Auto merge of #18310 - nnethercote:bug-1394729, r=heycam

Measure memory usage of Stylo's Rule Tree.

<!-- Please describe your changes on the following line: -->
This is for https://bugzilla.mozilla.org/show_bug.cgi?id=1394729, which was r=heycam.

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because tests exist in Gecko.

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7 files changed, 126 insertions, 10 deletions

diff --git a/components/style/gecko/data.rs b/components/style/gecko/data.rs
index 7c1bb6f68e3..67bbcc26a44 100644
--- a/components/style/gecko/data.rs
+++ b/components/style/gecko/data.rs
@@ -7,8 +7,8 @@
 use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
 use dom::TElement;
 use gecko_bindings::bindings::{self, RawServoStyleSet};
-use gecko_bindings::structs::{ServoStyleSheet, StyleSheetInfo, ServoStyleSheetInner};
-use gecko_bindings::structs::RawGeckoPresContextOwned;
+use gecko_bindings::structs::{RawGeckoPresContextOwned, ServoStyleSetSizes, ServoStyleSheet};
+use gecko_bindings::structs::{StyleSheetInfo, ServoStyleSheetInner};
 use gecko_bindings::structs::nsIDocument;
 use gecko_bindings::sugar::ownership::{HasArcFFI, HasBoxFFI, HasFFI, HasSimpleFFI};
 use invalidation::media_queries::{MediaListKey, ToMediaListKey};
@@ -16,7 +16,7 @@ use media_queries::{Device, MediaList};
 use properties::ComputedValues;
 use servo_arc::Arc;
 use shared_lock::{Locked, StylesheetGuards, SharedRwLockReadGuard};
-use stylesheets::{PerOrigin, StylesheetContents, StylesheetInDocument};
+use stylesheets::{MallocSizeOfFn, PerOrigin, StylesheetContents, StylesheetInDocument};
 use stylist::{ExtraStyleData, Stylist};
 
 /// Little wrapper to a Gecko style sheet.
@@ -184,6 +184,14 @@ impl PerDocumentStyleDataImpl {
     pub fn visited_styles_enabled(&self) -> bool {
         self.visited_links_enabled() && !self.is_private_browsing_enabled()
     }
+
+    /// Measures heap usage.
+    pub fn malloc_add_size_of_children(&self, malloc_size_of: MallocSizeOfFn,
+                                       sizes: &mut ServoStyleSetSizes) {
+        self.stylist.malloc_add_size_of_children(malloc_size_of, sizes);
+
+        // We may measure more fields in the future if DMD says it's worth it.
+    }
 }
 
