Auto merge of #24708 - szeged:webgpu-base, r=gterzian,kvark

Initial implementation of WebGPU API

<!-- Please describe your changes on the following line: -->
- Added the WebIDL bindings for GPU and GPUadapter interfaces.
- Created a background thread for WebGPU api calls.
- Established the async communication between the background thread and the WebGPU interfaces.
- Implemented the `requesAdapter` function of `navigator.gpu`

`./mach test-tidy` reports an error due to the different `arrayvec` version used in `servo` and `webgpu`, so added it to the ignore list in `servo-tidy.toml`

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes addresses a part of #https://github.com/servo/servo/issues/24706

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

cc @jdm, cc @kvark

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/24708)
<!-- Reviewable:end -->

components/config/opts.rs

@@ -713,6 +713,12 @@ pub fn from_cmdline_args(mut opts: Options, args: &[String]) -> ArgumentParsingR
         "A preference to set to enable",
         "dom.bluetooth.enabled",
     );
+    opts.optmulti(
+        "",
+        "pref",
+        "A preference to set to enable",
+        "dom.webgpu.enabled",
+    );
     opts.optflag("b", "no-native-titlebar", "Do not use native titlebar");
     opts.optflag("w", "webrender", "Use webrender backend");
     opts.optopt("G", "graphics", "Select graphics backend (gl or es2)", "gl");

components/config/prefs.rs

@@ -159,6 +159,9 @@ mod gen {
                 },
             },
             dom: {
+                webgpu: {
+                    enabled: bool,
+                },
                 bluetooth: {
                     enabled: bool,
                     testing: {

components/constellation/Cargo.toml

@@ -47,6 +47,7 @@ servo_geometry = {path = "../geometry"}
 servo_rand = {path = "../rand"}
 servo_remutex = {path = "../remutex"}
 servo_url = {path = "../url"}
+webgpu = {path = "../webgpu"}
 webvr_traits = {path = "../webvr_traits"}
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 webxr-api = {git = "https://github.com/servo/webxr", features = ["ipc"]}

components/constellation/constellation.rs

@@ -172,6 +172,7 @@ use std::sync::Arc;
 use std::thread;
 use style_traits::viewport::ViewportConstraints;
 use style_traits::CSSPixel;
+use webgpu::WebGPU;
 use webvr_traits::{WebVREvent, WebVRMsg};
 
 type PendingApprovalNavigations = HashMap<PipelineId, (LoadData, HistoryEntryReplacement)>;
@@ -440,6 +441,10 @@ pub struct Constellation<Message, LTF, STF> {
     /// Entry point to create and get channels to a WebGLThread.
     webgl_threads: Option<WebGLThreads>,
 
+    /// An IPC channel for the constellation to send messages to the
+    /// WebGPU threads.
+    webgpu: Option<WebGPU>,
+
     /// A channel through which messages can be sent to the webvr thread.
     webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -521,6 +526,9 @@ pub struct InitialConstellationState {
     /// Entry point to create and get channels to a WebGLThread.
     pub webgl_threads: Option<WebGLThreads>,
 
+    /// A channel to the WebGPU threads.
+    pub webgpu: Option<WebGPU>,
+
     /// A channel to the webgl thread.
     pub webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -836,6 +844,7 @@ where
                         (rng, prob)
                     }),
                     webgl_threads: state.webgl_threads,
+                    webgpu: state.webgpu,
                     webvr_chan: state.webvr_chan,
                     webxr_registry: state.webxr_registry,
                     canvas_chan: CanvasPaintThread::start(),
@@ -1090,6 +1099,7 @@ where
                 .webgl_threads
                 .as_ref()
                 .map(|threads| threads.pipeline()),
+            webgpu: self.webgpu.clone(),
             webvr_chan: self.webvr_chan.clone(),
             webxr_registry: self.webxr_registry.clone(),
             player_context: self.player_context.clone(),
@@ -2355,6 +2365,17 @@ where
             }
         }
 
