Rip out the generic abstractions around ThreadLocalStyleContext.

MozReview-Commit-ID: 5WTLuk323Ac

7 files changed, 52 insertions, 102 deletions

diff --git a/components/layout/context.rs b/components/layout/context.rs
index 22b407d1fb6..d261fe5d8a7 100644
--- a/components/layout/context.rs
+++ b/components/layout/context.rs
@@ -18,39 +18,12 @@ use script_layout_interface::{PendingImage, PendingImageState};
 use script_traits::PaintWorkletExecutor;
 use script_traits::UntrustedNodeAddress;
 use servo_url::ServoUrl;
-use std::borrow::{Borrow, BorrowMut};
 use std::cell::{RefCell, RefMut};
 use std::collections::HashMap;
 use std::hash::BuildHasherDefault;
 use std::sync::{Arc, Mutex};
 use std::thread;
-use style::context::{SharedStyleContext, ThreadLocalStyleContext};
-use style::dom::TElement;
-
-/// TLS data scoped to the traversal.
-pub struct ScopedThreadLocalLayoutContext<E: TElement> {
-    pub style_context: ThreadLocalStyleContext<E>,
-}
-
-impl<E: TElement> ScopedThreadLocalLayoutContext<E> {
-    pub fn new(context: &LayoutContext) -> Self {
-        ScopedThreadLocalLayoutContext {
-            style_context: ThreadLocalStyleContext::new(&context.style_context),
-        }
-    }
-}
-
-impl<E: TElement> Borrow<ThreadLocalStyleContext<E>> for ScopedThreadLocalLayoutContext<E> {
-    fn borrow(&self) -> &ThreadLocalStyleContext<E> {
-        &self.style_context
-    }
-}
-
-impl<E: TElement> BorrowMut<ThreadLocalStyleContext<E>> for ScopedThreadLocalLayoutContext<E> {
-    fn borrow_mut(&mut self) -> &mut ThreadLocalStyleContext<E> {
-        &mut self.style_context
-    }
-}
+use style::context::SharedStyleContext;
 
 thread_local!(static FONT_CONTEXT_KEY: RefCell<Option<FontContext>> = RefCell::new(None));
 
diff --git a/components/layout/traversal.rs b/components/layout/traversal.rs
index ab4f2c2f1b6..f011925ebb8 100644
--- a/components/layout/traversal.rs
+++ b/components/layout/traversal.rs
@@ -6,7 +6,7 @@
 
 use atomic_refcell::AtomicRefCell;
 use construct::FlowConstructor;
-use context::{LayoutContext, ScopedThreadLocalLayoutContext};
+use context::LayoutContext;
 use display_list_builder::DisplayListBuildState;
 use flow::{self, PreorderFlowTraversal};
 use flow::{CAN_BE_FRAGMENTED, Flow, ImmutableFlowUtils, PostorderFlowTraversal};
@@ -55,10 +55,8 @@ impl<'a, E> DomTraversal<E> for RecalcStyleAndConstructFlows<'a>
           E::ConcreteNode: LayoutNode,
           E::FontMetricsProvider: Send,
 {
-    type ThreadLocalContext = ScopedThreadLocalLayoutContext<E>;
-
     fn process_preorder(&self, traversal_data: &PerLevelTraversalData,
-                        thread_local: &mut Self::ThreadLocalContext, node: E::ConcreteNode) {
+                        context: &mut StyleContext<E>, node: E::ConcreteNode) {
         // FIXME(pcwalton): Stop allocating here. Ideally this should just be
         // done by the HTML parser.
         node.initialize_data();
@@ -66,16 +64,12 @@ impl<'a, E> DomTraversal<E> for RecalcStyleAndConstructFlows<'a>
         if !node.is_text_node() {
             let el = node.as_element().unwrap();
             let mut data = el.mutate_data().unwrap();
-            let mut context = StyleContext {
-                shared: &self.context.shared_context(),
-                thread_local: &mut thread_local.style_context,
-            };
-            recalc_style_at(self, traversal_data, &mut context, el, &mut data);
+            recalc_style_at(self, traversal_data, context, el, &mut data);
         }
     }
 
