auto merge of #558 : tkuehn/servo/master, r=metajack

* constellation grants permission to renderers instead of passing tokens
* render tasks wrap layer buffer sets in ARCs
* removed no-longer-used field (constellation chan) from render task struct

5 files changed, 61 insertions, 81 deletions

diff --git a/src/components/gfx/render_task.rs b/src/components/gfx/render_task.rs
index e51ee22e08c..e81337ef0ef 100644
--- a/src/components/gfx/render_task.rs
+++ b/src/components/gfx/render_task.rs
@@ -8,8 +8,7 @@ use azure::{AzFloat, AzGLContext};
 use azure::azure_hl::{B8G8R8A8, DrawTarget};
 use display_list::DisplayList;
 use servo_msg::compositor_msg::{RenderListener, IdleRenderState, RenderingRenderState, LayerBuffer};
-use servo_msg::compositor_msg::{CompositorToken, LayerBufferSet};
-use servo_msg::constellation_msg::{ConstellationChan};
+use servo_msg::compositor_msg::{LayerBufferSet};
 use font_context::FontContext;
 use geom::matrix2d::Matrix2D;
 use geom::point::Point2D;
@@ -25,6 +24,8 @@ use std::uint;
 use servo_util::time::{ProfilerChan, profile};
 use servo_util::time;
 
+use extra::arc;
+
 pub struct RenderLayer {
     display_list: DisplayList<()>,
     size: Size2D<uint>
@@ -33,8 +34,8 @@ pub struct RenderLayer {
 pub enum Msg {
     RenderMsg(RenderLayer),
     ReRenderMsg(f32),
-    TokenBestowMsg(CompositorToken),
-    TokenInvalidateMsg,
+    PaintPermissionGranted,
+    PaintPermissionRevoked,
     ExitMsg(Chan<()>),
 }
 
@@ -68,12 +69,10 @@ priv struct RenderTask<C> {
 
     /// The layer to be rendered
     render_layer: Option<RenderLayer>,
-    /// A channel to the constellation for surrendering token
-    constellation_chan: ConstellationChan,
-    /// A token that grants permission to send paint messages to compositor
-    compositor_token: Option<CompositorToken>,
+    /// Permission to send paint messages to the compositor
+    paint_permission: bool,
     /// Cached copy of last layers rendered
-    last_paint_msg: Option<(LayerBufferSet, Size2D<uint>)>,
+    last_paint_msg: Option<(arc::ARC<LayerBufferSet>, Size2D<uint>)>,
 }
 
 impl<C: RenderListener + Owned> RenderTask<C> {
@@ -81,35 +80,32 @@ impl<C: RenderListener + Owned> RenderTask<C> {
                   port: Port<Msg>,
                   compositor: C,
                   opts: Opts,
-                  constellation_chan: ConstellationChan,
                   profiler_chan: ProfilerChan) {
-        let compositor_cell = Cell::new(compositor);
-        let opts_cell = Cell::new(opts);
+        let compositor = Cell::new(compositor);
+        let opts = Cell::new(opts);
         let port = Cell::new(port);
-        let constellation_chan = Cell::new(constellation_chan);
+        let profiler_chan = Cell::new(profiler_chan);
 
         do spawn {
-            let compositor = compositor_cell.take();
+            let compositor = compositor.take();
             let share_gl_context = compositor.get_gl_context();
-            let opts = opts_cell.with_ref(|o| copy *o);
-            let profiler_chan = profiler_chan.clone();
-            let profiler_chan_clone = profiler_chan.clone();
+            let opts = opts.take();
+            let profiler_chan = profiler_chan.take();
 
             // FIXME: rust/#5967
             let mut render_task = RenderTask {
                 id: id,
                 port: port.take(),
                 compositor: compositor,
-                font_ctx: @mut FontContext::new(opts.render_backend,
+                font_ctx: @mut FontContext::new(copy opts.render_backend,
                                                 false,
-                                                profiler_chan),
-                opts: opts_cell.take(),
-                profiler_chan: profiler_chan_clone,
+                                                profiler_chan.clone()),
+                opts: opts,
+                profiler_chan: profiler_chan,
                 share_gl_context: share_gl_context,
                 render_layer: None,
 
