script: Reduce ScriptThread TLS usage (#38875)

We store a pointer to the ScriptThread singleton for a thread in
thread-local storage. While we don't have yet have profiles pointing to
this TLS access as a hot spot, we can remove a potential performance
footgun without a lot of effort by passing around small pieces of data
that we otherwise need to fetch from the ScriptThread.

Testing: Existing WPT is sufficient
Fixes: part of #37969

---------

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

components/script/dom/servoparser/async_html.rs

@@ -8,6 +8,7 @@ use std::borrow::Cow;
 use std::cell::{Cell, Ref, RefCell, RefMut};
 use std::collections::HashMap;
 use std::collections::vec_deque::VecDeque;
+use std::rc::Rc;
 use std::thread;
 
 use crossbeam_channel::{Receiver, Sender, unbounded};
@@ -29,6 +30,7 @@ use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::str::DOMString;
 use crate::dom::comment::Comment;
+use crate::dom::customelementregistry::CustomElementReactionStack;
 use crate::dom::document::Document;
 use crate::dom::documenttype::DocumentType;
 use crate::dom::element::{Element, ElementCreator};
@@ -228,6 +230,8 @@ pub(crate) struct Tokenizer {
     #[no_trace]
     url: ServoUrl,
     parsing_algorithm: ParsingAlgorithm,
+    #[conditional_malloc_size_of]
+    custom_element_reaction_stack: Rc<CustomElementReactionStack>,
 }
 
 impl Tokenizer {
@@ -246,6 +250,7 @@ impl Tokenizer {
             None => ParsingAlgorithm::Normal,
         };
 
+        let custom_element_reaction_stack = document.custom_element_reaction_stack();
         let tokenizer = Tokenizer {
             document: Dom::from_ref(document),
             receiver: tokenizer_receiver,
@@ -253,6 +258,7 @@ impl Tokenizer {
             nodes: RefCell::new(HashMap::new()),
             url,
             parsing_algorithm: algorithm,
+            custom_element_reaction_stack,
         };
         tokenizer.insert_node(0, Dom::from_ref(document.upcast()));
 
@@ -397,7 +403,14 @@ impl Tokenizer {
             .GetParentNode()
             .expect("append_before_sibling called on node without parent");
 
-        super::insert(parent, Some(sibling), node, self.parsing_algorithm, can_gc);
+        super::insert(
+            parent,
+            Some(sibling),
+            node,
+            self.parsing_algorithm,
+            &self.custom_element_reaction_stack,
+            can_gc,
+        );
     }
 
     fn append(&self, parent: ParseNodeId, node: NodeOrText, can_gc: CanGc) {
@@ -409,7 +422,14 @@ impl Tokenizer {
         };
 
         let parent = &**self.get_node(&parent);
-        super::insert(parent, None, node, self.parsing_algorithm, can_gc);
+        super::insert(
+            parent,
+            None,
+            node,
+            self.parsing_algorithm,
+            &self.custom_element_reaction_stack,
+            can_gc,
+        );
     }
 
     fn has_parent_node(&self, node: ParseNodeId) -> bool {
@@ -454,6 +474,7 @@ impl Tokenizer {
                     &self.document,
                     ElementCreator::ParserCreated(current_line),
                     ParsingAlgorithm::Normal,
+                    &self.custom_element_reaction_stack,
                     can_gc,
                 );
                 self.insert_node(node, Dom::from_ref(element.upcast()));

components/script/dom/servoparser/html.rs

@@ -52,12 +52,14 @@ impl Tokenizer {
         fragment_context: Option<super::FragmentContext>,
         parsing_algorithm: ParsingAlgorithm,
     ) -> Self {
+        let custom_element_reaction_stack = document.custom_element_reaction_stack();
         let sink = Sink {
             base_url: url,
             document: Dom::from_ref(document),
             current_line: Cell::new(1),
             script: Default::default(),
             parsing_algorithm,
+            custom_element_reaction_stack,
         };
 
         let quirks_mode = match document.quirks_mode() {

components/script/dom/servoparser/mod.rs

@@ -4,6 +4,7 @@
 
 use std::borrow::Cow;
 use std::cell::Cell;
+use std::rc::Rc;
 
 use base::cross_process_instant::CrossProcessInstant;
 use base::id::PipelineId;
@@ -57,6 +58,7 @@ use crate::dom::bindings::str::{DOMString, USVString};
 use crate::dom::characterdata::CharacterData;
 use crate::dom::comment::Comment;
 use crate::dom::csp::{CspReporting, GlobalCspReporting, Violation, parse_csp_list_from_metadata};
+use crate::dom::customelementregistry::CustomElementReactionStack;
 use crate::dom::document::{Document, DocumentSource, HasBrowsingContext, IsHTMLDocument};
 use crate::dom::documentfragment::DocumentFragment;
 use crate::dom::documenttype::DocumentType;
@@ -244,6 +246,7 @@ impl ServoParser {
             allow_declarative_shadow_roots,
             Some(context_document.insecure_requests_policy()),
             context_document.has_trustworthy_ancestor_or_current_origin(),
+            context_document.custom_element_reaction_stack(),
             can_gc,
         );
 