+        if let Some(webgpu) = self.webgpu.as_ref() {
+            debug!("Exiting WebGPU thread.");
+            let (sender, receiver) = ipc::channel().expect("Failed to create IPC channel!");
+            if let Err(e) = webgpu.exit(sender) {
+                warn!("Exit WebGPU Thread failed ({})", e);
+            }
+            if let Err(e) = receiver.recv() {
+                warn!("Failed to receive exit response from WebGPU ({})", e);
+            }
+        }
+
         if let Some(chan) = self.webvr_chan.as_ref() {
             debug!("Exiting WebVR thread.");
             if let Err(e) = chan.send(WebVRMsg::Exit) {

components/constellation/pipeline.rs

@@ -46,6 +46,7 @@ use std::process;
 use std::rc::Rc;
 use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
+use webgpu::WebGPU;
 use webvr_traits::WebVRMsg;
 
 /// A `Pipeline` is the constellation's view of a `Document`. Each pipeline has an
@@ -188,6 +189,9 @@ pub struct InitialPipelineState {
     /// A channel to the WebGL thread.
     pub webgl_chan: Option<WebGLPipeline>,
 
+    /// A channel to the WebGPU threads.
+    pub webgpu: Option<WebGPU>,
+
     /// A channel to the webvr thread.
     pub webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -299,6 +303,7 @@ impl Pipeline {
                     webrender_document: state.webrender_document,
                     webgl_chan: state.webgl_chan,
                     webvr_chan: state.webvr_chan,
+                    webgpu: state.webgpu,
                     webxr_registry: state.webxr_registry,
                     player_context: state.player_context,
                 };
@@ -504,6 +509,7 @@ pub struct UnprivilegedPipelineContent {
     webrender_api_sender: webrender_api::RenderApiSender,
     webrender_document: webrender_api::DocumentId,
     webgl_chan: Option<WebGLPipeline>,
+    webgpu: Option<WebGPU>,
     webvr_chan: Option<IpcSender<WebVRMsg>>,
     webxr_registry: webxr_api::Registry,
     player_context: WindowGLContext,
@@ -556,6 +562,7 @@ impl UnprivilegedPipelineContent {
                 pipeline_namespace_id: self.pipeline_namespace_id,
                 content_process_shutdown_chan: content_process_shutdown_chan,
                 webgl_chan: self.webgl_chan,
+                webgpu: self.webgpu,
                 webvr_chan: self.webvr_chan,
                 webxr_registry: self.webxr_registry,
                 webrender_document: self.webrender_document,

components/script/Cargo.toml

@@ -113,6 +113,7 @@ utf-8 = "0.7"
 uuid = {version = "0.8", features = ["v4"]}
 xml5ever = "0.16"
 webdriver = "0.40"
+webgpu = {path = "../webgpu"}
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 webvr_traits = {path = "../webvr_traits"}
 webxr-api = {git = "https://github.com/servo/webxr", features = ["ipc"]}

components/script/dom/bindings/codegen/Bindings.conf

@@ -134,7 +134,10 @@ DOMInterfaces = {
 
 'XR': {
     'inCompartments': ['SupportsSessionMode', 'RequestSession'],
+},
+
+'GPU': {
+    'inCompartments': ['RequestAdapter'],
 }
 
-
 }

components/script/dom/bindings/trace.rs

@@ -145,6 +145,7 @@ use tendril::stream::LossyDecoder;
 use tendril::{StrTendril, TendrilSink};
 use time::{Duration, Timespec};
 use uuid::Uuid;
+use webgpu::{WebGPU, WebGPUAdapter};
 use webrender_api::{DocumentId, ImageKey, RenderApiSender};
 use webvr_traits::{WebVRGamepadData, WebVRGamepadHand, WebVRGamepadState};
 use webxr_api::SwapChainId as WebXRSwapChainId;
@@ -502,6 +503,8 @@ unsafe_no_jsmanaged_fields!(WebGLTextureId);
 unsafe_no_jsmanaged_fields!(WebGLVertexArrayId);
 unsafe_no_jsmanaged_fields!(WebGLVersion);
 unsafe_no_jsmanaged_fields!(WebGLSLVersion);
+unsafe_no_jsmanaged_fields!(WebGPU);
+unsafe_no_jsmanaged_fields!(WebGPUAdapter);
 unsafe_no_jsmanaged_fields!(WebXRSwapChainId);
 unsafe_no_jsmanaged_fields!(MediaList);
 unsafe_no_jsmanaged_fields!(WebVRGamepadData, WebVRGamepadState, WebVRGamepadHand);

