Make it easier to exit a background task when the socket disconnects

[masenf]

Describe the Features For some use cases, I want to have an infinite loop that runs while the page is active and connected. Currently this can be accomplished via

@rx.event(background=True)
async def my_infinite_task(self):
        from app.app import app

        task_sid = self.router.session.session_id

        while task_sid == (
            app._event_namespace.token_to_sid.get(self.router.session.client_token, None)
        ):
            # do stuff
            await asyncio.sleep(5)

        # do cleanup

• What is the purpose of the feature?

I want to write that same thing as

@rx.event(background=True, cancel=rx.Cancel.ON_DISCONNECT)
async def my_infinite_task(self):
    try:
        while True:
            # do stuff
            await asyncio.sleep(5)
    except asyncio.CancelledError:
        # do cleanup

Additional context Although there are more event driven ways to accomplish this (like rx.moment), this method is probably the most familiar approach (and common in llm generated code)

[linear[bot]]

ENG-5306 Make it easier to exit a background task when the socket disconnects

[SheldonHolmgren]

In case it matters, this would be useful also in non-background tasks. In my use case, I'm using reflex for generating a constantly growing report that doesn't require the reflex event loop.

BTW, thanks a lot for posting this issue and the workaround, masenf. I ran into this and would spend a lot more time dealing with it if it wasn't for you.

[musa-cypher]

Talking about background tasks, could this be a way to connect to mqtt broker from reflex and plot the data being collected in real time? I opened an issue [https://github.com/reflex-dev/reflex/issues/5061] over a week ago regarding this problem and my sample code but haven't gotten any response from anyone regarding a way to accomplish this.