compositing: Move messages that go over the `ScriptListener` to go over

an IPC channel instead.

Because this used a boxed trait object to invoke messages across a
process boundary, and boxed trait objects are not supported across IPC,
we spawn a helper thread inside the compositor to perform the marshaling
for us.

components/compositing/Cargo.toml

@@ -52,6 +52,9 @@ git = "https://github.com/servo/rust-png"
 [dependencies.clipboard]
 git = "https://github.com/aweinstock314/rust-clipboard"
 
+[dependencies.ipc-channel]
+git = "https://github.com/pcwalton/ipc-channel"
+
 [dependencies]
 log = "*"
 num = "0.1.24"

components/compositing/compositor_task.rs

@@ -13,10 +13,11 @@ use windowing::{WindowEvent, WindowMethods};
 
 use euclid::point::Point2D;
 use euclid::rect::Rect;
+use ipc_channel::ipc::IpcReceiver;
 use layers::platform::surface::NativeDisplay;
 use layers::layers::{BufferRequest, LayerBuffer, LayerBufferSet};
 use msg::compositor_msg::{Epoch, LayerId, LayerProperties, FrameTreeId};
-use msg::compositor_msg::{PaintListener, ScriptListener};
+use msg::compositor_msg::{PaintListener, ScriptToCompositorMsg};
 use msg::constellation_msg::{AnimationState, ConstellationChan, PipelineId};
 use msg::constellation_msg::{Key, KeyState, KeyModifiers};
 use profile_traits::mem;
@@ -61,31 +62,28 @@ impl CompositorReceiver for Receiver<Msg> {
     }
 }
 
-/// Implementation of the abstract `ScriptListener` interface.
-impl ScriptListener for Box<CompositorProxy+'static+Send> {
-    fn scroll_fragment_point(&mut self,
-                             pipeline_id: PipelineId,
-                             layer_id: LayerId,
-                             point: Point2D<f32>) {
-        self.send(Msg::ScrollFragmentPoint(pipeline_id, layer_id, point));
-    }
-
-    fn close(&mut self) {
-        let (chan, port) = channel();
-        self.send(Msg::Exit(chan));
-        port.recv().unwrap();
-    }
+pub fn run_script_listener_thread(mut compositor_proxy: Box<CompositorProxy + 'static + Send>,
+                                  receiver: IpcReceiver<ScriptToCompositorMsg>) {
+    while let Ok(msg) = receiver.recv() {
+        match msg {
+            ScriptToCompositorMsg::ScrollFragmentPoint(pipeline_id, layer_id, point) => {
+                compositor_proxy.send(Msg::ScrollFragmentPoint(pipeline_id, layer_id, point));
+            }
 
-    fn dup(&mut self) -> Box<ScriptListener+'static> {
-        box self.clone_compositor_proxy() as Box<ScriptListener+'static>
-    }
+            ScriptToCompositorMsg::Exit => {
+                let (chan, port) = channel();
+                compositor_proxy.send(Msg::Exit(chan));
+                port.recv().unwrap();
+            }
 
-    fn set_title(&mut self, pipeline_id: PipelineId, title: Option<String>) {
-        self.send(Msg::ChangePageTitle(pipeline_id, title))
-    }
+            ScriptToCompositorMsg::SetTitle(pipeline_id, title) => {
+                compositor_proxy.send(Msg::ChangePageTitle(pipeline_id, title))
+            }
 