-                constellation_chan: constellation_chan.take(),
-                compositor_token: None,
+                paint_permission: false,
                 last_paint_msg: None,
             };
 
@@ -129,8 +125,8 @@ impl<C: RenderListener + Owned> RenderTask<C> {
                 ReRenderMsg(scale) => {
                     self.render(scale);
                 }
-                TokenBestowMsg(token) => {
-                    self.compositor_token = Some(token);
+                PaintPermissionGranted => {
+                    self.paint_permission = true;
                     match self.last_paint_msg {
                         Some((ref layer_buffer_set, ref layer_size)) => {
                             self.compositor.paint(self.id, layer_buffer_set.clone(), *layer_size);
@@ -139,8 +135,8 @@ impl<C: RenderListener + Owned> RenderTask<C> {
                         None => {}
                     }
                 }
-                TokenInvalidateMsg => {
-                    self.compositor_token = None;
+                PaintPermissionRevoked => {
+                    self.paint_permission = false;
                 }
                 ExitMsg(response_ch) => {
                     response_ch.send(());
@@ -232,9 +228,10 @@ impl<C: RenderListener + Owned> RenderTask<C> {
             let layer_buffer_set = LayerBufferSet {
                 buffers: new_buffers,
             };
+            let layer_buffer_set = arc::ARC(layer_buffer_set);
 
             debug!("render_task: returning surface");
-            if self.compositor_token.is_some() {
+            if self.paint_permission {
                 self.compositor.paint(self.id, layer_buffer_set.clone(), render_layer.size);
             }
             debug!("caching paint msg");
diff --git a/src/components/main/compositing/mod.rs b/src/components/main/compositing/mod.rs
index 5d7a11b2bed..ebd1a81636f 100644
--- a/src/components/main/compositing/mod.rs
+++ b/src/components/main/compositing/mod.rs
@@ -23,7 +23,6 @@ use std::comm;
 use std::comm::{Chan, SharedChan, Port};
 use std::num::Orderable;
 use std::task;
-use std::util;
 use geom::matrix::identity;
 use geom::point::Point2D;
 use geom::size::Size2D;
@@ -36,6 +35,7 @@ use servo_util::{time, url};
 use servo_util::time::profile;
 use servo_util::time::ProfilerChan;
 
+use extra::arc;
 pub use windowing;
 
 /// The implementation of the layers-based compositor.
@@ -47,28 +47,34 @@ pub struct CompositorChan {
 
 /// Implementation of the abstract `ScriptListener` interface.
 impl ScriptListener for CompositorChan {
+
     fn set_ready_state(&self, ready_state: ReadyState) {
         let msg = ChangeReadyState(ready_state);
         self.chan.send(msg);
     }
+
 }
 
 /// Implementation of the abstract `RenderListener` interface.
 impl RenderListener for CompositorChan {
+
     fn get_gl_context(&self) -> AzGLContext {
         let (port, chan) = comm::stream();
         self.chan.send(GetGLContext(chan));
         port.recv()
     }
-    fn paint(&self, id: uint, layer_buffer_set: LayerBufferSet, new_size: Size2D<uint>) {
+
+    fn paint(&self, id: uint, layer_buffer_set: arc::ARC<LayerBufferSet>, new_size: Size2D<uint>) {
         self.chan.send(Paint(id, layer_buffer_set, new_size))
     }
+
     fn set_render_state(&self, render_state: RenderState) {
         self.chan.send(ChangeRenderState(render_state))
     }
 }
 
 impl CompositorChan {
+
     pub fn new(chan: Chan<Msg>) -> CompositorChan {
         CompositorChan {
             chan: SharedChan::new(chan),
@@ -86,7 +92,7 @@ pub enum Msg {
     /// Requests the compositors GL context.
     GetGLContext(Chan<AzGLContext>),
     /// Requests that the compositor paint the given layer buffer set for the given page size.
-    Paint(uint, LayerBufferSet, Size2D<uint>),
+    Paint(uint, arc::ARC<LayerBufferSet>, Size2D<uint>),
     /// Alerts the compositor to the current status of page loading.
     ChangeReadyState(ReadyState),
     /// Alerts the compositor to the current status of rendering.
@@ -277,16 +283,12 @@ impl CompositorTask {
 
