auto merge of #1405 : pcwalton/servo/defuture, r=larsbergstrom

This will allow us to stop going to the DOM in order to handle iframe
sizing. Instead we can just store the pipeline and frame IDs of iframes
inside the flow tree itself.

r? @kmcallister

1 files changed, 66 insertions, 44 deletions

diff --git a/src/components/script/script_task.rs b/src/components/script/script_task.rs
index b77b383f4ed..4676639a6a4 100644
--- a/src/components/script/script_task.rs
+++ b/src/components/script/script_task.rs
@@ -27,11 +27,9 @@ use layout_interface::ContentChangedDocumentDamage;
 use layout_interface;
 
 use dom::node::ScriptView;
-use extra::future::Future;
 use extra::url::Url;
-use std::str::eq_slice;
-use geom::size::Size2D;
 use geom::point::Point2D;
+use geom::size::Size2D;
 use js::JSVAL_NULL;
 use js::global::debug_fns;
 use js::glue::RUST_JSVAL_TO_OBJECT;
@@ -53,6 +51,7 @@ use std::cell::Cell;
 use std::comm::{Port, SharedChan};
 use std::comm;
 use std::ptr;
+use std::str::eq_slice;
 use std::task::{spawn_sched, SingleThreaded};
 use std::util::replace;
 
@@ -84,7 +83,6 @@ pub struct NewLayoutInfo {
     old_id: PipelineId,
     new_id: PipelineId,
     layout_chan: LayoutChan,
-    size_future: Future<Size2D<uint>>,
 }
 
 /// Encapsulates external communication with the script task.
@@ -118,8 +116,8 @@ pub struct Page {
     /// What parts of the document are dirty, if any.
     damage: Option<DocumentDamage>,
 
-    /// The current size of the window, in pixels.
-    window_size: Future<Size2D<uint>>,
+    /// The current size of the window, in pixels. If `None`, we do not know the window size yet.
+    window_size: Option<Size2D<uint>>,
 
     js_info: Option<JSPageInfo>,
 
@@ -148,7 +146,7 @@ pub struct PageTreeIterator<'self> {
 }
 
 impl PageTree {
-    fn new(id: PipelineId, layout_chan: LayoutChan, size_future: Future<Size2D<uint>>) -> PageTree {
+    fn new(id: PipelineId, layout_chan: LayoutChan) -> PageTree {
         PageTree {
             page: @mut Page {
                 id: id,
@@ -156,7 +154,7 @@ impl PageTree {
                 layout_chan: layout_chan,
                 layout_join_port: None,
                 damage: None,
-                window_size: size_future,
+                window_size: None,
                 js_info: None,
                 url: None,
                 next_subpage_id: SubpageId(0),
@@ -280,18 +278,32 @@ impl Page {
         response_port.recv()
     }
 
-    /// This method will wait until the layout task has completed its current action, join the
-    /// layout task, and then request a new layout run. It won't wait for the new layout
-    /// computation to finish.
+    /// Reflows the page if it's possible to do so. This method will wait until the layout task has
+    /// completed its current action, join the layout task, and then request a new layout run. It
+    /// won't wait for the new layout computation to finish.
+    ///
+    /// If there is no window size yet, the page is presumed invisible and no reflow is performed.
     ///
     /// This function fails if there is no root frame.
-    pub fn reflow(&mut self, goal: ReflowGoal, script_chan: ScriptChan, compositor: @ScriptListener) {
+    pub fn reflow(&mut self,
+                  goal: ReflowGoal,
+                  script_chan: ScriptChan,
+                  compositor: @ScriptListener) {
         let root = match self.frame {
             None => return,
             Some(ref frame) => {
                 frame.document.document().GetDocumentElement()
             }
         };
+
+        let window_size = match self.window_size {
+            None => {
+                debug!("not reflowing due to lack of a window size");
+                return
+            }
+            Some(window_size) => window_size,
+        };
+
         match root {
             None => {},
             Some(root) => {
@@ -314,7 +326,7 @@ impl Page {
                     document_root: root,
                     url: self.url.get_ref().first().clone(),
                     goal: goal,
-                    window_size: self.window_size.get(),
+                    window_size: window_size,
                     script_chan: script_chan,
                     script_join_chan: join_chan,
                     damage: replace(&mut self.damage, None).unwrap(),
@@ -329,8 +341,8 @@ impl Page {
     }
 
