"halted for unexpected reason awaited" Error

[physics515]

Hello all,

I can't seem to figure this one out. I'm trying to write an async function following the docs for 0.12 (https://github.com/rune-rs/rune/blob/0.12.x/scripts/async.rn) and I get an error.

Function:

pub async fn scoped_test_script() { 
    let timeout = 200; 
    let request = http::get(`http://httpstat.us/200?sleep=${timeout}`); 
    let timeout = time::sleep(time::Duration::from_secs(2)); 
    let result = select { _ = timeout => timeout, res = request => res, }?; 
    result.text().await? 
}

Error on the vm.call() function:

halted for unexpected reason `awaited`

Context is:

let runtime_context: RuneContext = rune_modules::default_context().unwrap();

Any idea what I'm missing here?

Thanks!

[udoprog]

Hi! You have to use async variants of call / execution functions when running asynchronous code in Rune, like async_call.

[physics515]

@udoprog, I was able to figure that out but I'm stuck in another way. I'm building an app with Tauri and calling the VM from a Tauri Command.

I'm following this example: https://github.com/rune-rs/rune/blob/0.12.x/examples/examples/tokio_spawn.rs but I keep running into an issue with the Vm not implementing Send. Do you know any way to fix this?

[udoprog]

Yeah, pass the Arc<Unit> and Arc<RuntimeContext> around, and construct a Vm (which is a cheap operation) when you need to execute something with send_execute.

[physics515]

But the error is on the send_execute call. I was looking into how Tauri does async and it appears their async implementation runs every await point on a new thread...? So that means send_execute is being run on a different thread than the other code, meaning it requires Vm to require a Send implementation.

I did try to spin up a new thread to get out of the Tauri runtime and run a generic tokio runtim, but I was trying to move the Vm into that thread. I'll try to pass the Uint and Runtime to the thread and create the Vm on the thread and see if that works.

I'll report back!

Thank you for your help.

[udoprog]

Note that send_execute returns a VmSendExecution, which is 'static and implements Send.

If you keep having issues, place put together a minimal reproduction and I might be able to help.

[physics515]

@udoprog, I figured out my issue. It is actually a Rust language bug where it doesn't drop() references correctly in async runtime.
rust-lang/rust#69663

Instead of this:

let vm = Vm::new(runtime, Arc::new(unit));
let execution = vm.clone().send_execute(["main"], (5u32,))?;

It should be this:

let execution = {
    let vm = Vm::new(runtime, Arc::new(unit));
    vm.clone().send_execute(["main"], (5u32,))?;
};

So that vm is out of scope before the await in:

execution.async_complete().await.unwrap();

or else there is a potential the vm will be moved to a new thread at the await point.

Thank you for your help! I hope this helps someone else.

[udoprog]

Glad to hear it. Note that you can do without the .clone() too since you're constructing a Vm for the call.