Auto merge of #8958 - jkachmar:separate-layout-msg, r=KiChjang

Separate script and layout messages, issue #8843

Separated layout-specific messages to the constellation out from the `ScriptMsg` enum into a `LayoutMsg` enum within `script_traits/script_msg.rs`, addresses [#8843](https://github.com/servo/servo/issues/8843).

I initially tried to move `LayoutMsg` into `layout_traits/lib.rs`, but this introduced a cyclic dependency: `layout_traits` depends on `script_traits` for the `LayoutTaskFactory` implementation, and `script_traits/script_task.rs` now depends on `LayoutMsg` for new layout channels in `InitialScriptState` and `ScriptTask`.

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11 files changed, 80 insertions, 27 deletions

diff --git a/components/compositing/constellation.rs b/components/compositing/constellation.rs
index 0d59d06d028..7edb7c32282 100644
--- a/components/compositing/constellation.rs
+++ b/components/compositing/constellation.rs
@@ -45,7 +45,7 @@ use profile_traits::mem;
 use profile_traits::time;
 use sandboxing;
 use script_traits::{CompositorEvent, ConstellationControlMsg, LayoutControlMsg};
-use script_traits::{ScriptMsg as FromScriptMsg, ScriptTaskFactory};
+use script_traits::{LayoutMsg as FromLayoutMsg, ScriptMsg as FromScriptMsg, ScriptTaskFactory};
 use script_traits::{TimerEventRequest};
 use std::borrow::ToOwned;
 use std::collections::HashMap;
@@ -87,6 +87,9 @@ pub struct Constellation<LTF, STF> {
     /// A channel through which compositor messages can be sent to this object.
     pub compositor_sender: Sender<FromCompositorMsg>,
 
+    /// A channel through which layout task messages can be sent to this object.
+    pub layout_sender: ConstellationChan<FromLayoutMsg>,
+
     /// A channel through which paint task messages can be sent to this object.
     pub painter_sender: ConstellationChan<FromPaintMsg>,
 
@@ -96,6 +99,9 @@ pub struct Constellation<LTF, STF> {
     /// Receives messages from the compositor
     pub compositor_receiver: Receiver<FromCompositorMsg>,
 
+    /// Receives messages from the layout task
+    pub layout_receiver: Receiver<FromLayoutMsg>,
+
     /// Receives messages from paint task.
     pub painter_receiver: Receiver<FromPaintMsg>,
 
@@ -287,6 +293,8 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
         let (ipc_script_receiver, ipc_script_sender) = ConstellationChan::<FromScriptMsg>::new();
         let script_receiver = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_script_receiver);
         let (compositor_sender, compositor_receiver) = channel();
+        let (ipc_layout_receiver, ipc_layout_sender) = ConstellationChan::<FromLayoutMsg>::new();
+        let layout_receiver = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_layout_receiver);
         let (ipc_painter_receiver, ipc_painter_sender) = ConstellationChan::<FromPaintMsg>::new();
         let painter_receiver = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_painter_receiver);
         let compositor_sender_clone = compositor_sender.clone();
@@ -294,9 +302,11 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
             let mut constellation: Constellation<LTF, STF> = Constellation {
                 script_sender: ipc_script_sender,
                 compositor_sender: compositor_sender_clone,
+                layout_sender: ipc_layout_sender,
                 painter_sender: ipc_painter_sender,
                 script_receiver: script_receiver,
                 compositor_receiver: compositor_receiver,
+                layout_receiver: layout_receiver,
                 painter_receiver: painter_receiver,
                 compositor_proxy: state.compositor_proxy,
                 devtools_chan: state.devtools_chan,
@@ -371,6 +381,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                 id: pipeline_id,
                 parent_info: parent_info,
                 constellation_chan: self.script_sender.clone(),
+                layout_to_constellation_chan: self.layout_sender.clone(),
                 painter_chan: self.painter_sender.clone(),
                 scheduler_chan: self.scheduler_chan.clone(),
                 compositor_proxy: self.compositor_proxy.clone_compositor_proxy(),
@@ -474,18 +485,22 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
         enum Request {
             Script(FromScriptMsg),
             Compositor(FromCompositorMsg),
+            Layout(FromLayoutMsg),
             Paint(FromPaintMsg)
         }
 
