Remove the extra level of GeckoDeclarationBlock.

components/style/gecko/conversions.rs

@@ -9,10 +9,11 @@
 #![allow(unsafe_code)]
 
 use app_units::Au;
-use gecko_bindings::bindings::{RawServoStyleSheet, ServoComputedValues};
+use gecko_bindings::bindings::{RawServoStyleSheet, ServoComputedValues, RawServoDeclarationBlock};
 use gecko_bindings::structs::nsStyleCoord_CalcValue;
 use gecko_bindings::sugar::ownership::{HasArcFFI, HasFFI};
-use properties::ComputedValues;
+use parking_lot::RwLock;
+use properties::{ComputedValues, PropertyDeclarationBlock};
 use stylesheets::Stylesheet;
 use values::computed::{CalcLengthOrPercentage, LengthOrPercentage, LengthOrPercentageOrAuto};
 
@@ -25,6 +26,11 @@ unsafe impl HasFFI for ComputedValues {
 }
 unsafe impl HasArcFFI for ComputedValues {}
 
+unsafe impl HasFFI for RwLock<PropertyDeclarationBlock> {
+    type FFIType = RawServoDeclarationBlock;
+}
+unsafe impl HasArcFFI for RwLock<PropertyDeclarationBlock> {}
+
 impl From<CalcLengthOrPercentage> for nsStyleCoord_CalcValue {
     fn from(other: CalcLengthOrPercentage) -> nsStyleCoord_CalcValue {
         let has_percentage = other.percentage.is_some();

components/style/gecko/wrapper.rs

@@ -30,7 +30,7 @@ use gecko_bindings::structs::{NODE_HAS_DIRTY_DESCENDANTS_FOR_SERVO, NODE_IS_DIRT
 use gecko_bindings::structs::{RawGeckoDocument, RawGeckoElement, RawGeckoNode};
 use gecko_bindings::structs::{nsChangeHint, nsIAtom, nsIContent, nsStyleContext};
 use gecko_bindings::structs::OpaqueStyleData;
-use gecko_bindings::sugar::ownership::{FFIArcHelpers, HasArcFFI, HasFFI};
+use gecko_bindings::sugar::ownership::FFIArcHelpers;
 use libc::uintptr_t;
 use parking_lot::RwLock;
 use parser::ParserContextExtraData;
@@ -45,7 +45,6 @@ use std::fmt;
 use std::ops::BitOr;
 use std::ptr;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, AtomicPtr};
 use string_cache::{Atom, Namespace, WeakAtom, WeakNamespace};
 use url::Url;
 
@@ -57,35 +56,6 @@ impl NonOpaqueStyleData {
     }
 }
 
-
-pub struct GeckoDeclarationBlock {
-    pub declarations: Option<Arc<RwLock<PropertyDeclarationBlock>>>,
-    // XXX The following two fields are made atomic to work around the
-    // ownership system so that they can be changed inside a shared
-    // instance. It wouldn't provide safety as Rust usually promises,
-    // but it is fine as far as we only access them in a single thread.
-    // If we need to access them in different threads, we would need
-    // to redesign how it works with MiscContainer in Gecko side.
-    pub cache: AtomicPtr<bindings::nsHTMLCSSStyleSheet>,
-    pub immutable: AtomicBool,
-}
-
-impl PartialEq for GeckoDeclarationBlock {
-    fn eq(&self, other: &GeckoDeclarationBlock) -> bool {
-        match (&self.declarations, &other.declarations) {
-            (&None, &None) => true,
-            (&Some(ref s), &Some(ref other)) => *s.read() == *other.read(),
-            _ => false,
-        }
-    }
-}
-
-unsafe impl HasFFI for GeckoDeclarationBlock {
-    type FFIType = bindings::RawServoDeclarationBlock;
-}
-unsafe impl HasArcFFI for GeckoDeclarationBlock {}
-
-
 // We can eliminate OpaqueStyleData when the bindings move into the style crate.
 fn to_opaque_style_data(d: *mut NonOpaqueStyleData) -> *mut OpaqueStyleData {
     d as *mut OpaqueStyleData
@@ -486,13 +456,13 @@ impl<'le> fmt::Debug for GeckoElement<'le> {
 }
 
