Auto merge of #26484 - servo:layout-2020-style-prep, r=SimonSapin

Implement concept of dirty root

components/script/dom/bindings/cell.rs

@@ -45,11 +45,12 @@ impl<T> DomRefCell<T> {
         &mut *self.value.as_ptr()
     }
 
-    /// Version of the above that we use during restyle while the script thread
-    /// is blocked.
-    pub fn borrow_mut_for_layout(&self) -> RefMut<T> {
+    /// Mutably borrow a cell for layout. Ideally this would use
+    /// `RefCell::try_borrow_mut_unguarded` but that doesn't exist yet.
+    #[allow(unsafe_code)]
+    pub unsafe fn borrow_mut_for_layout(&self) -> &mut T {
         debug_assert!(thread_state::get().is_layout());
-        self.value.borrow_mut()
+        &mut *self.value.as_ptr()
     }
 }
 

components/script/dom/document.rs

@@ -387,6 +387,8 @@ pub struct Document {
     animation_timeline: DomRefCell<AnimationTimeline>,
     /// Animations for this Document
     animations: DomRefCell<Animations>,
+    /// The nearest inclusive ancestors to all the nodes that require a restyle.
+    dirty_root: MutNullableDom<Element>,
 }
 
 #[derive(JSTraceable, MallocSizeOf)]
@@ -446,6 +448,112 @@ enum ElementLookupResult {
 
 #[allow(non_snake_case)]
 impl Document {
+    pub fn note_node_with_dirty_descendants(&self, node: &Node) {
+        debug_assert!(*node.owner_doc() == *self);
+        if !node.is_connected() {
+            return;
+        }
+
+        let parent = match node.inclusive_ancestors(ShadowIncluding::Yes).nth(1) {
+            Some(parent) => parent,
+            None => {
+                // There is no parent so this is the Document node, so we
+                // behave as if we were called with the document element.
+                let document_element = match self.GetDocumentElement() {
+                    Some(element) => element,
+                    None => return,
+                };
+                if let Some(dirty_root) = self.dirty_root.get() {
+                    // There was an existing dirty root so we mark its
+                    // ancestors as dirty until the document element.
+                    for ancestor in dirty_root
+                        .upcast::<Node>()
+                        .inclusive_ancestors(ShadowIncluding::Yes)
+                    {
+                        if ancestor.is::<Element>() {
+                            ancestor.set_flag(NodeFlags::HAS_DIRTY_DESCENDANTS, true);
+                        }
+                    }
+                }
+                self.dirty_root.set(Some(&document_element));
+                return;
+            },
+        };
+
+        if parent.is::<Element>() {
+            if !parent.is_styled() {
+                return;
+            }
+
+            if parent.is_display_none() {
+                return;
+            }
+        }
+
+        let element_parent: DomRoot<Element>;
+        let element = match node.downcast::<Element>() {
+            Some(element) => element,
+            None => {
+                // Current node is not an element, it's probably a text node,
+                // we try to get its element parent.
+                match DomRoot::downcast::<Element>(parent) {
+                    Some(parent) => {
+                        element_parent = parent;
+                        &element_parent
+                    },
+                    None => {
+                        // Parent is not an element so it must be a document,
+                        // and this is not an element either, so there is
+                        // nothing to do.
+                        return;
+                    },
+                }
+            },
+        };
+
+        let dirty_root = match self.dirty_root.get() {
+            None => {
+                element
+                    .upcast::<Node>()
+                    .set_flag(NodeFlags::HAS_DIRTY_DESCENDANTS, true);
+                self.dirty_root.set(Some(element));
+                return;
+            },
+            Some(root) => root,
+        };
+
+        for ancestor in element
+            .upcast::<Node>()
+            .inclusive_ancestors(ShadowIncluding::Yes)
+        {
+            if ancestor.get_flag(NodeFlags::HAS_DIRTY_DESCENDANTS) {
+                return;
+            }
+            if ancestor.is::<Element>() {
+                ancestor.set_flag(NodeFlags::HAS_DIRTY_DESCENDANTS, true);
+            }
+        }
+
+        let new_dirty_root = element
+            .upcast::<Node>()
+            .common_ancestor(dirty_root.upcast(), ShadowIncluding::Yes);
+
+        let mut has_dirty_descendants = true;
+        for ancestor in dirty_root
+            .upcast::<Node>()
+            .inclusive_ancestors(ShadowIncluding::Yes)
+        {
+            ancestor.set_flag(NodeFlags::HAS_DIRTY_DESCENDANTS, has_dirty_descendants);
+            has_dirty_descendants &= *ancestor != *new_dirty_root;
+        }
+        self.dirty_root
+            .set(Some(new_dirty_root.downcast::<Element>().unwrap()));
+    }
+
+    pub fn take_dirty_root(&self) -> Option<DomRoot<Element>> {
+        self.dirty_root.take()
+    }
+
     #[inline]
     pub fn loader(&self) -> Ref<DocumentLoader> {
         self.loader.borrow()
@@ -967,8 +1075,14 @@ impl Document {
     }
 
