kml.py

class KmlUpdateHandler(tornado.web.RequestHandler):
    counter = 0 
    timeout = 10
    global_dict = {}
    lock = threading.Lock()

    @classmethod
    def add_to_global_dict(cls, reference, unique_id):
        cls.global_dict[unique_id] = reference

    @classmethod
    def get_unique_id(cls):
        with cls.lock:
            unique_id = cls.counter
            cls.counter += 1
        return unique_id

    @classmethod
    def finish_all_requests(cls):
        for req in cls.global_dict.itervalues():
            req.get(True)
        cls.global_dict = {}

    @classmethod
    def get_scene_msg(cls, msg):
        try:
            cls.finish_all_requests()
        except Exception as e:
            rospy.loginfo("Exception getting scene changes"+str(e))
            pass

    def initialize(self):
        self.asset_service = self.application.asset_service
        
    def get(self):
        yield gen.sleep(KmlUpdateHandler.timeout)
        if self.unique_id in KmlUpdateHandler.global_dict:
            del KmlUpdateHandler.global_dict[self.unique_id]