Auto merge of #18516 - jdm:stringshare, r=heycam

Share specified URLs with Gecko

This makes use of our Arc offset machinery to allow Gecko to store Arc<String> values and ensure there are used appropriately.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix [bug 1397971](https://bugzilla.mozilla.org/show_bug.cgi?id=1397971).

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---
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components/style/gecko/generated/bindings.rs

@@ -19,6 +19,7 @@ use gecko_bindings::structs::mozilla::MallocSizeOf;
 use gecko_bindings::structs::mozilla::OriginFlags;
 use gecko_bindings::structs::mozilla::Side;
 use gecko_bindings::structs::mozilla::UniquePtr;
+use gecko_bindings::structs::ServoRawOffsetArc;
 use gecko_bindings::structs::nsIContent;
 use gecko_bindings::structs::nsIDocument;
 use gecko_bindings::structs::nsIDocument_DocumentTheme;
@@ -46,6 +47,7 @@ use gecko_bindings::structs::RawGeckoServoStyleRuleList;
 use gecko_bindings::structs::RawGeckoURLExtraData;
 use gecko_bindings::structs::RawGeckoXBLBinding;
 use gecko_bindings::structs::RefPtr;
+use gecko_bindings::structs::RustString;
 use gecko_bindings::structs::CSSPseudoClassType;
 use gecko_bindings::structs::CSSPseudoElementType;
 use gecko_bindings::structs::ServoTraversalFlags;
@@ -998,7 +1000,9 @@ extern "C" {
     pub fn Gecko_ReleaseImageValueArbitraryThread(aPtr: *mut ImageValue);
 }
 extern "C" {
-    pub fn Gecko_ImageValue_Create(aURI: ServoBundledURI) -> *mut ImageValue;
+    pub fn Gecko_ImageValue_Create(aURI: ServoBundledURI,
+                                   aURIString: ServoRawOffsetArc<RustString>)
+     -> *mut ImageValue;
 }
 extern "C" {
     pub fn Gecko_ImageValue_SizeOfIncludingThis(aImageValue: *mut ImageValue)