components/script/dom/gpu.rs

@@ -0,0 +1,158 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::compartments::InCompartment;
+use crate::dom::bindings::codegen::Bindings::GPUBinding::GPURequestAdapterOptions;
+use crate::dom::bindings::codegen::Bindings::GPUBinding::{self, GPUMethods, GPUPowerPreference};
+use crate::dom::bindings::error::Error;
+use crate::dom::bindings::refcounted::{Trusted, TrustedPromise};
+use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::str::DOMString;
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::gpuadapter::GPUAdapter;
+use crate::dom::promise::Promise;
+use crate::task_source::TaskSource;
+use dom_struct::dom_struct;
+use ipc_channel::ipc::{self, IpcSender};
+use ipc_channel::router::ROUTER;
+use js::jsapi::Heap;
+use std::rc::Rc;
+use webgpu::wgpu;
+use webgpu::{WebGPU, WebGPURequest, WebGPUResponse, WebGPUResponseResult};
+
+#[dom_struct]
+pub struct GPU {
+    reflector_: Reflector,
+}
+
+impl GPU {
+    pub fn new_inherited() -> GPU {
+        GPU {
+            reflector_: Reflector::new(),
+        }
+    }
+
+    pub fn new(global: &GlobalScope) -> DomRoot<GPU> {
+        reflect_dom_object(Box::new(GPU::new_inherited()), global, GPUBinding::Wrap)
+    }
+
+    fn wgpu_channel(&self) -> Option<WebGPU> {
+        self.global().as_window().webgpu_channel()
+    }
+}
+
+pub trait AsyncWGPUListener {
+    fn handle_response(&self, response: WebGPUResponse, promise: &Rc<Promise>);
+}
+
+struct WGPUResponse<T: AsyncWGPUListener + DomObject> {
+    trusted: TrustedPromise,
+    receiver: Trusted<T>,
+}
+
+impl<T: AsyncWGPUListener + DomObject> WGPUResponse<T> {
+    #[allow(unrooted_must_root)]
+    fn response(self, response: WebGPUResponseResult) {
+        let promise = self.trusted.root();
+        match response {
+            Ok(response) => self.receiver.root().handle_response(response, &promise),
+            Err(error) => promise.reject_error(Error::Type(format!(
+                "Received error from WebGPU thread: {}",
+                error
+            ))),
+        }
+    }
+}
+
+pub fn response_async<T: AsyncWGPUListener + DomObject + 'static>(
+    promise: &Rc<Promise>,
+    receiver: &T,
+) -> IpcSender<WebGPUResponseResult> {
+    let (action_sender, action_receiver) = ipc::channel().unwrap();
+    let (task_source, canceller) = receiver
+        .global()
+        .as_window()
+        .task_manager()
+        .dom_manipulation_task_source_with_canceller();
+    let mut trusted = Some(TrustedPromise::new(promise.clone()));
+    let trusted_receiver = Trusted::new(receiver);
+    ROUTER.add_route(
+        action_receiver.to_opaque(),
+        Box::new(move |message| {
+            let trusted = if let Some(trusted) = trusted.take() {
+                trusted
+            } else {
+                error!("WebGPU callback called twice!");
+                return;
+            };
+
+            let context = WGPUResponse {
+                trusted,
+                receiver: trusted_receiver.clone(),
+            };
+            let result = task_source.queue_with_canceller(
+                task!(process_webgpu_task: move|| {
+                    context.response(message.to().unwrap());
+                }),
+                &canceller,
+            );
+            if let Err(err) = result {
+                error!("Failed to queue GPU listener-task: {:?}", err);
+            }
+        }),
+    );
+    action_sender
+}
+
+impl GPUMethods for GPU {
+    // https://gpuweb.github.io/gpuweb/#dom-gpu-requestadapter
+    fn RequestAdapter(
+        &self,
+        options: &GPURequestAdapterOptions,
+        comp: InCompartment,
+    ) -> Rc<Promise> {
+        let promise = Promise::new_in_current_compartment(&self.global(), comp);
+        let sender = response_async(&promise, self);
+        let power_preference = match options.powerPreference {
+            Some(GPUPowerPreference::Low_power) => wgpu::PowerPreference::LowPower,
+            Some(GPUPowerPreference::High_performance) => wgpu::PowerPreference::HighPerformance,
+            None => wgpu::PowerPreference::Default,
+        };
+
+        match self.wgpu_channel() {
+            Some(channel) => {
+                channel
+                    .0
+                    .send(WebGPURequest::RequestAdapter(
+                        sender,
+                        wgpu::RequestAdapterOptions { power_preference },
+                    ))
+                    .unwrap();
+            },
+            None => promise.reject_error(Error::Type("No WebGPU thread...".to_owned())),
+        };
+        promise
+    }
+}
+
+impl AsyncWGPUListener for GPU {
+    fn handle_response(&self, response: WebGPUResponse, promise: &Rc<Promise>) {
+        match response {
+            WebGPUResponse::RequestAdapter(name, adapter) => {
+                let adapter = GPUAdapter::new(
+                    &self.global(),
+                    DOMString::from(name),
+                    Heap::default(),
+                    adapter,
+                );
+                promise.resolve_native(&adapter);
+            },
+            response => promise.reject_error(Error::Type(format!(
+                "Wrong response received for GPU from WebGPU thread {:?}",
+                response,
+            ))),
+        }
+    }
+}