         let request = {
             let receiver_from_script = &self.script_receiver;
             let receiver_from_compositor = &self.compositor_receiver;
+            let receiver_from_layout = &self.layout_receiver;
             let receiver_from_paint = &self.painter_receiver;
             select! {
                 msg = receiver_from_script.recv() =>
                     Request::Script(msg.unwrap()),
                 msg = receiver_from_compositor.recv() =>
                     Request::Compositor(msg.unwrap()),
+                msg = receiver_from_layout.recv() =>
+                    Request::Layout(msg.unwrap()),
                 msg = receiver_from_paint.recv() =>
                     Request::Paint(msg.unwrap())
             }
@@ -577,9 +592,6 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                        load_info.new_subpage_id);
                 self.handle_script_loaded_url_in_iframe_msg(load_info);
             }
-            Request::Script(FromScriptMsg::SetCursor(cursor)) => {
-                self.handle_set_cursor_msg(cursor)
-            }
             Request::Script(FromScriptMsg::ChangeRunningAnimationsState(pipeline_id, animation_state)) => {
                 self.handle_change_running_animations_state(pipeline_id, animation_state)
             }
@@ -652,10 +664,6 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                     }
                 }
             }
-            Request::Script(FromScriptMsg::ViewportConstrained(pipeline_id, constraints)) => {
-                debug!("constellation got viewport-constrained event message");
-                self.handle_viewport_constrained_msg(pipeline_id, constraints);
-            }
             Request::Script(FromScriptMsg::RemoveIFrame(pipeline_id)) => {
                 debug!("constellation got remove iframe message");
                 self.handle_remove_iframe_msg(pipeline_id);
@@ -686,6 +694,24 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
             }
 
 
+            // Messages from layout task
+
+            Request::Layout(FromLayoutMsg::ChangeRunningAnimationsState(pipeline_id, animation_state)) => {
+                self.handle_change_running_animations_state(pipeline_id, animation_state)
+            }
+            Request::Layout(FromLayoutMsg::Failure(Failure { pipeline_id, parent_info })) => {
+                debug!("handling paint failure message from pipeline {:?}, {:?}", pipeline_id, parent_info);
+                self.handle_failure_msg(pipeline_id, parent_info);
+            }
+            Request::Layout(FromLayoutMsg::SetCursor(cursor)) => {
+                self.handle_set_cursor_msg(cursor)
+            }
+            Request::Layout(FromLayoutMsg::ViewportConstrained(pipeline_id, constraints)) => {
+                debug!("constellation got viewport-constrained event message");
+                self.handle_viewport_constrained_msg(pipeline_id, constraints);
+            }
+
+
             // Messages from paint task
 
