Wire up the JS engine's memory reporting.

SpiderMonkey provides an extremely fine-grained breakdown of memory
usage, but for Servo we aggregate the measurements into a small number
of coarse buckets, which seems appropriate for the current level of
detail provided by Servo's memory profiler. Sample output:
```
|   10.99 MiB -- pages
|       7.75 MiB -- url(http://html5demos.com/worker)
|          4.63 MiB -- js
|             2.00 MiB -- gc-heap
|                0.94 MiB -- decommitted
|                0.92 MiB -- used
|                0.09 MiB -- unused
|                0.05 MiB -- admin
|             1.44 MiB -- malloc-heap
|             1.19 MiB -- non-heap
|          [...]
|       3.24 MiB -- url(http://html5demos.com/js/worker-cruncher.js)
|          3.24 MiB -- js
|             1.17 MiB -- malloc-heap
|             1.06 MiB -- non-heap
|             1.00 MiB -- gc-heap
|                0.69 MiB -- used
|                0.19 MiB -- decommitted
|                0.09 MiB -- unused
|                0.03 MiB -- admin
```
Most of the changes are plumbing to get the script and worker tasks
communicating with the memory profiler task.

1 files changed, 78 insertions, 5 deletions

diff --git a/components/script/script_task.rs b/components/script/script_task.rs
index d079d9f3e75..b1f7357a613 100644
--- a/components/script/script_task.rs
+++ b/components/script/script_task.rs
@@ -70,6 +70,7 @@ use net_traits::{ResourceTask, LoadConsumer, ControlMsg, Metadata};
 use net_traits::LoadData as NetLoadData;
 use net_traits::image_cache_task::{ImageCacheChan, ImageCacheTask, ImageCacheResult};
 use net_traits::storage_task::StorageTask;
+use profile_traits::mem::{self, Report, Reporter, ReportsChan};
 use string_cache::Atom;
 use util::str::DOMString;
 use util::task::spawn_named_with_send_on_failure;
@@ -78,9 +79,10 @@ use util::task_state;
 use euclid::Rect;
 use euclid::point::Point2D;
 use hyper::header::{LastModified, Headers};
+use js::glue::CollectServoSizes;
 use js::jsapi::{JS_SetWrapObjectCallbacks, JS_AddExtraGCRootsTracer, DisableIncrementalGC};
 use js::jsapi::{JSContext, JSRuntime, JSTracer};
-use js::jsapi::{JS_SetGCCallback, JSGCStatus, JSAutoRequest, SetDOMCallbacks};
+use js::jsapi::{JS_GetRuntime, JS_SetGCCallback, JSGCStatus, JSAutoRequest, SetDOMCallbacks};
 use js::jsapi::{SetDOMProxyInformation, DOMProxyShadowsResult, HandleObject, HandleId, RootedValue};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
@@ -91,7 +93,7 @@ use std::any::Any;
 use std::borrow::ToOwned;
 use std::cell::{Cell, RefCell};
 use std::collections::HashSet;
-use std::mem;
+use std::mem as std_mem;
 use std::option::Option;
 use std::ptr;
 use std::rc::Rc;
@@ -196,6 +198,9 @@ pub enum ScriptMsg {
     RefcountCleanup(TrustedReference),
     /// Notify a document that all pending loads are complete.
     DocumentLoadsComplete(PipelineId),
+    /// Requests that the script task measure its memory usage. The results are sent back via the
+    /// supplied channel.
+    CollectReports(ReportsChan),
 }
 
 /// A cloneable interface for communicating with an event loop.
@@ -247,6 +252,18 @@ impl NonWorkerScriptChan {
         let (chan, port) = channel();
         (port, box NonWorkerScriptChan(chan))
     }
+
+    fn clone_as_reporter(&self) -> Box<Reporter+Send> {
+        let NonWorkerScriptChan(ref chan) = *self;
+        box NonWorkerScriptChan((*chan).clone())
+    }
+}
+
+impl Reporter for NonWorkerScriptChan {
+    // Just injects an appropriate event into the script task's queue.
+    fn collect_reports(&self, reports_chan: ReportsChan) -> bool {
+        self.send(ScriptMsg::CollectReports(reports_chan)).is_ok()
+    }
 }
 
 pub struct StackRootTLS;
@@ -307,6 +324,9 @@ pub struct ScriptTask {
     /// The channel on which the image cache can send messages to ourself.
     image_cache_channel: ImageCacheChan,
 
+    /// For providing contact with the memory profiler.
+    mem_profiler_chan: mem::ProfilerChan,
+
     /// For providing instructions to an optional devtools server.
     devtools_chan: Option<DevtoolsControlChan>,
     /// For receiving commands from an optional devtools server. Will be ignored if
@@ -387,6 +407,7 @@ impl ScriptTaskFactory for ScriptTask {
               resource_task: ResourceTask,
               storage_task: StorageTask,
               image_cache_task: ImageCacheTask,
+              mem_profiler_chan: mem::ProfilerChan,
               devtools_chan: Option<DevtoolsControlChan>,
               window_size: Option<WindowSizeData>,
               load_data: LoadData) {
@@ -396,15 +417,18 @@ impl ScriptTaskFactory for ScriptTask {
         spawn_named_with_send_on_failure(format!("ScriptTask {:?}", id), task_state::SCRIPT, move || {
             let roots = RootCollection::new();
             let _stack_roots_tls = StackRootTLS::new(&roots);
+            let chan = NonWorkerScriptChan(script_chan);
+            let reporter = chan.clone_as_reporter();
             let script_task = ScriptTask::new(compositor,
                                               script_port,
-                                              NonWorkerScriptChan(script_chan),
+                                              chan,
                                               control_chan,
                                               control_port,
                                               constellation_chan,
                                               resource_task,
                                               storage_task,
                                               image_cache_task,
+                                              mem_profiler_chan.clone(),
                                               devtools_chan);
 
