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Added a bloom filter to CSS selector matching.

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This commit is contained in:
Clark Gaebel 2014-09-02 10:16:11 -07:00
parent d161d0ad47
commit acd83ff47b
20 changed files with 817 additions and 78 deletions
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122
components/style/selector_matching.rs
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@ -10,6 +10,7 @@ use sync::Arc;
use url::Url;
use servo_util::atom::Atom;
use servo_util::bloom::BloomFilter;
use servo_util::namespace;
use servo_util::smallvec::VecLike;
use servo_util::sort;
@ -27,7 +28,7 @@ pub enum StylesheetOrigin {
}
/// The definition of whitespace per CSS Selectors Level 3 § 4.
static SELECTOR_WHITESPACE: &'static [char] = &[' ', '\t', '\n', '\r', '\x0C'];
pub static SELECTOR_WHITESPACE: &'static [char] = &[' ', '\t', '\n', '\r', '\x0C'];
/// Map node attributes to Rules whose last simple selector starts with them.
///
@ -83,6 +84,7 @@ impl SelectorMap {
V:VecLike<DeclarationBlock>>(
&self,
node: &N,
parent_bf: &Option<BloomFilter>,
matching_rules_list: &mut V,
shareable: &mut bool) {
if self.empty {
@ -95,6 +97,7 @@ impl SelectorMap {
match element.get_id() {
Some(id) => {
SelectorMap::get_matching_rules_from_hash(node,
parent_bf,
&self.id_hash,
&id,
matching_rules_list,
@ -108,10 +111,11 @@ impl SelectorMap {
// FIXME: Store classes pre-split as atoms to make the loop below faster.
for class in class_attr.split(SELECTOR_WHITESPACE) {
SelectorMap::get_matching_rules_from_hash(node,
&self.class_hash,
&Atom::from_slice(class),
matching_rules_list,
shareable);
parent_bf,
&self.class_hash,
&Atom::from_slice(class),
matching_rules_list,
shareable);
}
}
None => {}
@ -123,12 +127,14 @@ impl SelectorMap {
&self.local_name_hash
};
SelectorMap::get_matching_rules_from_hash(node,
parent_bf,
local_name_hash,
element.get_local_name(),
matching_rules_list,
shareable);
SelectorMap::get_matching_rules(node,
parent_bf,
self.universal_rules.as_slice(),
matching_rules_list,
shareable);
@ -145,13 +151,14 @@ impl SelectorMap {
N:TNode<E>,
V:VecLike<DeclarationBlock>>(
node: &N,
parent_bf: &Option<BloomFilter>,
hash: &HashMap<Atom, Vec<Rule>>,
key: &Atom,
matching_rules: &mut V,
shareable: &mut bool) {
match hash.find(key) {
Some(rules) => {
SelectorMap::get_matching_rules(node, rules.as_slice(), matching_rules, shareable)
SelectorMap::get_matching_rules(node, parent_bf, rules.as_slice(), matching_rules, shareable)
}
None => {}
}
@ -162,11 +169,12 @@ impl SelectorMap {
N:TNode<E>,
V:VecLike<DeclarationBlock>>(
node: &N,
parent_bf: &Option<BloomFilter>,
rules: &[Rule],
matching_rules: &mut V,
shareable: &mut bool) {
for rule in rules.iter() {
if matches_compound_selector(&*rule.selector, node, shareable) {
if matches_compound_selector(&*rule.selector, node, parent_bf, shareable) {
matching_rules.vec_push(rule.declarations.clone());
}
}
@ -247,6 +255,11 @@ impl SelectorMap {
}
}
// The bloom filter for descendant CSS selectors will have a <1% false
// positive rate until it has this many selectors in it, then it will
// rapidly increase.
pub static RECOMMENDED_SELECTOR_BLOOM_FILTER_SIZE: uint = 4096;
pub struct Stylist {
element_map: PerPseudoElementSelectorMap,
before_map: PerPseudoElementSelectorMap,
@ -336,6 +349,7 @@ impl Stylist {
V:VecLike<DeclarationBlock>>(
&self,
element: &N,
parent_bf: &Option<BloomFilter>,
style_attribute: Option<&PropertyDeclarationBlock>,
pseudo_element: Option<PseudoElement>,
applicable_declarations: &mut V)
@ -354,10 +368,11 @@ impl Stylist {
// Step 1: Normal rules.
map.user_agent.normal.get_all_matching_rules(element,
parent_bf,
applicable_declarations,
&mut shareable);
map.user.normal.get_all_matching_rules(element, applicable_declarations, &mut shareable);
map.author.normal.get_all_matching_rules(element, applicable_declarations, &mut shareable);
map.user.normal.get_all_matching_rules(element, parent_bf, applicable_declarations, &mut shareable);
map.author.normal.get_all_matching_rules(element, parent_bf, applicable_declarations, &mut shareable);
// Step 2: Normal style attributes.
