I did some quick research and found that there is an "async job" API in OpenSSL. That one appears to do IO though, it even says that creating a job is a very expensive operation and thus jobs should be reused.

Is the similarity you are seeing that the work itself that gets scheduled via a job is agnostic over how it is executed?

From this example [0] it looks more like that async API is very similar to Rust's futures:

- Within a job you can access a "wait context"

- You can suspend on some condition

- You can trigger a wake-up to continue executing

[0]: https://www.openssl.org/docs/man1.1.1/man3/ASYNC_is_capable....