     pub fn dirty_all_nodes(&self) {
-        let root = self.upcast::<Node>();
-        for node in root.traverse_preorder(ShadowIncluding::Yes) {
+        let root = match self.GetDocumentElement() {
+            Some(root) => root,
+            None => return,
+        };
+        for node in root
+            .upcast::<Node>()
+            .traverse_preorder(ShadowIncluding::Yes)
+        {
             node.dirty(NodeDamage::OtherNodeDamage)
         }
     }
@@ -2917,6 +3031,7 @@ impl Document {
                 DomRefCell::new(AnimationTimeline::new())
             },
             animations: DomRefCell::new(Animations::new()),
+            dirty_root: Default::default(),
         }
     }
 

components/script/dom/element.rs

@@ -309,6 +309,7 @@ impl Element {
         restyle.hint.insert(RestyleHint::RESTYLE_SELF);
 
         if damage == NodeDamage::OtherNodeDamage {
+            doc.note_node_with_dirty_descendants(self.upcast());
             restyle.damage = RestyleDamage::rebuild_and_reflow();
         }
     }
@@ -515,6 +516,7 @@ impl Element {
 
     pub fn detach_shadow(&self) {
         if let Some(ref shadow_root) = self.shadow_root() {
+            self.upcast::<Node>().note_dirty_descendants();
             shadow_root.detach();
             self.ensure_rare_data().shadow_root = None;
         } else {

components/script/dom/node.rs

@@ -150,12 +150,9 @@ pub struct Node {
     /// are this node.
     ranges: WeakRangeVec,
 
-    /// Style+Layout information. Only the layout thread may touch this data.
-    ///
-    /// Must be sent back to the layout thread to be destroyed when this
-    /// node is finalized.
-    #[ignore_malloc_size_of = "Unsafe cell"]
-    style_and_layout_data: UnsafeCell<Option<Box<StyleAndOpaqueLayoutData>>>,
+    /// Style+Layout information.
+    #[ignore_malloc_size_of = "trait object"]
+    style_and_layout_data: DomRefCell<Option<Box<StyleAndOpaqueLayoutData>>>,
 }
 
 bitflags! {
@@ -318,6 +315,8 @@ impl Node {
     /// Fails unless `child` is a child of this node.
     fn remove_child(&self, child: &Node, cached_index: Option<u32>) {
         assert!(child.parent_node.get().as_deref() == Some(self));
+        self.note_dirty_descendants();
+
         let prev_sibling = child.GetPreviousSibling();
         match prev_sibling {
             None => {
@@ -630,17 +629,7 @@ impl Node {
 