                         *page_size = Size2D(new_size.width as f32, new_size.height as f32);
 
-                        let mut new_layer_buffer_set = new_layer_buffer_set;
+                        let new_layer_buffer_set = new_layer_buffer_set.get();
 
                         // Iterate over the children of the container layer.
                         let mut current_layer_child = root_layer.first_child;
 
-                        // Replace the image layer data with the buffer data. Also compute the page
-                        // size here.
-                        let buffers = util::replace(&mut new_layer_buffer_set.buffers, ~[]);
-
-                        for buffers.each |buffer| {
+                        for new_layer_buffer_set.buffers.iter().advance |buffer| {
                             let width = buffer.rect.size.width as uint;
                             let height = buffer.rect.size.height as uint;
 
diff --git a/src/components/main/constellation.rs b/src/components/main/constellation.rs
index a18b56cbd50..9439c0d7674 100644
--- a/src/components/main/constellation.rs
+++ b/src/components/main/constellation.rs
@@ -9,9 +9,8 @@ use std::comm;
 use std::comm::Port;
 use std::task;
 use gfx::opts::Opts;
-use gfx::render_task::{TokenBestowMsg, TokenInvalidateMsg};
+use gfx::render_task::{PaintPermissionGranted, PaintPermissionRevoked};
 use pipeline::Pipeline;
-use servo_msg::compositor_msg::{CompositorToken};
 use servo_msg::constellation_msg::{CompositorAck, ConstellationChan, ExitMsg};
 use servo_msg::constellation_msg::{LoadUrlMsg, Msg, NavigateMsg, RendererReadyMsg};
 use servo_msg::constellation_msg;
@@ -33,8 +32,8 @@ pub struct Constellation {
     pipelines: HashMap<uint, Pipeline>,
     navigation_context: NavigationContext,
     next_id: uint,
-    current_token_bearer: Option<uint>,
-    next_token_bearer: Option<uint>,
+    current_painter: Option<uint>,
+    next_painter: Option<uint>,
     profiler_chan: ProfilerChan,
     opts: Opts,
 }
@@ -113,8 +112,8 @@ impl Constellation {
                 pipelines: HashMap::new(),
                 navigation_context: NavigationContext::new(),
                 next_id: 0,
-                current_token_bearer: None,
-                next_token_bearer: None,
+                current_painter: None,
+                next_painter: None,
                 profiler_chan: profiler_chan.take(),
                 opts: opts.take(),
             };
@@ -157,7 +156,7 @@ impl Constellation {
                 } else {
                     pipeline.load(url);
                     pipeline.navigation_type = Some(constellation_msg::Load);
-                    self.next_token_bearer = Some(pipeline_id);
+                    self.next_painter = Some(pipeline_id);
                 }
                 self.pipelines.insert(pipeline_id, pipeline);
             }
@@ -186,23 +185,23 @@ impl Constellation {
                 pipeline.navigation_type = Some(constellation_msg::Navigate);
                 pipeline.reload();
                 self.pipelines.insert(destination_id, pipeline);
-                self.next_token_bearer = Some(destination_id);
-                self.update_token_bearer();
+                self.next_painter = Some(destination_id);
+                self.update_painter();
             }
 
             // Notification that rendering has finished and is requesting permission to paint.
             RendererReadyMsg(pipeline_id) => {
-                let next_token_bearer = self.next_token_bearer;
-                for next_token_bearer.iter().advance |&id| {
+                let next_painter = self.next_painter;
+                for next_painter.iter().advance |&id| {
                     if pipeline_id == id {
-                        self.update_token_bearer();
+                        self.update_painter();
                     }
                 }
             }
 
             // Acknowledgement from the compositor that it has updated its active pipeline id
             CompositorAck(id) => {
-                self.bestow_compositor_token(id);
+                self.grant_paint_permission(id);
             }
 
             ExitMsg(sender) => {
@@ -219,12 +218,12 @@ impl Constellation {
         true
     }
     
