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Auto merge of #15317 - emilio:style-attr-restyle, r=bholley

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style: Avoid selector-matching when only the style attribute is changed.

r? @bholley

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This commit is contained in:
bors-servo 2017-02-02 03:00:22 -08:00 • committed by GitHub
commit fb7f65fc57
5 changed files with 336 additions and 93 deletions
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103
components/style/data.rs
View file

@ -9,7 +9,7 @@
use dom::TElement;
use properties::ComputedValues;
use properties::longhands::display::computed_value as display;
use restyle_hints::{RESTYLE_LATER_SIBLINGS, RestyleHint};
use restyle_hints::{RESTYLE_LATER_SIBLINGS, RESTYLE_SELF, RestyleHint};
use rule_tree::StrongRuleNode;
use selector_parser::{PseudoElement, RestyleDamage, Snapshot};
use std::collections::HashMap;
@ -44,8 +44,8 @@ impl ComputedStyle {
}
}
// We manually implement Debug for ComputedStyle so tht we can avoid the verbose
// stringification of ComputedValues for normal logging.
// We manually implement Debug for ComputedStyle so that we can avoid the
// verbose stringification of ComputedValues for normal logging.
impl fmt::Debug for ComputedStyle {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "ComputedStyle {{ rules: {:?}, values: {{..}} }}", self.rules)
@ -55,6 +55,13 @@ impl fmt::Debug for ComputedStyle {
type PseudoStylesInner = HashMap<PseudoElement, ComputedStyle,
BuildHasherDefault<::fnv::FnvHasher>>;
/// The rule nodes for each of the pseudo-elements of an element.
///
/// TODO(emilio): Probably shouldn't be a `HashMap` by default, but a smaller
/// array.
pub type PseudoRuleNodes = HashMap<PseudoElement, StrongRuleNode,
BuildHasherDefault<::fnv::FnvHasher>>;
/// A set of styles for a given element's pseudo-elements.
///
/// This is a map from pseudo-element to `ComputedStyle`.
@ -69,6 +76,19 @@ impl PseudoStyles {
pub fn empty() -> Self {
PseudoStyles(HashMap::with_hasher(Default::default()))
}
/// Gets the rules that the different pseudo-elements matched.
///
/// FIXME(emilio): We could in theory avoid creating these when we have
/// support for just re-cascading an element. Then the input to
/// `cascade_node` could be `MatchResults` or just `UseExistingStyle`.
pub fn get_rules(&self) -> PseudoRuleNodes {
let mut rules = HashMap::with_hasher(Default::default());
for (pseudo, style) in &self.0 {
rules.insert(pseudo.clone(), style.rules.clone());
}
rules
}
}
impl Deref for PseudoStyles {
@ -144,8 +164,11 @@ impl DescendantRestyleHint {
/// to provide more type safety while propagating restyle hints down the tree.
#[derive(Clone, Debug)]
pub struct StoredRestyleHint {
/// Whether this element should be restyled during the traversal.
pub restyle_self: bool,
/// Whether this element should be restyled during the traversal, and how.
///
/// This hint is stripped down, and only contains hints that are a subset of
/// RestyleHint::for_single_element().
pub self_: RestyleHint,
/// Whether the descendants of this element need to be restyled.
pub descendants: DescendantRestyleHint,
}
@ -154,7 +177,11 @@ impl StoredRestyleHint {
/// Propagates this restyle hint to a child element.
pub fn propagate(&self) -> Self {
StoredRestyleHint {
restyle_self: self.descendants != DescendantRestyleHint::Empty,
self_: if self.descendants == DescendantRestyleHint::Empty {
RestyleHint::empty()
} else {
RESTYLE_SELF
},
descendants: self.descendants.propagate(),
}
}
@ -162,7 +189,7 @@ impl StoredRestyleHint {