components/script/dom/gpuadapter.rs

@@ -0,0 +1,63 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::bindings::codegen::Bindings::GPUAdapterBinding::{self, GPUAdapterMethods};
+use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::str::DOMString;
+use crate::dom::globalscope::GlobalScope;
+use crate::script_runtime::JSContext as SafeJSContext;
+use dom_struct::dom_struct;
+use js::jsapi::{Heap, JSObject};
+use std::ptr::NonNull;
+use webgpu::WebGPUAdapter;
+
+#[dom_struct]
+pub struct GPUAdapter {
+    reflector_: Reflector,
+    name: DOMString,
+    #[ignore_malloc_size_of = "mozjs"]
+    extensions: Heap<*mut JSObject>,
+    adapter: WebGPUAdapter,
+}
+
+impl GPUAdapter {
+    pub fn new_inherited(
+        name: DOMString,
+        extensions: Heap<*mut JSObject>,
+        adapter: WebGPUAdapter,
+    ) -> GPUAdapter {
+        GPUAdapter {
+            reflector_: Reflector::new(),
+            name,
+            extensions,
+            adapter,
+        }
+    }
+
+    pub fn new(
+        global: &GlobalScope,
+        name: DOMString,
+        extensions: Heap<*mut JSObject>,
+        adapter: WebGPUAdapter,
+    ) -> DomRoot<GPUAdapter> {
+        reflect_dom_object(
+            Box::new(GPUAdapter::new_inherited(name, extensions, adapter)),
+            global,
+            GPUAdapterBinding::Wrap,
+        )
+    }
+}
+
+impl GPUAdapterMethods for GPUAdapter {
+    // https://gpuweb.github.io/gpuweb/#dom-gpuadapter-name
+    fn Name(&self) -> DOMString {
+        self.name.clone()
+    }
+
+    // https://gpuweb.github.io/gpuweb/#dom-gpuadapter-extensions
+    fn Extensions(&self, _cx: SafeJSContext) -> NonNull<JSObject> {
+        NonNull::new(self.extensions.get()).unwrap()
+    }
+}