     // FIXME(emilio): This and the function below should move to Element.
     pub fn note_dirty_descendants(&self) {
-        debug_assert!(self.is_connected());
-
-        for ancestor in self.inclusive_ancestors(ShadowIncluding::Yes) {
-            if ancestor.get_flag(NodeFlags::HAS_DIRTY_DESCENDANTS) {
-                return;
-            }
-
-            if ancestor.is::<Element>() {
-                ancestor.set_flag(NodeFlags::HAS_DIRTY_DESCENDANTS, true);
-            }
-        }
+        self.owner_doc().note_node_with_dirty_descendants(self);
     }
 
     pub fn has_dirty_descendants(&self) -> bool {
@@ -708,6 +697,22 @@ impl Node {
         }
     }
 
+    pub fn common_ancestor(
+        &self,
+        other: &Node,
+        shadow_including: ShadowIncluding,
+    ) -> DomRoot<Node> {
+        for ancestor in self.inclusive_ancestors(shadow_including) {
+            if other
+                .inclusive_ancestors(shadow_including)
+                .any(|node| node == ancestor)
+            {
+                return ancestor;
+            }
+        }
+        unreachable!();
+    }
+
     pub fn is_inclusive_ancestor_of(&self, parent: &Node) -> bool {
         self == parent || self.is_ancestor_of(parent)
     }
@@ -1246,21 +1251,38 @@ impl Node {
         }
     }
 
-    #[allow(unsafe_code)]
-    pub fn style(&self) -> Option<Arc<ComputedValues>> {
-        if !window_from_node(self).layout_reflow(QueryMsg::StyleQuery) {
-            return None;
-        }
-        unsafe {
-            (*self.style_and_layout_data.get()).as_ref().map(|data| {
+    pub fn is_styled(&self) -> bool {
+        self.style_and_layout_data.borrow().is_some()
+    }
+
+    pub fn is_display_none(&self) -> bool {
+        self.style_and_layout_data
+            .borrow()
+            .as_ref()
+            .map_or(true, |data| {
                 data.style_data
                     .element_data
                     .borrow()
                     .styles
                     .primary()
-                    .clone()
+                    .get_box()
+                    .display
+                    .is_none()
             })
+    }
+
+    pub fn style(&self) -> Option<Arc<ComputedValues>> {
+        if !window_from_node(self).layout_reflow(QueryMsg::StyleQuery) {
+            return None;
         }
+        self.style_and_layout_data.borrow().as_ref().map(|data| {
+            data.style_data
+                .element_data
+                .borrow()
+                .styles
+                .primary()
+                .clone()
+        })
     }
 }
 
@@ -1444,13 +1466,21 @@ impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
     #[inline]
     #[allow(unsafe_code)]
     fn get_style_and_opaque_layout_data(self) -> Option<&'dom StyleAndOpaqueLayoutData> {
-        unsafe { (*self.unsafe_get().style_and_layout_data.get()).as_deref() }
+        unsafe {
+            self.unsafe_get()
+                .style_and_layout_data
+                .borrow_for_layout()
+                .as_deref()
+        }
     }
 
     #[inline]
     #[allow(unsafe_code)]
     unsafe fn init_style_and_opaque_layout_data(self, val: Box<StyleAndOpaqueLayoutData>) {
-        let data = &mut *self.unsafe_get().style_and_layout_data.get();
+        let data = self
+            .unsafe_get()
+            .style_and_layout_data
+            .borrow_mut_for_layout();
         debug_assert!(data.is_none());
         *data = Some(val);
     }
@@ -1458,7 +1488,9 @@ impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
     #[inline]
     #[allow(unsafe_code)]
     unsafe fn take_style_and_opaque_layout_data(self) -> Box<StyleAndOpaqueLayoutData> {
-        (*self.unsafe_get().style_and_layout_data.get())
+        self.unsafe_get()
+            .style_and_layout_data
+            .borrow_mut_for_layout()
             .take()
             .unwrap()
     }
@@ -1649,7 +1681,7 @@ where
 }
 
