script: implement navigator.hardwareConcurrency (#31268)

Signed-off-by: syvb <me@iter.ca>

components/script/Cargo.toml

@@ -75,6 +75,7 @@ mime = { workspace = true }
 mime_guess = { workspace = true }
 msg = { workspace = true }
 net_traits = { workspace = true }
+num_cpus = { workspace = true }
 num-traits = { workspace = true }
 parking_lot = { workspace = true }
 percent-encoding = { workspace = true }

components/script/dom/navigator.rs

@@ -2,8 +2,11 @@
  * 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 std::convert::TryInto;
+
 use dom_struct::dom_struct;
 use js::jsval::JSVal;
+use lazy_static::lazy_static;
 
 use crate::dom::bindings::codegen::Bindings::NavigatorBinding::NavigatorMethods;
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
@@ -24,6 +27,13 @@ use crate::dom::window::Window;
 use crate::dom::xrsystem::XRSystem;
 use crate::script_runtime::JSContext;
 
+pub(super) fn hardware_concurrency() -> u64 {
+    lazy_static! {
+        static ref CPUS: u64 = num_cpus::get().try_into().unwrap_or(1);
+    }
+    *CPUS
+}
+
 #[dom_struct]
 pub struct Navigator {
     reflector_: Reflector,
@@ -206,4 +216,9 @@ impl NavigatorMethods for Navigator {
     fn Gpu(&self) -> DomRoot<GPU> {
         self.gpu.or_init(|| GPU::new(&self.global()))
     }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-navigator-hardwareconcurrency>
+    fn HardwareConcurrency(&self) -> u64 {
+        hardware_concurrency()
+    }
 }

components/script/dom/webidls/Navigator.webidl

@@ -15,6 +15,7 @@ Navigator includes NavigatorLanguage;
 Navigator includes NavigatorPlugins;
 Navigator includes NavigatorCookies;
 Navigator includes NavigatorGPU;
+Navigator includes NavigatorConcurrentHardware;
 
 // https://html.spec.whatwg.org/multipage/#navigatorid
 [Exposed=(Window,Worker)]
@@ -70,3 +71,8 @@ partial interface Navigator {
 partial interface Navigator {
     [Pref="dom.gamepad.enabled"] GamepadList getGamepads();
 };
+
+// https://html.spec.whatwg.org/multipage/#navigatorconcurrenthardware
+interface mixin NavigatorConcurrentHardware {
+  readonly attribute unsigned long long hardwareConcurrency;
+};

components/script/dom/webidls/WorkerNavigator.webidl

@@ -8,6 +8,7 @@ interface WorkerNavigator {};
 WorkerNavigator includes NavigatorID;
 WorkerNavigator includes NavigatorLanguage;
 //WorkerNavigator includes NavigatorOnLine;
+WorkerNavigator includes NavigatorConcurrentHardware;
 
 // https://w3c.github.io/permissions/#navigator-and-workernavigator-extension
 

components/script/dom/workernavigator.rs

@@ -11,6 +11,7 @@ use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::bindings::str::DOMString;
 use crate::dom::bindings::utils::to_frozen_array;
 use crate::dom::gpu::GPU;
+use crate::dom::navigator::hardware_concurrency;
 use crate::dom::navigatorinfo;
 use crate::dom::permissions::Permissions;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
@@ -110,4 +111,9 @@ impl WorkerNavigatorMethods for WorkerNavigator {
     fn Gpu(&self) -> DomRoot<GPU> {
         self.gpu.or_init(|| GPU::new(&self.global()))
     }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-navigator-hardwareconcurrency>
+    fn HardwareConcurrency(&self) -> u64 {
+        hardware_concurrency()
+    }
 }