     pub fn initialize_js_info(&mut self, js_context: @Cx, global: *JSObject) {
-        // Note that the order that these variables are initialized is _not_ arbitrary. Switching them around
-        // can -- and likely will -- lead to things breaking.
+        // Note that the order that these variables are initialized is _not_ arbitrary. Switching
+        // them around can -- and likely will -- lead to things breaking.
 
         js_context.set_default_options_and_version();
         js_context.set_logging_error_reporter();
@@ -425,13 +437,12 @@ impl ScriptTask {
                chan: ScriptChan,
                constellation_chan: ConstellationChan,
                resource_task: ResourceTask,
-               img_cache_task: ImageCacheTask,
-               initial_size: Future<Size2D<uint>>)
+               img_cache_task: ImageCacheTask)
                -> @mut ScriptTask {
         let js_runtime = js::rust::rt();
 
         let script_task = @mut ScriptTask {
-            page_tree: PageTree::new(id, layout_chan, initial_size),
+            page_tree: PageTree::new(id, layout_chan),
 
             image_cache_task: img_cache_task,
             resource_task: resource_task,
@@ -463,25 +474,33 @@ impl ScriptTask {
                   chan: ScriptChan,
                   constellation_chan: ConstellationChan,
                   resource_task: ResourceTask,
-                  image_cache_task: ImageCacheTask,
-                  initial_size: Future<Size2D<uint>>) {
-        let parms = Cell::new((compositor, layout_chan, port, chan, constellation_chan,
-                               resource_task, image_cache_task, initial_size));
+                  image_cache_task: ImageCacheTask) {
+        let parms = Cell::new((compositor,
+                               layout_chan,
+                               port,
+                               chan,
+                               constellation_chan,
+                               resource_task,
+                               image_cache_task));
         // Since SpiderMonkey is blocking it needs to run in its own thread.
         // If we don't do this then we'll just end up with a bunch of SpiderMonkeys
         // starving all the other tasks.
         do spawn_sched(SingleThreaded) {
-            let (compositor, layout_chan, port, chan, constellation_chan,
-                 resource_task, image_cache_task, initial_size) = parms.take();
+            let (compositor,
+                 layout_chan,
+                 port,
+                 chan,
+                 constellation_chan,
+                 resource_task,
+                 image_cache_task) = parms.take();
             let script_task = ScriptTask::new(id,
-                @compositor as @ScriptListener,
-                layout_chan,
-                port,
-                chan,
-                constellation_chan,
-                resource_task,
-                image_cache_task,
-                initial_size);
+                                              @compositor as @ScriptListener,
+                                              layout_chan,
+                                              port,
+                                              chan,
+                                              constellation_chan,
+                                              resource_task,
+                                              image_cache_task);
             script_task.start();
         }
     }
@@ -512,6 +531,7 @@ impl ScriptTask {
             let event = self.port.recv();
             match event {
                 ResizeMsg(id, size) => {
+                    debug!("script got resize message");
                     let page = self.page_tree.find(id).expect("resize sent to nonexistent pipeline").page;
                     page.resize_event = Some(size);
                 }
@@ -538,7 +558,10 @@ impl ScriptTask {
                 ReflowCompleteMsg(id, reflow_id) => self.handle_reflow_complete_msg(id, reflow_id),
                 ResizeInactiveMsg(id, new_size) => self.handle_resize_inactive_msg(id, new_size),
                 ExitPipelineMsg(id) => if self.handle_exit_pipeline_msg(id) { return false },
-                ExitWindowMsg(id) => if self.handle_exit_window_msg(id) { return false },
+                ExitWindowMsg(id) => {
+                    self.handle_exit_window_msg(id);
+                    return false
+                },
                 ResizeMsg(*) => fail!("should have handled ResizeMsg already"),
             }
         }
@@ -551,14 +574,13 @@ impl ScriptTask {
         let NewLayoutInfo {
             old_id,
             new_id,
-            layout_chan,
-            size_future
+            layout_chan
         } = new_layout_info;
 
