Added asynchronous note playing

src/context.cc

@@ -7,8 +7,8 @@ Note Context::fill(Note note) const
 	return note;
 }
 
-std::chrono::duration<float> Context::length_to_duration(std::optional<Number> length) const
+Context::Duration Context::length_to_duration(std::optional<Number> length) const
 {
 	auto const len = length ? *length : this->length;
-	return std::chrono::duration<float>(float(len.num * (60.f / (float(bpm) / 4))) / len.den);
+	return Context::Duration(float(len.num * (60.f / (float(bpm) / 4))) / len.den);
 }

src/interpreter.cc

@@ -61,13 +61,27 @@ void Interpreter::register_callbacks()
 {
 	assert(callbacks != nullptr, "Interpreter constructor should initialize this field");
 	callbacks->add_callbacks(*midi_connection, *this);
-
-	callbacks->note_on = Value(+[](Interpreter &, std::vector<Value> args) -> Result<Value> {
-		std::cout << "Received: " << args[1] << "\r\n" << std::flush;
-		return Value{};
-	});
 }
 
+template<size_t N>
+static inline void await(Interpreter &interpreter, std::array<scheduler::Job_Id, N> dependencies)
+{
+	std::mutex mu;
+	std::unique_lock lock(mu);
+
+	std::condition_variable wait_for_finish;
+	bool finished = false;
+
+	interpreter.scheduler.schedule(dependencies, [&] { finished = true; wait_for_finish.notify_one(); });
+	wait_for_finish.wait(lock, [&finished] { return finished; });
+}
+
+static inline void await(Interpreter &interpreter, scheduler::Job_Id dependency)
+{
+	return await(interpreter, std::array { dependency });
+}
+
+
 /// Intrinsic implementation primitive providing a short way to check if arguments match required type signature
 static inline bool typecheck(std::vector<Value> const& args, auto const& ...expected_types)
 {
@@ -345,6 +359,7 @@ static inline Result<void> create_chord(std::vector<Note> &chord, Interpreter &i
 	return {};
 }
 
+
 template<Iterable T>
 static inline Result<void> play_notes(Interpreter &interpreter, T args)
 {
@@ -360,13 +375,13 @@ static inline Result<void> play_notes(Interpreter &interpreter, T args)
 		case Value::Type::Array:
 		case Value::Type::Block:
 			Try(play_notes(interpreter, std::move(arg)));
-			break;
 
-		case Value::Type::Music:
-			interpreter.play(arg.chord);
-			break;
+		break; case Value::Type::Music:
+			{
+				await(interpreter, std::array{ interpreter.play(arg.chord) });
+			}
 
-		default:
+		break; default:
 			assert(false, "this type does not support playing");
 		}
 	}
@@ -565,7 +580,7 @@ error:
 		global.force_define("par", +[](Interpreter &i, std::vector<Value> args) -> Result<Value> {
 			assert(args.size() >= 1, "par only makes sense for at least one argument"); // TODO(assert)
 			if (args.size() == 1) {
-				i.play(std::move(args.front()).chord);
+				await(i, i.play(std::move(args.front()).chord));
 				return Value{};
 			}
 
@@ -578,7 +593,7 @@ error:
 			}
 
 			for (auto it = std::next(args.begin()); it != args.end(); ++it) {
-				i.play(std::move(*it).chord);
+				await(i, i.play(std::move(*it).chord));
 			}
 
 			for (auto const& note : chord.notes) {
@@ -886,7 +901,7 @@ void Interpreter::leave_scope()
 	env = env->leave();
 }
 
-void Interpreter::play(Chord chord)
+scheduler::Job_Id Interpreter::play(Chord chord)
 {
 	assert(midi_connection, "To play midi Interpreter requires instance of MIDI connection");
 
@@ -895,22 +910,26 @@ void Interpreter::play(Chord chord)
 	// Fill all notes that don't have octave or length with defaults
 	std::transform(chord.notes.begin(), chord.notes.end(), chord.notes.begin(), [&](Note note) { return ctx.fill(note); });
 