-    fn update_token_bearer(&mut self) {
-        let current_token_bearer = replace(&mut self.current_token_bearer, None);
-        for current_token_bearer.iter().advance |id| {
-            self.pipelines.get(id).render_chan.send(TokenInvalidateMsg);
+    fn update_painter(&mut self) {
+        let current_painter = replace(&mut self.current_painter, None);
+        for current_painter.iter().advance |id| {
+            self.pipelines.get(id).render_chan.send(PaintPermissionRevoked);
         }
-        let id = self.next_token_bearer.get();
+        let id = self.next_painter.get();
         let pipeline = self.pipelines.get(&id);
         self.compositor_chan.send(SetLayoutRenderChans(pipeline.layout_chan.clone(),
                                                        pipeline.render_chan.clone(),
@@ -232,12 +231,12 @@ impl Constellation {
                                                        self.chan.clone()));
     }
 
-    // Sends a compositor token to a renderer; optionally updates navigation to reflect a new page
-    fn bestow_compositor_token(&mut self, id: uint) {
+    // Grants a renderer permission to paint; optionally updates navigation to reflect a new page
+    fn grant_paint_permission(&mut self, id: uint) {
         let pipeline = self.pipelines.get(&id);
-        pipeline.render_chan.send(TokenBestowMsg(CompositorToken::new()));
-        self.current_token_bearer = Some(id);
-        self.next_token_bearer = None;
+        pipeline.render_chan.send(PaintPermissionGranted);
+        self.current_painter = Some(id);
+        self.next_painter = None;
         // Don't navigate on Navigate type, because that is handled by forward/back
         match pipeline.navigation_type.get() {
             constellation_msg::Load => {
diff --git a/src/components/main/pipeline.rs b/src/components/main/pipeline.rs
index f5b6cf9c664..ab9ccc6cade 100644
--- a/src/components/main/pipeline.rs
+++ b/src/components/main/pipeline.rs
@@ -47,7 +47,6 @@ impl Pipeline {
                            render_port,
                            compositor_chan.clone(),
                            copy opts,
-                           constellation_chan.clone(),
                            profiler_chan.clone());
 
         LayoutTask::create(layout_port,
diff --git a/src/components/msg/compositor_msg.rs b/src/components/msg/compositor_msg.rs
index 666a40d4b9b..d9dd02f2671 100644
--- a/src/components/msg/compositor_msg.rs
+++ b/src/components/msg/compositor_msg.rs
@@ -6,7 +6,8 @@ use azure::azure_hl::DrawTarget;
 use azure::azure::AzGLContext;
 use geom::rect::Rect;
 use geom::size::Size2D;
-use std::util::NonCopyable;
+
+use extra::arc;
 
 #[deriving(Clone)]
 pub struct LayerBuffer {
@@ -24,7 +25,6 @@ pub struct LayerBuffer {
 
 /// A set of layer buffers. This is an atomic unit used to switch between the front and back
 /// buffers.
-#[deriving(Clone)]
 pub struct LayerBufferSet {
     buffers: ~[LayerBuffer]
 }
@@ -49,7 +49,7 @@ pub enum ReadyState {
 /// submit them to be drawn to the display.
 pub trait RenderListener {
     fn get_gl_context(&self) -> AzGLContext;
-    fn paint(&self, id: uint, layer_buffer_set: LayerBufferSet, new_size: Size2D<uint>);
+    fn paint(&self, id: uint, layer_buffer_set: arc::ARC<LayerBufferSet>, new_size: Size2D<uint>);
     fn set_render_state(&self, render_state: RenderState);
 }
 
@@ -58,20 +58,3 @@ pub trait RenderListener {
 pub trait ScriptListener : Clone {
     fn set_ready_state(&self, ReadyState);
 }
-
-/// Signifies to the renderer likely control of the compositor. Controlling the compositor token
-/// is necessary but not sufficient for the renderer to successfully send paint messages to the
-/// compositor. Only the render tasks controlling compositor tokens may send messages, and the
-/// compositor is guaranteed to only accept messages from one of those tasks at a time.
-pub struct CompositorToken {
-    construction_restrictor: NonCopyable,
-}
-
-impl CompositorToken {
-    pub fn new() -> CompositorToken {
-        CompositorToken {
-            // Of course, this doesn't guarantee that renderers will invalidate their tokens
-            construction_restrictor: NonCopyable::new(),
-        }
-    }
-}