servo: Merge #5193 - Add memory reporting infrastructure and use it to measure the display list (from nnethercote:measure-display-list); r=jdm

These changeset implements the beginnings of fine-grained measurement of Servo's data structures.

@pcwalton, @jdm: are you likely reviewers for this?

Source-Repo: https://github.com/servo/servo
Source-Revision: f093620922621e1877393b03968ed0ce767fdf12

servo/components/compositing/compositor.rs

@@ -1348,12 +1348,8 @@ impl<Window> CompositorEventListener for IOCompositor<Window> where Window: Wind
         while self.port.try_recv_compositor_msg().is_some() {}
 
         // Tell the profiler, memory profiler, and scrolling timer to shut down.
-        let TimeProfilerChan(ref time_profiler_chan) = self.time_profiler_chan;
+        self.time_profiler_chan.send(time::TimeProfilerMsg::Exit);
-        time_profiler_chan.send(time::TimeProfilerMsg::Exit).unwrap();
+        self.memory_profiler_chan.send(memory::MemoryProfilerMsg::Exit);
-
-        let MemoryProfilerChan(ref memory_profiler_chan) = self.memory_profiler_chan;
-        memory_profiler_chan.send(memory::MemoryProfilerMsg::Exit).unwrap();
-
         self.scrolling_timer.shutdown();
     }
 

servo/components/compositing/constellation.rs

@@ -27,6 +27,7 @@ use net::resource_task;
 use net::storage_task::{StorageTask, StorageTaskMsg};
 use util::cursor::Cursor;
 use util::geometry::PagePx;
+use util::memory::MemoryProfilerChan;
 use util::opts;
 use util::task::spawn_named;
 use util::time::TimeProfilerChan;
@@ -91,6 +92,9 @@ pub struct Constellation<LTF, STF> {
     /// A channel through which messages can be sent to the time profiler.
     pub time_profiler_chan: TimeProfilerChan,
 
+    /// A channel through which messages can be sent to the memory profiler.
+    pub memory_profiler_chan: MemoryProfilerChan,
+
     pub window_size: WindowSizeData,
 }
 
@@ -167,6 +171,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                  image_cache_task: ImageCacheTask,
                  font_cache_task: FontCacheTask,
                  time_profiler_chan: TimeProfilerChan,
+                 memory_profiler_chan: MemoryProfilerChan,
                  devtools_chan: Option<DevtoolsControlChan>,
                  storage_task: StorageTask)
                  -> ConstellationChan {
@@ -191,6 +196,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                 root_frame_id: None,
                 next_frame_id: FrameId(0),
                 time_profiler_chan: time_profiler_chan,
+                memory_profiler_chan: memory_profiler_chan,
                 window_size: WindowSizeData {
                     visible_viewport: opts::get().initial_window_size.as_f32() * ScaleFactor(1.0),
                     initial_viewport: opts::get().initial_window_size.as_f32() * ScaleFactor(1.0),
@@ -240,6 +246,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                                                     self.resource_task.clone(),
                                                     self.storage_task.clone(),
                                                     self.time_profiler_chan.clone(),
+                                                    self.memory_profiler_chan.clone(),
                                                     window_size,
                                                     script_channel,
                                                     load_data);

servo/components/compositing/pipeline.rs

@@ -19,6 +19,7 @@ use net::resource_task::ResourceTask;
 use net::storage_task::StorageTask;
 use url::Url;
 use util::geometry::{PagePx};
+use util::memory::MemoryProfilerChan;
 use util::time::TimeProfilerChan;
 use std::sync::mpsc::{Receiver, channel};
 
@@ -61,6 +62,7 @@ impl Pipeline {
                            resource_task: ResourceTask,
                            storage_task: StorageTask,
                            time_profiler_chan: TimeProfilerChan,
+                           memory_profiler_chan: MemoryProfilerChan,
                            window_size: Option<WindowSizeData>,
                            script_chan: Option<ScriptControlChan>,
                            load_data: LoadData)
@@ -123,6 +125,7 @@ impl Pipeline {
 
         LayoutTaskFactory::create(None::<&mut LTF>,
                                   id,
+                                  load_data.url.clone(),
                                   layout_pair,
                                   pipeline_port,
                                   constellation_chan,
@@ -133,6 +136,7 @@ impl Pipeline {
                                   image_cache_task,
                                   font_cache_task,
                                   time_profiler_chan,
+                                  memory_profiler_chan,
                                   layout_shutdown_chan);
 
         Pipeline::new(id,

servo/components/gfx/display_list/mod.rs

@@ -37,6 +37,7 @@ use net::image::base::Image;
 use util::cursor::Cursor;
 use util::dlist as servo_dlist;
 use util::geometry::{self, Au, MAX_RECT, ZERO_RECT};
+use util::memory::SizeOf;
 use util::range::Range;
 use util::smallvec::{SmallVec, SmallVec8};
 use std::fmt;
@@ -198,6 +199,17 @@ impl DisplayList {
     }
 }
 
