split script_task::ExitMsg into WindowExitMsg and PipelineExitMsg

src/components/main/constellation.rs

@@ -760,6 +760,28 @@ impl Constellation {
         }
     }
 
+    // Close all pipelines at and beneath a given frame
+    fn close_pipelines(&mut self, frame_tree: @mut FrameTree) {
+        // TODO(tkuehn): should only exit once per unique script task,
+        // and then that script task will handle sub-exits
+        for @FrameTree { pipeline, _ } in frame_tree.iter() {
+            pipeline.exit();
+            self.pipelines.remove(&pipeline.id);
+        }
+    }
+
+    fn handle_evicted_frames(&mut self, evicted: ~[@mut FrameTree]) {
+        for &frame_tree in evicted.iter() {
+            if !self.navigation_context.contains(frame_tree.pipeline.id) {
+                self.close_pipelines(frame_tree);
+            } else {
+                self.handle_evicted_frames(frame_tree.children.iter()
+                    .map(|child| child.frame_tree)
+                    .collect());
+            }
+        }
+    }
+
     // Grants a frame tree permission to paint; optionally updates navigation to reflect a new page
     fn grant_paint_permission(&mut self, frame_tree: @mut FrameTree, navigation_type: NavigationType) {
         // Give permission to paint to the new frame and all child frames
@@ -770,20 +792,7 @@ impl Constellation {
         match navigation_type {
             constellation_msg::Load => {
                 let evicted = self.navigation_context.load(frame_tree);
-                let mut exited = HashSet::new();
-                // exit any pipelines that don't exist outside the evicted frame trees
-                for frame_tree in evicted.iter() {
-                    for @FrameTree { pipeline, _ } in frame_tree.iter() {
-                        if !self.navigation_context.contains(pipeline.id) &&
-                            !exited.contains(&pipeline.id) {
-                            debug!("Constellation: shutting down pipeline %?", pipeline.id);
-                            pipeline.exit();
-                            self.pipelines.remove(&pipeline.id);
-
-                            exited.insert(pipeline.id);
-                        }
-                    }
-                }
+                self.handle_evicted_frames(evicted);
             }
             _ => {}
         }

src/components/main/layout/layout_task.rs

@@ -26,6 +26,7 @@ use gfx::font_context::FontContext;
 use gfx::geometry::Au;
 use gfx::opts::Opts;
 use gfx::render_task::{RenderMsg, RenderChan, RenderLayer};
+use gfx::render_task;
 use newcss::select::SelectCtx;
 use newcss::stylesheet::Stylesheet;
 use newcss::types::OriginAuthor;
@@ -162,6 +163,9 @@ impl LayoutTask {
             }
             ExitMsg => {
                 debug!("layout: ExitMsg received");
+                let (response_port, response_chan) = stream();
+                self.render_chan.send(render_task::ExitMsg(response_chan));
+                response_port.recv();
                 return false
             }
         }

src/components/main/macros.rs

@@ -5,7 +5,7 @@
 macro_rules! special_stream(
     ($Chan:ident) => (
         {
-            let (port, chan) = comm::stream::();
+            let (port, chan) = stream::();
             (port, $Chan::new(chan))
         }
     );

src/components/main/pipeline.rs

@@ -6,7 +6,6 @@ use extra::url::Url;
 use compositing::CompositorChan;
 use gfx::render_task::{RenderChan, RenderTask};
 use gfx::render_task::{PaintPermissionGranted, PaintPermissionRevoked};
-use gfx::render_task;
 use gfx::opts::Opts;
 use layout::layout_task::LayoutTask;
 use script::layout_interface::LayoutChan;
@@ -21,7 +20,6 @@ use servo_util::time::ProfilerChan;
 use geom::size::Size2D;
 use extra::future::Future;
 use std::cell::Cell;
-use std::comm;
 use std::task;
 
