Auto merge of servo#6152 - glennw:runnable-panic, r=jdm

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Author: bors-servo

components/gfx/paint_task.rs

@@ -308,7 +308,7 @@ impl<C> PaintTask<C> where C: PaintListener + Send + 'static {
                     // If we own buffers in the compositor and we are not exiting completely, wait
                     // for the compositor to return buffers, so that we can release them properly.
                     // When doing a complete exit, the compositor lets all buffers leak.
-                    println!("PaintTask {:?}: Saw ExitMsg, {} buffers in use", self.id, self.used_buffer_count);
+                    debug!("PaintTask {:?}: Saw ExitMsg, {} buffers in use", self.id, self.used_buffer_count);
                     waiting_for_compositor_buffers_to_exit = true;
                     exit_response_channel = response_channel;
                 }

components/script/dom/document.rs

@@ -1830,13 +1830,17 @@ impl DocumentProgressHandler {
 
 impl Runnable for DocumentProgressHandler {
     fn handler(self: Box<DocumentProgressHandler>) {
-        match self.task {
-            DocumentProgressTask::DOMContentLoaded => {
-                self.dispatch_dom_content_loaded();
-            }
-            DocumentProgressTask::Load => {
-                self.set_ready_state_complete();
-                self.dispatch_load();
+        let document = self.addr.to_temporary().root();
+        let window = document.r().window().root();
+        if window.r().is_alive() {
+            match self.task {
+                DocumentProgressTask::DOMContentLoaded => {
+                    self.dispatch_dom_content_loaded();
+                }
+                DocumentProgressTask::Load => {
+                    self.set_ready_state_complete();
+                    self.dispatch_load();
+                }
             }
         }
     }

components/script/dom/window.rs

@@ -69,6 +69,14 @@ use std::sync::mpsc::{channel, Receiver, Sender};
 use std::sync::mpsc::TryRecvError::{Empty, Disconnected};
 use time;
 
+/// Current state of the window object
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[jstraceable]
+enum WindowState {
+    Alive,
+    Zombie,     // Pipeline is closed, but the window hasn't been GCed yet.
+}
+
 /// Extra information concerning the reason for reflowing.
 #[derive(Debug)]
 pub enum ReflowReason {
@@ -170,7 +178,10 @@ pub struct Window {
     pending_reflow_count: Cell<u32>,
 
     /// A channel for communicating results of async scripts back to the webdriver server
-    webdriver_script_chan: RefCell<Option<Sender<WebDriverJSResult>>>
+    webdriver_script_chan: RefCell<Option<Sender<WebDriverJSResult>>>,
+
+    /// The current state of the window object
+    current_state: Cell<WindowState>,
 }
 
 impl Window {
@@ -179,6 +190,7 @@ impl Window {
         unsafe {
             *self.js_runtime.borrow_for_script_deallocation() = None;
             *self.browser_context.borrow_for_script_deallocation() = None;
+            self.current_state.set(WindowState::Zombie);
         }
     }
 
@@ -544,6 +556,7 @@ pub trait WindowHelpers {
     fn set_devtools_timeline_marker(self, marker: TimelineMarkerType, reply: Sender<TimelineMarker>);
     fn drop_devtools_timeline_markers(self);
     fn set_webdriver_script_chan(self, chan: Option<Sender<WebDriverJSResult>>);
+    fn is_alive(self) -> bool;
 }
 
 pub trait ScriptHelpers {
@@ -595,6 +608,7 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
         // which causes a panic!
         self.Gc();
 
+        self.current_state.set(WindowState::Zombie);
         *self.js_runtime.borrow_mut() = None;
         *self.browser_context.borrow_mut() = None;
     }
@@ -916,6 +930,10 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
     fn set_webdriver_script_chan(self, chan: Option<Sender<WebDriverJSResult>>) {
         *self.webdriver_script_chan.borrow_mut() = chan;
     }
+
+    fn is_alive(self) -> bool {
+        self.current_state.get() == WindowState::Alive
+    }
 }
 
 impl Window {
@@ -979,6 +997,7 @@ impl Window {
             layout_join_port: DOMRefCell::new(None),
             window_size: Cell::new(window_size),
             pending_reflow_count: Cell::new(0),
+            current_state: Cell::new(WindowState::Alive),
 
             devtools_marker_sender: RefCell::new(None),
             devtools_markers: RefCell::new(HashSet::new()),