transmission/libtransmission/torrents.h

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// This file Copyright © 2022-2023 Mnemosyne LLC.
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// 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.
#pragma once
#ifndef __TRANSMISSION__
#error only libtransmission should #include this header.
#endif
#include <cstddef> // size_t
#include <ctime>
#include <string_view>
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#include <utility>
#include <vector>
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#include "libtransmission/transmission.h"
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#include "libtransmission/torrent-metainfo.h"
#include "libtransmission/tr-macros.h"
struct tr_torrent;
struct tr_torrent_metainfo;
// A helper class to manage tracking sets of tr_torrent objects.
class tr_torrents
{
public:
// returns a fast lookup id for `tor`
[[nodiscard]] tr_torrent_id_t add(tr_torrent* tor);
void remove(tr_torrent const* tor, time_t current_time);
// O(1)
[[nodiscard]] TR_CONSTEXPR20 tr_torrent* get(tr_torrent_id_t id)
{
auto const uid = static_cast<size_t>(id);
return uid >= std::size(by_id_) ? nullptr : by_id_.at(uid);
}
// O(log n)
[[nodiscard]] tr_torrent const* get(tr_sha1_digest_t const& hash) const;
[[nodiscard]] tr_torrent* get(tr_sha1_digest_t const& hash);
[[nodiscard]] tr_torrent const* get(tr_torrent_metainfo const& metainfo) const
{
return get(metainfo.info_hash());
}
[[nodiscard]] tr_torrent* get(tr_torrent_metainfo const& metainfo)
{
return get(metainfo.info_hash());
}
// These convenience functions use get(tr_sha1_digest_t const&)
// after parsing the magnet link to get the info hash. If you have
// the info hash already, use get() instead to avoid excess parsing.
[[nodiscard]] tr_torrent* get(std::string_view magnet_link);
template<typename T>
[[nodiscard]] bool contains(T const& key) const
{
return get(key) != nullptr;
}
[[nodiscard]] std::vector<tr_torrent_id_t> removedSince(time_t timestamp) const;
[[nodiscard]] TR_CONSTEXPR20 auto cbegin() const noexcept
{
return std::cbegin(by_hash_);
}
[[nodiscard]] TR_CONSTEXPR20 auto begin() const noexcept
{
return cbegin();
}
[[nodiscard]] TR_CONSTEXPR20 auto begin() noexcept
{
return std::begin(by_hash_);
}
[[nodiscard]] TR_CONSTEXPR20 auto cend() const noexcept
{
return std::cend(by_hash_);
}
[[nodiscard]] TR_CONSTEXPR20 auto end() const noexcept
{
return cend();
}
[[nodiscard]] TR_CONSTEXPR20 auto end() noexcept
{
return std::end(by_hash_);
}
[[nodiscard]] TR_CONSTEXPR20 auto size() const noexcept
{
return std::size(by_hash_);
}
[[nodiscard]] TR_CONSTEXPR20 auto empty() const noexcept
{
return std::empty(by_hash_);
}
private:
std::vector<tr_torrent*> by_hash_;
// This is a lookup table where by_id_[id]->id() == id.
// There is a small tradeoff here -- lookup is O(1) at the cost
// of a wasted slot in the lookup table whenever a torrent is
// removed. This improves speed for all use cases at the cost of
// wasting a small amount of memory in uncommon use cases, e.g. a
// long-lived session where thousands of torrents are removed.
//
// Insert an empty pointer at by_id_[0] to ensure that the first
// added torrent doesn't get an ID of 0; ie, that every torrent has
// a positive ID number. This constraint isn't needed by libtransmission
// code but the ID is exported in the RPC API to 3rd party clients that
// may be testing for >0 as a validity check.
std::vector<tr_torrent*> by_id_{ nullptr };
std::vector<std::pair<tr_torrent_id_t, time_t>> removed_;
};