Integration with Rust futures?

[sxlijin]

There's not a lot online about this, so I'm guessing discussion about this has primarily happened in-person, over email, Slack/Discord, or other non-discoverable channels, and I'd like to gather information about this here.

Approaches I'm aware of:

@antstorm has implemented this for temporal.io, using a callback loop and a callback that enqueues events

@ianks with rb-sys has implemented "most of a working fiber scheduler with tokio" but there were performance problems with it and he suspects that mio may be necessary