-    fn process_postorder(&self, thread_local: &mut Self::ThreadLocalContext, node: E::ConcreteNode) {
-        construct_flows_at(&self.context, thread_local, node);
+    fn process_postorder(&self, _style_context: &mut StyleContext<E>, node: E::ConcreteNode) {
+        construct_flows_at(&self.context, node);
     }
 
     fn text_node_needs_traversal(node: E::ConcreteNode) -> bool {
@@ -100,10 +94,6 @@ impl<'a, E> DomTraversal<E> for RecalcStyleAndConstructFlows<'a>
         &self.context.style_context
     }
 
-    fn create_thread_local_context(&self) -> Self::ThreadLocalContext {
-        ScopedThreadLocalLayoutContext::new(&self.context)
-    }
-
     fn is_parallel(&self) -> bool {
         self.driver.is_parallel()
     }
@@ -118,9 +108,7 @@ pub trait PostorderNodeMutTraversal<ConcreteThreadSafeLayoutNode: ThreadSafeLayo
 /// The flow construction traversal, which builds flows for styled nodes.
 #[inline]
 #[allow(unsafe_code)]
-fn construct_flows_at<N>(context: &LayoutContext,
-                             _thread_local: &mut ScopedThreadLocalLayoutContext<N::ConcreteElement>,
-                             node: N)
+fn construct_flows_at<N>(context: &LayoutContext, node: N)
     where N: LayoutNode,
 {
     debug!("construct_flows_at: {:?}", node);
diff --git a/components/style/dom.rs b/components/style/dom.rs
index 7d8112a0554..ac5d051e865 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -296,7 +296,7 @@ pub trait TElement : Eq + PartialEq + Debug + Hash + Sized + Copy + Clone +
     ///
     /// XXXManishearth It would be better to make this a type parameter on
     /// ThreadLocalStyleContext and StyleContext
-    type FontMetricsProvider: FontMetricsProvider;
+    type FontMetricsProvider: FontMetricsProvider + Send;
 
     /// Get this element as a node.
     fn as_node(&self) -> Self::ConcreteNode;
diff --git a/components/style/gecko/traversal.rs b/components/style/gecko/traversal.rs
index eb7f52ad269..35683ba08e3 100644
--- a/components/style/gecko/traversal.rs
+++ b/components/style/gecko/traversal.rs
@@ -5,7 +5,7 @@
 //! Gecko-specific bits for the styling DOM traversal.
 
 use atomic_refcell::AtomicRefCell;
-use context::{SharedStyleContext, StyleContext, ThreadLocalStyleContext};
+use context::{SharedStyleContext, StyleContext};
 use data::ElementData;
 use dom::{NodeInfo, TNode};
 use gecko::wrapper::{GeckoElement, GeckoNode};
@@ -29,25 +29,19 @@ impl<'a> RecalcStyleOnly<'a> {
 }
 
 impl<'recalc, 'le> DomTraversal<GeckoElement<'le>> for RecalcStyleOnly<'recalc> {
-    type ThreadLocalContext = ThreadLocalStyleContext<GeckoElement<'le>>;
-
     fn process_preorder(&self,
                         traversal_data: &PerLevelTraversalData,
-                        thread_local: &mut Self::ThreadLocalContext,
+                        context: &mut StyleContext<GeckoElement<'le>>,
                         node: GeckoNode<'le>)
     {
         if node.is_element() {
             let el = node.as_element().unwrap();
             let mut data = unsafe { el.ensure_data() }.borrow_mut();
-            let mut context = StyleContext {
-                shared: &self.shared,
-                thread_local: thread_local,
-            };
-            recalc_style_at(self, traversal_data, &mut context, el, &mut data);
+            recalc_style_at(self, traversal_data, context, el, &mut data);
         }
     }
 
-    fn process_postorder(&self, _: &mut Self::ThreadLocalContext, _: GeckoNode<'le>) {
+    fn process_postorder(&self, _: &mut StyleContext<GeckoElement<'le>>, _: GeckoNode<'le>) {
         unreachable!();
     }
 
@@ -66,10 +60,6 @@ impl<'recalc, 'le> DomTraversal<GeckoElement<'le>> for RecalcStyleOnly<'recalc>
         &self.shared
     }
 