+impl SizeOf for DisplayList {
+    fn size_of_excluding_self(&self) -> usize {
+        self.background_and_borders.size_of_excluding_self() +
+            self.block_backgrounds_and_borders.size_of_excluding_self() +
+            self.floats.size_of_excluding_self() +
+            self.content.size_of_excluding_self() +
+            self.outlines.size_of_excluding_self() +
+            self.children.size_of_excluding_self()
+    }
+}
+
 /// Represents one CSS stacking context, which may or may not have a hardware layer.
 pub struct StackingContext {
     /// The display items that make up this stacking context.
@@ -501,6 +513,14 @@ impl StackingContext {
     }
 }
 
+impl SizeOf for StackingContext {
+    fn size_of_excluding_self(&self) -> usize {
+        self.display_list.size_of_excluding_self()
+
+        // FIXME(njn): other fields may be measured later, esp. `layer`
+    }
+}
+
 /// Returns the stacking context in the given tree of stacking contexts with a specific layer ID.
 pub fn find_stacking_context_with_layer_id(this: &Arc<StackingContext>, layer_id: LayerId)
                                            -> Option<Arc<StackingContext>> {
@@ -556,6 +576,13 @@ impl BaseDisplayItem {
     }
 }
 
+impl SizeOf for BaseDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.metadata.size_of_excluding_self() +
+            self.clip.size_of_excluding_self()
+    }
+}
+
 /// A clipping region for a display item. Currently, this can describe rectangles, rounded
 /// rectangles (for `border-radius`), or arbitrary intersections of the two. Arbitrary transforms
 /// are not supported because those are handled by the higher-level `StackingContext` abstraction.
@@ -681,6 +708,18 @@ impl ClippingRegion {
     }
 }
 
+impl SizeOf for ClippingRegion {
+    fn size_of_excluding_self(&self) -> usize {
+        self.complex.size_of_excluding_self()
+    }
+}
+
+impl SizeOf for ComplexClippingRegion {
+    fn size_of_excluding_self(&self) -> usize {
+        0
+    }
+}
+
 /// Metadata attached to each display item. This is useful for performing auxiliary tasks with
 /// the display list involving hit testing: finding the originating DOM node and determining the
 /// cursor to use when the element is hovered over.
@@ -712,6 +751,12 @@ impl DisplayItemMetadata {
     }
 }
 
+impl SizeOf for DisplayItemMetadata {
+    fn size_of_excluding_self(&self) -> usize {
+        0
+    }
+}
+
 /// Paints a solid color.
 #[derive(Clone)]
 pub struct SolidColorDisplayItem {
@@ -722,6 +767,12 @@ pub struct SolidColorDisplayItem {
     pub color: Color,
 }
 
+impl SizeOf for SolidColorDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.base.size_of_excluding_self()
+    }
+}
+
 /// Paints text.
 #[derive(Clone)]
 pub struct TextDisplayItem {
@@ -747,6 +798,13 @@ pub struct TextDisplayItem {
     pub blur_radius: Au,
 }
 
+impl SizeOf for TextDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.base.size_of_excluding_self()
+        // We exclude `text_run` because it is non-owning.
+    }
+}
+
 #[derive(Clone, Eq, PartialEq)]
 pub enum TextOrientation {
     Upright,
@@ -770,6 +828,13 @@ pub struct ImageDisplayItem {
     pub image_rendering: image_rendering::T,
 }
 
+impl SizeOf for ImageDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.base.size_of_excluding_self()
+        // We exclude `image` here because it is non-owning.
+    }
+}
+
 /// Paints a gradient.
 #[derive(Clone)]
 pub struct GradientDisplayItem {
@@ -786,6 +851,20 @@ pub struct GradientDisplayItem {
     pub stops: Vec<GradientStop>,
 }
 
+impl SizeOf for GradientDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        use libc::c_void;
+        use util::memory::heap_size_of;
+
+        // We can't measure `stops` via Vec's SizeOf implementation because GradientStop isn't
+        // defined in this module, and we don't want to import GradientStop into util::memory where
+        // the SizeOf trait is defined. So we measure the elements directly.
+        self.base.size_of_excluding_self() +
+            heap_size_of(self.stops.as_ptr() as *const c_void)
+    }
+}
+
+
 /// Paints a border.
 #[derive(Clone)]
 pub struct BorderDisplayItem {
@@ -807,6 +886,12 @@ pub struct BorderDisplayItem {
     pub radius: BorderRadii<Au>,
 }
 
