Auto merge of #15888 - emilio:caching, r=Ms2ger

style: Simplify style sharing code.

No functional changes, just some code cleanup.

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This commit is contained in:
bors-servo 2017-03-09 11:33:33 -08:00 committed by GitHub
commit 5c46e86546
4 changed files with 17 additions and 80 deletions

View file

@ -11,14 +11,14 @@ use std::slice::{Iter, IterMut};
/// A LRU cache used to store a set of at most `n` elements at the same time.
///
/// Currently used for the style sharing candidate cache.
pub struct LRUCache<K, V> {
entries: Vec<(K, V)>,
pub struct LRUCache<K> {
entries: Vec<K>,
cache_size: usize,
}
impl<K: PartialEq, V: Clone> LRUCache<K, V> {
impl<K: PartialEq> LRUCache<K> {
/// Create a new LRU cache with `size` elements at most.
pub fn new(size: usize) -> LRUCache<K, V> {
pub fn new(size: usize) -> Self {
LRUCache {
entries: vec![],
cache_size: size,
@ -27,54 +27,30 @@ impl<K: PartialEq, V: Clone> LRUCache<K, V> {
#[inline]
/// Touch a given position, and put it in the last item on the list.
pub fn touch(&mut self, pos: usize) -> &V {
pub fn touch(&mut self, pos: usize) {
let last_index = self.entries.len() - 1;
if pos != last_index {
let entry = self.entries.remove(pos);
self.entries.push(entry);
}
&self.entries[last_index].1
}
/// Iterate over the contents of this cache.
pub fn iter(&self) -> Iter<(K, V)> {
pub fn iter(&self) -> Iter<K> {
self.entries.iter()
}
/// Iterate mutably over the contents of this cache.
pub fn iter_mut(&mut self) -> IterMut<(K, V)> {
pub fn iter_mut(&mut self) -> IterMut<K> {
self.entries.iter_mut()
}
/// Insert a given key and value in the cache.
pub fn insert(&mut self, key: K, val: V) {
/// Insert a given key in the cache.
pub fn insert(&mut self, key: K) {
if self.entries.len() == self.cache_size {
self.entries.remove(0);
}
self.entries.push((key, val));
}
/// Try to find a key in the cache.
pub fn find(&mut self, key: &K) -> Option<V> {
match self.entries.iter().position(|&(ref k, _)| key == k) {
Some(pos) => Some(self.touch(pos).clone()),
None => None,
}
}
/// Try to find a given key, or create a given item with that key executing
/// `blk`.
pub fn find_or_create<F>(&mut self, key: K, mut blk: F) -> V
where F: FnMut() -> V,
{
match self.entries.iter().position(|&(ref k, _)| *k == key) {
Some(pos) => self.touch(pos).clone(),
None => {
let val = blk();
self.insert(key, val.clone());
val
}
}
self.entries.push(key);
}
/// Evict all elements from the cache.

View file

@ -110,7 +110,7 @@ impl<E: TElement> PartialEq<StyleSharingCandidate<E>> for StyleSharingCandidate<
/// Note that this cache is flushed every time we steal work from the queue, so
/// storing nodes here temporarily is safe.
pub struct StyleSharingCandidateCache<E: TElement> {
cache: LRUCache<StyleSharingCandidate<E>, ()>,
cache: LRUCache<StyleSharingCandidate<E>>,
}
/// A cache miss result.
@ -366,7 +366,7 @@ impl<E: TElement> StyleSharingCandidateCache<E> {
}
}
fn iter_mut(&mut self) -> IterMut<(StyleSharingCandidate<E>, ())> {
fn iter_mut(&mut self) -> IterMut<StyleSharingCandidate<E>> {
self.cache.iter_mut()
}
@ -410,7 +410,7 @@ impl<E: TElement> StyleSharingCandidateCache<E> {
element: unsafe { SendElement::new(*element) },
common_style_affecting_attributes: None,
class_attributes: None,
}, ());
});
}
/// Touch a given index in the style sharing candidate cache.
@ -881,8 +881,10 @@ pub trait MatchMethods : TElement {
}
let mut should_clear_cache = false;
for (i, &mut (ref mut candidate, ())) in style_sharing_candidate_cache.iter_mut().enumerate() {
let sharing_result = self.share_style_with_candidate_if_possible(shared_context, candidate);
for (i, candidate) in style_sharing_candidate_cache.iter_mut().enumerate() {
let sharing_result =
self.share_style_with_candidate_if_possible(shared_context,
candidate);
match sharing_result {
Ok(shared_style) => {
// Yay, cache hit. Share the style.