-    fn send_key_event(&mut self, key: Key, state: KeyState, modifiers: KeyModifiers) {
-        self.send(Msg::KeyEvent(key, state, modifiers));
+            ScriptToCompositorMsg::SendKeyEvent(key, key_state, key_modifiers) => {
+                compositor_proxy.send(Msg::KeyEvent(key, key_state, key_modifiers))
+            }
+        }
     }
 }
 

components/compositing/lib.rs

@@ -14,6 +14,7 @@ extern crate azure;
 extern crate devtools_traits;
 extern crate euclid;
 extern crate gfx;
+extern crate ipc_channel;
 extern crate layers;
 extern crate layout_traits;
 extern crate png;

components/compositing/pipeline.rs

@@ -7,13 +7,16 @@ use layout_traits::{LayoutControlMsg, LayoutTaskFactory, LayoutControlChan};
 use script_traits::{ScriptControlChan, ScriptTaskFactory};
 use script_traits::{NewLayoutInfo, ConstellationControlMsg};
 
+use compositor_task;
 use devtools_traits::DevtoolsControlChan;
 use euclid::rect::{TypedRect};
 use euclid::scale_factor::ScaleFactor;
 use gfx::paint_task::Msg as PaintMsg;
 use gfx::paint_task::{PaintChan, PaintTask};
 use gfx::font_cache_task::FontCacheTask;
+use ipc_channel::ipc;
 use layers::geometry::DevicePixel;
+use msg::compositor_msg::ScriptListener;
 use msg::constellation_msg::{ConstellationChan, Failure, FrameId, PipelineId, SubpageId};
 use msg::constellation_msg::{LoadData, WindowSizeData, PipelineExitType, MozBrowserEvent};
 use profile_traits::mem;
@@ -22,6 +25,7 @@ use net_traits::ResourceTask;
 use net_traits::image_cache_task::ImageCacheTask;
 use net_traits::storage_task::StorageTask;
 use std::sync::mpsc::{Receiver, channel};
+use std::thread;
 use url::Url;
 use util::geometry::{PagePx, ViewportPx};
 use util::opts;
@@ -91,6 +95,8 @@ impl Pipeline {
         let script_chan = match script_chan {
             None => {
                 let (script_chan, script_port) = channel();
+                let (script_to_compositor_chan, script_to_compositor_port) =
+                    ipc::channel().unwrap();
 
                 let window_size = window_rect.map(|rect| {
                     WindowSizeData {
@@ -100,10 +106,18 @@ impl Pipeline {
                     }
                 });
 
+                let compositor_proxy_for_script_listener_thread =
+                    compositor_proxy.clone_compositor_proxy();
+                thread::spawn(move || {
+                    compositor_task::run_script_listener_thread(
+                        compositor_proxy_for_script_listener_thread,
+                        script_to_compositor_port)
+                });
+
                 ScriptTaskFactory::create(None::<&mut STF>,
                                           id,
                                           parent_info,
-                                          compositor_proxy.clone_compositor_proxy(),
+                                          ScriptListener::new(script_to_compositor_chan),
                                           &layout_pair,
                                           ScriptControlChan(script_chan.clone()),
                                           script_port,

components/msg/Cargo.toml

@@ -22,12 +22,17 @@ git = "https://github.com/servo/rust-layers"
 [dependencies.png]
 git = "https://github.com/servo/rust-png"
 
+[dependencies.ipc-channel]
+git = "https://github.com/pcwalton/ipc-channel"
+
 [dependencies]
 url = "0.2.35"
 bitflags = "*"
 hyper = "0.5"
 rustc-serialize = "0.3.4"
 euclid = "0.1"
+serde = "*"
+serde_macros = "*"
 
 [target.x86_64-apple-darwin.dependencies]
 core-foundation = "*"

components/msg/compositor_msg.rs

@@ -7,6 +7,7 @@ use constellation_msg::{Key, KeyState, KeyModifiers};
 use euclid::point::Point2D;
 use euclid::rect::Rect;
 use euclid::Matrix4;
+use ipc_channel::ipc::IpcSender;
 use layers::platform::surface::NativeDisplay;
 use layers::layers::{BufferRequest, LayerBufferSet};
 use std::fmt::{Formatter, Debug};
@@ -35,7 +36,7 @@ impl FrameTreeId {
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Copy, Hash)]
+#[derive(Clone, PartialEq, Eq, Copy, Hash, Deserialize, Serialize)]
 pub struct LayerId(pub usize, pub u32);
 
 impl Debug for LayerId {
@@ -115,16 +116,47 @@ pub trait PaintListener {
     fn notify_paint_task_exiting(&mut self, pipeline_id: PipelineId);
 }
 
