Hoist retrieval of layout_threads from opts into Constellation

components/constellation/pipeline.rs

@@ -160,6 +160,7 @@ impl Pipeline {
                     pipeline_port: pipeline_port,
                     layout_to_constellation_chan: state.layout_to_constellation_chan.clone(),
                     content_process_shutdown_chan: layout_content_process_shutdown_chan.clone(),
+                    layout_threads: opts::get().layout_threads,
                 };
 
                 if let Err(e) = script_chan.send(ConstellationControlMsg::AttachLayout(new_layout_info)) {
@@ -470,7 +471,8 @@ impl UnprivilegedPipelineContent {
                     self.time_profiler_chan,
                     self.mem_profiler_chan,
                     self.layout_content_process_shutdown_chan,
-                    self.webrender_api_sender);
+                    self.webrender_api_sender,
+                    opts::get().layout_threads);
 
         if wait_for_completion {
             let _ = self.script_content_process_shutdown_port.recv();

components/layout_thread/lib.rs

@@ -232,6 +232,10 @@ pub struct LayoutThread {
     /// The timer object to control the timing of the animations. This should
     /// only be a test-mode timer during testing for animations.
     timer: Timer,
+
+    // Number of layout threads. This is copied from `util::opts`, but we'd
+    // rather limit the dependency on that module here.
+    layout_threads: usize,
 }
 
 impl LayoutThreadFactory for LayoutThread {
@@ -251,7 +255,8 @@ impl LayoutThreadFactory for LayoutThread {
               time_profiler_chan: time::ProfilerChan,
               mem_profiler_chan: mem::ProfilerChan,
               content_process_shutdown_chan: IpcSender<()>,
-              webrender_api_sender: Option<webrender_traits::RenderApiSender>) {
+              webrender_api_sender: Option<webrender_traits::RenderApiSender>,
+              layout_threads: usize) {
         thread::spawn_named(format!("LayoutThread {:?}", id),
                       move || {
             thread_state::initialize(thread_state::LAYOUT);
@@ -270,7 +275,8 @@ impl LayoutThreadFactory for LayoutThread {
                                              font_cache_thread,
                                              time_profiler_chan,
                                              mem_profiler_chan.clone(),
-                                             webrender_api_sender);
+                                             webrender_api_sender,
+                                             layout_threads);
 
                 let reporter_name = format!("layout-reporter-{}", id);
                 mem_profiler_chan.run_with_memory_reporting(|| {
@@ -381,14 +387,14 @@ impl LayoutThread {
            font_cache_thread: FontCacheThread,
            time_profiler_chan: time::ProfilerChan,
            mem_profiler_chan: mem::ProfilerChan,
-           webrender_api_sender: Option<webrender_traits::RenderApiSender>)
+           webrender_api_sender: Option<webrender_traits::RenderApiSender>,
+           layout_threads: usize)
            -> LayoutThread {
         let device = Device::new(
             MediaType::Screen,
             opts::get().initial_window_size.as_f32() * ScaleFactor::new(1.0));
-        let parallel_traversal = if opts::get().layout_threads != 1 {
+        let parallel_traversal = if layout_threads != 1 {
-            Some(WorkQueue::new("LayoutWorker", thread_state::LAYOUT,
+            Some(WorkQueue::new("LayoutWorker", thread_state::LAYOUT, layout_threads))
-                                opts::get().layout_threads))
         } else {
             None
         };
@@ -479,6 +485,7 @@ impl LayoutThread {
                 } else {
                     Timer::new()
                 },
+            layout_threads: layout_threads,
         }
     }
 
@@ -754,7 +761,8 @@ impl LayoutThread {
                              self.time_profiler_chan.clone(),
                              self.mem_profiler_chan.clone(),
                              info.content_process_shutdown_chan,
-                             self.webrender_api.as_ref().map(|wr| wr.clone_sender()));
+                             self.webrender_api.as_ref().map(|wr| wr.clone_sender()),
+                             info.layout_threads);
     }
 
     /// Enters a quiescent state in which no new messages will be processed until an `ExitNow` is
@@ -1158,7 +1166,7 @@ impl LayoutThread {
             // TODO(pcwalton): Measure energy usage of text shaping, perhaps?
             let text_shaping_time =
                 (font::get_and_reset_text_shaping_performance_counter() as u64) /
-                (opts::get().layout_threads as u64);
+                (self.layout_threads as u64);
             time::send_profile_data(time::ProfilerCategory::LayoutTextShaping,
                                     self.profiler_metadata(),
                                     self.time_profiler_chan.clone(),

components/layout_traits/lib.rs

@@ -48,5 +48,6 @@ pub trait LayoutThreadFactory {
               time_profiler_chan: time::ProfilerChan,
               mem_profiler_chan: mem::ProfilerChan,
               content_process_shutdown_chan: IpcSender<()>,
-              webrender_api_sender: Option<webrender_traits::RenderApiSender>);
+              webrender_api_sender: Option<webrender_traits::RenderApiSender>,
+              layout_threads: usize);
 }

components/script/script_thread.rs

@@ -1142,6 +1142,7 @@ impl ScriptThread {
             pipeline_port,
             layout_to_constellation_chan,
             content_process_shutdown_chan,
+            layout_threads,
         } = new_layout_info;
 
         let layout_pair = channel();
@@ -1158,6 +1159,7 @@ impl ScriptThread {
             script_chan: self.control_chan.clone(),
             image_cache_thread: self.image_cache_thread.clone(),
             content_process_shutdown_chan: content_process_shutdown_chan,
+            layout_threads: layout_threads,
         };
 
         let context = self.root_browsing_context();

components/script_layout_interface/message.rs

@@ -149,4 +149,5 @@ pub struct NewLayoutThreadInfo {
     pub image_cache_thread: ImageCacheThread,
     pub paint_chan: OptionalOpaqueIpcSender,
     pub content_process_shutdown_chan: IpcSender<()>,
+    pub layout_threads: usize,
 }

components/script_traits/lib.rs

@@ -146,6 +146,8 @@ pub struct NewLayoutInfo {
     pub layout_to_constellation_chan: IpcSender<LayoutMsg>,
     /// A shutdown channel so that layout can tell the content process to shut down when it's done.
     pub content_process_shutdown_chan: IpcSender<()>,
+    /// Number of threads to use for layout.
+    pub layout_threads: usize,
 }
 
 /// Messages sent from the constellation or layout to the script thread.