Store a pointer to the Worker in the DedicatedWorkerGlobalScope.

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

@@ -48,6 +48,7 @@
 use dom::bindings::utils::{Reflector, Reflectable};
 use dom::node::Node;
 use dom::xmlhttprequest::{XMLHttpRequest, TrustedXHRAddress};
+use dom::worker::{Worker, TrustedWorkerAddress};
 use js::jsapi::JSObject;
 use layout_interface::TrustedNodeAddress;
 use script_task::StackRoots;
@@ -143,6 +144,15 @@ impl JS<XMLHttpRequest> {
     }
 }
 
+impl JS<Worker> {
+    pub unsafe fn from_trusted_worker_address(inner: TrustedWorkerAddress) -> JS<Worker> {
+        let TrustedWorkerAddress(addr) = inner;
+        JS {
+            ptr: addr as *const Worker
+        }
+    }
+}
+
 impl<T: Reflectable> JS<T> {
     /// Create a new JS-owned value wrapped from a raw Rust pointer.
     pub unsafe fn from_raw(raw: *const T) -> JS<T> {

src/components/script/dom/dedicatedworkerglobalscope.rs

@@ -12,10 +12,12 @@ use dom::bindings::utils::{Reflectable, Reflector};
 use dom::eventtarget::EventTarget;
 use dom::eventtarget::WorkerGlobalScopeTypeId;
 use dom::messageevent::MessageEvent;
+use dom::worker::{Worker, TrustedWorkerAddress};
 use dom::workerglobalscope::DedicatedGlobalScope;
 use dom::workerglobalscope::WorkerGlobalScope;
 use dom::xmlhttprequest::XMLHttpRequest;
-use script_task::{ScriptTask, ScriptChan, ScriptMsg, DOMMessage, XHRProgressMsg};
+use script_task::{ScriptTask, ScriptChan};
+use script_task::{ScriptMsg, DOMMessage, XHRProgressMsg, WorkerRelease};
 use script_task::StackRootTLS;
 
 use servo_net::resource_task::{ResourceTask, load_whole_resource};
@@ -31,10 +33,12 @@ use url::Url;
 pub struct DedicatedWorkerGlobalScope {
     workerglobalscope: WorkerGlobalScope,
     receiver: Untraceable<Receiver<ScriptMsg>>,
+    worker: Untraceable<TrustedWorkerAddress>,
 }
 
 impl DedicatedWorkerGlobalScope {
     pub fn new_inherited(worker_url: Url,
+                         worker: TrustedWorkerAddress,
                          cx: Rc<Cx>,
                          receiver: Receiver<ScriptMsg>,
                          resource_task: ResourceTask,
@@ -45,23 +49,27 @@ impl DedicatedWorkerGlobalScope {
                 DedicatedGlobalScope, worker_url, cx, resource_task,
                 script_chan),
             receiver: Untraceable::new(receiver),
+            worker: Untraceable::new(worker),
         }
     }
 
     pub fn new(worker_url: Url,
+               worker: TrustedWorkerAddress,
                cx: Rc<Cx>,
                receiver: Receiver<ScriptMsg>,
                resource_task: ResourceTask,
                script_chan: ScriptChan)
                -> Temporary<DedicatedWorkerGlobalScope> {
         let scope = box DedicatedWorkerGlobalScope::new_inherited(
-            worker_url, cx.clone(), receiver, resource_task, script_chan);
+            worker_url, worker, cx.clone(), receiver, resource_task,
+            script_chan);
         DedicatedWorkerGlobalScopeBinding::Wrap(cx.ptr, scope)
     }
 }
 
 impl DedicatedWorkerGlobalScope {
     pub fn run_worker_scope(worker_url: Url,
+                            worker: TrustedWorkerAddress,
                             resource_task: ResourceTask,
                             receiver: Receiver<ScriptMsg>,
                             sender: ScriptChan) {
@@ -84,13 +92,14 @@ impl DedicatedWorkerGlobalScope {
 
