Crate wgpu_async

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WGPU-Async

WGPU offers some async methods when initialising adapters and devices, but during program execution much of the timing between the CPU and GPU is managed through callbacks and polling. A common pattern is to do something like the following:

ⓘ
wgpu.do_something();
wgpu.on_something_done(|result| { /* Handle results */ });
wgpu.poll();

This is a very JavaScript-esque pattern, while in Rust we might expect to write code that looks more like:

ⓘ
let result = wgpu.do_something().await;

Or, if we still wanted a callback:

ⓘ
wgpu.do_something().then(|result| { /* Handle results */ }).await;

This crate adds a global poll loop thread on non-WASM platforms that can be used to create a WgpuFuture holding the completion of a task. The poll loop is conservative, parking itself when no futures are waiting on it, meaining that this crate adds little to no overhead in changing paradigms.

Note that this crate does not aim to improve the performance of anything, and fast applications should reduce CPU-GPU communication and synchronisation as much as possible, irrespective of the paradigm used.

Usage

To do things in an async way, your wgpu::Device and wgpu::Queue need to be wrapped in async smart-pointer versions. These implement Deref<Device> and Deref<Queue>, so can be used as a slot-in replacement for existing wgpu code.

ⓘ
// Create a device and queue like normal
let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::default());

let adapter = instance
    .request_adapter(&wgpu::RequestAdapterOptions {
        power_preference: wgpu::PowerPreference::HighPerformance,
        compatible_surface: None,
        force_fallback_adapter: true,
    })
    .await
    .expect("missing adapter");

let (device, queue) = adapter
    .request_device(
        &wgpu::DeviceDescriptor {
            features: wgpu::Features::empty(),
            limits: adapter.limits(),
            label: None,
        },
        None,
    )
    .await
    .expect("missing device");

// Make them async
let (device, queue) = wgpu_async::wrap(Arc::new(device), Arc::new(queue));

Then you can use shadowed wgpu methods with the exact same signatures, but with extra async-ness:

ⓘ
queue.submit(&[/* commands */]).await; // An awaitable `Queue::submit`!

Just like their base wgpu counterparts, these methods begin their work on the GPU immediately. However the device won’t begin to be polled until the future is awaited.

You can also convert any non-shadowed callback-and-poll method to an async one using AsyncDevice::do_async:

ⓘ
wgpu.do_something();
let future = device.do_async(move |callback| {
    wgpu.on_something_done(|result| callback(result));
});

let result = future.await;

Structs

Functions