serversidesignals.py

class Data:
    def __init__(self):
        self.state = {}
        self.cond = asyncio.Condition()



async def clock_waiter(m, cb):
    while True:
        try:
            async with m.cond:
                await m.cond.wait()
                await cb(m.state)
        except asyncio.CancelledError:
            pass
        except Exception as e:
            logging.warning(e)


@routes.get('/ws')
async def websocket_handler(request):
    ws = web.WebSocketResponse(heartbeat=10)
    await ws.prepare(request)
    m = request.app['clocked']

    point_task = asyncio.get_running_loop().create_task(
        point_waiter(m, ws.send_json)
    )

    async for msg in ws:
        if msg.type == aiohttp.WSMsgType.TEXT:
            pass
        elif msg.type == aiohttp.WSMsgType.ERROR:
            logging.debug(
                'ws connection closed with exception %s', ws.exception()
            )

    logging.debug('websocket connection closed')
    point_task.cancel()
    return ws


async def clock(m):
    while asyncio.sleep(2):
        async with m.cond:
            m.state = {time: time.time()}
            m.cond.notify_all()


            
app['tracks'] = Data()
loop.create_task(clock(app['clocked']))