             SCRIPT_TASK_ROOT.with(|root| {
@@ -417,8 +441,17 @@ impl ScriptTaskFactory for ScriptTask {
                                                load_data.url.clone());
             script_task.start_page_load(new_load, load_data);
 
+            // Register this task as a memory reporter.
+            let reporter_name = format!("script-reporter-{}", id.0);
+            let msg = mem::ProfilerMsg::RegisterReporter(reporter_name.clone(), reporter);
+            mem_profiler_chan.send(msg);
+
             script_task.start();
 
+            // Unregister this task as a memory reporter.
+            let msg = mem::ProfilerMsg::UnregisterReporter(reporter_name);
+            mem_profiler_chan.send(msg);
+
             // This must always be the very last operation performed before the task completes
             failsafe.neuter();
         }, ConstellationMsg::Failure(failure_msg), const_chan);
@@ -473,6 +506,7 @@ impl ScriptTask {
                resource_task: ResourceTask,
                storage_task: StorageTask,
                image_cache_task: ImageCacheTask,
+               mem_profiler_chan: mem::ProfilerChan,
                devtools_chan: Option<DevtoolsControlChan>)
                -> ScriptTask {
         let runtime = ScriptTask::new_rt_and_cx();
@@ -502,6 +536,8 @@ impl ScriptTask {
             control_port: control_port,
             constellation_chan: constellation_chan,
             compositor: DOMRefCell::new(compositor),
+            mem_profiler_chan: mem_profiler_chan,
+
             devtools_chan: devtools_chan,
             devtools_port: devtools_receiver,
             devtools_sender: devtools_sender,
@@ -783,6 +819,8 @@ impl ScriptTask {
                 LiveDOMReferences::cleanup(addr),
             ScriptMsg::DocumentLoadsComplete(id) =>
                 self.handle_loads_complete(id),
+            ScriptMsg::CollectReports(reports_chan) =>
+                self.collect_reports(reports_chan),
         }
     }
 
@@ -989,6 +1027,40 @@ impl ScriptTask {
         chan.send(ConstellationMsg::LoadComplete(pipeline)).unwrap();
     }
 
+    pub fn get_reports(cx: *mut JSContext, path_seg: String) -> Vec<Report> {
+        let mut reports = vec![];
+
+        unsafe {
+            let rt = JS_GetRuntime(cx);
+            let mut stats = ::std::mem::zeroed();
+            if CollectServoSizes(rt, &mut stats) {
+                let mut report = |mut path_suffix, size| {
+                    let mut path = path!["pages", path_seg, "js"];
+                    path.append(&mut path_suffix);
+                    reports.push(Report { path: path, size: size as usize })
+                };
+
+                report(path!["gc-heap", "used"], stats.gcHeapUsed);
+                report(path!["gc-heap", "unused"], stats.gcHeapUnused);
+                report(path!["gc-heap", "admin"], stats.gcHeapAdmin);
+                report(path!["gc-heap", "decommitted"], stats.gcHeapDecommitted);
+                report(path!["malloc-heap"], stats.mallocHeap);
+                report(path!["non-heap"], stats.nonHeap);
+            }
+        }
+        reports
+    }
+
+    fn collect_reports(&self, reports_chan: ReportsChan) {
+        let mut urls = vec![];
+        for it_page in self.root_page().iter() {
+            urls.push(it_page.document().url().serialize());
+        }
+        let path_seg = format!("url({})", urls.connect(", "));
+        let reports = ScriptTask::get_reports(self.get_cx(), path_seg);
+        reports_chan.send(reports);
+    }
+
     /// Handles a timer that fired.
     fn handle_fire_timer_msg(&self, id: PipelineId, timer_id: TimerId) {
         let page = self.root_page();
@@ -1287,6 +1359,7 @@ impl ScriptTask {
                                  self.image_cache_task.clone(),
                                  self.resource_task.clone(),
                                  self.storage_task.clone(),
+                                 self.mem_profiler_chan.clone(),
                                  self.devtools_chan.clone(),
                                  self.constellation_chan.clone(),
                                  incomplete.layout_chan,
@@ -1429,9 +1502,9 @@ impl ScriptTask {
                 // We temporarily steal the list of targets over which the mouse is to pass it to
                 // handle_mouse_move_event() in a safe RootedVec container.
                 let mut mouse_over_targets = RootedVec::new();
-                mem::swap(&mut *self.mouse_over_targets.borrow_mut(), &mut *mouse_over_targets);
+                std_mem::swap(&mut *self.mouse_over_targets.borrow_mut(), &mut *mouse_over_targets);
                 document.r().handle_mouse_move_event(self.js_runtime.rt(), point, &mut mouse_over_targets);
-                mem::swap(&mut *self.mouse_over_targets.borrow_mut(), &mut *mouse_over_targets);
+                std_mem::swap(&mut *self.mouse_over_targets.borrow_mut(), &mut *mouse_over_targets);
             }
 
             KeyEvent(key, state, modifiers) => {