components/script/dom/mod.rs

@@ -315,6 +315,8 @@ pub mod gamepadbuttonlist;
 pub mod gamepadevent;
 pub mod gamepadlist;
 pub mod globalscope;
+pub mod gpu;
+pub mod gpuadapter;
 pub mod hashchangeevent;
 pub mod headers;
 pub mod history;

components/script/dom/navigator.rs

@@ -11,6 +11,7 @@ use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::bindings::str::DOMString;
 use crate::dom::bluetooth::Bluetooth;
 use crate::dom::gamepadlist::GamepadList;
+use crate::dom::gpu::GPU;
 use crate::dom::mediadevices::MediaDevices;
 use crate::dom::mediasession::MediaSession;
 use crate::dom::mimetypearray::MimeTypeArray;
@@ -36,6 +37,7 @@ pub struct Navigator {
     gamepads: MutNullableDom<GamepadList>,
     permissions: MutNullableDom<Permissions>,
     mediasession: MutNullableDom<MediaSession>,
+    gpu: MutNullableDom<GPU>,
 }
 
 impl Navigator {
@@ -51,6 +53,7 @@ impl Navigator {
             gamepads: Default::default(),
             permissions: Default::default(),
             mediasession: Default::default(),
+            gpu: Default::default(),
         }
     }
 
@@ -205,4 +208,9 @@ impl NavigatorMethods for Navigator {
             MediaSession::new(window)
         })
     }
+
+    // https://gpuweb.github.io/gpuweb/#dom-navigator-gpu
+    fn Gpu(&self) -> DomRoot<GPU> {
+        self.gpu.or_init(|| GPU::new(&self.global()))
+    }
 }

components/script/dom/webidls/GPU.webidl

@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://gpuweb.github.io/gpuweb/#gpu-interface
+[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+interface GPU {
+    // May reject with DOMException  // TODO: DOMException("OperationError")?
+    Promise<GPUAdapter> requestAdapter(optional GPURequestAdapterOptions options = {});
+};
+
+// https://gpuweb.github.io/gpuweb/#dictdef-gpurequestadapteroptions
+dictionary GPURequestAdapterOptions {
+    GPUPowerPreference powerPreference;
+};
+
+// https://gpuweb.github.io/gpuweb/#enumdef-gpupowerpreference
+enum GPUPowerPreference {
+    "low-power",
+    "high-performance"
+};

components/script/dom/webidls/GPUAdapter.webidl

@@ -0,0 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://gpuweb.github.io/gpuweb/#gpuadapter
+[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+interface GPUAdapter {
+    readonly attribute DOMString name;
+    readonly attribute object extensions;
+    //readonly attribute GPULimits limits; Don’t expose higher limits for now.
+
+    // May reject with DOMException  // TODO: DOMException("OperationError")?
+    // Promise<GPUDevice> requestDevice(optional GPUDeviceDescriptor descriptor = {});
+};

components/script/dom/webidls/Navigator.webidl

@@ -75,3 +75,8 @@ partial interface Navigator {
 partial interface Navigator {
     [Pref="dom.gamepad.enabled"] GamepadList getGamepads();
 };
+
+[Exposed=Window]
+partial interface Navigator {
+    [SameObject, Pref="dom.webgpu.enabled"] readonly attribute GPU gpu;
+};

components/script/dom/webidls/WorkerNavigator.webidl

@@ -15,3 +15,8 @@ WorkerNavigator includes NavigatorLanguage;
 partial interface WorkerNavigator {
   [Pref="dom.permissions.enabled"] readonly attribute Permissions permissions;
 };
+
+[Exposed=DedicatedWorker]
+partial interface WorkerNavigator {
+    [SameObject, Pref="dom.webgpu.enabled"] readonly attribute GPU gpu;
+};

components/script/dom/window.rs

@@ -136,6 +136,7 @@ use style::str::HTML_SPACE_CHARACTERS;
 use style::stylesheets::CssRuleType;
 use style_traits::{CSSPixel, DevicePixel, ParsingMode};
 use url::Position;
+use webgpu::WebGPU;
 use webrender_api::units::{DeviceIntPoint, DeviceIntSize, LayoutPixel};
 use webrender_api::{DocumentId, ExternalScrollId, RenderApiSender};
 use webvr_traits::WebVRMsg;
@@ -267,6 +268,10 @@ pub struct Window {
     #[ignore_malloc_size_of = "channels are hard"]
     webgl_chan: Option<WebGLChan>,
 