/// Creates an empty `StoredRestyleHint`.
pub fn empty() -> Self {
StoredRestyleHint {
restyle_self: false,
self_: RestyleHint::empty(),
descendants: DescendantRestyleHint::Empty,
}
}
@ -171,29 +198,32 @@ impl StoredRestyleHint {
/// including the element.
pub fn subtree() -> Self {
StoredRestyleHint {
restyle_self: true,
self_: RESTYLE_SELF,
descendants: DescendantRestyleHint::Descendants,
}
}
/// Returns true if the hint indicates that our style may be invalidated.
pub fn has_self_invalidations(&self) -> bool {
!self.self_.is_empty()
}
/// Whether the restyle hint is empty (nothing requires to be restyled).
pub fn is_empty(&self) -> bool {
!self.restyle_self && self.descendants == DescendantRestyleHint::Empty
!self.has_self_invalidations() &&
self.descendants == DescendantRestyleHint::Empty
}
/// Insert another restyle hint, effectively resulting in the union of both.
pub fn insert(&mut self, other: &Self) {
self.restyle_self = self.restyle_self || other.restyle_self;
self.self_ |= other.self_;
self.descendants = self.descendants.union(other.descendants);
}
}
impl Default for StoredRestyleHint {
fn default() -> Self {
StoredRestyleHint {
restyle_self: false,
descendants: DescendantRestyleHint::Empty,
}
StoredRestyleHint::empty()
}
}
@ -203,7 +233,7 @@ impl From<RestyleHint> for StoredRestyleHint {
use self::DescendantRestyleHint::*;
debug_assert!(!hint.contains(RESTYLE_LATER_SIBLINGS), "Caller should apply sibling hints");
StoredRestyleHint {
restyle_self: hint.contains(RESTYLE_SELF) || hint.contains(RESTYLE_STYLE_ATTRIBUTE),
self_: hint & RestyleHint::for_self(),
descendants: if hint.contains(RESTYLE_DESCENDANTS) { Descendants } else { Empty },
}
}
@ -319,7 +349,9 @@ impl RestyleData {
/// Returns true if this RestyleData might invalidate the current style.
pub fn has_invalidations(&self) -> bool {
self.hint.restyle_self || self.recascade || self.snapshot.is_some()
self.hint.has_self_invalidations() ||
self.recascade ||
self.snapshot.is_some()
}
}
@ -338,6 +370,19 @@ pub struct ElementData {
restyle: Option<Box<RestyleData>>,
}
/// The kind of restyle that a single element should do.
pub enum RestyleKind {
/// We need to run selector matching plus re-cascade, that is, a full
/// restyle.
MatchAndCascade,
/// We need to recascade with some replacement rule, such as the style
/// attribute, or animation rules.
CascadeWithReplacements(RestyleHint),
/// We only need to recascade, for example, because only inherited
/// properties in the parent changed.
CascadeOnly,
}
impl ElementData {
/// Trivially construct an ElementData.
pub fn new(existing: Option<ElementStyles>) -> Self {
@ -356,7 +401,31 @@ impl ElementData {
/// invalidation.
pub fn has_current_styles(&self) -> bool {
self.has_styles() &&
self.restyle.as_ref().map_or(true, |r| !r.has_invalidations())
self.restyle.as_ref().map_or(true, |r| !r.has_invalidations())
}
/// Returns the kind of restyling that we're going to need to do on this
/// element, based of the stored restyle hint.
pub fn restyle_kind(&self) -> RestyleKind {
debug_assert!(!self.has_current_styles(), "Should've stopped earlier");
if !self.has_styles() {
return RestyleKind::MatchAndCascade;
}
debug_assert!(self.restyle.is_some());
let restyle_data = self.restyle.as_ref().unwrap();
let hint = restyle_data.hint.self_;
if hint.contains(RESTYLE_SELF) {
return RestyleKind::MatchAndCascade;
}
if !hint.is_empty() {
return RestyleKind::CascadeWithReplacements(hint);
}
debug_assert!(restyle_data.recascade,
"We definitely need to do something!");
return RestyleKind::CascadeOnly;
}
/// Gets the element styles, if any.

