Replace RwLock<MediaList> with shared_lock::Locked<MediaList>

components/script/dom/bindings/trace.rs

@@ -99,6 +99,7 @@ use style::keyframes::Keyframe;
 use style::media_queries::MediaList;
 use style::properties::PropertyDeclarationBlock;
 use style::selector_parser::{PseudoElement, Snapshot};
+use style::shared_lock::SharedRwLock as StyleSharedRwLock;
 use style::stylesheets::{CssRules, KeyframesRule, MediaRule, NamespaceRule, StyleRule, ImportRule};
 use style::stylesheets::SupportsRule;
 use style::values::specified::Length;
@@ -360,6 +361,7 @@ unsafe_no_jsmanaged_fields!(HttpsState);
 unsafe_no_jsmanaged_fields!(Request);
 unsafe_no_jsmanaged_fields!(RequestInit);
 unsafe_no_jsmanaged_fields!(SharedRt);
+unsafe_no_jsmanaged_fields!(StyleSharedRwLock);
 unsafe_no_jsmanaged_fields!(TouchpadPressurePhase);
 unsafe_no_jsmanaged_fields!(USVString);
 unsafe_no_jsmanaged_fields!(ReferrerPolicy);

components/script/dom/document.rs

@@ -134,6 +134,7 @@ use style::attr::AttrValue;
 use style::context::{QuirksMode, ReflowGoal};
 use style::restyle_hints::{RestyleHint, RESTYLE_STYLE_ATTRIBUTE};
 use style::selector_parser::{RestyleDamage, Snapshot};
+use style::shared_lock::SharedRwLock as StyleSharedRwLock;
 use style::str::{HTML_SPACE_CHARACTERS, split_html_space_chars, str_join};
 use style::stylesheets::Stylesheet;
 use task_source::TaskSource;
@@ -220,6 +221,9 @@ pub struct Document {
     scripts: MutNullableJS<HTMLCollection>,
     anchors: MutNullableJS<HTMLCollection>,
     applets: MutNullableJS<HTMLCollection>,
+    /// Lock use for style attributes and author-origin stylesheet objects in this document.
+    /// Can be acquired once for accessing many objects.
+    style_shared_lock: StyleSharedRwLock,
     /// List of stylesheets associated with nodes in this document. |None| if the list needs to be refreshed.
     stylesheets: DOMRefCell<Option<Vec<StylesheetInDocument>>>,
     /// Whether the list of stylesheets has changed since the last reflow was triggered.
@@ -1964,6 +1968,7 @@ pub trait LayoutDocumentHelpers {
     unsafe fn needs_paint_from_layout(&self);
     unsafe fn will_paint(&self);
     unsafe fn quirks_mode(&self) -> QuirksMode;
+    unsafe fn style_shared_lock(&self) -> &StyleSharedRwLock;
 }
 
 #[allow(unsafe_code)]
@@ -2000,6 +2005,11 @@ impl LayoutDocumentHelpers for LayoutJS<Document> {
     unsafe fn quirks_mode(&self) -> QuirksMode {
         (*self.unsafe_get()).quirks_mode()
     }
+
+    #[inline]
+    unsafe fn style_shared_lock(&self) -> &StyleSharedRwLock {
+        (*self.unsafe_get()).style_shared_lock()
+    }
 }
 
 // https://html.spec.whatwg.org/multipage/#is-a-registrable-domain-suffix-of-or-is-equal-to
@@ -2121,6 +2131,7 @@ impl Document {
             scripts: Default::default(),
             anchors: Default::default(),
             applets: Default::default(),
+            style_shared_lock: StyleSharedRwLock::new(),
             stylesheets: DOMRefCell::new(None),
             stylesheets_changed_since_reflow: Cell::new(false),
             stylesheet_list: MutNullableJS::new(None),
@@ -2250,6 +2261,11 @@ impl Document {
         };
     }
 
+    /// Return a reference to the per-document shared lock used in stylesheets.
+    pub fn style_shared_lock(&self) -> &StyleSharedRwLock {
+        &self.style_shared_lock
+    }
+
     /// Returns the list of stylesheets associated with nodes in the document.
     pub fn stylesheets(&self) -> Vec<Arc<Stylesheet>> {
         self.ensure_stylesheets();

components/script/dom/htmlmetaelement.rs

@@ -99,12 +99,15 @@ impl HTMLMetaElement {
             let content = content.value();
             if !content.is_empty() {
                 if let Some(translated_rule) = ViewportRule::from_meta(&**content) {
+                    let document = self.upcast::<Node>().owner_doc();
+                    let shared_lock = document.style_shared_lock();
                     *self.stylesheet.borrow_mut() = Some(Arc::new(Stylesheet {
                         rules: CssRules::new(vec![CssRule::Viewport(Arc::new(RwLock::new(translated_rule)))]),
                         origin: Origin::Author,
+                        shared_lock: shared_lock.clone(),
                         base_url: window_from_node(self).get_url(),
                         namespaces: Default::default(),
-                        media: Default::default(),
+                        media: Arc::new(shared_lock.wrap(Default::default())),
                         // Viewport constraints are always recomputed on resize; they don't need to
                         // force all styles to be recomputed.
                         dirty_on_viewport_size_change: AtomicBool::new(false),

components/script/dom/htmlstyleelement.rs

@@ -84,9 +84,10 @@ impl HTMLStyleElement {
 
         let data = node.GetTextContent().expect("Element.textContent must be a string");
         let mq = parse_media_query_list(&mut CssParser::new(&mq_str));
+        let shared_lock = node.owner_doc().style_shared_lock().clone();
         let loader = StylesheetLoader::for_element(self.upcast());
         let sheet = Stylesheet::from_str(&data, url, Origin::Author, mq,
-                                         Some(&loader),
+                                         shared_lock, Some(&loader),
                                          win.css_error_reporter(),
                                          ParserContextExtraData::default());
 

components/script/layout_wrapper.rs

@@ -69,6 +69,7 @@ use style::dom::UnsafeNode;
 use style::element_state::*;
 use style::properties::{ComputedValues, PropertyDeclarationBlock};
 use style::selector_parser::{NonTSPseudoClass, PseudoElement, SelectorImpl};
+use style::shared_lock::SharedRwLock as StyleSharedRwLock;
 use style::sink::Push;
 use style::str::is_whitespace;
 use style::stylist::ApplicableDeclarationBlock;
@@ -330,6 +331,10 @@ impl<'ld> ServoLayoutDocument<'ld> {
         unsafe { self.document.quirks_mode() }
     }
 
+    pub fn style_shared_lock(&self) -> &StyleSharedRwLock {
+        unsafe { self.document.style_shared_lock() }
+    }
+
     pub fn from_layout_js(doc: LayoutJS<Document>) -> ServoLayoutDocument<'ld> {
         ServoLayoutDocument {
             document: doc,

components/script/stylesheet_loader.rs

@@ -152,12 +152,14 @@ impl FetchResponseListener for StylesheetContext {
                     let is_stylesheet_load_applicable =
                         self.request_generation_id.map_or(true, |gen| gen == link.get_request_generation_id());
                     if is_stylesheet_load_applicable {
+                        let shared_lock = document.style_shared_lock().clone();
                         let sheet =
                             Arc::new(Stylesheet::from_bytes(&data, final_url,
                                                             protocol_encoding_label,
                                                             Some(environment_encoding),
                                                             Origin::Author,
                                                             media.take().unwrap(),
+                                                            shared_lock,
                                                             Some(&loader),
                                                             win.css_error_reporter(),
                                                             ParserContextExtraData::default()));