+    #[ignore_malloc_size_of = "channels are hard"]
+    /// A handle for communicating messages to the WebGPU threads.
+    webgpu: Option<WebGPU>,
+
     /// A handle for communicating messages to the webvr thread, if available.
     #[ignore_malloc_size_of = "channels are hard"]
     webvr_chan: Option<IpcSender<WebVRMsg>>,
@@ -462,6 +467,10 @@ impl Window {
             .map(|chan| WebGLCommandSender::new(chan.clone(), self.get_event_loop_waker()))
     }
 
+    pub fn webgpu_channel(&self) -> Option<WebGPU> {
+        self.webgpu.clone()
+    }
+
     pub fn webvr_thread(&self) -> Option<IpcSender<WebVRMsg>> {
         self.webvr_chan.clone()
     }
@@ -2206,6 +2215,7 @@ impl Window {
         navigation_start: u64,
         navigation_start_precise: u64,
         webgl_chan: Option<WebGLChan>,
+        webgpu: Option<WebGPU>,
         webvr_chan: Option<IpcSender<WebVRMsg>>,
         webxr_registry: webxr_api::Registry,
         microtask_queue: Rc<MicrotaskQueue>,
@@ -2285,6 +2295,7 @@ impl Window {
             media_query_lists: DOMTracker::new(),
             test_runner: Default::default(),
             webgl_chan,
+            webgpu,
             webvr_chan,
             webxr_registry,
             permission_state_invocation_results: Default::default(),

components/script/dom/workernavigator.rs

@@ -7,6 +7,7 @@ use crate::dom::bindings::codegen::Bindings::WorkerNavigatorBinding::WorkerNavig
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
 use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::bindings::str::DOMString;
+use crate::dom::gpu::GPU;
 use crate::dom::navigatorinfo;
 use crate::dom::permissions::Permissions;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
@@ -17,6 +18,7 @@ use dom_struct::dom_struct;
 pub struct WorkerNavigator {
     reflector_: Reflector,
     permissions: MutNullableDom<Permissions>,
+    gpu: MutNullableDom<GPU>,
 }
 
 impl WorkerNavigator {
@@ -24,6 +26,7 @@ impl WorkerNavigator {
         WorkerNavigator {
             reflector_: Reflector::new(),
             permissions: Default::default(),
+            gpu: Default::default(),
         }
     }
 
@@ -97,4 +100,9 @@ impl WorkerNavigatorMethods for WorkerNavigator {
         self.permissions
             .or_init(|| Permissions::new(&self.global()))
     }
+
+    // https://gpuweb.github.io/gpuweb/#dom-navigator-gpu
+    fn Gpu(&self) -> DomRoot<GPU> {
+        self.gpu.or_init(|| GPU::new(&self.global()))
+    }
 }

components/script/script_thread.rs

@@ -163,6 +163,7 @@ use style::dom::OpaqueNode;
 use style::thread_state::{self, ThreadState};
 use time::{at_utc, get_time, precise_time_ns, Timespec};
 use url::Position;
+use webgpu::WebGPU;
 use webrender_api::units::LayoutPixel;
 use webrender_api::{DocumentId, RenderApiSender};
 use webvr_traits::{WebVREvent, WebVRMsg};
@@ -629,6 +630,9 @@ pub struct ScriptThread {
     /// A handle to the WebGL thread
     webgl_chan: Option<WebGLPipeline>,
 
+    /// A handle to the WebGPU threads
+    webgpu: Option<WebGPU>,
+
     /// A handle to the webvr thread, if available
     webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -1338,6 +1342,7 @@ impl ScriptThread {
             layout_to_constellation_chan: state.layout_to_constellation_chan,
 
             webgl_chan: state.webgl_chan,
+            webgpu: state.webgpu,
             webvr_chan: state.webvr_chan,
             webxr_registry: state.webxr_registry,
 
