Make DOM own the style and layout data, in an UnsafeCell

The previous Cell was a lie.

2 files changed, 16 insertions, 29 deletions

diff --git a/components/layout_thread/dom_wrapper.rs b/components/layout_thread/dom_wrapper.rs
index 381a0cfa77d..cbd0df1f9a4 100644
--- a/components/layout_thread/dom_wrapper.rs
+++ b/components/layout_thread/dom_wrapper.rs
@@ -91,10 +91,6 @@ use style::str::is_whitespace;
 use style::stylist::CascadeData;
 use style::CaseSensitivityExt;
 
-pub unsafe fn drop_style_and_layout_data(data: OpaqueStyleAndLayoutData) {
-    drop(Box::from_raw(data.as_ptr()));
-}
-
 #[derive(Clone, Copy)]
 pub struct ServoLayoutNode<'dom> {
     /// The wrapped node.
@@ -234,7 +230,7 @@ impl<'ln> TNode for ServoLayoutNode<'ln> {
     }
 
     fn opaque(&self) -> OpaqueNode {
-        unsafe { self.get_jsmanaged().opaque() }
+        self.get_jsmanaged().opaque()
     }
 
     fn debug_id(self) -> usize {
@@ -291,34 +287,33 @@ impl<'ln> LayoutNode<'ln> for ServoLayoutNode<'ln> {
     }
 }
 
-impl<'ln> GetLayoutData<'ln> for ServoLayoutNode<'ln> {
-    fn get_style_and_layout_data(&self) -> Option<OpaqueStyleAndLayoutData> {
-        unsafe { self.get_jsmanaged().get_style_and_layout_data() }
+impl<'dom> GetLayoutData<'dom> for ServoLayoutNode<'dom> {
+    fn get_style_and_layout_data(self) -> Option<&'dom OpaqueStyleAndLayoutData> {
+        self.get_jsmanaged().get_style_and_layout_data()
     }
 }
 
-impl<'le> GetLayoutData<'le> for ServoLayoutElement<'le> {
-    fn get_style_and_layout_data(&self) -> Option<OpaqueStyleAndLayoutData> {
+impl<'dom> GetLayoutData<'dom> for ServoLayoutElement<'dom> {
+    fn get_style_and_layout_data(self) -> Option<&'dom OpaqueStyleAndLayoutData> {
         self.as_node().get_style_and_layout_data()
     }
 }
 
-impl<'ln> GetLayoutData<'ln> for ServoThreadSafeLayoutNode<'ln> {
-    fn get_style_and_layout_data(&self) -> Option<OpaqueStyleAndLayoutData> {
+impl<'dom> GetLayoutData<'dom> for ServoThreadSafeLayoutNode<'dom> {
+    fn get_style_and_layout_data(self) -> Option<&'dom OpaqueStyleAndLayoutData> {
         self.node.get_style_and_layout_data()
     }
 }
 
-impl<'le> GetLayoutData<'le> for ServoThreadSafeLayoutElement<'le> {
-    fn get_style_and_layout_data(&self) -> Option<OpaqueStyleAndLayoutData> {
+impl<'dom> GetLayoutData<'dom> for ServoThreadSafeLayoutElement<'dom> {
+    fn get_style_and_layout_data(self) -> Option<&'dom OpaqueStyleAndLayoutData> {
         self.element.as_node().get_style_and_layout_data()
     }
 }
 
-impl<'ln> ServoLayoutNode<'ln> {
-    /// Returns the interior of this node as a `LayoutDom`. This is highly unsafe for layout to
-    /// call and as such is marked `unsafe`.
-    pub unsafe fn get_jsmanaged(&self) -> LayoutDom<'ln, Node> {
+impl<'dom> ServoLayoutNode<'dom> {
+    /// Returns the interior of this node as a `LayoutDom`.
+    pub fn get_jsmanaged(self) -> LayoutDom<'dom, Node> {
         self.node
     }
 }
@@ -542,7 +537,7 @@ impl<'le> TElement for ServoLayoutElement<'le> {
 
     unsafe fn clear_data(&self) {
         if self.get_raw_data().is_some() {
-            drop_style_and_layout_data(self.as_node().take_style_and_layout_data());
+            drop(self.as_node().take_style_and_layout_data());
         }
     }
 
@@ -700,7 +695,7 @@ impl<'le> ServoLayoutElement<'le> {
     }
 
     fn get_style_data(&self) -> Option<&StyleData> {
-        self.get_style_and_layout_data().map(|opaque| unsafe {
+        self.get_style_and_layout_data().map(|opaque| {
             &opaque
                 .downcast_ref::<StyleAndLayoutData>()
                 .unwrap()
@@ -1065,7 +1060,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> for ServoThreadSafeLayoutNode<'ln> {
             })
     }
 
-    fn get_style_and_layout_data(&self) -> Option<OpaqueStyleAndLayoutData> {
+    fn get_style_and_layout_data(self) -> Option<&'ln OpaqueStyleAndLayoutData> {
         self.node.get_style_and_layout_data()
     }
 
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 2e50a2f7764..4c458065986 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -23,7 +23,6 @@ extern crate profile_traits;
 
 mod dom_wrapper;
 
-use crate::dom_wrapper::drop_style_and_layout_data;
 use crate::dom_wrapper::{ServoLayoutDocument, ServoLayoutElement, ServoLayoutNode};
 use app_units::Au;
 use crossbeam_channel::{unbounded, Receiver, Sender};
@@ -692,7 +691,6 @@ impl LayoutThread {
             Msg::GetRPC(..) => LayoutHangAnnotation::GetRPC,
             Msg::TickAnimations(..) => LayoutHangAnnotation::TickAnimations,
             Msg::AdvanceClockMs(..) => LayoutHangAnnotation::AdvanceClockMs,
-            Msg::ReapStyleAndLayoutData(..) => LayoutHangAnnotation::ReapStyleAndLayoutData,
             Msg::CollectReports(..) => LayoutHangAnnotation::CollectReports,
             Msg::PrepareToExit(..) => LayoutHangAnnotation::PrepareToExit,
             Msg::ExitNow => LayoutHangAnnotation::ExitNow,
@@ -833,9 +831,6 @@ impl LayoutThread {
                     webrender_api::ScrollClamping::ToContentBounds,
                 );
             },
-            Msg::ReapStyleAndLayoutData(dead_data) => unsafe {
-                drop_style_and_layout_data(dead_data)
-            },
             Msg::CollectReports(reports_chan) => {
                 self.collect_reports(reports_chan, possibly_locked_rw_data);
             },
@@ -967,9 +962,6 @@ impl LayoutThread {
         response_chan.send(()).unwrap();
         loop {
             match self.port.recv().unwrap() {
-                Msg::ReapStyleAndLayoutData(dead_data) => unsafe {
-                    drop_style_and_layout_data(dead_data)
-                },
                 Msg::ExitNow => {
                     debug!("layout thread is exiting...");
                     self.exit_now();