#this is an example daemon thread we use for sending events out to firebase. We dont care to much about the consistency of data on firebase.
class FirebaseEventSender(threading.Thread):

    @ThreadAutoRestartCachedClassProperty
    def _instance(cls) -> 'FirebaseEventSender':
        lc = FirebaseEventSender()
        lc.start()
        return lc

    @classmethod
    def schedule(cls, tasks: List[Callable], firebase: 'Firebase'):
        try:
            for task in tasks:
                cls._instance.events_to_send.put((task, firebase), block=False)
        except Full:
            pass

    def __init__(self):
        super().__init__(daemon=True)
        self.tasks = []
        self.events_to_send = Queue()
        self.terminate_flag = threading.Event()

    @terminating_method
    def wait_on_task(self):
        event = self.events_to_send.get()
        self.tasks.append(event)

    @terminating_method
    def get_tasks(self):
        try:
            while True:
                self.tasks.append(self.events_to_send.get_nowait())
        except Empty:
            pass

    @terminating_method
    def poll(self):
        if not self.tasks:
            self.wait_on_task()
        self.get_tasks()
        self.send()
        self.tasks = []

    @terminating_method
    def send(self):
        for task in self.tasks:
            func, firebase = task
            func(firebase)

    def start(self):
        self.terminate_flag = threading.Event()
        super().start()

    def terminate(self):
        if self.is_alive():
            self.terminate_flag.set()
            self.join()

    def run(self):
        from django.conf import settings
        while True:
            self.poll()
            if not self.tasks:
                if settings.IS_UNIT_TESTING:
                    self.terminate_flag.set()
                time.sleep(0.1)