 /// A uniquely-identifiable pipeline of script task, layout task, and render task. 
@@ -216,12 +214,9 @@ impl Pipeline {
     }
 
     pub fn exit(&self) {
-        // Script task handles shutting down layout, as well
-        self.script_chan.send(script_task::ExitMsg(self.id));
-
-        let (response_port, response_chan) = comm::stream();
-        self.render_chan.send(render_task::ExitMsg(response_chan));
-        response_port.recv();
+        // Script task handles shutting down layout, 
+        // and layout handles shutting down the renderer.
+        self.script_chan.try_send(script_task::ExitPipelineMsg(self.id));
     }
 }
 

src/components/script/dom/window.rs

@@ -10,7 +10,7 @@ use dom::node::{AbstractNode, ScriptView};
 use dom::navigator::Navigator;
 
 use layout_interface::ReflowForDisplay;
-use script_task::{ExitMsg, FireTimerMsg, Page, ScriptChan};
+use script_task::{ExitWindowMsg, FireTimerMsg, Page, ScriptChan};
 use servo_msg::compositor_msg::ScriptListener;
 use servo_net::image_cache_task::ImageCacheTask;
 
@@ -212,7 +212,7 @@ impl Window {
                         match timer_port.recv() {
                             TimerMessage_Close => break,
                             TimerMessage_Fire(td) => script_chan.send(FireTimerMsg(id, td)),
-                            TimerMessage_TriggerExit => script_chan.send(ExitMsg(id)),
+                            TimerMessage_TriggerExit => script_chan.send(ExitWindowMsg(id)),
                         }
                     }
                 }

src/components/script/script_task.rs

@@ -70,8 +70,10 @@ pub enum ScriptMsg {
     ReflowCompleteMsg(PipelineId, uint),
     /// Notifies script that window has been resized but to not take immediate action.
     ResizeInactiveMsg(PipelineId, Size2D<uint>),
-    /// Exits the constellation.
-    ExitMsg(PipelineId),
+    /// Notifies the script that a pipeline should be closed.
+    ExitPipelineMsg(PipelineId),
+    /// Notifies the script that a window associated with a particular pipeline should be closed.
+    ExitWindowMsg(PipelineId),
 }
 
 pub struct NewLayoutInfo {
@@ -516,9 +518,8 @@ impl ScriptTask {
                 NavigateMsg(direction) => self.handle_navigate_msg(direction),
                 ReflowCompleteMsg(id, reflow_id) => self.handle_reflow_complete_msg(id, reflow_id),
                 ResizeInactiveMsg(id, new_size) => self.handle_resize_inactive_msg(id, new_size),
-                ExitMsg(id) => {
-                    if self.handle_exit_msg(id) { return false }
-                },
+                ExitPipelineMsg(id) => if self.handle_exit_pipeline_msg(id) { return false },
+                ExitWindowMsg(id) => if self.handle_exit_window_msg(id) { return false },
                 ResizeMsg(*) => fail!("should have handled ResizeMsg already"),
             }
         }
@@ -623,9 +624,17 @@ impl ScriptTask {
         }
     }
 
+    fn handle_exit_window_msg(&mut self, _id: PipelineId) -> bool {
+        // TODO(tkuehn): currently there is only one window,
+        // so this can afford to be naive and just shut down the
+        // compositor. In the future it'll need to be smarter.
+        self.compositor.close();
+        true
+    }
+
     /// Handles a request to exit the script task and shut down layout.
     /// Returns true if the script task should shut down and false otherwise.
-    fn handle_exit_msg(&mut self, id: PipelineId) -> bool {
+    fn handle_exit_pipeline_msg(&mut self, id: PipelineId) -> bool {
         // If root is being exited, shut down all pages
         if self.page_tree.page.id == id {
             for page in self.page_tree.iter() {
@@ -641,10 +650,12 @@ impl ScriptTask {
                     page.join_layout();
                     page.layout_chan.send(layout_interface::ExitMsg);
                 }
-                return false
+                false
             }
-            None => fail!("ScriptTask: Received exit message from
-                           pipeline whose id is not in page tree"),
+            // TODO(tkuehn): pipeline closing is currently duplicated across
+            // script and constellation, which can cause this to happen. Constellation
+            // needs to be smarter about exiting pipelines.
+            None => false,
         }
 
     }