style_attribute.map(|sa| {
@ -367,6 +382,7 @@ impl Stylist {
// Step 3: Author-supplied `!important` rules.
map.author.important.get_all_matching_rules(element,
parent_bf,
applicable_declarations,
&mut shareable);
@ -378,9 +394,11 @@ impl Stylist {
// Step 5: User and UA `!important` rules.
map.user.important.get_all_matching_rules(element,
parent_bf,
applicable_declarations,
&mut shareable);
map.user_agent.important.get_all_matching_rules(element,
parent_bf,
applicable_declarations,
&mut shareable);
@ -449,13 +467,12 @@ impl DeclarationBlock {
}
}
pub fn matches<E:TElement, N:TNode<E>>(selector_list: &SelectorList, element: &N) -> bool {
pub fn matches<E:TElement, N:TNode<E>>(selector_list: &SelectorList, element: &N, parent_bf: &Option<BloomFilter>) -> bool {
get_selector_list_selectors(selector_list).iter().any(|selector|
selector.pseudo_element.is_none() &&
matches_compound_selector(&*selector.compound_selectors, element, &mut false))
matches_compound_selector(&*selector.compound_selectors, element, parent_bf, &mut false))
}
/// Determines whether the given element matches the given single or compound selector.
///
/// NB: If you add support for any new kinds of selectors to this routine, be sure to set
@ -466,9 +483,10 @@ fn matches_compound_selector<E:TElement,
N:TNode<E>>(
selector: &CompoundSelector,
element: &N,
parent_bf: &Option<BloomFilter>,
shareable: &mut bool)
-> bool {
match matches_compound_selector_internal(selector, element, shareable) {
match matches_compound_selector_internal(selector, element, parent_bf, shareable) {
Matched => true,
_ => false
}
@ -523,17 +541,82 @@ enum SelectorMatchingResult {
NotMatchedGlobally,
}
/// Quickly figures out whether or not the compound selector is worth doing more
/// work on. If the simple selectors don't match, or there's a child selector
/// that does not appear in the bloom parent bloom filter, we can exit early.
fn can_fast_reject<E: TElement, N: TNode<E>>(
mut selector: &CompoundSelector,
element: &N,
parent_bf: &Option<BloomFilter>,
shareable: &mut bool) -> Option<SelectorMatchingResult> {
if !selector.simple_selectors.iter().all(|simple_selector| {
matches_simple_selector(simple_selector, element, shareable) }) {
return Some(NotMatchedAndRestartFromClosestLaterSibling);
}
let bf: &BloomFilter =
match *parent_bf {
None => return None,
Some(ref bf) => bf,
};
// See if the bloom filter can exclude any of the descendant selectors, and
// reject if we can.
loop {
match selector.next {
None => break,
Some((ref cs, Descendant)) => selector = &**cs,
Some((ref cs, _)) => {
selector = &**cs;
continue;
}
};
for ss in selector.simple_selectors.iter() {
match *ss {
LocalNameSelector(LocalNameSelector { ref name, ref lower_name }) => {
if bf.definitely_excludes(name)
&& bf.definitely_excludes(lower_name) {
return Some(NotMatchedGlobally);
}
},
NamespaceSelector(ref namespace) => {
if bf.definitely_excludes(namespace) {
return Some(NotMatchedGlobally);
}
},
IDSelector(ref id) => {
if bf.definitely_excludes(id) {
return Some(NotMatchedGlobally);
}
},
ClassSelector(ref class) => {
if bf.definitely_excludes(&class.as_slice()) {
return Some(NotMatchedGlobally);
}
},
_ => {},
}
}
}
// Can't fast reject.
return None;
}
fn matches_compound_selector_internal<E:TElement,
N:TNode<E>>(
selector: &CompoundSelector,
element: &N,
parent_bf: &Option<BloomFilter>,
shareable: &mut bool)
-> SelectorMatchingResult {
if !selector.simple_selectors.iter().all(|simple_selector| {
matches_simple_selector(simple_selector, element, shareable)
}) {
return NotMatchedAndRestartFromClosestLaterSibling
}
match can_fast_reject(selector, element, parent_bf, shareable) {
None => {},
Some(result) => return result,
};
match selector.next {
None => Matched,
Some((ref next_selector, combinator)) => {
@ -557,6 +640,7 @@ fn matches_compound_selector_internal<E:TElement,
if node.is_element() {
let result = matches_compound_selector_internal(&**next_selector,
&node,
parent_bf,
shareable);
match (result, combinator) {
// Return the status immediately.
@ -596,7 +680,7 @@ fn matches_compound_selector_internal<E:TElement,
/// will almost certainly break as nodes will start mistakenly sharing styles. (See the code in
/// `main/css/matching.rs`.)
#[inline]
fn matches_simple_selector<E:TElement,
pub fn matches_simple_selector<E:TElement,
N:TNode<E>>(
selector: &SimpleSelector,
element: &N,