 unsafe impl HasFFI for PerDocumentStyleData {
diff --git a/components/style/gecko/generated/bindings.rs b/components/style/gecko/generated/bindings.rs
index c76b1d11ce1..a0da289b765 100644
--- a/components/style/gecko/generated/bindings.rs
+++ b/components/style/gecko/generated/bindings.rs
@@ -61,6 +61,7 @@ use gecko_bindings::structs::SeenPtrs;
 use gecko_bindings::structs::ServoBundledURI;
 use gecko_bindings::structs::ServoElementSnapshot;
 use gecko_bindings::structs::ServoElementSnapshotTable;
+use gecko_bindings::structs::ServoStyleSetSizes;
 use gecko_bindings::structs::SheetParsingMode;
 use gecko_bindings::structs::StyleBasicShape;
 use gecko_bindings::structs::StyleBasicShapeType;
@@ -2068,6 +2069,11 @@ extern "C" {
      -> ServoStyleContextStrong;
 }
 extern "C" {
+    pub fn Servo_StyleSet_AddSizeOfExcludingThis(malloc_size_of: MallocSizeOf,
+                                                 sizes: *mut ServoStyleSetSizes,
+                                                 set: RawServoStyleSetBorrowed);
+}
+extern "C" {
     pub fn Servo_StyleContext_AddRef(ctx: ServoStyleContextBorrowed);
 }
 extern "C" {
diff --git a/components/style/gecko/generated/structs_debug.rs b/components/style/gecko/generated/structs_debug.rs
index ff7d3d0436d..ba87266ca7d 100644
--- a/components/style/gecko/generated/structs_debug.rs
+++ b/components/style/gecko/generated/structs_debug.rs
@@ -5456,6 +5456,38 @@ pub mod root {
                         "Alignment of field: " , stringify ! ( GeckoEffects )
                         , "::" , stringify ! ( gecko ) ));
         }
+        #[repr(C)]
+        #[derive(Debug, Copy)]
+        pub struct ServoStyleSetSizes {
+            pub mStylistRuleTree: usize,
+            pub mOther: usize,
+        }
+        #[test]
+        fn bindgen_test_layout_ServoStyleSetSizes() {
+            assert_eq!(::std::mem::size_of::<ServoStyleSetSizes>() , 16usize ,
+                       concat ! (
+                       "Size of: " , stringify ! ( ServoStyleSetSizes ) ));
+            assert_eq! (::std::mem::align_of::<ServoStyleSetSizes>() , 8usize
+                        , concat ! (
+                        "Alignment of " , stringify ! ( ServoStyleSetSizes )
+                        ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) .
+                        mStylistRuleTree as * const _ as usize } , 0usize ,
+                        concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! (
+                        mStylistRuleTree ) ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) . mOther
+                        as * const _ as usize } , 8usize , concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! ( mOther )
+                        ));
+        }
+        impl Clone for ServoStyleSetSizes {
+            fn clone(&self) -> Self { *self }
+        }
         #[repr(u8)]
         /// Enumeration that represents one of the two supported style system backends.
         #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
diff --git a/components/style/gecko/generated/structs_release.rs b/components/style/gecko/generated/structs_release.rs
index 6a7e959abc6..0f735b985d3 100644
--- a/components/style/gecko/generated/structs_release.rs
+++ b/components/style/gecko/generated/structs_release.rs
@@ -5344,6 +5344,38 @@ pub mod root {
                         "Alignment of field: " , stringify ! ( GeckoEffects )
                         , "::" , stringify ! ( gecko ) ));
         }
+        #[repr(C)]
+        #[derive(Debug, Copy)]
+        pub struct ServoStyleSetSizes {
+            pub mStylistRuleTree: usize,
+            pub mOther: usize,
+        }
+        #[test]
+        fn bindgen_test_layout_ServoStyleSetSizes() {
+            assert_eq!(::std::mem::size_of::<ServoStyleSetSizes>() , 16usize ,
+                       concat ! (
+                       "Size of: " , stringify ! ( ServoStyleSetSizes ) ));
+            assert_eq! (::std::mem::align_of::<ServoStyleSetSizes>() , 8usize
+                        , concat ! (
+                        "Alignment of " , stringify ! ( ServoStyleSetSizes )
+                        ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) .
+                        mStylistRuleTree as * const _ as usize } , 0usize ,
+                        concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! (
+                        mStylistRuleTree ) ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) . mOther
+                        as * const _ as usize } , 8usize , concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! ( mOther )
+                        ));
+        }
+        impl Clone for ServoStyleSetSizes {
+            fn clone(&self) -> Self { *self }
+        }
         #[repr(u8)]
         /// Enumeration that represents one of the two supported style system backends.
         #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
diff --git a/components/style/rule_tree/mod.rs b/components/style/rule_tree/mod.rs
index ceb94aa15f6..7e76d3b34d4 100644
--- a/components/style/rule_tree/mod.rs
+++ b/components/style/rule_tree/mod.rs
@@ -17,7 +17,7 @@ use std::io::{self, Write};
 use std::mem;
 use std::ptr;
 use std::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
-use stylesheets::StyleRule;
+use stylesheets::{MallocSizeOf, MallocSizeOfFn, StyleRule};
 use thread_state;
 
 /// The rule tree, the structure servo uses to preserve the results of selector
@@ -62,6 +62,12 @@ impl Drop for RuleTree {
     }
 }
 
+impl MallocSizeOf for RuleTree {
+    fn malloc_size_of_children(&self, malloc_size_of: MallocSizeOfFn) -> usize {
+        self.root.get().malloc_size_of_including_self(malloc_size_of)
+    }
+}
+
 /// A style source for the rule node. It can either be a CSS style rule or a
 /// declaration block.
 ///
@@ -781,6 +787,14 @@ impl RuleNode {
             }
         }
     }
+
+    fn malloc_size_of_including_self(&self, malloc_size_of: MallocSizeOfFn) -> usize {
+        let mut n = unsafe { malloc_size_of(self as *const _ as *const _) };
+        for child in self.iter_children() {
+            n += unsafe { (*child.ptr()).malloc_size_of_including_self(malloc_size_of) };
+        }
+        n
+    }
 }
 