 
diff --git a/components/compositing/pipeline.rs b/components/compositing/pipeline.rs
index 64a6ada7593..47aab2126e2 100644
--- a/components/compositing/pipeline.rs
+++ b/components/compositing/pipeline.rs
@@ -24,7 +24,7 @@ use net_traits::storage_task::StorageTask;
 use profile_traits::mem as profile_mem;
 use profile_traits::time;
 use script_traits::{ConstellationControlMsg, InitialScriptState};
-use script_traits::{LayoutControlMsg, NewLayoutInfo, ScriptMsg as ConstellationMsg};
+use script_traits::{LayoutControlMsg, LayoutMsg, NewLayoutInfo, ScriptMsg};
 use script_traits::{ScriptToCompositorMsg, ScriptTaskFactory, TimerEventRequest};
 use std::mem;
 use std::sync::mpsc::{Receiver, Sender, channel};
@@ -79,7 +79,9 @@ pub struct InitialPipelineState {
     /// If `None`, this is the root.
     pub parent_info: Option<(PipelineId, SubpageId)>,
     /// A channel to the associated constellation.
-    pub constellation_chan: ConstellationChan<ConstellationMsg>,
+    pub constellation_chan: ConstellationChan<ScriptMsg>,
+    /// A channel for the layout task to send messages to the constellation.
+    pub layout_to_constellation_chan: ConstellationChan<LayoutMsg>,
     /// A channel to the associated paint task.
     pub painter_chan: ConstellationChan<PaintMsg>,
     /// A channel to schedule timer events.
@@ -207,6 +209,7 @@ impl Pipeline {
             time_profiler_chan: state.time_profiler_chan.clone(),
             mem_profiler_chan: state.mem_profiler_chan.clone(),
             window_size: window_size,
+            layout_to_constellation_chan: state.layout_to_constellation_chan,
             script_chan: script_chan,
             load_data: state.load_data.clone(),
             failure: failure,
@@ -347,7 +350,8 @@ impl Pipeline {
 pub struct UnprivilegedPipelineContent {
     id: PipelineId,
     parent_info: Option<(PipelineId, SubpageId)>,
-    constellation_chan: ConstellationChan<ConstellationMsg>,
+    constellation_chan: ConstellationChan<ScriptMsg>,
+    layout_to_constellation_chan: ConstellationChan<LayoutMsg>,
     scheduler_chan: IpcSender<TimerEventRequest>,
     devtools_chan: Option<IpcSender<ScriptToDevtoolsControlMsg>>,
     script_to_compositor_chan: IpcSender<ScriptToCompositorMsg>,
@@ -386,6 +390,7 @@ impl UnprivilegedPipelineContent {
             control_chan: self.script_chan.clone(),
             control_port: mem::replace(&mut self.script_port, None).unwrap(),
             constellation_chan: self.constellation_chan.clone(),
+            layout_to_constellation_chan: self.layout_to_constellation_chan.clone(),
             scheduler_chan: self.scheduler_chan.clone(),
             failure_info: self.failure.clone(),
             resource_task: self.resource_task,
@@ -405,7 +410,7 @@ impl UnprivilegedPipelineContent {
                                   self.parent_info.is_some(),
                                   layout_pair,
                                   self.pipeline_port.unwrap(),
-                                  self.constellation_chan,
+                                  self.layout_to_constellation_chan,
                                   self.failure,
                                   self.script_chan.clone(),
                                   self.layout_to_paint_chan.clone(),
diff --git a/components/layout/animation.rs b/components/layout/animation.rs
index 628b693a2c0..9160c317a5a 100644
--- a/components/layout/animation.rs
+++ b/components/layout/animation.rs
@@ -9,7 +9,7 @@ use gfx::display_list::OpaqueNode;
 use incremental::{self, RestyleDamage};
 use msg::constellation_msg::{AnimationState, ConstellationChan, PipelineId};
 use script::layout_interface::Animation;
-use script_traits::ScriptMsg as ConstellationMsg;
+use script_traits::LayoutMsg as ConstellationMsg;
 use std::collections::HashMap;
 use std::collections::hash_map::Entry;
 use std::sync::mpsc::{Sender, Receiver};
diff --git a/components/layout/layout_task.rs b/components/layout/layout_task.rs
index 3063690778d..7e69042ff9e 100644
--- a/components/layout/layout_task.rs
+++ b/components/layout/layout_task.rs
@@ -51,8 +51,8 @@ use script::layout_interface::{LayoutRPC, OffsetParentResponse};
 use script::layout_interface::{Msg, NewLayoutTaskInfo, Reflow, ReflowGoal, ReflowQueryType};
 use script::layout_interface::{ScriptLayoutChan, ScriptReflow};
 use script::reporter::CSSErrorReporter;
-use script_traits::ScriptMsg as ConstellationMsg;
-use script_traits::{ConstellationControlMsg, LayoutControlMsg, OpaqueScriptLayoutChannel};
+use script_traits::ConstellationControlMsg;
+use script_traits::{LayoutControlMsg, LayoutMsg as ConstellationMsg, OpaqueScriptLayoutChannel};
 use sequential;
 use serde_json;
 use std::borrow::ToOwned;
diff --git a/components/layout/query.rs b/components/layout/query.rs
index 83f758b0f50..11fc0b2b2f3 100644
--- a/components/layout/query.rs
+++ b/components/layout/query.rs
@@ -18,7 +18,7 @@ use opaque_node::OpaqueNodeMethods;
 use script::layout_interface::{ContentBoxResponse, ContentBoxesResponse, NodeGeometryResponse};
 use script::layout_interface::{HitTestResponse, LayoutRPC, MouseOverResponse, OffsetParentResponse};
 use script::layout_interface::{ResolvedStyleResponse, ScriptLayoutChan};
-use script_traits::ScriptMsg as ConstellationMsg;
+use script_traits::LayoutMsg as ConstellationMsg;
 use selectors::parser::PseudoElement;
 use sequential;
 use std::ops::Deref;
diff --git a/components/layout_traits/lib.rs b/components/layout_traits/lib.rs
index f595e0a7f16..065fbf0192a 100644
--- a/components/layout_traits/lib.rs
+++ b/components/layout_traits/lib.rs
@@ -27,7 +27,7 @@ use ipc_channel::ipc::{IpcReceiver, IpcSender};
 use msg::constellation_msg::{ConstellationChan, Failure, PipelineId};
 use net_traits::image_cache_task::ImageCacheTask;
 use profile_traits::{mem, time};
-use script_traits::ScriptMsg as ConstellationMsg;
+use script_traits::LayoutMsg as ConstellationMsg;
 use script_traits::{LayoutControlMsg, ConstellationControlMsg, OpaqueScriptLayoutChannel};
 use url::Url;
 use util::ipc::OptionalIpcSender;
diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index cbe870f073c..496d70add18 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -63,7 +63,7 @@ use net_traits::storage_task::StorageType;
 use profile_traits::mem::ProfilerChan as MemProfilerChan;
 use profile_traits::time::ProfilerChan as TimeProfilerChan;
 use script_task::ScriptChan;
-use script_traits::{ScriptMsg, TimerEventId, TimerSource, UntrustedNodeAddress};
+use script_traits::{LayoutMsg, ScriptMsg, TimerEventId, TimerSource, UntrustedNodeAddress};
 use selectors::parser::PseudoElement;
 use selectors::states::*;
 use serde::{Deserialize, Serialize};
@@ -306,6 +306,13 @@ impl JSTraceable for ConstellationChan<ScriptMsg> {
     }
 }
 
