Auto merge of #10587 - asajeffrey:add-failure-panic-message, r=Manishearth

Added panic message to failures.

Added the panic message to failures. This is a step towards #10334, since it gives us access to the panic error message when we fire a `mozbrowsererror` event. The remaining steps are also to record the backtrace, and to report the failure in the event.

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9 files changed, 88 insertions, 37 deletions

diff --git a/components/compositing/constellation.rs b/components/compositing/constellation.rs
index 97d3fca36c2..e824340c1a4 100644
--- a/components/compositing/constellation.rs
+++ b/components/compositing/constellation.rs
@@ -653,9 +653,9 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
             // Messages from script
 
 
-            Request::Script(FromScriptMsg::Failure(Failure { pipeline_id, parent_info })) => {
-                debug!("handling script failure message from pipeline {:?}, {:?}", pipeline_id, parent_info);
-                self.handle_failure_msg(pipeline_id, parent_info);
+            Request::Script(FromScriptMsg::Failure(failure)) => {
+                debug!("handling script failure message from pipeline {:?}", failure);
+                self.handle_failure_msg(failure);
             }
             Request::Script(FromScriptMsg::ScriptLoadedURLInIFrame(load_info)) => {
                 debug!("constellation got iframe URL load message {:?} {:?} {:?}",
@@ -786,9 +786,9 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
             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::Failure(failure)) => {
+                debug!("handling paint failure message from pipeline {:?}", failure);
+                self.handle_failure_msg(failure);
             }
             Request::Layout(FromLayoutMsg::SetCursor(cursor)) => {
                 self.handle_set_cursor_msg(cursor)
@@ -803,9 +803,9 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
 
 
             // Notification that painting has finished and is requesting permission to paint.
-            Request::Paint(FromPaintMsg::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::Paint(FromPaintMsg::Failure(failure)) => {
+                debug!("handling paint failure message from pipeline {:?}", failure);
+                self.handle_failure_msg(failure);
             }
 
         }
@@ -835,12 +835,11 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
             Some(pipeline) => pipeline.parent_info,
         };
         // Treat send error the same as receiving a failure message
-        self.handle_failure_msg(pipeline_id, parent_info);
+        let failure = Failure::new(pipeline_id, parent_info);
+        self.handle_failure_msg(failure);
     }
 
-    fn handle_failure_msg(&mut self,
-                          pipeline_id: PipelineId,
-                          parent_info: Option<(PipelineId, SubpageId)>) {
+    fn handle_failure_msg(&mut self, failure: Failure) {
         if opts::get().hard_fail {
             // It's quite difficult to make Servo exit cleanly if some threads have failed.
             // Hard fail exists for test runners so we crash and that's good enough.
@@ -850,12 +849,12 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
             process::exit(1);
         }
 
-        let window_size = self.pipelines.get(&pipeline_id).and_then(|pipeline| pipeline.size);
+        let window_size = self.pipelines.get(&failure.pipeline_id).and_then(|pipeline| pipeline.size);
 
-        self.close_pipeline(pipeline_id, ExitPipelineMode::Force);
+        self.close_pipeline(failure.pipeline_id, ExitPipelineMode::Force);
 
         while let Some(pending_pipeline_id) = self.pending_frames.iter().find(|pending| {
-            pending.old_pipeline_id == Some(pipeline_id)
+            pending.old_pipeline_id == Some(failure.pipeline_id)
         }).map(|frame| frame.new_pipeline_id) {
             warn!("removing pending frame change for failed pipeline");
             self.close_pipeline(pending_pipeline_id, ExitPipelineMode::Force);
@@ -865,12 +864,12 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
 
         let new_pipeline_id = PipelineId::new();
         self.new_pipeline(new_pipeline_id,
-                          parent_info,
+                          failure.parent_info,
                           window_size,
                           None,
                           LoadData::new(Url::parse("about:failure").unwrap()));
 
-        self.push_pending_frame(new_pipeline_id, Some(pipeline_id));
+        self.push_pending_frame(new_pipeline_id, Some(failure.pipeline_id));
 
     }
 
diff --git a/components/compositing/pipeline.rs b/components/compositing/pipeline.rs
index 3a45a486b8a..3de923ba858 100644
--- a/components/compositing/pipeline.rs
+++ b/components/compositing/pipeline.rs
@@ -140,10 +140,7 @@ impl Pipeline {
             .expect("Pipeline script to compositor chan");
         let mut pipeline_port = Some(pipeline_port);
 