-	// Sort that we have smaller times first
-	std::sort(chord.notes.begin(), chord.notes.end(), [](Note const& lhs, Note const& rhs) { return lhs.length < rhs.length; });
-
-	Number max_time = *chord.notes.back().length;
-
 	// Turn all notes on
 	for (auto const& note : chord.notes) {
 		midi_connection->send_note_on(0, *note.into_midi_note(), 127);
 	}
 
-	// Turn off each note at right time
+	Context::Duration max_duration;
+	auto last_job_id = 0;
+
+	// Register all note endings to scheduler
 	for (auto const& note : chord.notes) {
-		if (max_time != Number(0)) {
-			max_time -= *note.length;
-			std::this_thread::sleep_for(ctx.length_to_duration(*note.length));
-		}
-		midi_connection->send_note_off(0, *note.into_midi_note(), 127);
+		auto duration = ctx.length_to_duration(*note.length);
+		auto job_id = scheduler.schedule(
+			std::chrono::duration_cast<scheduler::Clock::duration>(duration),
+			[this, note = note] { midi_connection->send_note_off(0, *note.into_midi_note(), 127); }
+		);
+		if (duration > max_duration) {
+			max_duration = duration;
+			last_job_id = job_id;
 		}
 	}
+
+	return last_job_id;
+}

src/main.cc

@@ -81,6 +81,7 @@ struct Runner
 	midi::ALSA alsa;
 	Interpreter interpreter;
 	std::thread midi_input_event_loop;
+	std::optional<std::jthread> scheduler_thread;
 	std::stop_source stop_source;
 
 	/// Setup interpreter and midi connection with given port
@@ -110,6 +111,8 @@ struct Runner
 			midi_input_event_loop.detach();
 		}
 
+		scheduler_thread = std::jthread([this](std::stop_token tok) { interpreter.scheduler.activate(tok); });
+
 		Env::global->force_define("say", +[](Interpreter&, std::vector<Value> args) -> Result<Value> {
 			for (auto it = args.begin(); it != args.end(); ++it) {
 			std::cout << *it;

src/musique.hh

@@ -12,6 +12,7 @@
 #include <variant>
 
 #include <midi.hh>
+#include <scheduler.hh>
 #include <tl/expected.hpp>
 
 #if defined(__cpp_lib_source_location)
@@ -890,6 +891,8 @@ private:
 /// Context holds default values for music related actions
 struct Context
 {
+	using Duration = std::chrono::duration<float>;
+
 	/// Default note octave
 	i8 octave = 4;
 
@@ -903,7 +906,7 @@ struct Context
 	Note fill(Note) const;
 
 	/// Converts length to seconds with current bpm
-	std::chrono::duration<float> length_to_duration(std::optional<Number> length) const;
+	Duration length_to_duration(std::optional<Number> length) const;
 };
 
 /// Given program tree evaluates it into Value
@@ -912,6 +915,7 @@ struct Interpreter
 	/// MIDI connection that is used to play music.
 	/// It's optional for simple interpreter testing.
 	midi::Connection *midi_connection = nullptr;
+	scheduler::Scheduler scheduler;
 
 	/// Operators defined for language
 	std::unordered_map<std::string, Intrinsic> operators;
@@ -930,7 +934,7 @@ struct Interpreter
 	Interpreter();
 	~Interpreter();
 	Interpreter(Interpreter const&) = delete;
-	Interpreter(Interpreter &&) = default;
+	Interpreter(Interpreter &&) = delete;
 
 	/// Try to evaluate given program tree
 	Result<Value> eval(Ast &&ast);
@@ -941,8 +945,9 @@ struct Interpreter
 	// Leave scope by changing current environment
 	void leave_scope();
 
-	/// Play note resolving any missing parameters with context via `midi_connection` member.
-	void play(Chord);
+	/// Play note resolving any missing parameters with context via `midi_connection` member
+	/// @returns Total time of notes played
+	scheduler::Job_Id play(Chord);
 };
 
 namespace errors