+impl JSTraceable for ConstellationChan<LayoutMsg> {
+    #[inline]
+    fn trace(&self, _trc: *mut JSTracer) {
+        // Do nothing
+    }
+}
+
 impl JSTraceable for Box<ScriptChan + Send> {
     #[inline]
     fn trace(&self, _trc: *mut JSTracer) {
diff --git a/components/script/layout_interface.rs b/components/script/layout_interface.rs
index a533fd6418d..4570192f6fb 100644
--- a/components/script/layout_interface.rs
+++ b/components/script/layout_interface.rs
@@ -18,8 +18,8 @@ use msg::constellation_msg::{ConstellationChan, Failure, PipelineId};
 use msg::constellation_msg::{WindowSizeData};
 use net_traits::image_cache_task::ImageCacheTask;
 use profile_traits::mem::ReportsChan;
-use script_traits::{ConstellationControlMsg, LayoutControlMsg, OpaqueScriptLayoutChannel};
-use script_traits::{ScriptMsg as ConstellationMsg, UntrustedNodeAddress};
+use script_traits::{ConstellationControlMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg};
+use script_traits::{OpaqueScriptLayoutChannel, UntrustedNodeAddress};
 use selectors::parser::PseudoElement;
 use std::any::Any;
 use std::sync::Arc;
diff --git a/components/script/script_task.rs b/components/script/script_task.rs
index 953bf3dacde..b07b5086f45 100644
--- a/components/script/script_task.rs
+++ b/components/script/script_task.rs
@@ -80,7 +80,7 @@ use profile_traits::time::{self, ProfilerCategory, profile};
 use script_traits::CompositorEvent::{KeyEvent, MouseButtonEvent, MouseMoveEvent, ResizeEvent};
 use script_traits::CompositorEvent::{TouchEvent};
 use script_traits::{CompositorEvent, ConstellationControlMsg, EventResult, InitialScriptState, NewLayoutInfo};
-use script_traits::{OpaqueScriptLayoutChannel, ScriptMsg as ConstellationMsg};
+use script_traits::{LayoutMsg, OpaqueScriptLayoutChannel, ScriptMsg as ConstellationMsg};
 use script_traits::{ScriptTaskFactory, ScriptToCompositorMsg, TimerEvent, TimerEventRequest, TimerSource};
 use script_traits::{TouchEventType, TouchId};
 use std::any::Any;
@@ -406,6 +406,9 @@ pub struct ScriptTask {
     /// For communicating load url messages to the constellation
     constellation_chan: ConstellationChan<ConstellationMsg>,
 