+impl SizeOf for BorderDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.base.size_of_excluding_self()
+    }
+}
+
 /// Information about the border radii.
 ///
 /// TODO(pcwalton): Elliptical radii.
@@ -851,6 +936,12 @@ pub struct LineDisplayItem {
     pub style: border_style::T
 }
 
+impl SizeOf for LineDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.base.size_of_excluding_self()
+    }
+}
+
 /// Paints a box shadow per CSS-BACKGROUNDS.
 #[derive(Clone)]
 pub struct BoxShadowDisplayItem {
@@ -876,6 +967,12 @@ pub struct BoxShadowDisplayItem {
     pub clip_mode: BoxShadowClipMode,
 }
 
+impl SizeOf for BoxShadowDisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        self.base.size_of_excluding_self()
+    }
+}
+
 /// How a box shadow should be clipped.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum BoxShadowClipMode {
@@ -1038,3 +1135,17 @@ impl fmt::Debug for DisplayItem {
     }
 }
 
+impl SizeOf for DisplayItem {
+    fn size_of_excluding_self(&self) -> usize {
+        match *self {
+            SolidColorClass(ref item) => item.size_of_excluding_self(),
+            TextClass(ref item)       => item.size_of_excluding_self(),
+            ImageClass(ref item)      => item.size_of_excluding_self(),
+            BorderClass(ref item)     => item.size_of_excluding_self(),
+            GradientClass(ref item)   => item.size_of_excluding_self(),
+            LineClass(ref item)       => item.size_of_excluding_self(),
+            BoxShadowClass(ref item)  => item.size_of_excluding_self(),
+        }
+    }
+}
+

servo/components/layout/layout_task.rs

@@ -56,6 +56,8 @@ use net::resource_task::{ResourceTask, load_bytes_iter};
 use util::cursor::Cursor;
 use util::geometry::Au;
 use util::logical_geometry::LogicalPoint;
+use util::memory::{MemoryProfilerChan, MemoryProfilerMsg, MemoryReport, MemoryReportsChan};
+use util::memory::{SizeOf};
 use util::opts;
 use util::smallvec::{SmallVec, SmallVec1, VecLike};
 use util::task::spawn_named_with_send_on_failure;
@@ -117,6 +119,9 @@ pub struct LayoutTask {
     /// The ID of the pipeline that we belong to.
     pub id: PipelineId,
 
+    /// The URL of the pipeline that we belong to.
+    pub url: Url,
+
     /// The port on which we receive messages from the script task.
     pub port: Receiver<Msg>,
 
@@ -138,6 +143,12 @@ pub struct LayoutTask {
     /// The channel on which messages can be sent to the time profiler.
     pub time_profiler_chan: TimeProfilerChan,
 
+    /// The channel on which messages can be sent to the memory profiler.
+    pub memory_profiler_chan: MemoryProfilerChan,
+
+    /// The name used for the task's memory reporter.
+    pub memory_reporter_name: String,
+
     /// The channel on which messages can be sent to the resource task.
     pub resource_task: ResourceTask,
 
@@ -181,6 +192,7 @@ impl LayoutTaskFactory for LayoutTask {
     /// Spawns a new layout task.
     fn create(_phantom: Option<&mut LayoutTask>,
                   id: PipelineId,
+                  url: Url,
                   chan: OpaqueScriptLayoutChannel,
                   pipeline_port: Receiver<LayoutControlMsg>,
                   constellation_chan: ConstellationChan,
@@ -191,6 +203,7 @@ impl LayoutTaskFactory for LayoutTask {
                   img_cache_task: ImageCacheTask,
                   font_cache_task: FontCacheTask,
                   time_profiler_chan: TimeProfilerChan,
+                  memory_profiler_chan: MemoryProfilerChan,
                   shutdown_chan: Sender<()>) {
         let ConstellationChan(con_chan) = constellation_chan.clone();
         spawn_named_with_send_on_failure("LayoutTask", task_state::LAYOUT, move || {
@@ -199,6 +212,7 @@ impl LayoutTaskFactory for LayoutTask {
                 let layout =
                     LayoutTask::new(
                         id,
+                        url,
                         chan.receiver(),
                         LayoutChan(sender),
                         pipeline_port,
@@ -208,7 +222,8 @@ impl LayoutTaskFactory for LayoutTask {
                         resource_task,
                         img_cache_task,
                         font_cache_task,
-                        time_profiler_chan);
+                        time_profiler_chan,
+                        memory_profiler_chan);
                 layout.start();
             }
             shutdown_chan.send(()).unwrap();
@@ -249,6 +264,7 @@ impl<'a> DerefMut for RWGuard<'a> {
 impl LayoutTask {
     /// Creates a new `LayoutTask` structure.
     fn new(id: PipelineId,
+           url: Url,
            port: Receiver<Msg>,
            chan: LayoutChan,
            pipeline_port: Receiver<LayoutControlMsg>,
@@ -258,7 +274,8 @@ impl LayoutTask {
            resource_task: ResourceTask,
            image_cache_task: ImageCacheTask,
            font_cache_task: FontCacheTask,
-           time_profiler_chan: TimeProfilerChan)
+           time_profiler_chan: TimeProfilerChan,
+           memory_profiler_chan: MemoryProfilerChan)
            -> LayoutTask {
         let local_image_cache =
             Arc::new(Mutex::new(LocalImageCache::new(image_cache_task.clone())));
@@ -271,8 +288,15 @@ impl LayoutTask {
             None
         };
 