 impl<'le> GeckoElement<'le> {
-    pub fn parse_style_attribute(value: &str) -> Option<PropertyDeclarationBlock> {
+    pub fn parse_style_attribute(value: &str) -> PropertyDeclarationBlock {
         // FIXME(bholley): Real base URL and error reporter.
         let base_url = &*DUMMY_BASE_URL;
         // FIXME(heycam): Needs real ParserContextExtraData so that URLs parse
         // properly.
         let extra_data = ParserContextExtraData::default();
-        Some(parse_style_attribute(value, &base_url, Box::new(StdoutErrorReporter), extra_data))
+        parse_style_attribute(value, &base_url, Box::new(StdoutErrorReporter), extra_data)
     }
 }
 
@@ -512,12 +482,7 @@ impl<'le> TElement for GeckoElement<'le> {
 
     fn style_attribute(&self) -> Option<&Arc<RwLock<PropertyDeclarationBlock>>> {
         let declarations = unsafe { Gecko_GetServoDeclarationBlock(self.0) };
-        if declarations.is_none() {
-            None
-        } else {
-            let declarations = GeckoDeclarationBlock::arc_from_borrowed(&declarations).unwrap();
-            declarations.declarations.as_ref().map(|r| r as *const Arc<_>).map(|ptr| unsafe { &*ptr })
-        }
+        declarations.map(|s| s.as_arc_opt()).unwrap_or(None)
     }
 
     fn get_state(&self) -> ElementState {

components/style/gecko_bindings/bindings.rs

@@ -178,14 +178,6 @@ extern "C" {
     pub fn Gecko_ClearPODTArray(aArray: *mut ::std::os::raw::c_void,
                                 aElementSize: usize, aElementAlign: usize);
 }
-#[repr(C)]
-#[derive(Debug, Copy)]
-pub struct nsHTMLCSSStyleSheet {
-    pub _address: u8,
-}
-impl Clone for nsHTMLCSSStyleSheet {
-    fn clone(&self) -> Self { *self }
-}
 extern "C" {
     pub fn Gecko_ChildrenCount(node: RawGeckoNodeBorrowed) -> u32;
 }
@@ -372,7 +364,7 @@ extern "C" {
 }
 extern "C" {
     pub fn Gecko_GetServoDeclarationBlock(element: RawGeckoElementBorrowed)
-     -> RawServoDeclarationBlockBorrowedOrNull;
+     -> RawServoDeclarationBlockStrongBorrowedOrNull;
 }
 extern "C" {
     pub fn Gecko_Atomize(aString: *const ::std::os::raw::c_char, aLength: u32)
@@ -877,8 +869,7 @@ extern "C" {
      -> ServoComputedValuesStrong;
 }
 extern "C" {
-    pub fn Servo_ParseStyleAttribute(bytes: *const u8, length: u32,
-                                     cache: *mut nsHTMLCSSStyleSheet)
+    pub fn Servo_ParseStyleAttribute(bytes: *const u8, length: u32)
      -> RawServoDeclarationBlockStrong;
 }
 extern "C" {
@@ -894,19 +885,6 @@ extern "C" {
                                          b: RawServoDeclarationBlockBorrowed)
      -> bool;
 }
-extern "C" {
-    pub fn Servo_DeclarationBlock_GetCache(declarations:
-                                               RawServoDeclarationBlockBorrowed)
-     -> *mut nsHTMLCSSStyleSheet;
-}
-extern "C" {
-    pub fn Servo_DeclarationBlock_SetImmutable(declarations:
-                                                   RawServoDeclarationBlockBorrowed);
-}
-extern "C" {
-    pub fn Servo_DeclarationBlock_ClearCachePointer(declarations:
-                                                        RawServoDeclarationBlockBorrowed);
-}
 extern "C" {
     pub fn Servo_DeclarationBlock_SerializeOneValue(declarations:
                                                         RawServoDeclarationBlockBorrowed,