128 lines
4.1 KiB
C++
128 lines
4.1 KiB
C++
/*
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Copyright (c) 2016, 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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#ifndef TORRENT_SUGGEST_PIECE_HPP_INCLUDE
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#define TORRENT_SUGGEST_PIECE_HPP_INCLUDE
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#include <vector>
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#include <algorithm>
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#include "libtorrent/bitfield.hpp"
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#include "libtorrent/sliding_average.hpp"
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#include "libtorrent/aux_/vector.hpp"
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namespace libtorrent { namespace aux {
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struct suggest_piece
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{
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// pick at most n piece indices that are _not_ in p (which represents
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// pieces the peer has already sent a suggest for) nor in bits (which are
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// pieces the peer already has, and should not be suggested)
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int get_pieces(std::vector<piece_index_t>& p
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, typed_bitfield<piece_index_t> const& bits
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, int n)
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{
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if (m_priority_pieces.empty()) return 0;
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int ret = 0;
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// the highest priority pieces are at the end of m_priority_pieces.
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// is we add any piece to the result (p), the farther back the better.
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// the prioritization in p is the same, which means we have to first push
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// back and then reverse the items we put there.
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for (int i = int(m_priority_pieces.size()) - 1; i >= 0; --i)
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{
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piece_index_t const piece = m_priority_pieces[i];
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if (bits.get_bit(piece)) continue;
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if (std::any_of(p.begin(), p.end() - ret
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, [piece](piece_index_t pi) { return pi == piece; }))
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continue;
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p.push_back(piece);
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++ret;
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--n;
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if (n == 0) break;
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}
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// this it to maintain a strict priority order of pieces. The farther
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// back, the higher priority
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std::reverse(p.end() - ret, p.end());
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return ret;
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}
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void add_piece(piece_index_t const index, int const availability
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, int const max_queue_size)
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{
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// keep a running average of the availability of pieces, and filter
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// anything above average.
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int const mean = m_availability.mean();
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m_availability.add_sample(availability);
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if (availability > mean) return;
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auto const it = std::find(m_priority_pieces.begin()
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, m_priority_pieces.end(), index);
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if (it != m_priority_pieces.end())
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{
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// increase the priority of this piece by moving it to the front
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// of the queue
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m_priority_pieces.erase(it);
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}
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if (int(m_priority_pieces.size()) >= max_queue_size)
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{
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int const to_remove = int(m_priority_pieces.size()) - max_queue_size + 1;
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m_priority_pieces.erase(m_priority_pieces.begin()
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, m_priority_pieces.begin() + to_remove);
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}
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m_priority_pieces.push_back(index);
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}
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private:
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// these are pieces that would be good candidates for suggesting
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// to a peer. They represent low availability pieces that we recently
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// read from disk (and are likely in our read cache).
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// pieces closer to the end were inserted into the cache more recently and
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// have higher priority
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vector<piece_index_t, int> m_priority_pieces;
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sliding_average<30> m_availability;
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};
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}}
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#endif
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