Auto-detect existing tokio runtime?

[TheBlueMatt]

When building, we could ask https://docs.rs/tokio/latest/tokio/runtime/struct.Handle.html#method.try_current if we're already in a runtime and use that, which would be nice. Sadly an outer library can't do that because they only get a Handle, not an Arc<Runtime>.

[tnull]

Yeah, I think historically we couldn't use Handle as we wanted to call Runtime::shutdown_timeout on Node::stop. However, by now we realized that the latter doesn't play well with taking an outer runtime anyways (as we'd need to own Runtime for it), and shutdown_timeout doesn't work the way you'd expect it to anyways.

TLDR: I think by now we could explore whether we can switch to use Handle everywhere, which would indeed allow us to auto-detect the outer runtime.