+#[derive(Deserialize, Serialize)]
+pub enum ScriptToCompositorMsg {
+    ScrollFragmentPoint(PipelineId, LayerId, Point2D<f32>),
+    SetTitle(PipelineId, Option<String>),
+    SendKeyEvent(Key, KeyState, KeyModifiers),
+    Exit,
+}
+
 /// The interface used by the script task to tell the compositor to update its ready state,
 /// which is used in displaying the appropriate message in the window's title.
-pub trait ScriptListener {
-    fn scroll_fragment_point(&mut self,
-                             pipeline_id: PipelineId,
-                             layer_id: LayerId,
-                             point: Point2D<f32>);
-    /// Informs the compositor that the title of the page with the given pipeline ID has changed.
-    fn set_title(&mut self, pipeline_id: PipelineId, new_title: Option<String>);
-    fn close(&mut self);
-    fn dup(&mut self) -> Box<ScriptListener+'static>;
-    fn send_key_event(&mut self, key: Key, state: KeyState, modifiers: KeyModifiers);
+#[derive(Clone)]
+pub struct ScriptListener(IpcSender<ScriptToCompositorMsg>);
+
+impl ScriptListener {
+    pub fn new(sender: IpcSender<ScriptToCompositorMsg>) -> ScriptListener {
+        ScriptListener(sender)
+    }
+
+    pub fn scroll_fragment_point(&mut self,
+                                 pipeline_id: PipelineId,
+                                 layer_id: LayerId,
+                                 point: Point2D<f32>) {
+        self.0
+            .send(ScriptToCompositorMsg::ScrollFragmentPoint(pipeline_id, layer_id, point))
+            .unwrap()
+    }
+
+    pub fn close(&mut self) {
+        self.0.send(ScriptToCompositorMsg::Exit).unwrap()
+    }
+
+    pub fn dup(&mut self) -> ScriptListener {
+        self.clone()
+    }
+
+    pub fn set_title(&mut self, pipeline_id: PipelineId, title: Option<String>) {
+        self.0.send(ScriptToCompositorMsg::SetTitle(pipeline_id, title)).unwrap()
+    }
+
+    pub fn send_key_event(&mut self, key: Key, state: KeyState, modifiers: KeyModifiers) {
+        self.0.send(ScriptToCompositorMsg::SendKeyEvent(key, state, modifiers)).unwrap()
+    }
 }
+

components/msg/constellation_msg.rs

@@ -57,15 +57,15 @@ pub struct WindowSizeData {
     pub device_pixel_ratio: ScaleFactor<ViewportPx, DevicePixel, f32>,
 }
 
-#[derive(PartialEq, Eq, Copy, Clone)]
+#[derive(PartialEq, Eq, Copy, Clone, Deserialize, Serialize)]
 pub enum KeyState {
     Pressed,
     Released,
     Repeated,
 }
 
 //N.B. Based on the glutin key enum
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone, Deserialize, Serialize)]
 pub enum Key {
     Space,
     Apostrophe,
@@ -191,6 +191,7 @@ pub enum Key {
 }
 
 bitflags! {
+    #[derive(Deserialize, Serialize)]
     flags KeyModifiers: u8 {
         const NONE = 0x00,
         const SHIFT = 0x01,
@@ -368,10 +369,10 @@ pub struct FrameId(pub u32);
 #[derive(Clone, PartialEq, Eq, Copy, Hash, Debug)]
 pub struct WorkerId(pub u32);
 