components/style/gecko/generated/structs_debug.rs

@@ -1727,17 +1727,52 @@ pub mod root {
                 pub vtable_: *const URLValueData__bindgen_vtable,
                 pub mRefCnt: root::mozilla::ThreadSafeAutoRefCnt,
                 pub mURI: root::nsMainThreadPtrHandle<root::nsIURI>,
-                pub mString: ::nsstring::nsStringRepr,
                 pub mExtraData: root::RefPtr<root::mozilla::URLExtraData>,
                 pub mURIResolved: bool,
                 pub mIsLocalRef: [u8; 2usize],
                 pub mMightHaveRef: [u8; 2usize],
+                pub mStrings: root::mozilla::css::URLValueData_RustOrGeckoString,
+                pub mUsingRustString: bool,
             }
             pub type URLValueData_HasThreadSafeRefCnt =
                 root::mozilla::TrueType;
+            #[repr(C)]
+            #[derive(Debug)]
+            pub struct URLValueData_RustOrGeckoString {
+                pub mString: root::__BindgenUnionField<::nsstring::nsStringRepr>,
+                pub mRustString: root::__BindgenUnionField<::gecko_bindings::structs::ServoRawOffsetArc<root::RustString>>,
+                pub bindgen_union_field: [u64; 2usize],
+            }
+            #[test]
+            fn bindgen_test_layout_URLValueData_RustOrGeckoString() {
+                assert_eq!(::std::mem::size_of::<URLValueData_RustOrGeckoString>()
+                           , 16usize , concat ! (
+                           "Size of: " , stringify ! (
+                           URLValueData_RustOrGeckoString ) ));
+                assert_eq! (::std::mem::align_of::<URLValueData_RustOrGeckoString>()
+                            , 8usize , concat ! (
+                            "Alignment of " , stringify ! (
+                            URLValueData_RustOrGeckoString ) ));
+                assert_eq! (unsafe {
+                            & (
+                            * ( 0 as * const URLValueData_RustOrGeckoString )
+                            ) . mString as * const _ as usize } , 0usize ,
+                            concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData_RustOrGeckoString ) , "::" ,
+                            stringify ! ( mString ) ));
+                assert_eq! (unsafe {
+                            & (
+                            * ( 0 as * const URLValueData_RustOrGeckoString )
+                            ) . mRustString as * const _ as usize } , 0usize ,
+                            concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData_RustOrGeckoString ) , "::" ,
+                            stringify ! ( mRustString ) ));
+            }
             #[test]
             fn bindgen_test_layout_URLValueData() {
-                assert_eq!(::std::mem::size_of::<URLValueData>() , 56usize ,
+                assert_eq!(::std::mem::size_of::<URLValueData>() , 64usize ,
                            concat ! (
                            "Size of: " , stringify ! ( URLValueData ) ));
                 assert_eq! (::std::mem::align_of::<URLValueData>() , 8usize ,
@@ -1754,39 +1789,46 @@ pub mod root {
                             const _ as usize } , 16usize , concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mURI ) ));
-                assert_eq! (unsafe {
-                            & ( * ( 0 as * const URLValueData ) ) . mString as
-                            * const _ as usize } , 24usize , concat ! (
-                            "Alignment of field: " , stringify ! (
-                            URLValueData ) , "::" , stringify ! ( mString )
-                            ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) . mExtraData
-                            as * const _ as usize } , 40usize , concat ! (
+                            as * const _ as usize } , 24usize , concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mExtraData )
                             ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) .
-                            mURIResolved as * const _ as usize } , 48usize ,
+                            mURIResolved as * const _ as usize } , 32usize ,
                             concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mURIResolved
                             ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) .
-                            mIsLocalRef as * const _ as usize } , 49usize ,
+                            mIsLocalRef as * const _ as usize } , 33usize ,
                             concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mIsLocalRef
                             ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) .
-                            mMightHaveRef as * const _ as usize } , 51usize ,
+                            mMightHaveRef as * const _ as usize } , 35usize ,
                             concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! (
                             mMightHaveRef ) ));
+                assert_eq! (unsafe {
+                            & ( * ( 0 as * const URLValueData ) ) . mStrings
+                            as * const _ as usize } , 40usize , concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData ) , "::" , stringify ! ( mStrings )
+                            ));
+                assert_eq! (unsafe {
+                            & ( * ( 0 as * const URLValueData ) ) .
+                            mUsingRustString as * const _ as usize } , 56usize
+                            , concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData ) , "::" , stringify ! (
+                            mUsingRustString ) ));
             }
             #[repr(C)]
             #[derive(Debug)]
@@ -1795,7 +1837,7 @@ pub mod root {
             }
             #[test]
             fn bindgen_test_layout_URLValue() {
-                assert_eq!(::std::mem::size_of::<URLValue>() , 56usize ,
+                assert_eq!(::std::mem::size_of::<URLValue>() , 64usize ,
                            concat ! ( "Size of: " , stringify ! ( URLValue )
                            ));
                 assert_eq! (::std::mem::align_of::<URLValue>() , 8usize ,
@@ -1811,7 +1853,7 @@ pub mod root {
             }
             #[test]
             fn bindgen_test_layout_ImageValue() {
-                assert_eq!(::std::mem::size_of::<ImageValue>() , 112usize ,
+                assert_eq!(::std::mem::size_of::<ImageValue>() , 120usize ,
                            concat ! ( "Size of: " , stringify ! ( ImageValue )
                            ));
                 assert_eq! (::std::mem::align_of::<ImageValue>() , 8usize ,
@@ -1819,12 +1861,12 @@ pub mod root {
                             "Alignment of " , stringify ! ( ImageValue ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const ImageValue ) ) . mRequests as
-                            * const _ as usize } , 56usize , concat ! (
+                            * const _ as usize } , 64usize , concat ! (
                             "Alignment of field: " , stringify ! ( ImageValue
                             ) , "::" , stringify ! ( mRequests ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const ImageValue ) ) . mLoadedImage
-                            as * const _ as usize } , 104usize , concat ! (
+                            as * const _ as usize } , 112usize , concat ! (
                             "Alignment of field: " , stringify ! ( ImageValue
                             ) , "::" , stringify ! ( mLoadedImage ) ));
             }
@@ -28801,6 +28843,11 @@ pub mod root {
              } | ((mHadDispatch as u8 as u8) << 6usize) & (64u64 as u8))
         }
     }
+    #[repr(C)]
+    #[derive(Debug, Copy, Clone)]
+    pub struct RustString {
+        _unused: [u8; 0],
+    }
     #[repr(u32)]
     #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
     pub enum nsCSSUnit {

