Handling the same update concurrently and/or independently

[LimeEng]

I want to receive all incoming updates, save those updates, and then check if any of them are messages with links in them. Crucially though, I do not want a failure in the update saving code to affect the next handler in the chain.

I realize that I can tag an inspect() onto dptree::entry() but that seems kinda hacky?

This is where I'm currently at. Here, every update receives stops in the first branch and never continues on to save_link. I do think I understand why after reading the documentation for dptree. But replacing it with chain() yields the same result. I guess it's because ControlFlow::Break is returned after both calls? Is there a way to achieve what I would like?

let handler = dptree::entry()
        .branch(dptree::endpoint(save_raw_update))
        .branch(Update::filter_message().branch(dptree::endpoint(save_link)));

[WaffleLapkin]

I think you do need inspect (potentially with a tokio::spawn or a queue, so that saving does not throttle the main update handliong) (or a map). The thing about endpoint is that it always stops execution, so nothing can be executed after it.

[LimeEng]

I see, then that's what I'm going to go ahead and do! This is where I ended up:

let handler = dptree::entry()
        .branch(
            dptree::entry()
                .filter_async(is_authorized)
                .inspect_async(save_raw_update)
                .branch(Update::filter_message().branch(dptree::endpoint(save_link))),
        )
        .branch(dptree::endpoint(try_to_leave));

with

async fn save_raw_update(update: Update) {
    tokio::spawn(async move {
        log::info!("Received update: {update:#?}");
        tokio::time::sleep(Duration::from_secs(10)).await; // Intense work
    });
}

Thanks for the help!

[WaffleLapkin]

tip: you don't need save_raw_update to be async (you can have a sync function and .filter(..)). Notice how there aren't any awaits inside save_raw_update's body (the .await near the // Intense work is inside the async block body)

[LimeEng]

I did realize that later on and replaced both filters and inspects with their sync variants. Thanks though, I could have easily overlooked that!