Use an Arc for eager pseudo styles.

MozReview-Commit-ID: BdYkXxYvUQ3
This commit is contained in:
Bobby Holley 2017-06-23 13:43:15 -07:00
parent af89c74ab7
commit eeb62edfea

View file

@ -99,10 +99,14 @@ impl RestyleData {
}
}
/// A list of styles for eagerly-cascaded pseudo-elements.
/// Lazily-allocated.
/// A lazily-allocated list of styles for eagerly-cascaded pseudo-elements.
///
/// We use an Arc so that sharing these styles via the style sharing cache does
/// not require duplicate allocations. We leverage the copy-on-write semantics of
/// Arc::make_mut(), which is free (i.e. does not require atomic RMU operations)
/// in servo_arc.
#[derive(Clone, Debug)]
pub struct EagerPseudoStyles(Option<Box<EagerPseudoArray>>);
pub struct EagerPseudoStyles(Option<Arc<EagerPseudoArray>>);
#[derive(Debug, Default)]
struct EagerPseudoArray(EagerPseudoArrayInner);
@ -156,7 +160,10 @@ impl EagerPseudoStyles {
/// Returns a mutable reference to the style for a given eager pseudo, if it exists.
pub fn get_mut(&mut self, pseudo: &PseudoElement) -> Option<&mut Arc<ComputedValues>> {
debug_assert!(pseudo.is_eager());
self.0.as_mut().and_then(|p| p[pseudo.eager_index()].as_mut())
match self.0 {
None => return None,
Some(ref mut arc) => Arc::make_mut(arc)[pseudo.eager_index()].as_mut(),
}
}
/// Returns true if the EagerPseudoStyles has the style for |pseudo|.
@ -167,9 +174,10 @@ impl EagerPseudoStyles {
/// Sets the style for the eager pseudo.
pub fn set(&mut self, pseudo: &PseudoElement, value: Arc<ComputedValues>) {
if self.0.is_none() {
self.0 = Some(Box::new(Default::default()));
self.0 = Some(Arc::new(Default::default()));
}
self.0.as_mut().unwrap()[pseudo.eager_index()] = Some(value);
let arr = Arc::make_mut(self.0.as_mut().unwrap());
arr[pseudo.eager_index()] = Some(value);
}
/// Inserts a pseudo-element. The pseudo-element must not already exist.
@ -180,9 +188,9 @@ impl EagerPseudoStyles {
/// Removes a pseudo-element style if it exists, and returns it.
pub fn take(&mut self, pseudo: &PseudoElement) -> Option<Arc<ComputedValues>> {
let result = match self.0.as_mut() {
let result = match self.0 {
None => return None,
Some(arr) => arr[pseudo.eager_index()].take(),
Some(ref mut arc) => Arc::make_mut(arc)[pseudo.eager_index()].take(),
};
let empty = self.0.as_ref().unwrap().iter().all(|x| x.is_none());
if empty {