             let (_js_runtime, js_context) = ScriptTask::new_rt_and_cx();
             let global = DedicatedWorkerGlobalScope::new(
-                worker_url, js_context.clone(), receiver, resource_task,
+                worker_url, worker, js_context.clone(), receiver, resource_task,
                 sender).root();
             match js_context.evaluate_script(
                 global.reflector().get_jsobject(), source, url.serialize(), 1) {
                 Ok(_) => (),
                 Err(_) => println!("evaluate_script failed")
             }
+            global.delayed_release_worker();
 
             let scope: &JSRef<WorkerGlobalScope> =
                 WorkerGlobalScopeCast::from_ref(&*global);
@@ -99,11 +108,15 @@ impl DedicatedWorkerGlobalScope {
             loop {
                 match global.receiver.recv_opt() {
                     Ok(DOMMessage(message)) => {
-                        MessageEvent::dispatch(target, &Worker(*scope), message)
+                        MessageEvent::dispatch(target, &Worker(*scope), message);
+                        global.delayed_release_worker();
                     },
                     Ok(XHRProgressMsg(addr, progress)) => {
                         XMLHttpRequest::handle_xhr_progress(addr, progress)
                     },
+                    Ok(WorkerRelease(addr)) => {
+                        Worker::handle_release(addr)
+                    },
                     Ok(_) => fail!("Unexpected message"),
                     Err(_) => break,
                 }
@@ -115,6 +128,19 @@ impl DedicatedWorkerGlobalScope {
 pub trait DedicatedWorkerGlobalScopeMethods {
 }
 
+trait PrivateDedicatedWorkerGlobalScopeHelpers {
+    fn delayed_release_worker(&self);
+}
+
+impl<'a> PrivateDedicatedWorkerGlobalScopeHelpers for JSRef<'a, DedicatedWorkerGlobalScope> {
+    fn delayed_release_worker(&self) {
+        let scope: &JSRef<WorkerGlobalScope> =
+            WorkerGlobalScopeCast::from_ref(self);
+        let ScriptChan(ref sender) = *scope.script_chan();
+        sender.send(WorkerRelease(*self.worker));
+    }
+}
+
 impl Reflectable for DedicatedWorkerGlobalScope {
     fn reflector<'a>(&'a self) -> &'a Reflector {
         self.workerglobalscope.reflector()

src/components/script/dom/worker.rs

@@ -5,32 +5,43 @@
 use dom::bindings::codegen::Bindings::WorkerBinding;
 use dom::bindings::codegen::Bindings::WorkerBinding::WorkerMethods;
 use dom::bindings::error::{Fallible, Syntax};
-use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{JSRef, Temporary};
+use dom::bindings::global::{GlobalRef, GlobalField};
+use dom::bindings::js::{JS, JSRef, Temporary};
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::dedicatedworkerglobalscope::DedicatedWorkerGlobalScope;
 use dom::eventtarget::{EventTarget, WorkerTypeId};
 use script_task::{ScriptChan, DOMMessage};
 
 use servo_util::str::DOMString;
+
+use js::jsapi::{JS_AddObjectRoot, JS_RemoveObjectRoot};
 use url::UrlParser;
 
+use libc::c_void;
+use std::cell::Cell;
+
+pub struct TrustedWorkerAddress(pub *const c_void);
+
 #[deriving(Encodable)]
 pub struct Worker {
     eventtarget: EventTarget,
+    refcount: Cell<uint>,
+    global: GlobalField,
     sender: ScriptChan,
 }
 
 impl Worker {
-    pub fn new_inherited(sender: ScriptChan) -> Worker {
+    pub fn new_inherited(global: &GlobalRef, sender: ScriptChan) -> Worker {
         Worker {
             eventtarget: EventTarget::new_inherited(WorkerTypeId),
+            refcount: Cell::new(0),
+            global: GlobalField::from_rooted(global),
             sender: sender,
         }
     }
 
