waybar/include/modules/mpd/state.hpp
Joseph Benden 21fdcf41c3
mpd: revamped to event-driven, single-threaded
Fix MPD connection issues by converting/rewriting module into a
state-machine driven system. It is fully single-threaded and uses
events for transitioning between states. It supports all features
and functionality of the previous MPD module.

Signed-off-by: Joseph Benden <joe@benden.us>
2020-10-08 16:43:22 -07:00

218 lines
5.8 KiB
C++

#pragma once
#include <mpd/client.h>
#include <spdlog/fmt/bundled/format.h>
#include <spdlog/spdlog.h>
#include <condition_variable>
#include <thread>
#include "ALabel.hpp"
namespace waybar::modules {
class MPD;
} // namespace waybar::modules
namespace waybar::modules::detail {
using unique_connection = std::unique_ptr<mpd_connection, decltype(&mpd_connection_free)>;
using unique_status = std::unique_ptr<mpd_status, decltype(&mpd_status_free)>;
using unique_song = std::unique_ptr<mpd_song, decltype(&mpd_song_free)>;
class Context;
/// This state machine loosely follows a non-hierarchical, statechart
/// pattern, and includes ENTRY and EXIT actions.
///
/// The State class is the base class for all other states. The
/// entry and exit methods are automatically called when entering
/// into a new state and exiting from the current state. This
/// includes initially entering (Disconnected class) and exiting
/// Waybar.
///
/// The following nested "top-level" states are represented:
/// 1. Idle - await notification of MPD activity.
/// 2. All Non-Idle states:
/// 1. Playing - An active song is producing audio output.
/// 2. Paused - The current song is paused.
/// 3. Stopped - No song is actively playing.
/// 3. Disconnected - periodically attempt MPD (re-)connection.
///
/// NOTE: Since this statechart is non-hierarchical, the above
/// states are flattened into a set.
class State {
public:
virtual ~State() noexcept = default;
virtual void entry() noexcept { spdlog::debug("mpd: ignore entry action"); }
virtual void exit() noexcept { spdlog::debug("mpd: ignore exit action"); }
virtual void play() { spdlog::debug("mpd: ignore play state transition"); }
virtual void stop() { spdlog::debug("mpd: ignore stop state transition"); }
virtual void pause() { spdlog::debug("mpd: ignore pause state transition"); }
/// Request state update the GUI.
virtual void update() noexcept { spdlog::debug("mpd: ignoring update method request"); }
};
class Idle : public State {
Context* const ctx_;
sigc::connection idle_connection_;
public:
Idle(Context* const ctx) : ctx_{ctx} {}
virtual ~Idle() noexcept { this->exit(); };
void entry() noexcept override;
void exit() noexcept override;
void play() override;
void stop() override;
void pause() override;
void update() noexcept override;
private:
Idle(const Idle&) = delete;
Idle& operator=(const Idle&) = delete;
bool on_io(Glib::IOCondition const&);
};
class Playing : public State {
Context* const ctx_;
sigc::connection timer_connection_;
public:
Playing(Context* const ctx) : ctx_{ctx} {}
virtual ~Playing() noexcept { this->exit(); }
void entry() noexcept override;
void exit() noexcept override;
void pause() override;
void stop() override;
void update() noexcept override;
private:
Playing(Playing const&) = delete;
Playing& operator=(Playing const&) = delete;
bool on_timer();
};
class Paused : public State {
Context* const ctx_;
sigc::connection timer_connection_;
public:
Paused(Context* const ctx) : ctx_{ctx} {}
virtual ~Paused() noexcept { this->exit(); }
void entry() noexcept override;
void exit() noexcept override;
void play() override;
void stop() override;
void update() noexcept override;
private:
Paused(Paused const&) = delete;
Paused& operator=(Paused const&) = delete;
bool on_timer();
};
class Stopped : public State {
Context* const ctx_;
sigc::connection timer_connection_;
public:
Stopped(Context* const ctx) : ctx_{ctx} {}
virtual ~Stopped() noexcept { this->exit(); }
void entry() noexcept override;
void exit() noexcept override;
void play() override;
void pause() override;
void update() noexcept override;
private:
Stopped(Stopped const&) = delete;
Stopped& operator=(Stopped const&) = delete;
bool on_timer();
};
class Disconnected : public State {
Context* const ctx_;
sigc::connection timer_connection_;
public:
Disconnected(Context* const ctx) : ctx_{ctx} {}
virtual ~Disconnected() noexcept { this->exit(); }
void entry() noexcept override;
void exit() noexcept override;
void update() noexcept override;
private:
Disconnected(Disconnected const&) = delete;
Disconnected& operator=(Disconnected const&) = delete;
void arm_timer(int interval) noexcept;
void disarm_timer() noexcept;
bool on_timer();
};
class Context {
std::unique_ptr<State> state_;
waybar::modules::MPD* mpd_module_;
friend class State;
friend class Playing;
friend class Paused;
friend class Stopped;
friend class Disconnected;
friend class Idle;
protected:
void setState(std::unique_ptr<State>&& new_state) noexcept {
if (state_.get() != nullptr) {
state_->exit();
}
state_ = std::move(new_state);
state_->entry();
}
bool is_connected() const;
bool is_playing() const;
bool is_paused() const;
bool is_stopped() const;
constexpr std::size_t interval() const;
void tryConnect() const;
void checkErrors(mpd_connection*) const;
void do_update();
void queryMPD() const;
void fetchState() const;
constexpr mpd_state state() const;
void emit() const;
[[nodiscard]] unique_connection& connection();
public:
explicit Context(waybar::modules::MPD* const mpd_module)
: state_{std::make_unique<Disconnected>(this)}, mpd_module_{mpd_module} {
state_->entry();
}
void play() { state_->play(); }
void stop() { state_->stop(); }
void pause() { state_->pause(); }
void update() noexcept { state_->update(); }
};
} // namespace waybar::modules::detail