+        // Register this thread as a memory reporter, via its own channel.
+        let reporter = Box::new(chan.clone());
+        let reporter_name = format!("layout-reporter-{}", id.0);
+        memory_profiler_chan.send(MemoryProfilerMsg::RegisterMemoryReporter(reporter_name.clone(),
+                                                                            reporter));
+
         LayoutTask {
             id: id,
+            url: url,
             port: port,
             pipeline_port: pipeline_port,
             chan: chan,
@@ -280,6 +304,8 @@ impl LayoutTask {
             constellation_chan: constellation_chan.clone(),
             paint_chan: paint_chan,
             time_profiler_chan: time_profiler_chan,
+            memory_profiler_chan: memory_profiler_chan,
+            memory_reporter_name: reporter_name,
             resource_task: resource_task,
             image_cache_task: image_cache_task.clone(),
             font_cache_task: font_cache_task,
@@ -361,13 +387,13 @@ impl LayoutTask {
             PortToRead::Pipeline => {
                 match self.pipeline_port.recv().unwrap() {
                     LayoutControlMsg::ExitNowMsg(exit_type) => {
-                        self.handle_script_request(Msg::ExitNow(exit_type), possibly_locked_rw_data)
+                        self.handle_request_helper(Msg::ExitNow(exit_type), possibly_locked_rw_data)
                     }
                 }
             },
             PortToRead::Script => {
                 let msg = self.port.recv().unwrap();
-                self.handle_script_request(msg, possibly_locked_rw_data)
+                self.handle_request_helper(msg, possibly_locked_rw_data)
             }
         }
     }
@@ -398,8 +424,8 @@ impl LayoutTask {
         }
     }
 
-    /// Receives and dispatches messages from the script task.
+    /// Receives and dispatches messages from other tasks.
-    fn handle_script_request<'a>(&'a self,
+    fn handle_request_helper<'a>(&'a self,
                                  request: Msg,
                                  possibly_locked_rw_data: &mut Option<MutexGuard<'a,
                                                                                  LayoutTaskData>>)
@@ -423,6 +449,9 @@ impl LayoutTask {
                     self.handle_reap_layout_data(dead_layout_data)
                 }
             },
+            Msg::CollectMemoryReports(reports_chan) => {
+                self.collect_memory_reports(reports_chan, possibly_locked_rw_data);
+            },
             Msg::PrepareToExit(response_chan) => {
                 debug!("layout: PrepareToExitMsg received");
                 self.prepare_to_exit(response_chan, possibly_locked_rw_data);
@@ -438,6 +467,23 @@ impl LayoutTask {
         true
     }
 
+    fn collect_memory_reports<'a>(&'a self,
+                                  reports_chan: MemoryReportsChan,
+                                  possibly_locked_rw_data:
+                                      &mut Option<MutexGuard<'a, LayoutTaskData>>) {
+        let mut reports = vec![];
+
+        // FIXME(njn): Just measuring the display tree for now.
+        let rw_data = self.lock_rw_data(possibly_locked_rw_data);
+        let stacking_context = rw_data.stacking_context.as_ref();
+        reports.push(MemoryReport {
+            name: format!("display-list::{}", self.url),
+            size: stacking_context.map_or(0, |sc| sc.size_of_excluding_self() as u64),
+        });
+
+        reports_chan.send(reports);
+    }
+
     /// Enters a quiescent state in which no new messages except for `layout_interface::Msg::ReapLayoutData` will be
     /// processed until an `ExitNowMsg` is received. A pong is immediately sent on the given
     /// response channel.
@@ -481,6 +527,10 @@ impl LayoutTask {
             LayoutTask::return_rw_data(possibly_locked_rw_data, rw_data);
         }
 
+        let unregister_msg =
+            MemoryProfilerMsg::UnregisterMemoryReporter(self.memory_reporter_name.clone());
+        self.memory_profiler_chan.send(unregister_msg);
+
         self.paint_chan.send(PaintMsg::Exit(Some(response_chan), exit_type));
         response_port.recv().unwrap()
     }

servo/components/layout_traits/Cargo.toml

@@ -21,3 +21,6 @@ path = "../net"
 
