compositing: Use an `OptionalIpcSender` for communication between the

layout and paint tasks.

components/compositing/pipeline.rs

@@ -29,7 +29,9 @@ use std::mem;
 use std::sync::mpsc::{Receiver, Sender, channel};
 use std::thread;
 use url::Url;
+use util;
 use util::geometry::{PagePx, ViewportPx};
+use util::ipc::OptionalIpcSender;
 use util::opts;
 
 /// A uniquely-identifiable pipeline of script task, layout task, and paint task.
@@ -83,7 +85,7 @@ impl Pipeline {
                            device_pixel_ratio: ScaleFactor<ViewportPx, DevicePixel, f32>)
                            -> (Pipeline, PipelineContent)
                            where LTF: LayoutTaskFactory, STF:ScriptTaskFactory {
-        let (layout_to_paint_chan, layout_to_paint_port) = channel();
+        let (layout_to_paint_chan, layout_to_paint_port) = util::ipc::optional_ipc_channel();
         let (chrome_to_paint_chan, chrome_to_paint_port) = channel();
         let (paint_shutdown_chan, paint_shutdown_port) = channel();
         let (layout_shutdown_chan, layout_shutdown_port) = channel();
@@ -206,12 +208,12 @@ impl Pipeline {
     }
 
     pub fn grant_paint_permission(&self) {
-        drop(self.chrome_to_paint_chan.send(ChromeToPaintMsg::PaintPermissionGranted));
+        let _ = self.chrome_to_paint_chan.send(ChromeToPaintMsg::PaintPermissionGranted);
     }
 
     pub fn revoke_paint_permission(&self) {
         debug!("pipeline revoking paint channel paint permission");
-        drop(self.chrome_to_paint_chan.send(ChromeToPaintMsg::PaintPermissionRevoked));
+        let _ = self.chrome_to_paint_chan.send(ChromeToPaintMsg::PaintPermissionRevoked);
     }
 
     pub fn exit(&self, exit_type: PipelineExitType) {
@@ -300,7 +302,7 @@ pub struct PipelineContent {
     load_data: LoadData,
     failure: Failure,
     script_port: Option<Receiver<ConstellationControlMsg>>,
-    layout_to_paint_chan: Sender<LayoutToPaintMsg>,
+    layout_to_paint_chan: OptionalIpcSender<LayoutToPaintMsg>,
     chrome_to_paint_chan: Sender<ChromeToPaintMsg>,
     layout_to_paint_port: Option<Receiver<LayoutToPaintMsg>>,
     chrome_to_paint_port: Option<Receiver<ChromeToPaintMsg>>,

components/layout/layout_task.rs

@@ -78,6 +78,7 @@ use style::stylesheets::{Origin, Stylesheet, CSSRuleIteratorExt};
 use url::Url;
 use util::cursor::Cursor;
 use util::geometry::{Au, MAX_RECT, ZERO_POINT};
+use util::ipc::OptionalIpcSender;
 use util::logical_geometry::{LogicalPoint, WritingMode};
 use util::mem::HeapSizeOf;
 use util::opts;
@@ -187,7 +188,7 @@ pub struct LayoutTask {
     pub script_chan: ScriptControlChan,
 
     /// The channel on which messages can be sent to the painting task.
-    pub paint_chan: Sender<LayoutToPaintMsg>,
+    pub paint_chan: OptionalIpcSender<LayoutToPaintMsg>,
 
     /// The channel on which messages can be sent to the time profiler.
     pub time_profiler_chan: time::ProfilerChan,
@@ -227,7 +228,7 @@ impl LayoutTaskFactory for LayoutTask {
               constellation_chan: ConstellationChan,
               failure_msg: Failure,
               script_chan: ScriptControlChan,
-              paint_chan: Sender<LayoutToPaintMsg>,
+              paint_chan: OptionalIpcSender<LayoutToPaintMsg>,
               image_cache_task: ImageCacheTask,
               font_cache_task: FontCacheTask,
               time_profiler_chan: time::ProfilerChan,
@@ -317,7 +318,7 @@ impl LayoutTask {
            pipeline_port: IpcReceiver<LayoutControlMsg>,
            constellation_chan: ConstellationChan,
            script_chan: ScriptControlChan,
-           paint_chan: Sender<LayoutToPaintMsg>,
+           paint_chan: OptionalIpcSender<LayoutToPaintMsg>,
            image_cache_task: ImageCacheTask,
            font_cache_task: FontCacheTask,
            time_profiler_chan: time::ProfilerChan,
@@ -647,7 +648,7 @@ impl LayoutTask {
                                   info.failure,
                                   ScriptControlChan(info.script_chan.clone()),
                                   *info.paint_chan
-                                       .downcast::<Sender<LayoutToPaintMsg>>()
+                                       .downcast::<OptionalIpcSender<LayoutToPaintMsg>>()
                                        .unwrap(),
                                   self.image_cache_task.clone(),
                                   self.font_cache_task.clone(),

components/layout_traits/lib.rs

@@ -31,6 +31,7 @@ use net_traits::image_cache_task::ImageCacheTask;
 use script_traits::{LayoutControlMsg, ScriptControlChan, OpaqueScriptLayoutChannel};
 use std::sync::mpsc::Sender;
 use url::Url;
+use util::ipc::OptionalIpcSender;
 
 /// A channel wrapper for constellation messages
 #[derive(Clone, Deserialize, Serialize)]
@@ -49,7 +50,7 @@ pub trait LayoutTaskFactory {
               constellation_chan: ConstellationChan,
               failure_msg: Failure,
               script_chan: ScriptControlChan,
-              layout_to_paint_chan: Sender<LayoutToPaintMsg>,
+              layout_to_paint_chan: OptionalIpcSender<LayoutToPaintMsg>,
               image_cache_task: ImageCacheTask,
               font_cache_task: FontCacheTask,
               time_profiler_chan: time::ProfilerChan,

components/util/ipc.rs

@@ -34,6 +34,19 @@ impl<T> OptionalIpcSender<T> where T: Deserialize + Serialize + Send + Any {
     }
 }
 
+impl<T> Clone for OptionalIpcSender<T> where T: Deserialize + Serialize + Send + Any {
+    fn clone(&self) -> OptionalIpcSender<T> {
+        match *self {
+            OptionalIpcSender::OutOfProcess(ref ipc_sender) => {
+                OptionalIpcSender::OutOfProcess((*ipc_sender).clone())
+            }
+            OptionalIpcSender::InProcess(ref sender) => {
+                OptionalIpcSender::InProcess((*sender).clone())
+            }
+        }
+    }
+}
+
 impl<T> Deserialize for OptionalIpcSender<T> where T: Deserialize + Serialize + Send + Any {
     fn deserialize<D>(deserializer: &mut D)
                       -> Result<OptionalIpcSender<T>,D::Error> where D: Deserializer {