tokio-trace-futures' instrument can be a little clunky for functions that return a Future but do other work first

[luser]

tokio-trace-futures' instrument can be a little clunky for functions that return a Future but do other work first

[carllerche]

We really need to figure out how tracing fits in with spawning. Obviously, Tokio can help and provide hooks :)

[hawkw]

This is a great idea, and definitely something the tokio-trace-futurescrate should be able to provide by way of an extension trait implemented for Span. Thanks for the suggestion 👍

[hawkw]

Another potential solution, which would be more general, is to add a method to the Instrument API to instrument a future in the current span. This way, you could say something like

span!("compile").enter(|| {
    let task = do_some_work();
    spawn(Box::new(task.in_current_span()));
});

However, we can't actually implement something like this with the current iteration of the Subscriber API as it doesn't currently specify a method to return the current span (something which we've had in the past). There's been some discussion of bringing something like that back, so if we do add a function for getting the current span, we could provide an Instrument::in_current.

With that said, I'm happy to add an enter_instrument-type function to Span in the short term, since it seems like there's a practical use-case for it, regardless of whether or not the more general solution becomes possible later.

[carllerche]

Another option might be something like:

let task = info_future!("compile", {
   do_work()
});

spawn(task);

[carllerche]

I agree we need to figure this out though...