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layout: Stop doing unsafe transmutes between refcell references.

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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
This commit is contained in:
Emilio Cobos Álvarez 2017-05-24 19:15:12 +02:00
parent bb310efbb9
commit deaa935f5b
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GPG key ID: 056B727BB9C1027C
9 changed files with 79 additions and 94 deletions
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70
components/layout/wrapper.rs
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@ -30,39 +30,37 @@
#![allow(unsafe_code)]
use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
use atomic_refcell::{AtomicRef, AtomicRefMut};
use core::nonzero::NonZero;
use data::{LayoutDataFlags, PersistentLayoutData};
use script_layout_interface::{OpaqueStyleAndLayoutData, PartialPersistentLayoutData};
use data::{LayoutData, LayoutDataFlags, StyleAndLayoutData};
use script_layout_interface::{OpaqueStyleAndLayoutData, StyleData};
use script_layout_interface::wrapper_traits::{LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode};
use script_layout_interface::wrapper_traits::GetLayoutData;
use style::computed_values::content::{self, ContentItem};
use style::dom::{NodeInfo, TNode};
use style::selector_parser::RestyleDamage;
pub type NonOpaqueStyleAndLayoutData = AtomicRefCell<PersistentLayoutData>;
pub unsafe fn drop_style_and_layout_data(data: OpaqueStyleAndLayoutData) {
let ptr: *mut AtomicRefCell<PartialPersistentLayoutData> = data.ptr.get();
let non_opaque: *mut NonOpaqueStyleAndLayoutData = ptr as *mut _;
let ptr: *mut StyleData = data.ptr.get();
let non_opaque: *mut StyleAndLayoutData = ptr as *mut _;
let _ = Box::from_raw(non_opaque);
}
pub trait LayoutNodeLayoutData {
/// Similar to borrow_data*, but returns the full PersistentLayoutData rather
/// than only the style::data::ElementData.
fn borrow_layout_data(&self) -> Option<AtomicRef<PersistentLayoutData>>;
fn mutate_layout_data(&self) -> Option<AtomicRefMut<PersistentLayoutData>>;
fn borrow_layout_data(&self) -> Option<AtomicRef<LayoutData>>;
fn mutate_layout_data(&self) -> Option<AtomicRefMut<LayoutData>>;
fn flow_debug_id(self) -> usize;
}
impl<T: GetLayoutData> LayoutNodeLayoutData for T {
fn borrow_layout_data(&self) -> Option<AtomicRef<PersistentLayoutData>> {
self.get_raw_data().map(|d| d.borrow())
fn borrow_layout_data(&self) -> Option<AtomicRef<LayoutData>> {
self.get_raw_data().map(|d| d.layout_data.borrow())
}
fn mutate_layout_data(&self) -> Option<AtomicRefMut<PersistentLayoutData>> {
self.get_raw_data().map(|d| d.borrow_mut())
fn mutate_layout_data(&self) -> Option<AtomicRefMut<LayoutData>> {
self.get_raw_data().map(|d| d.layout_data.borrow_mut())
}
fn flow_debug_id(self) -> usize {
@ -71,13 +69,13 @@ impl<T: GetLayoutData> LayoutNodeLayoutData for T {
}
pub trait GetRawData {
fn get_raw_data(&self) -> Option<&NonOpaqueStyleAndLayoutData>;
fn get_raw_data(&self) -> Option<&StyleAndLayoutData>;
}
impl<T: GetLayoutData> GetRawData for T {
fn get_raw_data(&self) -> Option<&NonOpaqueStyleAndLayoutData> {
fn get_raw_data(&self) -> Option<&StyleAndLayoutData> {
self.get_style_and_layout_data().map(|opaque| {
let container = opaque.ptr.get() as *mut NonOpaqueStyleAndLayoutData;
let container = opaque.ptr.get() as *mut StyleAndLayoutData;
unsafe { &*container }
})
}
@ -91,10 +89,10 @@ pub trait LayoutNodeHelpers {
impl<T: LayoutNode> LayoutNodeHelpers for T {
fn initialize_data(&self) {
if self.get_raw_data().is_none() {
let ptr: *mut NonOpaqueStyleAndLayoutData =
Box::into_raw(box AtomicRefCell::new(PersistentLayoutData::new()));
let ptr: *mut StyleAndLayoutData =
Box::into_raw(Box::new(StyleAndLayoutData::new()));
let opaque = OpaqueStyleAndLayoutData {
ptr: unsafe { NonZero::new(ptr as *mut AtomicRefCell<PartialPersistentLayoutData>) }
ptr: unsafe { NonZero::new(ptr as *mut StyleData) }
};
unsafe { self.init_style_and_layout_data(opaque) };
};
@ -171,21 +169,25 @@ impl<T: ThreadSafeLayoutNode> ThreadSafeLayoutNodeHelpers for T {
debug_assert!(node.is_element());
}
let data = node.borrow_layout_data().unwrap();
if let Some(r) = data.base.style_data.get_restyle() {
// We're reflowing a node that just got a restyle, and so the
// damage has been computed and stored in the RestyleData.
r.damage
} else if !data.flags.contains(::data::HAS_BEEN_TRAVERSED) {
// We're reflowing a node that was styled for the first time and
// has never been visited by layout. Return rebuild_and_reflow,
// because that's what the code expects.
RestyleDamage::rebuild_and_reflow()
} else {
// We're reflowing a node whose style data didn't change, but whose
// layout may change due to changes in ancestors or descendants.
RestyleDamage::empty()
}
let damage = {
let data = node.get_raw_data().unwrap();
if let Some(r) = data.style_data.element_data.borrow().get_restyle() {
// We're reflowing a node that just got a restyle, and so the
// damage has been computed and stored in the RestyleData.
r.damage
} else if !data.layout_data.borrow().flags.contains(::data::HAS_BEEN_TRAVERSED) {
// We're reflowing a node that was styled for the first time and
// has never been visited by layout. Return rebuild_and_reflow,
// because that's what the code expects.
RestyleDamage::rebuild_and_reflow()
} else {
// We're reflowing a node whose style data didn't change, but whose
// layout may change due to changes in ancestors or descendants.
RestyleDamage::empty()
}
};
damage
}
}