297 lines
10 KiB
C++
297 lines
10 KiB
C++
/*
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Copyright (c) 2003-2013, Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "libtorrent/bitfield.hpp"
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#include "libtorrent/peer_connection.hpp"
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#include "libtorrent/torrent.hpp"
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#include "libtorrent/socket_type.hpp"
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#include "libtorrent/peer_info.hpp" // for peer_info flags
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#include "libtorrent/performance_counters.hpp" // for counters
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#include <vector>
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namespace libtorrent
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{
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// returns the rank of a peer's source. We have an affinity
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// to connecting to peers with higher rank. This is to avoid
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// problems when our peer list is diluted by stale peers from
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// the resume data for instance
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int source_rank(int source_bitmask)
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{
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int ret = 0;
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if (source_bitmask & peer_info::tracker) ret |= 1 << 5;
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if (source_bitmask & peer_info::lsd) ret |= 1 << 4;
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if (source_bitmask & peer_info::dht) ret |= 1 << 3;
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if (source_bitmask & peer_info::pex) ret |= 1 << 2;
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return ret;
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}
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// the case where ignore_peer is motivated is if two peers
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// have only one piece that we don't have, and it's the
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// same piece for both peers. Then they might get into an
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// infinite loop, fighting to request the same blocks.
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// returns false if the function is aborted by an early-exit
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// condition.
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bool request_a_block(torrent& t, peer_connection& c)
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{
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if (t.is_seed()) return false;
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if (c.no_download()) return false;
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if (t.upload_mode()) return false;
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if (c.is_disconnecting()) return false;
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// don't request pieces before we have the metadata
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if (!t.valid_metadata()) return false;
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// don't request pieces before the peer is properly
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// initialized after we have the metadata
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if (!t.are_files_checked()) return false;
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TORRENT_ASSERT(c.peer_info_struct() != 0 || c.type() != peer_connection::bittorrent_connection);
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bool time_critical_mode = t.num_time_critical_pieces() > 0;
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int desired_queue_size = c.desired_queue_size();
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// in time critical mode, only have 1 outstanding request at a time
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// via normal requests
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if (time_critical_mode)
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desired_queue_size = (std::min)(1, desired_queue_size);
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int num_requests = desired_queue_size
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- (int)c.download_queue().size()
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- (int)c.request_queue().size();
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#ifdef TORRENT_LOGGING
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c.peer_log("*** PIECE_PICKER [ dlq: %d rqq: %d target: %d req: %d engame: %d ]"
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, int(c.download_queue().size()), int(c.request_queue().size())
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, c.desired_queue_size(), num_requests, c.endgame());
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#endif
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TORRENT_ASSERT(c.desired_queue_size() > 0);
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// if our request queue is already full, we
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// don't have to make any new requests yet
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if (num_requests <= 0) return false;
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t.need_picker();
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piece_picker& p = t.picker();
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std::vector<piece_block> interesting_pieces;
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interesting_pieces.reserve(100);
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int prefer_whole_pieces = c.prefer_whole_pieces();
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if (prefer_whole_pieces == 0 && !time_critical_mode)
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{
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prefer_whole_pieces = c.statistics().download_payload_rate()
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* t.settings().get_int(settings_pack::whole_pieces_threshold)
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> t.torrent_file().piece_length() ? 1 : 0;
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}
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// if we prefer whole pieces, the piece picker will pick at least
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// the number of blocks we want, but it will try to make the picked
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// blocks be from whole pieces, possibly by returning more blocks
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// than we requested.
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#ifdef TORRENT_DEBUG
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error_code ec;
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TORRENT_ASSERT(c.remote() == c.get_socket()->remote_endpoint(ec) || ec);
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#endif
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aux::session_interface& ses = t.session();
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std::vector<pending_block> const& dq = c.download_queue();
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std::vector<pending_block> const& rq = c.request_queue();
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std::vector<int> const& suggested = c.suggested_pieces();
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bitfield const* bits = &c.get_bitfield();
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bitfield fast_mask;
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if (c.has_peer_choked())
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{
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// if we are choked we can only pick pieces from the
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// allowed fast set. The allowed fast set is sorted
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// in ascending priority order
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std::vector<int> const& allowed_fast = c.allowed_fast();
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// build a bitmask with only the allowed pieces in it
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fast_mask.resize(c.get_bitfield().size(), false);
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for (std::vector<int>::const_iterator i = allowed_fast.begin()
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, end(allowed_fast.end()); i != end; ++i)
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if ((*bits)[*i]) fast_mask.set_bit(*i);
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bits = &fast_mask;
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}
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piece_picker::piece_state_t state;
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peer_connection::peer_speed_t speed = c.peer_speed();
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if (speed == peer_connection::fast) state = piece_picker::fast;
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else if (speed == peer_connection::medium) state = piece_picker::medium;
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else state = piece_picker::slow;
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// picks the interesting pieces from this peer
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// the integer is the number of pieces that
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// should be guaranteed to be available for download
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// (if num_requests is too big, too many pieces are
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// picked and cpu-time is wasted)
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// the last argument is if we should prefer whole pieces
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// for this peer. If we're downloading one piece in 20 seconds
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// then use this mode.
