Store per-ScriptTask RootCollection in TLS and use that in favour of per-frame collections.

src/components/script/dom/bindings/js.rs

@@ -6,9 +6,11 @@ use dom::bindings::utils::{Reflector, Reflectable, cx_for_dom_object};
 use dom::window::Window;
 use js::jsapi::{JSObject, JSContext, JS_AddObjectRoot, JS_RemoveObjectRoot};
 use layout_interface::TrustedNodeAddress;
+use script_task::StackRoots;
 
 use std::cast;
 use std::cell::RefCell;
+use std::local_data;
 
 /// A type that represents a JS-owned value that is rooted for the lifetime of this value.
 /// Importantly, it requires explicit rooting in order to interact with the inner value.
@@ -52,8 +54,13 @@ impl<T: Reflectable> Temporary<T> {
     }
 
     /// Root this unrooted value.
-    pub fn root<'a, 'b>(self, collection: &'a RootCollection) -> Root<'a, 'b, T> {
-        collection.new_root(&self.inner)
+    pub fn root<'a, 'b>(self, _collection: &'a RootCollection) -> Root<'a, 'b, T> {
+        local_data::get(StackRoots, |opt| {
+            let collection = opt.unwrap();
+            unsafe {
+                (**collection).new_root(&self.inner)
+            }
+        })
     }
 
     unsafe fn inner(&self) -> JS<T> {

src/components/script/script_task.rs

@@ -55,6 +55,7 @@ use servo_util::namespace::Null;
 use std::cast;
 use std::cell::{RefCell, Ref, RefMut};
 use std::comm::{channel, Sender, Receiver, Empty, Disconnected, Data};
+use std::local_data;
 use std::mem::replace;
 use std::ptr;
 use std::rc::Rc;
@@ -63,6 +64,8 @@ use url::Url;
 
 use serialize::{Encoder, Encodable};
 
+local_data_key!(pub StackRoots: *RootCollection)
+
 /// Messages used to control the script task.
 pub enum ScriptMsg {
     /// Loads a new URL on the specified pipeline.
@@ -510,6 +513,21 @@ pub struct JSPageInfo {
     pub js_context: Untraceable<Rc<Cx>>,
 }
 
+struct StackRootTLS;
+
+impl StackRootTLS {
+    fn new(roots: &RootCollection) -> StackRootTLS {
+        local_data::set(StackRoots, roots as *RootCollection);
+        StackRootTLS
+    }
+}
+
+impl Drop for StackRootTLS {
+    fn drop(&mut self) {
+        let _ = local_data::pop(StackRoots);
+    }
+}
+
 /// Information for an entire page. Pages are top-level browsing contexts and can contain multiple
 /// frames.
 ///
@@ -653,6 +671,9 @@ impl ScriptTask {
 
     /// Handle incoming control messages.
     fn handle_msgs(&self) -> bool {
+        let roots = RootCollection::new();
+        let _stack_roots_tls = StackRootTLS::new(&roots);
+
         // Handle pending resize events.
         // Gather them first to avoid a double mut borrow on self.
         let mut resizes = vec!();