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/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_STATE_FILE_HXX
#define MPD_STATE_FILE_HXX
#include "event/TimerEvent.hxx"
#include "fs/AllocatedPath.hxx"
#include "Compiler.h"
#include <string>
#include <chrono>
struct Partition;
class OutputStream;
class BufferedOutputStream;
class StateFile final {
const AllocatedPath path;
const std::string path_utf8;
const std::chrono::steady_clock::duration interval;
TimerEvent timer_event;
Partition &partition;
/**
* These version numbers determine whether we need to save the state
* file. If nothing has changed, we won't let the hard drive spin up.
*/
unsigned prev_volume_version = 0, prev_output_version = 0,
prev_playlist_version = 0;
public:
static constexpr std::chrono::steady_clock::duration DEFAULT_INTERVAL = std::chrono::minutes(2);
StateFile(AllocatedPath &&path, std::chrono::steady_clock::duration interval,
Partition &partition, EventLoop &loop);
void Read();
void Write();
/**
* Schedules a write if MPD's state was modified.
*/
void CheckModified();
private:
void Write(OutputStream &os);
void Write(BufferedOutputStream &os);
/**
* Save the current state versions for use with IsModified().
*/
void RememberVersions() noexcept;
/**
* Check if MPD's state was modified since the last
* RememberVersions() call.
*/
gcc_pure
bool IsModified() const noexcept;
/* callback for #timer_event */
void OnTimeout();
};
#endif /* STATE_FILE_H */
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