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layout: Stop doing unsafe transmutes between refcell references.
This commit splits the style and layout data in two separate refcells. These transmutes have been a source of trouble (for example on Android), and they feel like a hack anyway. Fixes #16982
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9 changed files with 79 additions and 94 deletions
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@ -30,39 +30,37 @@
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#![allow(unsafe_code)]
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use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
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use atomic_refcell::{AtomicRef, AtomicRefMut};
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use core::nonzero::NonZero;
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use data::{LayoutDataFlags, PersistentLayoutData};
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use script_layout_interface::{OpaqueStyleAndLayoutData, PartialPersistentLayoutData};
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use data::{LayoutData, LayoutDataFlags, StyleAndLayoutData};
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use script_layout_interface::{OpaqueStyleAndLayoutData, StyleData};
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use script_layout_interface::wrapper_traits::{LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode};
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use script_layout_interface::wrapper_traits::GetLayoutData;
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use style::computed_values::content::{self, ContentItem};
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use style::dom::{NodeInfo, TNode};
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use style::selector_parser::RestyleDamage;
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pub type NonOpaqueStyleAndLayoutData = AtomicRefCell<PersistentLayoutData>;
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pub unsafe fn drop_style_and_layout_data(data: OpaqueStyleAndLayoutData) {
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let ptr: *mut AtomicRefCell<PartialPersistentLayoutData> = data.ptr.get();
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let non_opaque: *mut NonOpaqueStyleAndLayoutData = ptr as *mut _;
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let ptr: *mut StyleData = data.ptr.get();
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let non_opaque: *mut StyleAndLayoutData = ptr as *mut _;
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let _ = Box::from_raw(non_opaque);
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}
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pub trait LayoutNodeLayoutData {
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/// Similar to borrow_data*, but returns the full PersistentLayoutData rather
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/// than only the style::data::ElementData.
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fn borrow_layout_data(&self) -> Option<AtomicRef<PersistentLayoutData>>;
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fn mutate_layout_data(&self) -> Option<AtomicRefMut<PersistentLayoutData>>;
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fn borrow_layout_data(&self) -> Option<AtomicRef<LayoutData>>;
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fn mutate_layout_data(&self) -> Option<AtomicRefMut<LayoutData>>;
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fn flow_debug_id(self) -> usize;
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}
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impl<T: GetLayoutData> LayoutNodeLayoutData for T {
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fn borrow_layout_data(&self) -> Option<AtomicRef<PersistentLayoutData>> {
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self.get_raw_data().map(|d| d.borrow())
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fn borrow_layout_data(&self) -> Option<AtomicRef<LayoutData>> {
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self.get_raw_data().map(|d| d.layout_data.borrow())
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}
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fn mutate_layout_data(&self) -> Option<AtomicRefMut<PersistentLayoutData>> {
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self.get_raw_data().map(|d| d.borrow_mut())
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fn mutate_layout_data(&self) -> Option<AtomicRefMut<LayoutData>> {
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self.get_raw_data().map(|d| d.layout_data.borrow_mut())
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}
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fn flow_debug_id(self) -> usize {
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@ -71,13 +69,13 @@ impl<T: GetLayoutData> LayoutNodeLayoutData for T {
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}
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pub trait GetRawData {
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fn get_raw_data(&self) -> Option<&NonOpaqueStyleAndLayoutData>;
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fn get_raw_data(&self) -> Option<&StyleAndLayoutData>;
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}
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impl<T: GetLayoutData> GetRawData for T {
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fn get_raw_data(&self) -> Option<&NonOpaqueStyleAndLayoutData> {
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fn get_raw_data(&self) -> Option<&StyleAndLayoutData> {
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self.get_style_and_layout_data().map(|opaque| {
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let container = opaque.ptr.get() as *mut NonOpaqueStyleAndLayoutData;
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let container = opaque.ptr.get() as *mut StyleAndLayoutData;
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unsafe { &*container }
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})
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}
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@ -91,10 +89,10 @@ pub trait LayoutNodeHelpers {
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impl<T: LayoutNode> LayoutNodeHelpers for T {
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fn initialize_data(&self) {
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if self.get_raw_data().is_none() {
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let ptr: *mut NonOpaqueStyleAndLayoutData =
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Box::into_raw(box AtomicRefCell::new(PersistentLayoutData::new()));
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let ptr: *mut StyleAndLayoutData =
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Box::into_raw(Box::new(StyleAndLayoutData::new()));
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let opaque = OpaqueStyleAndLayoutData {
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ptr: unsafe { NonZero::new(ptr as *mut AtomicRefCell<PartialPersistentLayoutData>) }
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ptr: unsafe { NonZero::new(ptr as *mut StyleData) }
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};
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unsafe { self.init_style_and_layout_data(opaque) };
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};
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@ -171,21 +169,25 @@ impl<T: ThreadSafeLayoutNode> ThreadSafeLayoutNodeHelpers for T {
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debug_assert!(node.is_element());
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}
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let data = node.borrow_layout_data().unwrap();
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if let Some(r) = data.base.style_data.get_restyle() {
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// We're reflowing a node that just got a restyle, and so the
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// damage has been computed and stored in the RestyleData.
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r.damage
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} else if !data.flags.contains(::data::HAS_BEEN_TRAVERSED) {
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// We're reflowing a node that was styled for the first time and
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// has never been visited by layout. Return rebuild_and_reflow,
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// because that's what the code expects.
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RestyleDamage::rebuild_and_reflow()
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} else {
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// We're reflowing a node whose style data didn't change, but whose
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// layout may change due to changes in ancestors or descendants.
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RestyleDamage::empty()
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}
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let damage = {
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let data = node.get_raw_data().unwrap();
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if let Some(r) = data.style_data.element_data.borrow().get_restyle() {
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// We're reflowing a node that just got a restyle, and so the
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// damage has been computed and stored in the RestyleData.
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r.damage
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} else if !data.layout_data.borrow().flags.contains(::data::HAS_BEEN_TRAVERSED) {
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// We're reflowing a node that was styled for the first time and
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// has never been visited by layout. Return rebuild_and_reflow,
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// because that's what the code expects.
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RestyleDamage::rebuild_and_reflow()
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} else {
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// We're reflowing a node whose style data didn't change, but whose
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// layout may change due to changes in ancestors or descendants.
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RestyleDamage::empty()
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}
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};
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damage
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}
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}
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