         let parent_page_tree = self.page_tree.find(old_id).expect("ScriptTask: received a layout
             whose parent has a PipelineId which does not correspond to a pipeline in the script
             task's page tree. This is a bug.");
-        let new_page_tree = PageTree::new(new_id, layout_chan, size_future);
+        let new_page_tree = PageTree::new(new_id, layout_chan);
         parent_page_tree.inner.push(new_page_tree);
     }
 
@@ -612,30 +634,30 @@ impl ScriptTask {
     fn handle_resize_inactive_msg(&mut self, id: PipelineId, new_size: Size2D<uint>) {
         let page = self.page_tree.find(id).expect("Received resize message for PipelineId not associated
             with a page in the page tree. This is a bug.").page;
-        page.window_size = Future::from_value(new_size);
+        page.window_size = Some(new_size);
         let last_loaded_url = replace(&mut page.url, None);
         for url in last_loaded_url.iter() {
             page.url = Some((url.first(), true));
         }
     }
 
-    fn handle_exit_window_msg(&mut self, id: PipelineId) -> bool {
+    fn handle_exit_window_msg(&mut self, id: PipelineId) {
+        debug!("script task handling exit window msg");
         self.handle_exit_pipeline_msg(id);
 
         // 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_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() {
+                debug!("shutting down layout for root page {:?}", page.id);
                 shut_down_layout(page)
             }
             return true
@@ -645,6 +667,7 @@ impl ScriptTask {
         match self.page_tree.remove(id) {
             Some(ref mut page_tree) => {
                 for page in page_tree.iter() {
+                    debug!("shutting down layout for page {:?}", page.id);
                     shut_down_layout(page)
                 }
                 false
@@ -727,7 +750,7 @@ impl ScriptTask {
                 Some(HtmlDiscoveredStyle(sheet)) => {
                     page.layout_chan.send(AddStylesheetMsg(sheet));
                 }
-                Some(HtmlDiscoveredIFrame((iframe_url, subpage_id, size_future, sandboxed))) => {
+                Some(HtmlDiscoveredIFrame((iframe_url, subpage_id, sandboxed))) => {
                     page.next_subpage_id = SubpageId(*subpage_id + 1);
                     let sandboxed = if sandboxed {
                         IFrameSandboxed
@@ -737,7 +760,6 @@ impl ScriptTask {
                     self.constellation_chan.send(LoadIframeUrlMsg(iframe_url,
                                                                   pipeline_id,
                                                                   subpage_id,
-                                                                  size_future,
                                                                   sandboxed));
                 }
                 None => break
@@ -824,7 +846,7 @@ impl ScriptTask {
             ResizeEvent(new_width, new_height) => {
                 debug!("script got resize event: {:u}, {:u}", new_width, new_height);
 
-                page.window_size = Future::from_value(Size2D(new_width, new_height));
+                page.window_size = Some(Size2D(new_width, new_height));
 
                 if page.frame.is_some() {
                     page.damage(ReflowDocumentDamage);
@@ -906,7 +928,7 @@ impl ScriptTask {
                     None => {}
                 }
             } else {
-                self.constellation_chan.send(LoadUrlMsg(page.id, url, Future::from_value(page.window_size.get())));
+                self.constellation_chan.send(LoadUrlMsg(page.id, url));
             } 
         }
     }