 [dependencies.util]
 path = "../util"
+
+[dependencies]
+url = "0.2.16"

servo/components/layout_traits/lib.rs

@@ -8,6 +8,7 @@ extern crate gfx;
 extern crate script_traits;
 extern crate msg;
 extern crate net;
+extern crate url;
 extern crate util;
 
 // This module contains traits in layout used generically
@@ -20,6 +21,8 @@ use gfx::paint_task::PaintChan;
 use msg::constellation_msg::{ConstellationChan, Failure, PipelineId, PipelineExitType};
 use net::image_cache_task::ImageCacheTask;
 use net::resource_task::ResourceTask;
+use url::Url;
+use util::memory::MemoryProfilerChan;
 use util::time::TimeProfilerChan;
 use script_traits::{ScriptControlChan, OpaqueScriptLayoutChannel};
 use std::sync::mpsc::{Sender, Receiver};
@@ -38,6 +41,7 @@ pub trait LayoutTaskFactory {
     // FIXME: use a proper static method
     fn create(_phantom: Option<&mut Self>,
               id: PipelineId,
+              url: Url,
               chan: OpaqueScriptLayoutChannel,
               pipeline_port: Receiver<LayoutControlMsg>,
               constellation_chan: ConstellationChan,
@@ -48,5 +52,6 @@ pub trait LayoutTaskFactory {
               img_cache_task: ImageCacheTask,
               font_cache_task: FontCacheTask,
               time_profiler_chan: TimeProfilerChan,
+              memory_profiler_chan: MemoryProfilerChan,
               shutdown_chan: Sender<()>);
 }

servo/components/script/layout_interface.rs

@@ -13,6 +13,7 @@ use geom::rect::Rect;
 use script_traits::{ScriptControlChan, OpaqueScriptLayoutChannel, UntrustedNodeAddress};
 use msg::constellation_msg::{PipelineExitType, WindowSizeData};
 use util::geometry::Au;
+use util::memory::{MemoryReporter, MemoryReportsChan};
 use std::any::Any;
 use std::sync::mpsc::{channel, Receiver, Sender};
 use std::boxed::BoxAny;
@@ -44,6 +45,10 @@ pub enum Msg {
     /// TODO(pcwalton): Maybe think about batching to avoid message traffic.
     ReapLayoutData(LayoutData),
 
+    /// Requests that the layout task measure its memory usage. The resulting reports are sent back
+    /// via the supplied channel.
+    CollectMemoryReports(MemoryReportsChan),
+
     /// Requests that the layout task enter a quiescent state in which no more messages are
     /// accepted except `ExitMsg`. A response message will be sent on the supplied channel when
     /// this happens.
@@ -128,6 +133,14 @@ impl LayoutChan {
     }
 }
 
+impl MemoryReporter for LayoutChan {
+    // Just injects an appropriate event into the layout task's queue.
+    fn collect_reports(&self, reports_chan: MemoryReportsChan) -> bool {
+        let LayoutChan(ref c) = *self;
+        c.send(Msg::CollectMemoryReports(reports_chan)).is_ok()
+    }
+}
+
 /// A trait to manage opaque references to script<->layout channels without needing
 /// to expose the message type to crates that don't need to know about them.
 pub trait ScriptLayoutChan {

servo/components/servo/Cargo.lock

@@ -534,6 +534,7 @@ dependencies = [
  "msg 0.0.1",
  "net 0.0.1",
  "script_traits 0.0.1",
+ "url 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "util 0.0.1",
 ]
 

servo/components/servo/lib.rs

@@ -82,6 +82,7 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
 
         let opts_clone = opts.clone();
         let time_profiler_chan_clone = time_profiler_chan.clone();
+        let memory_profiler_chan_clone = memory_profiler_chan.clone();
 
         let (result_chan, result_port) = channel();
         let compositor_proxy_for_constellation = compositor_proxy.clone_compositor_proxy();
@@ -109,6 +110,7 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
                                                           image_cache_task,
                                                           font_cache_task,
                                                           time_profiler_chan_clone,
+                                                          memory_profiler_chan_clone,
                                                           devtools_chan,
                                                           storage_task);
 

servo/components/util/memory.rs

@@ -6,20 +6,175 @@
 
 use libc::{c_char,c_int,c_void,size_t};
 use std::borrow::ToOwned;
+use std::collections::{DList, HashMap};
 use std::ffi::CString;
 #[cfg(target_os = "linux")]
 use std::iter::AdditiveIterator;
 use std::old_io::timer::sleep;
 #[cfg(target_os="linux")]
 use std::old_io::File;
-use std::mem::size_of;
+use std::mem::{size_of, transmute};
 use std::ptr::null_mut;
+use std::sync::Arc;
 use std::sync::mpsc::{Sender, channel, Receiver};
 use std::time::duration::Duration;
 use task::spawn_named;
 #[cfg(target_os="macos")]
 use task_info::task_basic_info::{virtual_size,resident_size};
 