-        let failure = Failure {
-            pipeline_id: state.id,
-            parent_info: state.parent_info,
-        };
+        let failure = Failure::new(state.id, state.parent_info);
 
         let window_size = state.window_size.map(|size| {
             WindowSizeData {
@@ -182,7 +179,7 @@ impl Pipeline {
                     subpage_id: subpage_id,
                     load_data: state.load_data.clone(),
                     paint_chan: layout_to_paint_chan.clone().to_opaque(),
-                    failure: failure,
+                    failure: failure.clone(),
                     pipeline_port: mem::replace(&mut pipeline_port, None)
                         .expect("script_pipeline != None but pipeline_port == None"),
                     layout_shutdown_chan: layout_shutdown_chan.clone(),
@@ -230,7 +227,7 @@ impl Pipeline {
             layout_to_constellation_chan: state.layout_to_constellation_chan,
             script_chan: script_chan,
             load_data: state.load_data.clone(),
-            failure: failure,
+            failure: failure.clone(),
             script_port: script_port,
             opts: (*opts::get()).clone(),
             prefs: prefs::get_cloned(),
diff --git a/components/gfx/paint_thread.rs b/components/gfx/paint_thread.rs
index 50afd79bd58..2de6b0c4628 100644
--- a/components/gfx/paint_thread.rs
+++ b/components/gfx/paint_thread.rs
@@ -441,7 +441,7 @@ impl<C> PaintThread<C> where C: PaintListener + Send + 'static {
 
             debug!("paint_thread: shutdown_chan send");
             shutdown_chan.send(()).unwrap();
-        }, ConstellationMsg::Failure(failure_msg), c);
+        }, failure_msg, c);
     }
 
     #[allow(unsafe_code)]
diff --git a/components/gfx_traits/lib.rs b/components/gfx_traits/lib.rs
index 6f5abcb1963..ed78a9c74b0 100644
--- a/components/gfx_traits/lib.rs
+++ b/components/gfx_traits/lib.rs
@@ -34,6 +34,12 @@ pub enum PaintMsg {
     Failure(Failure),
 }
 
+impl From<Failure> for PaintMsg {
+    fn from(failure: Failure) -> PaintMsg {
+        PaintMsg::Failure(failure)
+    }
+}
+
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum LayerKind {
     NoTransform,
diff --git a/components/layout/layout_thread.rs b/components/layout/layout_thread.rs
index f6f88a0f29b..9c184880ecd 100644
--- a/components/layout/layout_thread.rs
+++ b/components/layout/layout_thread.rs
@@ -286,7 +286,7 @@ impl LayoutThreadFactory for LayoutThread {
             }
             let _ = shutdown_chan.send(());
             let _ = content_process_shutdown_chan.send(());
-        }, ConstellationMsg::Failure(failure_msg), con_chan);
+        }, failure_msg, con_chan);
     }
 }
 
diff --git a/components/msg/constellation_msg.rs b/components/msg/constellation_msg.rs
index 8c1c02feaf0..c9b8d0acd88 100644
--- a/components/msg/constellation_msg.rs
+++ b/components/msg/constellation_msg.rs
@@ -16,6 +16,7 @@ use std::cell::Cell;
 use std::fmt;
 use url::Url;
 use util::geometry::{PagePx, ViewportPx};
+use util::thread::AddFailureDetails;
 use webdriver_msg::{LoadStatus, WebDriverScriptCommand};
 use webrender_traits;
 
@@ -36,10 +37,27 @@ impl<T: Serialize + Deserialize> Clone for ConstellationChan<T> {
 }
 
 // We pass this info to various threads, so it lives in a separate, cloneable struct.
-#[derive(Clone, Copy, Deserialize, Serialize)]
+#[derive(Clone, Deserialize, Serialize, Debug)]
 pub struct Failure {
     pub pipeline_id: PipelineId,
     pub parent_info: Option<(PipelineId, SubpageId)>,
+    pub panic_message: Option<String>,
+}
+
+impl Failure {
+    pub fn new(pipeline_id: PipelineId, parent_info: Option<(PipelineId, SubpageId)>) -> Failure {
+        Failure {
+            pipeline_id: pipeline_id,
+            parent_info: parent_info,
+            panic_message: None,
+        }
+    }
+}
+
+impl AddFailureDetails for Failure {
+    fn add_panic_message(&mut self, message: String) {
+        self.panic_message = Some(message);
+    }
 }
 
 #[derive(Copy, Clone, Deserialize, Serialize, HeapSizeOf)]
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 7029f34e753..5f2ecd095ba 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -445,7 +445,7 @@ impl ScriptThreadFactory for ScriptThread {
         let ConstellationChan(const_chan) = state.constellation_chan.clone();
         let (script_chan, script_port) = channel();
         let layout_chan = LayoutChan(layout_chan.sender());
-        let failure_info = state.failure_info;
+        let failure_info = state.failure_info.clone();
         thread::spawn_named_with_send_on_failure(format!("ScriptThread {:?}", state.id),
                                                thread_state::SCRIPT,
                                                move || {
@@ -481,7 +481,7 @@ impl ScriptThreadFactory for ScriptThread {
 
