remote_peer = kv.second;
632 if (remote_peer.am_interested) {
633 bool interested = false;
634 // Check if the peer still has a piece we want.
635 for (unsigned int i = 0; i < FILE_PIECES; i++)
636 if (remotePeerHasMissingPiece(&remote_peer, i)) {
641 if (not interested) { // no more piece to download from connection
642 remote_peer.am_interested = false;
643 sendMessage(remote_peer.mailbox_, MessageType::NOTINTERESTED, message_size(MessageType::NOTINTERESTED));
649 void Peer::updateBitfieldBlocks(int piece, int block_index, int block_length)
651 xbt_assert((piece >= 0 && static_cast<unsigned int>(piece) <= FILE_PIECES), "Wrong piece.");
652 xbt_assert((block_index >= 0 && static_cast<unsigned int>(block_index) <= PIECES_BLOCKS), "Wrong block : %d.",
654 for (int i = block_index; i < (block_index + block_length); i++)
655 bitfield_blocks |= (1ULL << static_cast<unsigned int>(piece * PIECES_BLOCKS + i));
658 bool Peer::hasCompletedPiece(unsigned int piece) const
660 for (unsigned int i = 0; i < PIECES_BLOCKS; i++)
661 if (not(bitfield_blocks & 1ULL << (piece * PIECES_BLOCKS + i)))
666 int Peer::getFirstMissingBlockFrom(int piece) const
668 for (unsigned int i = 0; i < PIECES_BLOCKS; i++)
669 if (not(bitfield_blocks & 1ULL << (piece * PIECES_BLOCKS + i)))
674 /** Returns a piece that is partially downloaded and stored by the remote peer if any -1 otherwise. */
675 int Peer::partiallyDownloadedPiece(const Connection* remote_peer) const
677 for (unsigned int i = 0; i < FILE_PIECES; i++)
678 if (remotePeerHasMissingPiece(remote_peer, i) && isNotDownloadingPiece(i) && getFirstMissingBlockFrom(i) > 0)