@@ -3247,6 +3252,7 @@ impl ScriptThread {
             incomplete.navigation_start,
             incomplete.navigation_start_precise,
             self.webgl_chan.as_ref().map(|chan| chan.channel()),
+            self.webgpu.clone(),
             self.webvr_chan.clone(),
             self.webxr_registry.clone(),
             self.microtask_queue.clone(),

components/script_traits/Cargo.toml

@@ -39,6 +39,7 @@ style_traits = {path = "../style_traits", features = ["servo"]}
 time = "0.1.12"
 url = "2.0"
 webdriver = "0.40"
+webgpu = {path = "../webgpu"}
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 webvr_traits = {path = "../webvr_traits"}
 webxr-api = {git = "https://github.com/servo/webxr", features = ["ipc"]}

components/script_traits/lib.rs

@@ -60,6 +60,7 @@ use std::sync::Arc;
 use std::time::Duration;
 use style_traits::CSSPixel;
 use style_traits::SpeculativePainter;
+use webgpu::WebGPU;
 use webrender_api::units::{DeviceIntSize, DevicePixel, LayoutPixel};
 use webrender_api::{DocumentId, ExternalScrollId, ImageKey, RenderApiSender};
 use webvr_traits::{WebVREvent, WebVRMsg};
@@ -656,6 +657,8 @@ pub struct InitialScriptState {
     pub content_process_shutdown_chan: Sender<()>,
     /// A channel to the WebGL thread used in this pipeline.
     pub webgl_chan: Option<WebGLPipeline>,
+    /// A channel to the WebGPU threads.
+    pub webgpu: Option<WebGPU>,
     /// A channel to the webvr thread, if available.
     pub webvr_chan: Option<IpcSender<WebVRMsg>>,
     /// The XR device registry

components/servo/Cargo.toml

@@ -79,6 +79,7 @@ servo_url = {path = "../url"}
 sparkle = "0.1"
 style = {path = "../style", features = ["servo"]}
 style_traits = {path = "../style_traits", features = ["servo"]}
+webgpu = {path = "../webgpu"}
 webrender = {git = "https://github.com/servo/webrender"}
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 webrender_traits = {path = "../webrender_traits"}

components/servo/lib.rs

@@ -49,6 +49,7 @@ pub use servo_geometry;
 pub use servo_url;
 pub use style;
 pub use style_traits;
+pub use webgpu;
 pub use webrender_api;
 pub use webrender_traits;
 pub use webvr;
@@ -863,6 +864,8 @@ fn create_constellation(
 
     let resource_sender = public_resource_threads.sender();
 
+    let webgpu = webgpu::WebGPU::new();
+
     let initial_state = InitialConstellationState {
         compositor_proxy,
         embedder_proxy,
@@ -877,6 +880,7 @@ fn create_constellation(
         webrender_document,
         webrender_api_sender,
         webgl_threads,
+        webgpu,
         webvr_chan,
         webxr_registry,
         glplayer_threads,

components/webgpu/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "webgpu"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+edition = "2018"
+publish = false
+
+[lib]
+name = "webgpu"
+path = "lib.rs"
+
+[dependencies]
+embedder_traits = {path = "../embedder_traits"}
+ipc-channel = "0.12"
+log = "0.4"
+malloc_size_of = { path = "../malloc_size_of" }
+serde = "1.0"
+servo_config = {path = "../config"}
+wgpu-native = { version = "0.4.0", features = ["serde"] }