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p.pick_pieces(*bits, interesting_pieces
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, num_requests, prefer_whole_pieces, c.peer_info_struct()
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, state, c.picker_options(), suggested, t.num_peers()
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, ses.stats_counters());
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#ifdef TORRENT_LOGGING
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c.peer_log("*** PIECE_PICKER [ prefer_whole: %d picked: %d ]"
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, prefer_whole_pieces, int(interesting_pieces.size()));
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#endif
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// if the number of pieces we have + the number of pieces
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// we're requesting from is less than the number of pieces
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// in the torrent, there are still some unrequested pieces
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// and we're not strictly speaking in end-game mode yet
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// also, if we already have at least one outstanding
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// request, we shouldn't pick any busy pieces either
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// in time critical mode, it's OK to request busy blocks
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bool dont_pick_busy_blocks
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= ((ses.settings().get_bool(settings_pack::strict_end_game_mode)
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&& p.get_download_queue_size() < p.num_want_left())
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|| dq.size() + rq.size() > 0)
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&& !time_critical_mode;
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// this is filled with an interesting piece
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// that some other peer is currently downloading
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piece_block busy_block = piece_block::invalid;
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for (std::vector<piece_block>::iterator i = interesting_pieces.begin();
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i != interesting_pieces.end(); ++i)
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{
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if (prefer_whole_pieces == 0 && num_requests <= 0) break;
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if (time_critical_mode && p.piece_priority(i->piece_index) != 7)
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{
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// assume the subsequent pieces are not prio 7 and
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// be done
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break;
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}
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int num_block_requests = p.num_peers(*i);
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if (num_block_requests > 0)
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{
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// have we picked enough pieces?
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if (num_requests <= 0) break;
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// this block is busy. This means all the following blocks
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// in the interesting_pieces list are busy as well, we might
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// as well just exit the loop
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if (dont_pick_busy_blocks) break;
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TORRENT_ASSERT(p.num_peers(*i) > 0);
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busy_block = *i;
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continue;
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}
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TORRENT_ASSERT(p.num_peers(*i) == 0);
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// don't request pieces we already have in our request queue
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// This happens when pieces time out or the peer sends us
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// pieces we didn't request. Those aren't marked in the
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// piece picker, but we still keep track of them in the
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// download queue
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if (std::find_if(dq.begin(), dq.end(), has_block(*i)) != dq.end()
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|| std::find_if(rq.begin(), rq.end(), has_block(*i)) != rq.end())
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{
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#ifdef TORRENT_DEBUG
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std::vector<pending_block>::const_iterator j
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= std::find_if(dq.begin(), dq.end(), has_block(*i));
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if (j != dq.end()) TORRENT_ASSERT(j->timed_out || j->not_wanted);
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#endif
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#ifdef TORRENT_LOGGING
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c.peer_log("*** PIECE_PICKER [ not_picking: %d,%d already in queue ]"
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, i->piece_index, i->block_index);
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#endif
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continue;
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}
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// ok, we found a piece that's not being downloaded
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// by somebody else. request it from this peer
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// and return
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if (!c.add_request(*i, 0)) continue;
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TORRENT_ASSERT(p.num_peers(*i) == 1);
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TORRENT_ASSERT(p.is_requested(*i));
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num_requests--;
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}
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// we have picked as many blocks as we should
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// we're done!
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if (num_requests <= 0)
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{
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// since we could pick as many blocks as we
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// requested without having to resort to picking
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// busy ones, we're not in end-game mode
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c.set_endgame(false);
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return true;
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}
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// we did not pick as many pieces as we wanted, because
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// there aren't enough. This means we're in end-game mode
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// as long as we have at least one request outstanding,
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// we shouldn't pick another piece
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// if we are attempting to download 'allowed' pieces
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// and can't find any, that doesn't count as end-game
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if (!c.has_peer_choked())
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c.set_endgame(true);
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// if we don't have any potential busy blocks to request
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// or if we already have outstanding requests, don't
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// pick a busy piece
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if (busy_block == piece_block::invalid
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|| dq.size() + rq.size() > 0)
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{
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return true;
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}
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#ifdef TORRENT_DEBUG
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piece_picker::downloading_piece st;
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p.piece_info(busy_block.piece_index, st);
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TORRENT_ASSERT(st.requested + st.finished + st.writing
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== p.blocks_in_piece(busy_block.piece_index));
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#endif
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TORRENT_ASSERT(p.is_requested(busy_block));
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TORRENT_ASSERT(!p.is_downloaded(busy_block));
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TORRENT_ASSERT(!p.is_finished(busy_block));
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TORRENT_ASSERT(p.num_peers(busy_block) > 0);
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c.add_request(busy_block, peer_connection::req_busy);
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return true;
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}
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}
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