transmission/libtransmission/file-piece-map.cc

242 lines
6.8 KiB
C++

// This file Copyright © Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <vector>
#include <small/set.hpp>
#include "libtransmission/transmission.h"
#include "libtransmission/bitfield.h"
#include "libtransmission/block-info.h"
#include "libtransmission/file-piece-map.h"
#include "libtransmission/torrent-metainfo.h"
#include "libtransmission/tr-assert.h"
tr_file_piece_map::tr_file_piece_map(tr_torrent_metainfo const& tm)
{
reset(tm);
}
tr_file_piece_map::tr_file_piece_map(tr_block_info const& block_info, uint64_t const* const file_sizes, size_t const n_files)
{
reset(block_info, file_sizes, n_files);
}
void tr_file_piece_map::reset(tr_block_info const& block_info, uint64_t const* const file_sizes, size_t const n_files)
{
file_bytes_.resize(n_files);
file_bytes_.shrink_to_fit();
file_pieces_.resize(n_files);
file_pieces_.shrink_to_fit();
auto edge_pieces = small::set<tr_piece_index_t, 1024U>{};
edge_pieces.reserve(n_files * 2U);
uint64_t offset = 0U;
for (tr_file_index_t i = 0U; i < n_files; ++i)
{
auto const file_size = file_sizes[i];
auto const begin_byte = offset;
auto end_byte = tr_byte_index_t{};
// N.B. If the last file in the torrent is 0 bytes, and the torrent size is a multiple of piece size,
// then the computed piece index will be past-the-end. We handle this with std::min.
auto const begin_piece = std::min(block_info.byte_loc(begin_byte).piece, block_info.piece_count() - 1U);
auto end_piece = tr_piece_index_t{};
edge_pieces.insert(begin_piece);
if (file_size != 0U)
{
end_byte = begin_byte + file_size;
auto const final_byte = end_byte - 1U;
auto const final_piece = block_info.byte_loc(final_byte).piece;
end_piece = final_piece + 1U;
edge_pieces.insert(final_piece);
}
else
{
end_byte = begin_byte;
end_piece = begin_piece + 1U;
}
file_bytes_[i] = byte_span_t{ begin_byte, end_byte };
file_pieces_[i] = piece_span_t{ begin_piece, end_piece };
offset += file_size;
}
edge_pieces_.assign(std::begin(edge_pieces), std::end(edge_pieces));
}
void tr_file_piece_map::reset(tr_torrent_metainfo const& tm)
{
auto const n = tm.file_count();
auto file_sizes = std::vector<uint64_t>(n);
for (tr_file_index_t i = 0U; i < n; ++i)
{
file_sizes[i] = tm.file_size(i);
}
reset({ tm.total_size(), tm.piece_size() }, std::data(file_sizes), std::size(file_sizes));
}
namespace
{
template<typename T>
struct CompareToSpan
{
using span_t = tr_file_piece_map::index_span_t<T>;
[[nodiscard]] constexpr int compare(T item, span_t span) const // <=>
{
if (item < span.begin)
{
return -1;
}
if (item >= span.end)
{
return 1;
}
return 0;
}
[[nodiscard]] constexpr bool operator()(T const item, span_t const span) const // <
{
return compare(item, span) < 0;
}
[[nodiscard]] constexpr int compare(span_t const span, T const item) const // <=>
{
return -compare(item, span);
}
[[nodiscard]] constexpr bool operator()(span_t const span, T const item) const // <
{
return compare(span, item) < 0;
}
};
} // namespace
tr_file_piece_map::file_span_t tr_file_piece_map::file_span_for_piece(tr_piece_index_t const piece) const
{
static constexpr auto Compare = CompareToSpan<tr_piece_index_t>{};
auto const begin = std::begin(file_pieces_);
auto const [equal_begin, equal_end] = std::equal_range(begin, std::end(file_pieces_), piece, Compare);
return { static_cast<tr_file_index_t>(equal_begin - begin), static_cast<tr_file_index_t>(equal_end - begin) };
}
tr_file_piece_map::file_offset_t tr_file_piece_map::file_offset(uint64_t const offset) const
{
static constexpr auto Compare = CompareToSpan<uint64_t>{};
auto const begin = std::begin(file_bytes_);
auto const it = std::lower_bound(begin, std::end(file_bytes_), offset, Compare);
tr_file_index_t const file_index = std::distance(begin, it);
auto const file_offset = offset - it->begin;
return file_offset_t{ file_index, file_offset };
}
// ---
void tr_file_priorities::set(tr_file_index_t const file, tr_priority_t const new_priority)
{
if (std::empty(priorities_))
{
if (new_priority == TR_PRI_NORMAL)
{
return;
}
priorities_.assign(fpm_->file_count(), TR_PRI_NORMAL);
priorities_.shrink_to_fit();
}
priorities_[file] = new_priority;
}
void tr_file_priorities::set(tr_file_index_t const* const files, size_t const n, tr_priority_t const new_priority)
{
for (size_t i = 0U; i < n; ++i)
{
set(files[i], new_priority);
}
}
tr_priority_t tr_file_priorities::file_priority(tr_file_index_t const file) const
{
TR_ASSERT(file < fpm_->file_count());
if (std::empty(priorities_))
{
return TR_PRI_NORMAL;
}
return priorities_[file];
}
tr_priority_t tr_file_priorities::piece_priority(tr_piece_index_t const piece) const
{
// increase priority if a file begins or ends in this piece
// because that makes life easier for code/users using at incomplete files.
// Xrefs: f2daeb242, https://forum.transmissionbt.com/viewtopic.php?t=10473
if (fpm_->is_edge_piece(piece))
{
return TR_PRI_HIGH;
}
// check the priorities of the files that touch this piece
if (auto const [begin_file, end_file] = fpm_->file_span_for_piece(piece); end_file <= std::size(priorities_))
{
auto const begin = std::begin(priorities_) + begin_file;
auto const end = std::begin(priorities_) + end_file;
if (auto const it = std::max_element(begin, end); it != end)
{
return *it;
}
}
return TR_PRI_NORMAL;
}
// ---
tr_files_wanted::tr_files_wanted(tr_file_piece_map const* const fpm)
: fpm_{ fpm }
, wanted_{ fpm->file_count() }
{
wanted_.set_has_all(); // by default we want all files
}
void tr_files_wanted::set(tr_file_index_t const file, bool const wanted)
{
wanted_.set(file, wanted);
}
void tr_files_wanted::set(tr_file_index_t const* const files, size_t const n_files, bool const wanted)
{
for (size_t idx = 0U; idx < n_files; ++idx)
{
set(files[idx], wanted);
}
}
bool tr_files_wanted::piece_wanted(tr_piece_index_t const piece) const
{
if (wanted_.has_all())
{
return true;
}
auto const [begin, end] = fpm_->file_span_for_piece(piece);
return wanted_.count(begin, end) != 0U;
}