transmission/libtransmission/open-files.h

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// This file Copyright © 2005-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0), GPLv3 (SPDX: GPL-3.0),
// 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 <cstdint>
#include <optional>
#include <utility>
#include "transmission.h"
#include "file.h" // tr_sys_file_t
#include "lru-cache.h"
struct tr_session;
// A pool of open files that are cached while reading / writing torrents' data
class tr_open_files
{
public:
[[nodiscard]] std::optional<tr_sys_file_t> get(tr_torrent_id_t tor_id, tr_file_index_t file_num, bool writable);
[[nodiscard]] std::optional<tr_sys_file_t> get(
tr_torrent_id_t tor_id,
tr_file_index_t file_num,
bool writable,
std::string_view filename,
tr_preallocation_mode mode,
uint64_t file_size);
void closeAll();
void closeTorrent(tr_torrent_id_t tor_id);
void closeFile(tr_torrent_id_t tor_id, tr_file_index_t file_num);
private:
using Key = std::pair<tr_torrent_id_t, tr_file_index_t>;
[[nodiscard]] static Key makeKey(tr_torrent_id_t tor_id, tr_file_index_t file_num) noexcept
{
return std::make_pair(tor_id, file_num);
}
struct Val
{
Val() noexcept = default;
Val(Val const&) = delete;
Val& operator=(Val const&) = delete;
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Val(Val&& that) noexcept
{
*this = std::move(that);
}
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Val& operator=(Val&& that) noexcept
{
std::swap(this->fd_, that.fd_);
std::swap(this->writable_, that.writable_);
return *this;
}
~Val();
tr_sys_file_t fd_ = TR_BAD_SYS_FILE;
bool writable_ = false;
};
static constexpr size_t MaxOpenFiles = 32;
tr_lru_cache<Key, Val, MaxOpenFiles> pool_;
};