+extern {
+    // Get the size of a heap block.
+    //
+    // Ideally Rust would expose a function like this in std::rt::heap, which would avoid the
+    // jemalloc dependence.
+    //
+    // The C prototype is `je_malloc_usable_size(JEMALLOC_USABLE_SIZE_CONST void *ptr)`. On some
+    // platforms `JEMALLOC_USABLE_SIZE_CONST` is `const` and on some it is empty. But in practice
+    // this function doesn't modify the contents of the block that `ptr` points to, so we use
+    // `*const c_void` here.
+    fn je_malloc_usable_size(ptr: *const c_void) -> size_t;
+}
+
+// A wrapper for je_malloc_usable_size that handles `EMPTY` and returns `usize`.
+pub fn heap_size_of(ptr: *const c_void) -> usize {
+    if ptr == ::std::rt::heap::EMPTY as *const c_void {
+        0
+    } else {
+        unsafe { je_malloc_usable_size(ptr) as usize }
+    }
+}
+
+// The simplest trait for measuring the size of heap data structures. More complex traits that
+// return multiple measurements -- e.g. measure text separately from images -- are also possible,
+// and should be used when appropriate.
+//
+// FIXME(njn): it would be nice to be able to derive this trait automatically, given that
+// implementations are mostly repetitive and mechanical.
+//
+pub trait SizeOf {
+    /// Measure the size of any heap-allocated structures that hang off this value, but not the
+    /// space taken up by the value itself (i.e. what size_of::<T> measures, more or less); that
+    /// space is handled by the implementation of SizeOf for Box<T> below.
+    fn size_of_excluding_self(&self) -> usize;
+}
+
+// There are two possible ways to measure the size of `self` when it's on the heap: compute it
+// (with `::std::rt::heap::usable_size(::std::mem::size_of::<T>(), 0)`) or measure it directly
+// using the heap allocator (with `heap_size_of`). We do the latter, for the following reasons.
+//
+// * The heap allocator is the true authority for the sizes of heap blocks; its measurement is
+//   guaranteed to be correct. In comparison, size computations are error-prone. (For example, the
+//   `rt::heap::usable_size` function used in some of Rust's non-default allocator implementations
+//   underestimate the true usable size of heap blocks, which is safe in general but would cause
+//   under-measurement here.)
+//
+// * If we measure something that isn't a heap block, we'll get a crash. This keeps us honest,
+//   which is important because unsafe code is involved and this can be gotten wrong.
+//
+// However, in the best case, the two approaches should give the same results.
+//
+impl<T: SizeOf> SizeOf for Box<T> {
+    fn size_of_excluding_self(&self) -> usize {
+        // Measure size of `self`.
+        heap_size_of(&**self as *const T as *const c_void) + (**self).size_of_excluding_self()
+    }
+}
+
+impl SizeOf for String {
+    fn size_of_excluding_self(&self) -> usize {
+        heap_size_of(self.as_ptr() as *const c_void)
+    }
+}
+
+impl<T: SizeOf> SizeOf for Option<T> {
+    fn size_of_excluding_self(&self) -> usize {
+        match *self {
+            None => 0,
+            Some(ref x) => x.size_of_excluding_self()
+        }
+    }
+}
+
+impl<T: SizeOf> SizeOf for Arc<T> {
+    fn size_of_excluding_self(&self) -> usize {
+        (**self).size_of_excluding_self()
+    }
+}
+
+impl<T: SizeOf> SizeOf for Vec<T> {
+    fn size_of_excluding_self(&self) -> usize {
+        heap_size_of(self.as_ptr() as *const c_void) +
+            self.iter().fold(0, |n, elem| n + elem.size_of_excluding_self())
+    }
+}
+
+// FIXME(njn): We can't implement SizeOf accurately for DList because it requires access to the
+// private Node type. Eventually we'll want to add SizeOf (or equivalent) to Rust itself. In the
+// meantime, we use the dirty hack of transmuting DList into an identical type (DList2) and
+// measuring that.
+impl<T: SizeOf> SizeOf for DList<T> {
+    fn size_of_excluding_self(&self) -> usize {
+        let list2: &DList2<T> = unsafe { transmute(self) };
+        list2.size_of_excluding_self()
+    }
+}
+
+struct DList2<T> {
+    _length: usize,
+    list_head: Link<T>,
+    _list_tail: Rawlink<Node<T>>,
+}
+
+type Link<T> = Option<Box<Node<T>>>;
+
+struct Rawlink<T> {
+    _p: *mut T,
+}
+
+struct Node<T> {
+    next: Link<T>,
+    _prev: Rawlink<Node<T>>,
+    value: T,
+}
+
+impl<T: SizeOf> SizeOf for Node<T> {
+    // Unlike most size_of_excluding_self() functions, this one does *not* measure descendents.
+    // Instead, DList2<T>::size_of_excluding_self() handles that, so that it can use iteration
+    // instead of recursion, which avoids potentially blowing the stack.
+    fn size_of_excluding_self(&self) -> usize {
+        self.value.size_of_excluding_self()
+    }
+}
+
+impl<T: SizeOf> SizeOf for DList2<T> {
+    fn size_of_excluding_self(&self) -> usize {
+        let mut size = 0;
+        let mut curr: &Link<T> = &self.list_head;
+        while curr.is_some() {
+            size += (*curr).size_of_excluding_self();
+            curr = &curr.as_ref().unwrap().next;
+        }
+        size
+    }
+}
+
+// This is a basic sanity check. If the representation of DList changes such that it becomes a
+// different size to DList2, this will fail at compile-time.
+#[allow(dead_code)]
+unsafe fn dlist2_check() {
+    transmute::<DList<i32>, DList2<i32>>(panic!());
+}
+
+// Currently, types that implement the Drop type are larger than those that don't. Because DList
+// implements Drop, DList2 must also so that dlist2_check() doesn't fail.
+#[unsafe_destructor]
+impl<T> Drop for DList2<T> {
+    fn drop(&mut self) {}
+}
+
+//---------------------------------------------------------------------------
+
+#[derive(Clone)]
 pub struct MemoryProfilerChan(pub Sender<MemoryProfilerMsg>);
 