-    fn create_thread_local_context(&self) -> Self::ThreadLocalContext {
-        ThreadLocalStyleContext::new(&self.shared)
-    }
-
     fn is_parallel(&self) -> bool {
         self.driver.is_parallel()
     }
diff --git a/components/style/parallel.rs b/components/style/parallel.rs
index 0526c07f94c..dd7072a201e 100644
--- a/components/style/parallel.rs
+++ b/components/style/parallel.rs
@@ -23,7 +23,7 @@
 #![deny(missing_docs)]
 
 use arrayvec::ArrayVec;
-use context::TraversalStatistics;
+use context::{StyleContext, ThreadLocalStyleContext, TraversalStatistics};
 use dom::{OpaqueNode, SendNode, TElement, TNode};
 use rayon;
 use scoped_tls::ScopedTLS;
@@ -84,7 +84,7 @@ pub fn traverse_dom<E, D>(traversal: &D,
     let traversal_data = PerLevelTraversalData {
         current_dom_depth: depth,
     };
-    let tls = ScopedTLS::<D::ThreadLocalContext>::new(pool);
+    let tls = ScopedTLS::<ThreadLocalStyleContext<E>>::new(pool);
     let root = root.as_node().opaque();
 
     pool.install(|| {
@@ -124,11 +124,11 @@ pub fn traverse_dom<E, D>(traversal: &D,
 #[inline(never)]
 fn create_thread_local_context<'scope, E, D>(
     traversal: &'scope D,
-    slot: &mut Option<D::ThreadLocalContext>)
+    slot: &mut Option<ThreadLocalStyleContext<E>>)
     where E: TElement + 'scope,
           D: DomTraversal<E>
 {
-    *slot = Some(traversal.create_thread_local_context())
+    *slot = Some(ThreadLocalStyleContext::new(traversal.shared_context()));
 }
 
 /// A parallel top-down DOM traversal.
@@ -152,7 +152,7 @@ fn top_down_dom<'a, 'scope, E, D>(nodes: &'a [SendNode<E::ConcreteNode>],
                                   scope: &'a rayon::Scope<'scope>,
                                   pool: &'scope rayon::ThreadPool,
                                   traversal: &'scope D,
-                                  tls: &'scope ScopedTLS<'scope, D::ThreadLocalContext>)
+                                  tls: &'scope ScopedTLS<'scope, ThreadLocalStyleContext<E>>)
     where E: TElement + 'scope,
           D: DomTraversal<E>,
 {
@@ -167,7 +167,11 @@ fn top_down_dom<'a, 'scope, E, D>(nodes: &'a [SendNode<E::ConcreteNode>],
         // Scope the borrow of the TLS so that the borrow is dropped before
         // a potential recursive call when we pass TailCall.
         let mut tlc = tls.ensure(
-            |slot: &mut Option<D::ThreadLocalContext>| create_thread_local_context(traversal, slot));
+            |slot: &mut Option<ThreadLocalStyleContext<E>>| create_thread_local_context(traversal, slot));
+        let mut context = StyleContext {
+            shared: traversal.shared_context(),
+            thread_local: &mut *tlc,
+        };
 
         for n in nodes {
             // If the last node we processed produced children, spawn them off
@@ -199,15 +203,15 @@ fn top_down_dom<'a, 'scope, E, D>(nodes: &'a [SendNode<E::ConcreteNode>],
 
             let node = **n;
             let mut children_to_process = 0isize;
-            traversal.process_preorder(&traversal_data, &mut *tlc, node);
+            traversal.process_preorder(&traversal_data, &mut context, node);
             if let Some(el) = node.as_element() {
-                traversal.traverse_children(&mut *tlc, el, |_tlc, kid| {
+                traversal.traverse_children(&mut context, el, |_context, kid| {
                     children_to_process += 1;
                     discovered_child_nodes.push(unsafe { SendNode::new(kid) })
                 });
             }
 
-            traversal.handle_postorder_traversal(&mut *tlc, root, node,
+            traversal.handle_postorder_traversal(&mut context, root, node,
                                                  children_to_process);
         }
     }
@@ -256,7 +260,7 @@ fn traverse_nodes<'a, 'scope, E, D>(nodes: &[SendNode<E::ConcreteNode>],
                                     scope: &'a rayon::Scope<'scope>,
                                     pool: &'scope rayon::ThreadPool,
                                     traversal: &'scope D,
-                                    tls: &'scope ScopedTLS<'scope, D::ThreadLocalContext>)
+                                    tls: &'scope ScopedTLS<'scope, ThreadLocalStyleContext<E>>)
     where E: TElement + 'scope,
           D: DomTraversal<E>,
 {
diff --git a/components/style/sequential.rs b/components/style/sequential.rs
index f2fa63c95f3..49bb3bb0c4f 100644
--- a/components/style/sequential.rs
+++ b/components/style/sequential.rs
@@ -6,8 +6,8 @@
 