@@ -1156,6 +1159,7 @@ fn insert(
     reference_child: Option<&Node>,
     child: NodeOrText<Dom<Node>>,
     parsing_algorithm: ParsingAlgorithm,
+    custom_element_reaction_stack: &CustomElementReactionStack,
     can_gc: CanGc,
 ) {
     match child {
@@ -1166,11 +1170,11 @@ fn insert(
             let element_in_non_fragment =
                 parsing_algorithm != ParsingAlgorithm::Fragment && n.is::<Element>();
             if element_in_non_fragment {
-                ScriptThread::push_new_element_queue();
+                custom_element_reaction_stack.push_new_element_queue();
             }
             parent.InsertBefore(&n, reference_child, can_gc).unwrap();
             if element_in_non_fragment {
-                ScriptThread::pop_current_element_queue(can_gc);
+                custom_element_reaction_stack.pop_current_element_queue(can_gc);
             }
         },
         NodeOrText::AppendText(t) => {
@@ -1201,6 +1205,8 @@ pub(crate) struct Sink {
     current_line: Cell<u64>,
     script: MutNullableDom<HTMLScriptElement>,
     parsing_algorithm: ParsingAlgorithm,
+    #[conditional_malloc_size_of]
+    custom_element_reaction_stack: Rc<CustomElementReactionStack>,
 }
 
 impl Sink {
@@ -1278,6 +1284,7 @@ impl TreeSink for Sink {
             &self.document,
             ElementCreator::ParserCreated(self.current_line.get()),
             parsing_algorithm,
+            &self.custom_element_reaction_stack,
             CanGc::note(),
         );
         Dom::from_ref(element.upcast())
@@ -1347,6 +1354,7 @@ impl TreeSink for Sink {
             Some(sibling),
             new_node,
             self.parsing_algorithm,
+            &self.custom_element_reaction_stack,
             CanGc::note(),
         );
     }
@@ -1366,7 +1374,14 @@ impl TreeSink for Sink {
 
     #[cfg_attr(crown, allow(crown::unrooted_must_root))]
     fn append(&self, parent: &Dom<Node>, child: NodeOrText<Dom<Node>>) {
-        insert(parent, None, child, self.parsing_algorithm, CanGc::note());
+        insert(
+            parent,
+            None,
+            child,
+            self.parsing_algorithm,
+            &self.custom_element_reaction_stack,
+            CanGc::note(),
+        );
     }
 
     #[cfg_attr(crown, allow(crown::unrooted_must_root))]
@@ -1479,6 +1494,7 @@ fn create_element_for_token(
     document: &Document,
     creator: ElementCreator,
     parsing_algorithm: ParsingAlgorithm,
+    custom_element_reaction_stack: &CustomElementReactionStack,
     can_gc: CanGc,
 ) -> DomRoot<Element> {
     // Step 3.
@@ -1506,7 +1522,7 @@ fn create_element_for_token(
                 .perform_a_microtask_checkpoint(can_gc);
         }
         // Step 6.3
-        ScriptThread::push_new_element_queue()
+        custom_element_reaction_stack.push_new_element_queue()
     }
 
     // Step 7.
@@ -1544,7 +1560,7 @@ fn create_element_for_token(
     // Step 9.
     if will_execute_script {
         // Steps 9.1 - 9.2.
-        ScriptThread::pop_current_element_queue(can_gc);
+        custom_element_reaction_stack.pop_current_element_queue(can_gc);
         // Step 9.3.
         document.decrement_throw_on_dynamic_markup_insertion_counter();
     }

components/script/dom/servoparser/xml.rs

@@ -35,6 +35,7 @@ impl Tokenizer {
             current_line: Cell::new(1),
             script: Default::default(),
             parsing_algorithm: ParsingAlgorithm::Normal,
+            custom_element_reaction_stack: document.custom_element_reaction_stack(),
         };
 
         let tb = XmlTreeBuilder::new(sink, Default::default());