 impl MemoryProfilerChan {
@@ -29,62 +184,98 @@ impl MemoryProfilerChan {
     }
 }
 
+pub struct MemoryReport {
+    /// The identifying name for this report.
+    pub name: String,
+
+    /// The size, in bytes.
+    pub size: u64,
+}
+
+/// A channel through which memory reports can be sent.
+#[derive(Clone)]
+pub struct MemoryReportsChan(pub Sender<Vec<MemoryReport>>);
+
+impl MemoryReportsChan {
+    pub fn send(&self, report: Vec<MemoryReport>) {
+        let MemoryReportsChan(ref c) = *self;
+        c.send(report).unwrap();
+    }
+}
+
+/// A memory reporter is capable of measuring some data structure of interest. Because it needs
+/// to be passed to and registered with the MemoryProfiler, it's typically a "small" (i.e. easily
+/// cloneable) value that provides access to a "large" data structure, e.g. a channel that can
+/// inject a request for measurements into the event queue associated with the "large" data
+/// structure.
+pub trait MemoryReporter {
+    /// Collect one or more memory reports. Returns true on success, and false on failure.
+    fn collect_reports(&self, reports_chan: MemoryReportsChan) -> bool;
+}
+
+/// Messages that can be sent to the memory profiler thread.
 pub enum MemoryProfilerMsg {
-    /// Message used to force print the memory profiling metrics.
+    /// Register a MemoryReporter with the memory profiler. The String is only used to identify the
+    /// reporter so it can be unregistered later. The String must be distinct from that used by any
+    /// other registered reporter otherwise a panic will occur.
+    RegisterMemoryReporter(String, Box<MemoryReporter + Send>),
+
+    /// Unregister a MemoryReporter with the memory profiler. The String must match the name given
+    /// when the reporter was registered. If the String does not match the name of a registered
+    /// reporter a panic will occur.
+    UnregisterMemoryReporter(String),
+
+    /// Triggers printing of the memory profiling metrics.
     Print,
+
     /// Tells the memory profiler to shut down.
     Exit,
 }
 
 pub struct MemoryProfiler {
+    /// The port through which messages are received.
     pub port: Receiver<MemoryProfilerMsg>,
+
+    /// Registered memory reporters.
+    reporters: HashMap<String, Box<MemoryReporter + Send>>,
 }
 
 impl MemoryProfiler {
     pub fn create(period: Option<f64>) -> MemoryProfilerChan {
         let (chan, port) = channel();
-        match period {
+
-            Some(period) => {
+        // Create the timer thread if a period was provided.
-                let period = Duration::milliseconds((period * 1000f64) as i64);
+        if let Some(period) = period {
+            let period_ms = Duration::milliseconds((period * 1000f64) as i64);
             let chan = chan.clone();
             spawn_named("Memory profiler timer".to_owned(), move || {
                 loop {
-                        sleep(period);
+                    sleep(period_ms);
                     if chan.send(MemoryProfilerMsg::Print).is_err() {
                         break;
                     }
                 }
             });
-                // Spawn the memory profiler.
+        }
+
+        // Always spawn the memory profiler. If there is no timer thread it won't receive regular
+        // `Print` events, but it will still receive the other events.
         spawn_named("Memory profiler".to_owned(), move || {
-                    let memory_profiler = MemoryProfiler::new(port);
+            let mut memory_profiler = MemoryProfiler::new(port);
             memory_profiler.start();
         });
-            }
-            None => {
-                // No-op to handle messages when the memory profiler is
-                // inactive.
-                spawn_named("Memory profiler".to_owned(), move || {
-                    loop {
-                        match port.recv() {
-                            Err(_) | Ok(MemoryProfilerMsg::Exit) => break,
-                            _ => {}
-                        }
-                    }
-                });
-            }
-        }
 