 #![deny(missing_docs)]
 
+use context::{StyleContext, ThreadLocalStyleContext};
 use dom::{TElement, TNode};
-use std::borrow::BorrowMut;
 use std::collections::VecDeque;
 use time;
 use traversal::{DomTraversal, PerLevelTraversalData, PreTraverseToken};
@@ -28,7 +28,12 @@ pub fn traverse_dom<E, D>(traversal: &D,
     debug_assert!(token.should_traverse());
 
     let mut discovered = VecDeque::<WorkItem<E::ConcreteNode>>::with_capacity(16);
-    let mut tlc = traversal.create_thread_local_context();
+    let mut tlc = ThreadLocalStyleContext::new(traversal.shared_context());
+    let mut context = StyleContext {
+        shared: traversal.shared_context(),
+        thread_local: &mut tlc,
+    };
+
     let root_depth = root.depth();
 
     if token.traverse_unstyled_children_only() {
@@ -47,25 +52,24 @@ pub fn traverse_dom<E, D>(traversal: &D,
     while let Some(WorkItem(node, depth)) = discovered.pop_front() {
         let mut children_to_process = 0isize;
         let traversal_data = PerLevelTraversalData { current_dom_depth: depth };
-        traversal.process_preorder(&traversal_data, &mut tlc, node);
+        traversal.process_preorder(&traversal_data, &mut context, node);
 
         if let Some(el) = node.as_element() {
-            traversal.traverse_children(&mut tlc, el, |_tlc, kid| {
+            traversal.traverse_children(&mut context, el, |_context, kid| {
                 children_to_process += 1;
                 discovered.push_back(WorkItem(kid, depth + 1))
             });
         }
 
-        traversal.handle_postorder_traversal(&mut tlc, root.as_node().opaque(),
+        traversal.handle_postorder_traversal(&mut context, root.as_node().opaque(),
                                              node, children_to_process);
     }
 
     // Dump statistics to stdout if requested.
     if dump_stats {
-        let tlsc = tlc.borrow_mut();
-        tlsc.statistics.finish(traversal, start_time.unwrap());
-        if tlsc.statistics.is_large_traversal() {
-            println!("{}", tlsc.statistics);
+        context.thread_local.statistics.finish(traversal, start_time.unwrap());
+        if context.thread_local.statistics.is_large_traversal() {
+            println!("{}", context.thread_local.statistics);
         }
     }
 }
diff --git a/components/style/traversal.rs b/components/style/traversal.rs
index ddb82e0950f..47203980fc5 100644
--- a/components/style/traversal.rs
+++ b/components/style/traversal.rs
@@ -5,7 +5,7 @@
 //! Traversing the DOM tree; the bloom filter.
 
 use atomic_refcell::AtomicRefCell;
-use context::{ElementCascadeInputs, StyleContext, SharedStyleContext, ThreadLocalStyleContext};
+use context::{ElementCascadeInputs, StyleContext, SharedStyleContext};
 use data::{ElementData, ElementStyles};
 use dom::{DirtyDescendants, NodeInfo, OpaqueNode, TElement, TNode};
 use invalidation::element::restyle_hints::{RECASCADE_SELF, RECASCADE_DESCENDANTS, RestyleHint};
@@ -13,7 +13,6 @@ use matching::{ChildCascadeRequirement, MatchMethods};
 use sharing::{StyleSharingBehavior, StyleSharingTarget};
 #[cfg(feature = "servo")] use servo_config::opts;
 use smallvec::SmallVec;
-use std::borrow::BorrowMut;
 
 /// A per-traversal-level chunk of data. This is sent down by the traversal, and
 /// currently only holds the dom depth for the bloom filter.
@@ -138,22 +137,17 @@ fn is_servo_nonincremental_layout() -> bool {
 /// A DOM Traversal trait, that is used to generically implement styling for
 /// Gecko and Servo.
 pub trait DomTraversal<E: TElement> : Sync {
-    /// The thread-local context, used to store non-thread-safe stuff that needs
-    /// to be used in the traversal, and of which we use one per worker, like
-    /// the bloom filter, for example.
-    type ThreadLocalContext: Send + BorrowMut<ThreadLocalStyleContext<E>>;
-
     /// Process `node` on the way down, before its children have been processed.
     fn process_preorder(&self,
                         data: &PerLevelTraversalData,
-                        thread_local: &mut Self::ThreadLocalContext,
+                        context: &mut StyleContext<E>,
                         node: E::ConcreteNode);
 