components/webgpu/lib.rs

@@ -0,0 +1,153 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#[macro_use]
+extern crate log;
+#[macro_use]
+extern crate serde;
+#[macro_use]
+pub extern crate wgpu_native as wgpu;
+
+use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
+use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
+use servo_config::pref;
+use wgpu::adapter_get_info;
+use wgpu::TypedId;
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum WebGPUResponse {
+    RequestAdapter(String, WebGPUAdapter),
+    RequestDevice,
+}
+
+pub type WebGPUResponseResult = Result<WebGPUResponse, String>;
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum WebGPURequest {
+    RequestAdapter(IpcSender<WebGPUResponseResult>, wgpu::RequestAdapterOptions),
+    RequestDevice,
+    Exit(IpcSender<()>),
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct WebGPU(pub IpcSender<WebGPURequest>);
+
+impl WebGPU {
+    pub fn new() -> Option<Self> {
+        if !pref!(dom.webgpu.enabled) {
+            return None;
+        }
+        let (sender, receiver) = match ipc::channel() {
+            Ok(sender_and_receiver) => sender_and_receiver,
+            Err(e) => {
+                warn!(
+                    "Failed to create sender and receiciver for WGPU thread ({})",
+                    e
+                );
+                return None;
+            },
+        };
+
+        if let Err(e) = std::thread::Builder::new()
+            .name("WGPU".to_owned())
+            .spawn(move || {
+                WGPU::new(receiver).run();
+            })
+        {
+            warn!("Failed to spwan WGPU thread ({})", e);
+            return None;
+        }
+        Some(WebGPU(sender))
+    }
+
+    pub fn exit(&self, sender: IpcSender<()>) -> Result<(), &'static str> {
+        self.0
+            .send(WebGPURequest::Exit(sender))
+            .map_err(|_| "Failed to send Exit message")
+    }
+}
+
+struct WGPU {
+    receiver: IpcReceiver<WebGPURequest>,
+    global: wgpu::Global,
+    adapters: Vec<WebGPUAdapter>,
+    // Track invalid adapters https://gpuweb.github.io/gpuweb/#invalid
+    _invalid_adapters: Vec<WebGPUAdapter>,
+}
+
+impl WGPU {
+    fn new(receiver: IpcReceiver<WebGPURequest>) -> Self {
+        WGPU {
+            receiver,
+            global: wgpu::Global::new("webgpu-native"),
+            adapters: Vec::new(),
+            _invalid_adapters: Vec::new(),
+        }
+    }
+
+    fn deinit(self) {
+        self.global.delete()
+    }
+
+    fn run(mut self) {
+        while let Ok(msg) = self.receiver.recv() {
+            match msg {
+                WebGPURequest::RequestAdapter(sender, options) => {
+                    let adapter_id = match wgpu::request_adapter(
+                        &self.global,
+                        &options,
+                        // TODO: The ids we pass here should be generated by the client
+                        &[
+                            wgpu::Id::zip(0, 0, wgpu::Backend::Vulkan),
+                            wgpu::Id::zip(0, 0, wgpu::Backend::Metal),
+                            wgpu::Id::zip(0, 0, wgpu::Backend::Dx12),
+                        ],
+                    ) {
+                        Some(id) => id,
+                        None => {
+                            if let Err(e) =
+                                sender.send(Err("Failed to get webgpu adapter".to_string()))
+                            {
+                                warn!(
+                                    "Failed to send response to WebGPURequest::RequestAdapter ({})",
+                                    e
+                                )
+                            }
+                            return;
+                        },
+                    };
+                    let adapter = WebGPUAdapter(adapter_id);
+                    self.adapters.push(adapter);
+                    let info =
+                        gfx_select!(adapter_id => adapter_get_info(&self.global, adapter_id));
+                    if let Err(e) =
+                        sender.send(Ok(WebGPUResponse::RequestAdapter(info.name, adapter)))
+                    {
+                        warn!(
+                            "Failed to send response to WebGPURequest::RequestAdapter ({})",
+                            e
+                        )
+                    }
+                },
+                WebGPURequest::RequestDevice => {},
+                WebGPURequest::Exit(sender) => {
+                    self.deinit();
+                    if let Err(e) = sender.send(()) {
+                        warn!("Failed to send response to WebGPURequest::Exit ({})", e)
+                    }
+                    return;
+                },
+            }
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub struct WebGPUAdapter(pub wgpu::AdapterId);
+
+impl MallocSizeOf for WebGPUAdapter {
+    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
+        0
+    }
+}