components/style/gecko/generated/structs_release.rs

@@ -1691,17 +1691,52 @@ pub mod root {
                 pub vtable_: *const URLValueData__bindgen_vtable,
                 pub mRefCnt: root::mozilla::ThreadSafeAutoRefCnt,
                 pub mURI: root::nsMainThreadPtrHandle<root::nsIURI>,
-                pub mString: ::nsstring::nsStringRepr,
                 pub mExtraData: root::RefPtr<root::mozilla::URLExtraData>,
                 pub mURIResolved: bool,
                 pub mIsLocalRef: [u8; 2usize],
                 pub mMightHaveRef: [u8; 2usize],
+                pub mStrings: root::mozilla::css::URLValueData_RustOrGeckoString,
+                pub mUsingRustString: bool,
             }
             pub type URLValueData_HasThreadSafeRefCnt =
                 root::mozilla::TrueType;
+            #[repr(C)]
+            #[derive(Debug)]
+            pub struct URLValueData_RustOrGeckoString {
+                pub mString: root::__BindgenUnionField<::nsstring::nsStringRepr>,
+                pub mRustString: root::__BindgenUnionField<::gecko_bindings::structs::ServoRawOffsetArc<root::RustString>>,
+                pub bindgen_union_field: [u64; 2usize],
+            }
+            #[test]
+            fn bindgen_test_layout_URLValueData_RustOrGeckoString() {
+                assert_eq!(::std::mem::size_of::<URLValueData_RustOrGeckoString>()
+                           , 16usize , concat ! (
+                           "Size of: " , stringify ! (
+                           URLValueData_RustOrGeckoString ) ));
+                assert_eq! (::std::mem::align_of::<URLValueData_RustOrGeckoString>()
+                            , 8usize , concat ! (
+                            "Alignment of " , stringify ! (
+                            URLValueData_RustOrGeckoString ) ));
+                assert_eq! (unsafe {
+                            & (
+                            * ( 0 as * const URLValueData_RustOrGeckoString )
+                            ) . mString as * const _ as usize } , 0usize ,
+                            concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData_RustOrGeckoString ) , "::" ,
+                            stringify ! ( mString ) ));
+                assert_eq! (unsafe {
+                            & (
+                            * ( 0 as * const URLValueData_RustOrGeckoString )
+                            ) . mRustString as * const _ as usize } , 0usize ,
+                            concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData_RustOrGeckoString ) , "::" ,
+                            stringify ! ( mRustString ) ));
+            }
             #[test]
             fn bindgen_test_layout_URLValueData() {
-                assert_eq!(::std::mem::size_of::<URLValueData>() , 56usize ,
+                assert_eq!(::std::mem::size_of::<URLValueData>() , 64usize ,
                            concat ! (
                            "Size of: " , stringify ! ( URLValueData ) ));
                 assert_eq! (::std::mem::align_of::<URLValueData>() , 8usize ,
@@ -1718,39 +1753,46 @@ pub mod root {
                             const _ as usize } , 16usize , concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mURI ) ));
-                assert_eq! (unsafe {
-                            & ( * ( 0 as * const URLValueData ) ) . mString as
-                            * const _ as usize } , 24usize , concat ! (
-                            "Alignment of field: " , stringify ! (
-                            URLValueData ) , "::" , stringify ! ( mString )
-                            ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) . mExtraData
-                            as * const _ as usize } , 40usize , concat ! (
+                            as * const _ as usize } , 24usize , concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mExtraData )
                             ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) .
-                            mURIResolved as * const _ as usize } , 48usize ,
+                            mURIResolved as * const _ as usize } , 32usize ,
                             concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mURIResolved
                             ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) .