             // This must always be the very last operation performed before the thread completes
             failsafe.neuter();
-        }, ConstellationMsg::Failure(failure_info), const_chan);
+        }, failure_info, const_chan);
     }
 }
 
diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index 10bb4864c4b..23920d150d1 100644
--- a/components/script_traits/script_msg.rs
+++ b/components/script_traits/script_msg.rs
@@ -32,6 +32,12 @@ pub enum LayoutMsg {
     ViewportConstrained(PipelineId, ViewportConstraints),
 }
 
+impl From<Failure> for LayoutMsg {
+    fn from(failure: Failure) -> LayoutMsg {
+        LayoutMsg::Failure(failure)
+    }
+}
+
 /// Messages from the script to the constellation.
 #[derive(Deserialize, Serialize)]
 pub enum ScriptMsg {
@@ -86,3 +92,9 @@ pub enum ScriptMsg {
     /// Update the pipeline Url, which can change after redirections.
     SetFinalUrl(PipelineId, Url),
 }
+
+impl From<Failure> for ScriptMsg {
+    fn from(failure: Failure) -> ScriptMsg {
+        ScriptMsg::Failure(failure)
+    }
+}
diff --git a/components/util/thread.rs b/components/util/thread.rs
index 9451d0a434f..b8fba1aa773 100644
--- a/components/util/thread.rs
+++ b/components/util/thread.rs
@@ -5,6 +5,7 @@
 use ipc_channel::ipc::IpcSender;
 use opts;
 use serde::Serialize;
+use std::any::Any;
 use std::borrow::ToOwned;
 use std::io::{Write, stderr};
 use std::panic::{PanicInfo, take_hook, set_hook};
@@ -13,6 +14,8 @@ use std::thread;
 use std::thread::Builder;
 use thread_state;
 
+pub type PanicReason = Option<String>;
+
 pub fn spawn_named<F>(name: String, f: F)
     where F: FnOnce() + Send + 'static
 {
@@ -52,6 +55,17 @@ pub fn spawn_named<F>(name: String, f: F)
     builder.spawn(f_with_hook).unwrap();
 }
 
+pub trait AddFailureDetails {
+    fn add_panic_message(&mut self, message: String);
+    fn add_panic_object(&mut self, object: Box<Any>) {
+        if let Some(message) = object.downcast_ref::<String>() {
+            self.add_panic_message(message.to_owned());
+        } else if let Some(&message) = object.downcast_ref::<&'static str>() {
+            self.add_panic_message(message.to_owned());
+        }
+    }
+}
+
 /// An abstraction over `Sender<T>` and `IpcSender<T>`, for use in
 /// `spawn_named_with_send_on_failure`.
 pub trait SendOnFailure {
@@ -62,14 +76,16 @@ pub trait SendOnFailure {
 impl<T> SendOnFailure for Sender<T> where T: Send + 'static {
     type Value = T;
     fn send_on_failure(&mut self, value: T) {
-        self.send(value).unwrap();
+        // Discard any errors to avoid double-panic
+        let _ = self.send(value);
     }
 }
 
 impl<T> SendOnFailure for IpcSender<T> where T: Send + Serialize + 'static {
     type Value = T;
     fn send_on_failure(&mut self, value: T) {
-        self.send(value).unwrap();
+        // Discard any errors to avoid double-panic
+        let _ = self.send(value);
     }
 }
 
@@ -77,11 +93,13 @@ impl<T> SendOnFailure for IpcSender<T> where T: Send + Serialize + 'static {
 pub fn spawn_named_with_send_on_failure<F, T, S>(name: String,
                                                  state: thread_state::ThreadState,
                                                  f: F,
-                                                 msg: T,
+                                                 mut msg: T,
                                                  mut dest: S)
-                                                 where F: FnOnce() + Send + 'static,
-                                                       T: Send + 'static,
-                                                       S: Send + SendOnFailure<Value=T> + 'static {
+    where F: FnOnce() + Send + 'static,
+          T: Send + AddFailureDetails + 'static,
+          S: Send + SendOnFailure + 'static,
+          S::Value: From<T>,
+{
     let future_handle = thread::Builder::new().name(name.to_owned()).spawn(move || {
         thread_state::initialize(state);
         f()
@@ -91,9 +109,10 @@ pub fn spawn_named_with_send_on_failure<F, T, S>(name: String,
     Builder::new().name(watcher_name).spawn(move || {
         match future_handle.join() {
             Ok(()) => (),
-            Err(..) => {
+            Err(err) => {
                 debug!("{} failed, notifying constellation", name);
-                dest.send_on_failure(msg);
+                msg.add_panic_object(err);
+                dest.send_on_failure(S::Value::from(msg));
             }
         }
     }).unwrap();