[gd_scene load_steps=2 format=3 uid="uid://cdt4rn31xeo85"]

[sub_resource type="GDScript" id="GDScript_r4hca"]
script/source = "extends Node

class Queue:
	extends RefCounted
	var _opaque:Array = []
	var _mutex:Mutex = Mutex.new()
	var _owner

	func size() -> int:
		var _size:int
		_mutex.lock()
		_size = _opaque.size()
		_mutex.unlock()
		return _size

	func enqueue(val, check_exist:bool = false) -> bool:
		_mutex.lock()
		if (!check_exist || !_opaque.has(val)):
			_opaque.push_back(val)
		_mutex.unlock()
		return true

	func dequeue() -> Variant:
		var ret = null
		_mutex.lock()
		ret = _opaque.pop_front()
		_mutex.unlock()
		return ret

	func bind_owner(owner:Variant) -> void:
		_mutex.lock()
		_owner = owner
		_mutex.unlock()

	func get_owner() -> Variant:
		var owner = null
		_mutex.lock()
		owner = _owner
		_mutex.unlock()
		return owner

	func unbind_owner() -> void:
		_mutex.lock()
		_owner = null
		_mutex.unlock()

class Worker:
	extends Thread
	var should_working:bool
	
	func _main(global_mq:Queue):
		print(\"Worker thread started [id: {0}]\".format([get_id()]))
		while should_working:
			var mq:Queue = global_mq.dequeue()
			if null == mq:
				OS.delay_msec(0)
			else:
				var msg = mq.dequeue()
				if null == msg:
					OS.delay_msec(0)
				else:
					var callback = mq.get_owner()
					if null == callback:
						continue
					else:
						callback.call(msg)
				global_mq.enqueue(mq)
		print(\"Worker thread stopped [id: {0}]\".format([get_id()]))

	func start_working(owner) -> void:
		should_working = true
		start(Callable(self, '_main').bind(owner._global_mq))

	func stop_working(wait:bool = true) -> void:
		should_working = false
		if wait:
			wait_to_finish()

const WORKER_AMOUNT_MIN:int = 1
var WORKER_AMOUNT_MAX:int = OS.get_processor_count()

var _should_running:bool = true
var _global_mq:Queue = Queue.new()
var _service_and_mq:Dictionary = {}
var _workers:Array = []

func _add_worker() -> void:
	if _workers.size() >= WORKER_AMOUNT_MAX:
		return
	var worker:Worker = Worker.new()
	worker.start_working(self)
	_workers.push_back(worker)
	print('worker count adjust to {0}'.format([_workers.size()]))

func _kick_worker(worker:Worker) -> void:
	worker.stop_working(false)
	print('worker count adjust to {0}'.format([_workers.size()]))

func start() -> void:
	stop()
	_should_running = true
	check_workers()

func stop() -> void:
	_should_running = false
	while _workers.size() > 0:
		var worker:Worker = _workers.pop_back() as Worker
		worker.stop_working()
	while true:
		var mq:Queue = _global_mq.dequeue() as Queue
		if null == mq:
			break
	_service_and_mq.clear()

func check_workers() -> void:
	if !_should_running:
		return
	# TODO: remove dead workers
	# check busy, and give more workers
	if _global_mq.size() > 0: # maybe 1 ?
		_add_worker()
	# ensure min services
	while _workers.size() < WORKER_AMOUNT_MIN:
		_add_worker()
	# release overamount services
	while _workers.size() > WORKER_AMOUNT_MAX:
		_kick_worker(_workers.pop_back() as Worker)

func send_message(service_id:int, message) -> void:
	var mq:Queue = instance_from_id(service_id) as Queue
	mq.enqueue(message)

func add_service(callback:Callable) -> int:
	if _service_and_mq.has(callback):
		return -1
	var mq:Queue = Queue.new()
	mq.bind_owner(callback)
	_service_and_mq[callback] = mq
	_global_mq.enqueue(mq)
	return mq.get_instance_id()

func remove_service(callback:Callable) -> bool:
	if _service_and_mq.has(callback):
		var mq:Queue = _service_and_mq[callback]
		mq.unbind_owner()
		_service_and_mq.erase(callback)
		return true
	return false
"

[node name="microserver" type="Node"]
script = SubResource("GDScript_r4hca")

[node name="thread_updator" type="Timer" parent="."]
autostart = true

[connection signal="tree_entered" from="." to="." method="start"]
[connection signal="tree_exiting" from="." to="." method="stop"]
[connection signal="timeout" from="thread_updator" to="." method="check_workers"]