-                            mIsLocalRef as * const _ as usize } , 49usize ,
+                            mIsLocalRef as * const _ as usize } , 33usize ,
                             concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! ( mIsLocalRef
                             ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const URLValueData ) ) .
-                            mMightHaveRef as * const _ as usize } , 51usize ,
+                            mMightHaveRef as * const _ as usize } , 35usize ,
                             concat ! (
                             "Alignment of field: " , stringify ! (
                             URLValueData ) , "::" , stringify ! (
                             mMightHaveRef ) ));
+                assert_eq! (unsafe {
+                            & ( * ( 0 as * const URLValueData ) ) . mStrings
+                            as * const _ as usize } , 40usize , concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData ) , "::" , stringify ! ( mStrings )
+                            ));
+                assert_eq! (unsafe {
+                            & ( * ( 0 as * const URLValueData ) ) .
+                            mUsingRustString as * const _ as usize } , 56usize
+                            , concat ! (
+                            "Alignment of field: " , stringify ! (
+                            URLValueData ) , "::" , stringify ! (
+                            mUsingRustString ) ));
             }
             #[repr(C)]
             #[derive(Debug)]
@@ -1759,7 +1801,7 @@ pub mod root {
             }
             #[test]
             fn bindgen_test_layout_URLValue() {
-                assert_eq!(::std::mem::size_of::<URLValue>() , 56usize ,
+                assert_eq!(::std::mem::size_of::<URLValue>() , 64usize ,
                            concat ! ( "Size of: " , stringify ! ( URLValue )
                            ));
                 assert_eq! (::std::mem::align_of::<URLValue>() , 8usize ,
@@ -1775,7 +1817,7 @@ pub mod root {
             }
             #[test]
             fn bindgen_test_layout_ImageValue() {
-                assert_eq!(::std::mem::size_of::<ImageValue>() , 104usize ,
+                assert_eq!(::std::mem::size_of::<ImageValue>() , 112usize ,
                            concat ! ( "Size of: " , stringify ! ( ImageValue )
                            ));
                 assert_eq! (::std::mem::align_of::<ImageValue>() , 8usize ,
@@ -1783,12 +1825,12 @@ pub mod root {
                             "Alignment of " , stringify ! ( ImageValue ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const ImageValue ) ) . mRequests as
-                            * const _ as usize } , 56usize , concat ! (
+                            * const _ as usize } , 64usize , concat ! (
                             "Alignment of field: " , stringify ! ( ImageValue
                             ) , "::" , stringify ! ( mRequests ) ));
                 assert_eq! (unsafe {
                             & ( * ( 0 as * const ImageValue ) ) . mLoadedImage
-                            as * const _ as usize } , 96usize , concat ! (
+                            as * const _ as usize } , 104usize , concat ! (
                             "Alignment of field: " , stringify ! ( ImageValue
                             ) , "::" , stringify ! ( mLoadedImage ) ));
             }
@@ -28446,6 +28488,11 @@ pub mod root {
              } | ((mHadDispatch as u8 as u8) << 6usize) & (64u64 as u8))
         }
     }
+    #[repr(C)]
+    #[derive(Debug, Copy, Clone)]
+    pub struct RustString {
+        _unused: [u8; 0],
+    }
     #[repr(u32)]
     #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
     pub enum nsCSSUnit {

components/style/gecko/url.rs

@@ -6,13 +6,14 @@
 
 use gecko_bindings::structs::{ServoBundledURI, URLExtraData};
 use gecko_bindings::structs::mozilla::css::URLValueData;
+use gecko_bindings::structs::root::{nsStyleImageRequest, RustString};
 use gecko_bindings::structs::root::mozilla::css::ImageValue;
-use gecko_bindings::structs::root::nsStyleImageRequest;
 use gecko_bindings::sugar::refptr::RefPtr;
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use parser::ParserContext;
-use servo_arc::Arc;
+use servo_arc::{Arc, RawOffsetArc};
 use std::fmt;
+use std::mem;
 use style_traits::{ToCss, ParseError};
 