+    /// For communicating layout messages to the constellation
+    layout_to_constellation_chan: ConstellationChan<LayoutMsg>,
+
     /// A handle to the compositor for communicating ready state messages.
     compositor: DOMRefCell<IpcSender<ScriptToCompositorMsg>>,
 
@@ -669,6 +672,7 @@ impl ScriptTask {
             control_chan: state.control_chan,
             control_port: control_port,
             constellation_chan: state.constellation_chan,
+            layout_to_constellation_chan: state.layout_to_constellation_chan,
             compositor: DOMRefCell::new(state.compositor),
             time_profiler_chan: state.time_profiler_chan,
             mem_profiler_chan: state.mem_profiler_chan,
@@ -1195,7 +1199,7 @@ impl ScriptTask {
             is_parent: false,
             layout_pair: layout_pair,
             pipeline_port: pipeline_port,
-            constellation_chan: self.constellation_chan.clone(),
+            constellation_chan: self.layout_to_constellation_chan.clone(),
             failure: failure,
             paint_chan: paint_chan,
             script_chan: self.control_chan.clone(),
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index c305b75e2fc..3ce9d064b14 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -52,7 +52,7 @@ use std::any::Any;
 use util::ipc::OptionalOpaqueIpcSender;
 use util::mem::HeapSizeOf;
 
-pub use script_msg::ScriptMsg;
+pub use script_msg::{LayoutMsg, ScriptMsg};
 
 /// The address of a node. Layout sends these back. They must be validated via
 /// `from_untrusted_node_address` before they can be used, because we do not trust layout.
@@ -250,6 +250,8 @@ pub struct InitialScriptState {
     pub control_port: IpcReceiver<ConstellationControlMsg>,
     /// A channel on which messages can be sent to the constellation from script.
     pub constellation_chan: ConstellationChan<ScriptMsg>,
+    /// A channel for the layout task to send messages to the constellation.
+    pub layout_to_constellation_chan: ConstellationChan<LayoutMsg>,
     /// A channel to schedule timer events.
     pub scheduler_chan: IpcSender<TimerEventRequest>,
     /// Information that script sends out when it panics.
diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index b19212dc2d1..1916551ed79 100644
--- a/components/script_traits/script_msg.rs
+++ b/components/script_traits/script_msg.rs
@@ -15,6 +15,19 @@ use style_traits::viewport::ViewportConstraints;
 use url::Url;
 use util::cursor::Cursor;
 
+/// Messages from the layout to the constellation.
+#[derive(Deserialize, Serialize)]
+pub enum LayoutMsg {
+    /// Indicates whether this pipeline is currently running animations.
+    ChangeRunningAnimationsState(PipelineId, AnimationState),
+    /// Layout task failure.
+    Failure(Failure),
+    /// Requests that the constellation inform the compositor of the a cursor change.
+    SetCursor(Cursor),
+    /// Notifies the constellation that the viewport has been constrained in some manner
+    ViewportConstrained(PipelineId, ViewportConstraints),
+}
+
 /// Messages from the script to the constellation.
 #[derive(Deserialize, Serialize)]
 pub enum ScriptMsg {
@@ -62,10 +75,6 @@ pub enum ScriptMsg {
     ScriptLoadedURLInIFrame(IframeLoadInfo),
     /// Requests that the constellation set the contents of the clipboard
     SetClipboardContents(String),
-    /// Requests that the constellation inform the compositor of the a cursor change.
-    SetCursor(Cursor),
-    /// Notifies the constellation that the viewport has been constrained in some manner
-    ViewportConstrained(PipelineId, ViewportConstraints),
     /// Mark a new document as active
     ActivateDocument(PipelineId),
     /// Set the document state for a pipeline (used by screenshot / reftests)