Reintroduce parent runtimes for worker threads.

components/script/dom/dedicatedworkerglobalscope.rs

@@ -23,7 +23,7 @@ use crate::dom::messageevent::MessageEvent;
 use crate::dom::worker::{TrustedWorkerAddress, Worker};
 use crate::dom::workerglobalscope::WorkerGlobalScope;
 use crate::script_runtime::ScriptThreadEventCategory::WorkerEvent;
-use crate::script_runtime::{new_rt_and_cx, CommonScriptMsg, Runtime, ScriptChan, ScriptPort};
+use crate::script_runtime::{new_child_runtime, CommonScriptMsg, Runtime, ScriptChan, ScriptPort};
 use crate::task_queue::{QueuedTask, QueuedTaskConversion, TaskQueue};
 use crate::task_source::TaskSourceName;
 use crossbeam_channel::{unbounded, Receiver, Sender};
@@ -272,11 +272,9 @@ impl DedicatedWorkerGlobalScope {
         let serialized_worker_url = worker_url.to_string();
         let name = format!("WebWorker for {}", serialized_worker_url);
         let top_level_browsing_context_id = TopLevelBrowsingContextId::installed();
-        let origin = GlobalScope::current()
-            .expect("No current global object")
-            .origin()
-            .immutable()
-            .clone();
+        let current_global = GlobalScope::current().expect("No current global object");
+        let origin = current_global.origin().immutable().clone();
+        let parent = current_global.runtime_handle();
 
         thread::Builder::new()
             .name(name)
@@ -327,7 +325,7 @@ impl DedicatedWorkerGlobalScope {
                 let url = metadata.final_url;
                 let source = String::from_utf8_lossy(&bytes);
 
-                let runtime = unsafe { new_rt_and_cx() };
+                let runtime = unsafe { new_child_runtime(parent) };
 
                 let (devtools_mpsc_chan, devtools_mpsc_port) = unbounded();
                 ROUTER.route_ipc_receiver_to_crossbeam_sender(

components/script/dom/globalscope.rs

@@ -47,7 +47,7 @@ use js::jsapi::{HandleObject, Heap};
 use js::jsapi::{JSAutoCompartment, JSContext};
 use js::panic::maybe_resume_unwind;
 use js::rust::wrappers::Evaluate2;
-use js::rust::{get_object_class, CompileOptionsWrapper, Runtime};
+use js::rust::{get_object_class, CompileOptionsWrapper, ParentRuntime, Runtime};
 use js::rust::{HandleValue, MutableHandleValue};
 use js::{JSCLASS_IS_DOMJSCLASS, JSCLASS_IS_GLOBAL};
 use msg::constellation_msg::PipelineId;
@@ -711,6 +711,16 @@ impl GlobalScope {
         unreachable!();
     }
 
+    pub fn runtime_handle(&self) -> ParentRuntime {
+        if self.is::<Window>() {
+            ScriptThread::runtime_handle()
+        } else if let Some(worker) = self.downcast::<WorkerGlobalScope>() {
+            worker.runtime_handle()
+        } else {
+            unreachable!()
+        }
+    }
+
     /// Returns the ["current"] global object.
     ///
     /// ["current"]: https://html.spec.whatwg.org/multipage/#current

components/script/dom/serviceworkerglobalscope.rs

@@ -292,7 +292,7 @@ impl ServiceWorkerGlobalScope {
                         },
                     };
 
-                let runtime = unsafe { new_rt_and_cx() };
+                let runtime = new_rt_and_cx();
 
                 let (devtools_mpsc_chan, devtools_mpsc_port) = unbounded();
                 ROUTER

components/script/dom/workerglobalscope.rs

@@ -39,7 +39,7 @@ use ipc_channel::ipc::IpcSender;
 use js::jsapi::{JSAutoCompartment, JSContext};
 use js::jsval::UndefinedValue;
 use js::panic::maybe_resume_unwind;
-use js::rust::HandleValue;
+use js::rust::{HandleValue, ParentRuntime};
 use msg::constellation_msg::PipelineId;
 use net_traits::request::{CredentialsMode, Destination, RequestInit as NetRequestInit};
 use net_traits::{load_whole_resource, IpcSend};
@@ -135,6 +135,10 @@ impl WorkerGlobalScope {
         }
     }
 
