Control

Starting the event controller

The event controller (event loop) can be started with the asyncio_event_hub.controller.EventController.start() method, which spins up an asyncio task inside and sleeps until en event is emitted. Since it creates a task, the asyncio framework must already be running.

import asyncio
import asyncio_event_hub as aeh


async def main():
    ctrl = aeh.EventController()
    ctrl.start()  # Start the controller here.

    while True:
        await asyncio.sleep(5)



asyncio.run(main())  # Start asyncio framework (asyncio's own event loop)

Stopping the event controller

Similar to how it can be started, the controller can be stopped with a method, in this case the method being asyncio_event_hub.controller.EventController.stop().

This method will instruct the controller to finish processing all the events and then stop it’s event loop, but it will do so asynchronously. This means that after calling the function and returning from it, the event controller is still running. If there is a requirement of waiting for the controller to stop, the method can also be awaited with the await keyword (the method returns an awaitable asyncio.Future object).

Listing 1 Not waiting for the controller to stop

import asyncio
import asyncio_event_hub as aeh


async def main():
    ctrl = aeh.EventController()
    ctrl.start()  # Start the controller here.

    while True:
        await asyncio.sleep(5)
        break

    ctrl.stop()  # Instruct the controller to stop asynchronously (not stopped instantly)
    await asyncio.sleep(5)


asyncio.run(main())  # Start asyncio framework (asyncio's own event loop)

Listing 2 Waiting for the controller to stop

import asyncio
import asyncio_event_hub as aeh


async def main():
    ctrl = aeh.EventController()
    ctrl.start()  # Start the controller here.

    while True:
        await asyncio.sleep(5)
        break

    await ctrl.stop()  # Instruct the controller and await until it is stopped


asyncio.run(main())  # Start asyncio framework (asyncio's own event loop)