 /// A specified url() value for gecko. Gecko does not eagerly resolve SpecifiedUrls.
@@ -59,7 +60,14 @@ impl SpecifiedUrl {
     pub unsafe fn from_url_value_data(url: &URLValueData)
                                        -> Result<SpecifiedUrl, ()> {
         Ok(SpecifiedUrl {
-            serialization: Arc::new(url.mString.to_string()),
+            serialization: if url.mUsingRustString {
+                let arc_type = url.mStrings.mRustString.as_ref()
+                    as *const _ as
+                    *const RawOffsetArc<String>;
+                Arc::from_raw_offset((*arc_type).clone())
+            } else {
+                Arc::new(url.mStrings.mString.as_ref().to_string())
+            },
             extra_data: url.mExtraData.to_safe(),
             image_value: None,
         })
@@ -115,7 +123,10 @@ impl SpecifiedUrl {
         debug_assert_eq!(self.image_value, None);
         self.image_value = {
             unsafe {
-                let ptr = Gecko_ImageValue_Create(self.for_ffi());
+                let arc_offset = Arc::into_raw_offset(self.serialization.clone());
+                let ptr = Gecko_ImageValue_Create(
+                    self.for_ffi(),
+                    mem::transmute::<_, RawOffsetArc<RustString>>(arc_offset));
                 // We do not expect Gecko_ImageValue_Create returns null.
                 debug_assert!(!ptr.is_null());
                 Some(RefPtr::from_addrefed(ptr))

ports/geckolib/glue.rs

@@ -13,6 +13,7 @@ use std::cell::RefCell;
 use std::env;
 use std::fmt::Write;
 use std::iter;
+use std::mem;
 use std::ptr;
 use style::applicable_declarations::ApplicableDeclarationBlock;
 use style::context::{CascadeInputs, QuirksMode, SharedStyleContext, StyleContext};
@@ -77,7 +78,7 @@ use style::gecko_bindings::bindings::nsTimingFunctionBorrowedMut;
 use style::gecko_bindings::structs;
 use style::gecko_bindings::structs::{CSSPseudoElementType, CompositeOperation};
 use style::gecko_bindings::structs::{Loader, LoaderReusableStyleSheets};
-use style::gecko_bindings::structs::{RawServoStyleRule, ServoStyleContextStrong};
+use style::gecko_bindings::structs::{RawServoStyleRule, ServoStyleContextStrong, RustString};
 use style::gecko_bindings::structs::{ServoStyleSheet, SheetParsingMode, nsIAtom, nsCSSPropertyID};
 use style::gecko_bindings::structs::{nsCSSFontFaceRule, nsCSSCounterStyleRule};
 use style::gecko_bindings::structs::{nsRestyleHint, nsChangeHint, PropertyValuePair};
@@ -3834,6 +3835,31 @@ pub extern "C" fn Servo_GetCustomPropertyNameAt(computed_values: ServoStyleConte
     true
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn Servo_ReleaseArcStringData(string: *const RawOffsetArc<RustString>) {
+    let string = string as *const RawOffsetArc<String>;
+    // Cause RawOffsetArc::drop to run, releasing the strong reference to the string data.
+    let _ = ptr::read(string);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Servo_CloneArcStringData(string: *const RawOffsetArc<RustString>)
+                                                  -> RawOffsetArc<RustString> {
+    let string = string as *const RawOffsetArc<String>;
+    let cloned = (*string).clone();
+    mem::transmute::<_, RawOffsetArc<RustString>>(cloned)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Servo_GetArcStringData(string: *const RustString,
+                                                utf8_chars: *mut *const u8,
+                                                utf8_len: *mut u32)
+{
+    let string = &*(string as *const String);
+    *utf8_len = string.len() as u32;
+    *utf8_chars = string.as_ptr();
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_ProcessInvalidations(set: RawServoStyleSetBorrowed,
                                              element: RawGeckoElementBorrowed,