+    pub fn runtime_handle(&self) -> ParentRuntime {
+        self.runtime.prepare_for_new_child()
+    }
+
     pub fn from_devtools_sender(&self) -> Option<IpcSender<DevtoolScriptControlMsg>> {
         self.from_devtools_sender.clone()
     }

components/script/dom/worklet.rs

@@ -470,7 +470,7 @@ impl WorkletThread {
                 global_init: init.global_init,
                 global_scopes: HashMap::new(),
                 control_buffer: None,
-                runtime: unsafe { new_rt_and_cx() },
+                runtime: new_rt_and_cx(),
                 should_gc: false,
                 gc_threshold: MIN_GC_THRESHOLD,
             });

components/script/script_runtime.rs

@@ -43,6 +43,7 @@ use js::rust::wrappers::{GetPromiseIsHandled, GetPromiseResult};
 use js::rust::Handle;
 use js::rust::IntoHandle;
 use js::rust::JSEngine;
+use js::rust::ParentRuntime;
 use js::rust::Runtime as RustRuntime;
 use malloc_size_of::MallocSizeOfOps;
 use msg::constellation_msg::PipelineId;
@@ -329,9 +330,23 @@ lazy_static! {
 }
 
 #[allow(unsafe_code)]
-pub unsafe fn new_rt_and_cx() -> Runtime {
+pub unsafe fn new_child_runtime(parent: ParentRuntime) -> Runtime {
+    new_rt_and_cx_with_parent(Some(parent))
+}
+
+#[allow(unsafe_code)]
+pub fn new_rt_and_cx() -> Runtime {
+    unsafe { new_rt_and_cx_with_parent(None) }
+}
+
+#[allow(unsafe_code)]
+unsafe fn new_rt_and_cx_with_parent(parent: Option<ParentRuntime>) -> Runtime {
     LiveDOMReferences::initialize();
-    let runtime = RustRuntime::new(JS_ENGINE.clone());
+    let runtime = if let Some(parent) = parent {
+        RustRuntime::create_with_parent(parent)
+    } else {
+        RustRuntime::new(JS_ENGINE.clone())
+    };
     let cx = runtime.cx();
 
     JS_AddExtraGCRootsTracer(cx, Some(trace_rust_roots), ptr::null_mut());

components/script/script_thread.rs

@@ -100,6 +100,7 @@ use js::glue::GetWindowProxyClass;
 use js::jsapi::{JSAutoCompartment, JSContext, JS_SetWrapObjectCallbacks};
 use js::jsapi::{JSTracer, SetWindowProxyClass};
 use js::jsval::UndefinedValue;
+use js::rust::ParentRuntime;
 use metrics::{PaintTimeMetrics, MAX_TASK_NS};
 use mime::{self, Mime};
 use msg::constellation_msg::{
@@ -725,6 +726,13 @@ impl ScriptThreadFactory for ScriptThread {
 }
 
 impl ScriptThread {
+    pub fn runtime_handle() -> ParentRuntime {
+        SCRIPT_THREAD_ROOT.with(|root| {
+            let script_thread = unsafe { &*root.get().unwrap() };
+            script_thread.js_runtime.prepare_for_new_child()
+        })
+    }
+
     pub unsafe fn note_newly_transitioning_nodes(nodes: Vec<UntrustedNodeAddress>) {
         SCRIPT_THREAD_ROOT.with(|root| {
             let script_thread = &*root.get().unwrap();
@@ -1009,7 +1017,7 @@ impl ScriptThread {
         port: Receiver<MainThreadScriptMsg>,
         chan: Sender<MainThreadScriptMsg>,
     ) -> ScriptThread {
-        let runtime = unsafe { new_rt_and_cx() };
+        let runtime = new_rt_and_cx();
         let cx = runtime.cx();
 
         unsafe {