 /// Whether a tree traversal should pass shadow tree boundaries.
-#[derive(PartialEq)]
+#[derive(Clone, Copy, PartialEq)]
 pub enum ShadowIncluding {
     No,
     Yes,
@@ -1775,7 +1807,7 @@ impl Node {
             inclusive_descendants_version: Cell::new(0),
             ranges: WeakRangeVec::new(),
 
-            style_and_layout_data: UnsafeCell::new(None),
+            style_and_layout_data: Default::default(),
         }
     }
 

components/script/dom/range.rs

@@ -296,19 +296,8 @@ impl RangeMethods for Range {
 
     // https://dom.spec.whatwg.org/#dom-range-commonancestorcontainer
     fn CommonAncestorContainer(&self) -> DomRoot<Node> {
-        let end_container = self.EndContainer();
-        // Step 1.
-        for container in self
-            .StartContainer()
-            .inclusive_ancestors(ShadowIncluding::No)
-        {
-            // Step 2.
-            if container.is_inclusive_ancestor_of(&end_container) {
-                // Step 3.
-                return container;
-            }
-        }
-        unreachable!();
+        self.EndContainer()
+            .common_ancestor(&self.StartContainer(), ShadowIncluding::No)
     }
 
     // https://dom.spec.whatwg.org/#dom-range-setstart

components/script/dom/shadowroot.rs

@@ -281,7 +281,7 @@ impl<'dom> LayoutShadowRootHelpers<'dom> for LayoutDom<'dom, ShadowRoot> {
         quirks_mode: QuirksMode,
         guard: &SharedRwLockReadGuard,
     ) {
-        let mut author_styles = (*self.unsafe_get()).author_styles.borrow_mut_for_layout();
+        let author_styles = self.unsafe_get().author_styles.borrow_mut_for_layout();
         if author_styles.stylesheets.dirty() {
             author_styles.flush::<E>(device, quirks_mode, guard);
         }

components/script/dom/window.rs

@@ -1659,6 +1659,14 @@ impl Window {
             document.flush_dirty_canvases();
         }
 
+        let pending_restyles = document.drain_pending_restyles();
+
+        let dirty_root = document
+            .take_dirty_root()
+            .filter(|_| !stylesheets_changed)
+            .or_else(|| document.GetDocumentElement())
+            .map(|root| root.upcast::<Node>().to_trusted_node_address());
+
         // Send new document and relevant styles to layout.
         let needs_display = reflow_goal.needs_display();
         let reflow = ScriptReflow {
@@ -1666,13 +1674,14 @@ impl Window {
                 page_clip_rect: self.page_clip_rect.get(),
             },
             document: document.upcast::<Node>().to_trusted_node_address(),
+            dirty_root,
             stylesheets_changed,
             window_size: self.window_size.get(),
             origin: self.origin().immutable().clone(),
             reflow_goal,
             script_join_chan: join_chan,
             dom_count: document.dom_count(),
-            pending_restyles: document.drain_pending_restyles(),
+            pending_restyles,
             animation_timeline_value: document.current_animation_timeline_value(),
             animations: document.animations().sets.clone(),
         };
@@ -1770,12 +1779,17 @@ impl Window {
 
             // We shouldn't need a reflow immediately after a
             // reflow, except if we're waiting for a deferred paint.
-            assert!({
-                let condition = self.Document().needs_reflow();
-                condition.is_none() ||
-                    (!for_display && condition == Some(ReflowTriggerCondition::PaintPostponed)) ||
-                    self.suppress_reflow.get()
-            });
+            let condition = self.Document().needs_reflow();
+            assert!(
+                {
+                    condition.is_none() ||
+                        (!for_display &&
+                            condition == Some(ReflowTriggerCondition::PaintPostponed)) ||
+                        self.suppress_reflow.get()
+                },
+                "condition was {:?}",
+                condition
+            );
         } else {
             debug!(
                 "Document doesn't need reflow - skipping it (reason {:?})",