     /// Process `node` on the way up, after its children have been processed.
     ///
     /// This is only executed if `needs_postorder_traversal` returns true.
     fn process_postorder(&self,
-                         thread_local: &mut Self::ThreadLocalContext,
+                         contect: &mut StyleContext<E>,
                          node: E::ConcreteNode);
 
     /// Boolean that specifies whether a bottom up traversal should be
@@ -177,7 +171,7 @@ pub trait DomTraversal<E: TElement> : Sync {
     /// call durign the parallel traversal.
     fn handle_postorder_traversal(
         &self,
-        thread_local: &mut Self::ThreadLocalContext,
+        context: &mut StyleContext<E>,
         root: OpaqueNode,
         mut node: E::ConcreteNode,
         children_to_process: isize
@@ -190,7 +184,7 @@ pub trait DomTraversal<E: TElement> : Sync {
         if children_to_process == 0 {
             // We are a leaf. Walk up the chain.
             loop {
-                self.process_postorder(thread_local, node);
+                self.process_postorder(context, node);
                 if node.opaque() == root {
                     break;
                 }
@@ -404,7 +398,7 @@ pub trait DomTraversal<E: TElement> : Sync {
     /// a parameter to keep the logs tidy.
     fn should_traverse_children(
         &self,
-        thread_local: &mut ThreadLocalStyleContext<E>,
+        context: &mut StyleContext<E>,
         parent: E,
         parent_data: &ElementData,
         log: LogBehavior
@@ -442,7 +436,7 @@ pub trait DomTraversal<E: TElement> : Sync {
         // happens, we may just end up doing wasted work, since Gecko
         // recursively drops Servo ElementData when the XBL insertion parent of
         // an Element is changed.
-        if cfg!(feature = "gecko") && thread_local.is_initial_style() &&
+        if cfg!(feature = "gecko") && context.thread_local.is_initial_style() &&
            parent_data.styles.primary().has_moz_binding() {
             if log.allow() {
                 debug!("Parent {:?} has XBL binding, deferring traversal",
@@ -458,23 +452,23 @@ pub trait DomTraversal<E: TElement> : Sync {
     /// should be enqueued for processing.
     fn traverse_children<F>(
         &self,
-        thread_local: &mut Self::ThreadLocalContext,
+        context: &mut StyleContext<E>,
         parent: E,
         mut f: F
     )
     where
-        F: FnMut(&mut Self::ThreadLocalContext, E::ConcreteNode)
+        F: FnMut(&mut StyleContext<E>, E::ConcreteNode)
     {
         // Check if we're allowed to traverse past this element.
         let should_traverse =
             self.should_traverse_children(
-                thread_local.borrow_mut(),
+                context,
                 parent,
                 &parent.borrow_data().unwrap(),
                 MayLog
             );
 
-        thread_local.borrow_mut().end_element(parent);
+        context.thread_local.end_element(parent);
         if !should_traverse {
             return;
         }
@@ -495,7 +489,7 @@ pub trait DomTraversal<E: TElement> : Sync {
                         }
                     }
                 }
-                f(thread_local, kid);
+                f(context, kid);
             }
         }
     }
@@ -517,9 +511,6 @@ pub trait DomTraversal<E: TElement> : Sync {
     /// Return the shared style context common to all worker threads.
     fn shared_context(&self) -> &SharedStyleContext;
 
-    /// Creates a thread-local context.
-    fn create_thread_local_context(&self) -> Self::ThreadLocalContext;
-
     /// Whether we're performing a parallel traversal.
     ///
     /// NB: We do this check on runtime. We could guarantee correctness in this
@@ -763,7 +754,7 @@ where
     // Preprocess children, propagating restyle hints and handling sibling
     // relationships.
     let should_traverse_children = traversal.should_traverse_children(
-        &mut context.thread_local,
+        context,
         element,
         &data,
         DontLog