-#[derive(Clone, PartialEq, Eq, Copy, Hash, Debug)]
+#[derive(Clone, PartialEq, Eq, Copy, Hash, Debug, Deserialize, Serialize)]
 pub struct PipelineId(pub u32);
 
-#[derive(Clone, PartialEq, Eq, Copy, Hash, Debug)]
+#[derive(Clone, PartialEq, Eq, Copy, Hash, Debug, Deserialize, Serialize)]
 pub struct SubpageId(pub u32);
 
 // The type of pipeline exit. During complete shutdowns, pipelines do not have to

components/msg/lib.rs

@@ -2,13 +2,18 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#![feature(custom_derive, plugin)]
+#![plugin(serde_macros)]
+
 extern crate azure;
 #[macro_use] extern crate bitflags;
 extern crate euclid;
 extern crate hyper;
+extern crate ipc_channel;
 extern crate layers;
 extern crate png;
 extern crate rustc_serialize;
+extern crate serde;
 extern crate util;
 extern crate url;
 extern crate style;

components/script/dom/bindings/trace.rs

@@ -328,7 +328,7 @@ impl<A,B> JSTraceable for fn(A) -> B {
     }
 }
 
-impl JSTraceable for Box<ScriptListener+'static> {
+impl JSTraceable for ScriptListener {
     #[inline]
     fn trace(&self, _: *mut JSTracer) {
         // Do nothing

components/script/dom/document.rs

@@ -251,8 +251,11 @@ pub trait DocumentHelpers<'a> {
     fn title_changed(self);
     fn send_title_to_compositor(self);
     fn dirty_all_nodes(self);
-    fn dispatch_key_event(self, key: Key, state: KeyState,
-        modifiers: KeyModifiers, compositor: &mut Box<ScriptListener+'static>);
+    fn dispatch_key_event(self,
+                          key: Key,
+                          state: KeyState,
+                          modifiers: KeyModifiers,
+                          compositor: &mut ScriptListener);
     fn node_from_nodes_and_strings(self, nodes: Vec<NodeOrString>)
                                    -> Fallible<Root<Node>>;
     fn get_body_attribute(self, local_name: &Atom) -> DOMString;
@@ -763,10 +766,11 @@ impl<'a> DocumentHelpers<'a> for &'a Document {
     }
 
     /// The entry point for all key processing for web content
-    fn dispatch_key_event(self, key: Key,
+    fn dispatch_key_event(self,
+                          key: Key,
                           state: KeyState,
                           modifiers: KeyModifiers,
-                          compositor: &mut Box<ScriptListener+'static>) {
+                          compositor: &mut ScriptListener) {
         let window = self.window.root();
         let focused = self.get_focused_element();
         let body = self.GetBody();

components/script/dom/window.rs

@@ -105,7 +105,7 @@ pub struct Window {
     navigator: MutNullableHeap<JS<Navigator>>,
     image_cache_task: ImageCacheTask,
     image_cache_chan: ImageCacheChan,
-    compositor: DOMRefCell<Box<ScriptListener+'static>>,
+    compositor: DOMRefCell<ScriptListener>,
     browser_context: DOMRefCell<Option<BrowserContext>>,
     page: Rc<Page>,
     performance: MutNullableHeap<JS<Performance>>,
@@ -241,7 +241,7 @@ impl Window {
         &self.image_cache_task
     }
 
-    pub fn compositor<'a>(&'a self) -> RefMut<'a, Box<ScriptListener+'static>> {
+    pub fn compositor<'a>(&'a self) -> RefMut<'a, ScriptListener> {
         self.compositor.borrow_mut()
     }
 
@@ -964,7 +964,7 @@ impl Window {
                script_chan: Box<ScriptChan+Send>,
                image_cache_chan: ImageCacheChan,
                control_chan: ScriptControlChan,
-               compositor: Box<ScriptListener+'static>,
+               compositor: ScriptListener,
                image_cache_task: ImageCacheTask,
                resource_task: ResourceTask,
                storage_task: StorageTask,