Deno FFI: Support async function calls

[rracariu]

The FFI interface should allow calling functions asynchronously.

This would be necessary as plugin interface allowed defining such async Ops, and in general this would be required in most cases where calling an function might block the event loop.

Some initial ideas in #11152 (comment)

[bartlomieju]

@piscisaureus do you have an opinion on this one? I think we might somehow shim it using https://github.com/littledivy/deno_bindgen

[littledivy]

Non blocking was implemented in 1.15. https://deno.land/[email protected]/runtime/ffi_api#non-blocking-ffi

btw here's how to use it with deno_bindgen:

// src/lib.rs
#[deno_bindgen(non_blocking)]
fn sleep(ms: u64) {
  let duration = std::time::Duration::from_millis(ms);
  std::thread::sleep(duration);
}

// main.ts
import { sleep } from "./bindings/bindings.ts";
await sleep(100);

[bartlomieju]

@rracariu does the non blocking option solve the issue for you?

[rracariu]

Yes, it does.

[ghost]

Is there any way to use 'await' inside a non_blocking async ffi call? for example boiler plate mongo db connection here:

let options = ClientOptions::parse_with_resolver_config(&db_url_tls, ResolverConfig::cloudflare()).await.unwrap();