     pub fn new(global: &GlobalRef, sender: ScriptChan) -> Temporary<Worker> {
-        reflect_dom_object(box Worker::new_inherited(sender),
+        reflect_dom_object(box Worker::new_inherited(global, sender),
                            global,
                            WorkerBinding::Wrap)
     }
@@ -46,14 +57,52 @@ impl Worker {
 
         let resource_task = global.resource_task();
         let (receiver, sender) = ScriptChan::new();
+
+        let worker = Worker::new(global, sender.clone()).root();
+        let worker_ref = worker.addref();
+
         DedicatedWorkerGlobalScope::run_worker_scope(
-            worker_url, resource_task, receiver, sender.clone());
-        Ok(Worker::new(global, sender))
+            worker_url, worker_ref, resource_task, receiver, sender);
+
+        Ok(Temporary::from_rooted(&*worker))
+    }
+}
+
+impl Worker {
+    // Creates a trusted address to the object, and roots it. Always pair this with a release()
+    pub fn addref(&self) -> TrustedWorkerAddress {
+        let refcount = self.refcount.get();
+        if refcount == 0 {
+            let cx = self.global.root().root_ref().get_cx();
+            unsafe {
+                JS_AddObjectRoot(cx, self.reflector().rootable());
+            }
+        }
+        self.refcount.set(refcount + 1);
+        TrustedWorkerAddress(self as *const Worker as *const c_void)
+    }
+
+    pub fn release(&self) {
+        let refcount = self.refcount.get();
+        assert!(refcount > 0)
+        self.refcount.set(refcount - 1);
+        if refcount == 1 {
+            let cx = self.global.root().root_ref().get_cx();
+            unsafe {
+                JS_RemoveObjectRoot(cx, self.reflector().rootable());
+            }
+        }
+    }
+
+    pub fn handle_release(address: TrustedWorkerAddress) {
+        let worker = unsafe { JS::from_trusted_worker_address(address).root() };
+        worker.release();
     }
 }
 
 impl<'a> WorkerMethods for JSRef<'a, Worker> {
     fn PostMessage(&self, message: DOMString) {
+        self.addref();
         let ScriptChan(ref sender) = self.sender;
         sender.send(DOMMessage(message));
     }

src/components/script/script_task.rs

@@ -20,6 +20,7 @@ use dom::eventtarget::{EventTarget, EventTargetHelpers};
 use dom::node;
 use dom::node::{ElementNodeTypeId, Node, NodeHelpers};
 use dom::window::{TimerId, Window, WindowHelpers};
+use dom::worker::{Worker, TrustedWorkerAddress};
 use dom::xmlhttprequest::{TrustedXHRAddress, XMLHttpRequest, XHRProgress};
 use html::hubbub_html_parser::HtmlParserResult;
 use html::hubbub_html_parser::{HtmlDiscoveredStyle, HtmlDiscoveredScript};
@@ -86,6 +87,8 @@ pub enum ScriptMsg {
     /// Message sent through Worker.postMessage (only dispatched to
     /// DedicatedWorkerGlobalScope).
     DOMMessage(DOMString),
+    /// Releases one reference to the Worker object (dispatched to all tasks).
+    WorkerRelease(TrustedWorkerAddress),
 }
 
 /// Encapsulates internal communication within the script task.
@@ -441,6 +444,7 @@ impl ScriptTask {
                 FromConstellation(ResizeMsg(..)) => fail!("should have handled ResizeMsg already"),
                 FromScript(XHRProgressMsg(addr, progress)) => XMLHttpRequest::handle_xhr_progress(addr, progress),
                 FromScript(DOMMessage(..)) => fail!("unexpected message"),
+                FromScript(WorkerRelease(addr)) => Worker::handle_release(addr),
             }
         }