RenderingDevice non blocking sync

[darthLeviN]

What this adds

https://github.com/godotengine/godot-proposals/issues/10481#issue-2471732290 the function try_sync was added to RenderingDevice. This function will not block. If the fence has been signaled (and thus the operation has finished) it will return true. Returns false otherwise.

Earlier you would've had to create a separate thread, call sync and let it get blocked till operation completes. That might add complications when trying to use the GPU compute in a certain way.

Test project

https://github.com/darthLeviN/godot-compute/tree/1d26e56df3e6be6a53c992261850aed4a2cff79b

this project contains a simple loop that calls

while(not rd.try_sync()):
    try_count += 1
    await get_tree().process_frame

and allows for logging the try count.

Notes

When this succeeds side effects are the equivalent of calling sync. So you shouldn't keep calling it again.

Issues

Currently i think we don't have good error handling. In case of an error this fails and returns false. and there won't be any way to know if it failed or we just need to wait for it. This is also true for sync because it's a void function.

Also, Signals can be implemented here. If desired, We can internally do the once per frame check if the pipeline is still processing. This improvement can be added on top of this implementation while keeping backwards compatibility.

Docs

Full docs entry with notes was added.

Testing

I have tested this on ubuntu 22.04 with a RTX 3070 for vulkan. DirectX12 needs to be tested.

I think running the test project will suffice.