         MemoryProfilerChan(chan)
     }
 
     pub fn new(port: Receiver<MemoryProfilerMsg>) -> MemoryProfiler {
         MemoryProfiler {
-            port: port
+            port: port,
+            reporters: HashMap::new(),
         }
     }
 
-    pub fn start(&self) {
+    pub fn start(&mut self) {
         loop {
             match self.port.recv() {
                Ok(msg) => {
@@ -97,12 +288,33 @@ impl MemoryProfiler {
         }
     }
 
-    fn handle_msg(&self, msg: MemoryProfilerMsg) -> bool {
+    fn handle_msg(&mut self, msg: MemoryProfilerMsg) -> bool {
         match msg {
+            MemoryProfilerMsg::RegisterMemoryReporter(name, reporter) => {
+                // Panic if it has already been registered.
+                let name_clone = name.clone();
+                match self.reporters.insert(name, reporter) {
+                    None => true,
+                    Some(_) =>
+                        panic!(format!("RegisterMemoryReporter: '{}' name is already in use",
+                                       name_clone)),
+                }
+            },
+
+            MemoryProfilerMsg::UnregisterMemoryReporter(name) => {
+                // Panic if it hasn't previously been registered.
+                match self.reporters.remove(&name) {
+                    Some(_) => true,
+                    None =>
+                        panic!(format!("UnregisterMemoryReporter: '{}' name is unknown", &name)),
+                }
+            },
+
             MemoryProfilerMsg::Print => {
                 self.handle_print_msg();
                 true
             },
+
             MemoryProfilerMsg::Exit => false
         }
     }
@@ -120,8 +332,11 @@ impl MemoryProfiler {
     }
 
     fn handle_print_msg(&self) {
+
         println!("{:12}: {}", "_size (MiB)_", "_category_");
 
+        // Collect global measurements from the OS and heap allocators.
+
         // Virtual and physical memory usage, as reported by the OS.
         MemoryProfiler::print_measurement("vsize", get_vsize());
         MemoryProfiler::print_measurement("resident", get_resident());
@@ -154,6 +369,24 @@ impl MemoryProfiler {
         MemoryProfiler::print_measurement("jemalloc-heap-mapped",
                                           get_jemalloc_stat("stats.mapped"));
 
+        // Collect reports from memory reporters.
+
+        // This serializes the report-gathering. It might be worth creating a new scoped thread for
+        // each reporter once we have enough of them.
+        //
+        // If anything goes wrong with a reporter, we just skip it.
+        for reporter in self.reporters.values() {
+            let (chan, port) = channel();
+            if reporter.collect_reports(MemoryReportsChan(chan)) {
+                if let Ok(reports) = port.recv() {
+                    for report in reports {
+                        MemoryProfiler::print_measurement(report.name.as_slice(),
+                                                          Some(report.size));
+                    }
+                }
+            }
+        }
+
         println!("");
     }
 }

servo/ports/cef/Cargo.lock

@@ -542,6 +542,7 @@ dependencies = [
  "msg 0.0.1",
  "net 0.0.1",
  "script_traits 0.0.1",
+ "url 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "util 0.0.1",
 ]
 

servo/ports/gonk/Cargo.lock

@@ -453,6 +453,7 @@ dependencies = [
  "msg 0.0.1",
  "net 0.0.1",
  "script_traits 0.0.1",
+ "url 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "util 0.0.1",
 ]
 

servo/ports/gonk/src/lib.rs

@@ -86,6 +86,7 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
 
         let opts_clone = opts.clone();
         let time_profiler_chan_clone = time_profiler_chan.clone();
+        let memory_profiler_chan_clone = memory_profiler_chan.clone();
 
         let (result_chan, result_port) = channel();
         let compositor_proxy_for_constellation = compositor_proxy.clone_compositor_proxy();
@@ -113,6 +114,7 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
                                                           image_cache_task,
                                                           font_cache_task,
                                                           time_profiler_chan_clone,
+                                                          memory_profiler_chan_clone,
                                                           devtools_chan,
                                                           storage_task);