 #[derive(Clone)]
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index d330c58cef3..3e9aea16f39 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -12,7 +12,7 @@ use dom::TElement;
 use element_state::ElementState;
 use font_metrics::FontMetricsProvider;
 #[cfg(feature = "gecko")]
-use gecko_bindings::structs::{nsIAtom, StyleRuleInclusion};
+use gecko_bindings::structs::{nsIAtom, ServoStyleSetSizes, StyleRuleInclusion};
 use invalidation::element::invalidation_map::InvalidationMap;
 use invalidation::media_queries::{EffectiveMediaQueryResults, ToMediaListKey};
 use media_queries::Device;
@@ -41,8 +41,11 @@ use style_traits::viewport::ViewportConstraints;
 use stylesheet_set::{OriginValidity, SheetRebuildKind, StylesheetSet, StylesheetIterator, StylesheetFlusher};
 #[cfg(feature = "gecko")]
 use stylesheets::{CounterStyleRule, FontFaceRule, FontFeatureValuesRule};
-use stylesheets::{CssRule, StyleRule};
-use stylesheets::{StylesheetInDocument, Origin, OriginSet, PerOrigin, PerOriginIter};
+use stylesheets::{CssRule, Origin, OriginSet, PerOrigin, PerOriginIter};
+#[cfg(feature = "gecko")]
+use stylesheets::{MallocSizeOf, MallocSizeOfFn};
+use stylesheets::StyleRule;
+use stylesheets::StylesheetInDocument;
 use stylesheets::UserAgentStylesheets;
 use stylesheets::keyframes_rule::KeyframesAnimation;
 use stylesheets::viewport_rule::{self, MaybeNew, ViewportRule};
@@ -1560,6 +1563,14 @@ impl Stylist {
     pub fn rule_tree(&self) -> &RuleTree {
         &self.rule_tree
     }
+
+    /// Measures heap usage.
+    #[cfg(feature = "gecko")]
+    pub fn malloc_add_size_of_children(&self, malloc_size_of: MallocSizeOfFn,
+                                       sizes: &mut ServoStyleSetSizes) {
+        // XXX: need to measure other fields
+        sizes.mStylistRuleTree += self.rule_tree.malloc_size_of_children(malloc_size_of);
+    }
 }
 
 /// This struct holds data which users of Stylist may want to extract
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 354bd3c194a..58ee5d3ec1f 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -77,7 +77,7 @@ use style::gecko_bindings::structs::{ServoStyleSheet, SheetParsingMode, nsIAtom,
 use style::gecko_bindings::structs::{nsCSSFontFaceRule, nsCSSCounterStyleRule};
 use style::gecko_bindings::structs::{nsRestyleHint, nsChangeHint, PropertyValuePair};
 use style::gecko_bindings::structs::IterationCompositeOperation;
-use style::gecko_bindings::structs::MallocSizeOf;
+use style::gecko_bindings::structs::MallocSizeOf as GeckoMallocSizeOf;
 use style::gecko_bindings::structs::OriginFlags;
 use style::gecko_bindings::structs::OriginFlags_Author;
 use style::gecko_bindings::structs::OriginFlags_User;
@@ -86,6 +86,7 @@ use style::gecko_bindings::structs::RawGeckoGfxMatrix4x4;
 use style::gecko_bindings::structs::RawGeckoPresContextOwned;
 use style::gecko_bindings::structs::SeenPtrs;
 use style::gecko_bindings::structs::ServoElementSnapshotTable;
+use style::gecko_bindings::structs::ServoStyleSetSizes;
 use style::gecko_bindings::structs::ServoTraversalFlags;
 use style::gecko_bindings::structs::StyleRuleInclusion;
 use style::gecko_bindings::structs::URLExtraData;
@@ -771,7 +772,7 @@ pub extern "C" fn Servo_Element_ClearData(element: RawGeckoElementBorrowed) {
 }
 
 #[no_mangle]
-pub extern "C" fn Servo_Element_SizeOfExcludingThisAndCVs(malloc_size_of: MallocSizeOf,
+pub extern "C" fn Servo_Element_SizeOfExcludingThisAndCVs(malloc_size_of: GeckoMallocSizeOf,
                                                           seen_ptrs: *mut SeenPtrs,
                                                           element: RawGeckoElementBorrowed) -> usize {
     let malloc_size_of = malloc_size_of.unwrap();
@@ -1055,7 +1056,7 @@ pub extern "C" fn Servo_StyleSheet_Clone(
 
 #[no_mangle]
 pub extern "C" fn Servo_StyleSheet_SizeOfIncludingThis(
-    malloc_size_of: MallocSizeOf,
+    malloc_size_of: GeckoMallocSizeOf,
     sheet: RawServoStyleSheetContentsBorrowed
 ) -> usize {
     let global_style_data = &*GLOBAL_STYLE_DATA;
@@ -3584,6 +3585,18 @@ pub extern "C" fn Servo_StyleSet_ResolveForDeclarations(
 }
 
 #[no_mangle]
+pub extern "C" fn Servo_StyleSet_AddSizeOfExcludingThis(
+    malloc_size_of: GeckoMallocSizeOf,
+    sizes: *mut ServoStyleSetSizes,
+    raw_data: RawServoStyleSetBorrowed
+) {
+    let data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
+    let malloc_size_of = malloc_size_of.unwrap();
+    let sizes = unsafe { sizes.as_mut() }.unwrap();
+    data.malloc_add_size_of_children(malloc_size_of, sizes);
+}
+
+#[no_mangle]
 pub extern "C" fn Servo_StyleSet_MightHaveAttributeDependency(
     raw_data: RawServoStyleSetBorrowed,
     element: RawGeckoElementBorrowed,