How do I run an async CLR function efficiently from Jint

[Ghostbird]

Note that to the script writer it shouldn't matter whether the code is async or not. I have an engine that runs some javascript expressions. It exposes some CLR methods. The underlying implementation of some of those methods is asynchronous in C#. Currently we simply block on those async calls, but I'd prefer not to.

Is there some way to use async await at the C# level, or is this impossible at the moment?

[lahma]

Previous discussions:

• Checking if a returned promise is complete #935
• an available solution to use async/await in jint at present #943
• Event Loop and async code #1081

[Ghostbird]

I had already read those partially, but it didn't seem to match my use case exactly. I'll give them a better look.

[Ghostbird]

I guess I really don't understand the way Jint works. None of these other discussions seem to match what I want.
The basics of what I want seem simple:

1. I create an engine instance.
2. I add a ClrFunctionInstance to it.
3. I call the ClrFunctionInstance and extract the result.
4. I discard the engine instance.

I'd like my ClrFunctionInstance to be a C# function that performs asynchronous operations. There's no concurrency on the engine instance, and nothing is going to access the engine instance if I temporarily yield the thread.

[lahma]

Currently the best option is to call GetAwaiter().GetResult() to get the async outcome.

[Ghostbird]

Yeah, that's what we do currently, I was wondering if I could improve upon that, but I guess I really don't know enough about this. Thanks for explaining!

[SebastianStehle]

The jint code is synchronous, which means you cannot just have a normal method that is asynchronous in C#, but looks synchronous in the script. This would also be my preferred method.

So I think you have 3 options for asynchronous code:

1. Give your users old school methods with a callback. I have followed this path.
2. Use promises and ask you users (or whoever writes the script) to use async await.
3. Just use .Wait() in your methods (not in your script). I remember that there is a better alternative, something with AsyncPump or so, but I cannot remember the details.

Sorry, lahma was faster ...

[Ghostbird]

Thanks for your reply. We've been using something very similar to this and it works well. It just left me wondering if there was some way to be less blocking.