72
components/style/matching.rs
View file

@ -13,19 +13,19 @@ use atomic_refcell::AtomicRefMut;
use cache::LRUCache;
use cascade_info::CascadeInfo;
use context::{SharedStyleContext, StyleContext};
use data::{ComputedStyle, ElementData, ElementStyles, PseudoStyles};
use data::{ComputedStyle, ElementData, ElementStyles, PseudoRuleNodes, PseudoStyles};
use dom::{SendElement, TElement, TNode};
use properties::{CascadeFlags, ComputedValues, SHAREABLE, SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP, cascade};
use properties::longhands::display::computed_value as display;
use rule_tree::StrongRuleNode;
use restyle_hints::{RESTYLE_STYLE_ATTRIBUTE, RestyleHint};
use rule_tree::{CascadeLevel, StrongRuleNode};
use selector_parser::{PseudoElement, RestyleDamage, SelectorImpl};
use selectors::MatchAttr;
use selectors::bloom::BloomFilter;
use selectors::matching::{AFFECTED_BY_PSEUDO_ELEMENTS, MatchingReason, StyleRelations};
use selectors::matching::{AFFECTED_BY_PSEUDO_ELEMENTS, AFFECTED_BY_STYLE_ATTRIBUTE, MatchingReason, StyleRelations};
use servo_config::opts;
use sink::ForgetfulSink;
use std::collections::HashMap;
use std::hash::BuildHasherDefault;
use std::slice::IterMut;
use std::sync::Arc;
use stylist::ApplicableDeclarationBlock;
@ -60,13 +60,6 @@ fn create_common_style_affecting_attributes_from_element<E: TElement>(element: &
flags
}
/// The rule nodes for each of the pseudo-elements of an element.
///
/// TODO(emilio): Probably shouldn't be a `HashMap` by default, but a smaller
/// array.
type PseudoRuleNodes = HashMap<PseudoElement, StrongRuleNode,
BuildHasherDefault<::fnv::FnvHasher>>;
/// The results of selector matching on an element.
pub struct MatchResults {
/// The rule node reference that represents the rules matched by the
@ -635,6 +628,59 @@ pub trait MatchMethods : TElement {
}
}
/// Get the appropriate MatchResults from the current styles, to perform a
/// recascade.
///
/// TODO(emilio): Stop using `MachResults`, use an enum, or something.
fn match_results_from_current_style(&self, data: &ElementData) -> MatchResults {
let rule_node = data.styles().primary.rules.clone();
MatchResults {
primary: rule_node,
// FIXME(emilio): Same concern as below.
relations: StyleRelations::empty(),
// The per-pseudo rule-nodes haven't changed, but still need to be
// recascaded.
per_pseudo: data.styles().pseudos.get_rules(),
}
}
/// Updates the rule nodes without re-running selector matching, using just
/// the rule tree.
fn cascade_with_replacements(&self,
hint: RestyleHint,
context: &StyleContext<Self>,
data: &mut AtomicRefMut<ElementData>)
-> MatchResults {
let mut rule_node = data.styles().primary.rules.clone();
if hint.contains(RESTYLE_STYLE_ATTRIBUTE) {
let style_attribute = self.style_attribute();
rule_node = context.shared.stylist.rule_tree
.update_rule_at_level(CascadeLevel::StyleAttributeNormal,
style_attribute,
rule_node);
rule_node = context.shared.stylist.rule_tree
.update_rule_at_level(CascadeLevel::StyleAttributeImportant,
style_attribute,
rule_node);
}
MatchResults {
primary: rule_node,
// FIXME(emilio): This is ok, for now, we shouldn't need to fake
// this.
relations: AFFECTED_BY_STYLE_ATTRIBUTE,
// The per-pseudo rule-nodes haven't changed, but still need to be
// recomputed.
//
// TODO(emilio): We could probably optimize this quite a bit.
per_pseudo: data.styles().pseudos.get_rules(),
}
}
/// Attempts to share a style with another node. This method is unsafe
/// because it depends on the `style_sharing_candidate_cache` having only
/// live nodes in it, and we have no way to guarantee that at the type
@ -649,6 +695,10 @@ pub trait MatchMethods : TElement {
return StyleSharingResult::CannotShare
}
if self.parent_element().is_none() {
return StyleSharingResult::CannotShare
}
if self.style_attribute().is_some() {
return StyleSharingResult::CannotShare
}

8
components/style/restyle_hints.rs
View file

@ -50,6 +50,14 @@ bitflags! {
}
}
impl RestyleHint {
/// The subset hints that affect the styling of a single element during the
/// traversal.
pub fn for_self() -> Self {
RESTYLE_SELF | RESTYLE_STYLE_ATTRIBUTE
}
}
#[cfg(feature = "gecko")]
impl From<nsRestyleHint> for RestyleHint {
fn from(raw: nsRestyleHint) -> Self {

131
components/style/rule_tree/mod.rs
View file

@ -153,9 +153,20 @@ impl RuleTree {
pub fn insert_ordered_rules<'a, I>(&self, iter: I) -> StrongRuleNode
where I: Iterator<Item=(StyleSource, CascadeLevel)>,
{
let mut current = self.root.clone();
self.insert_ordered_rules_from(self.root.clone(), iter)
}
fn insert_ordered_rules_from<'a, I>(&self,
from: StrongRuleNode,
iter: I) -> StrongRuleNode
where I: Iterator<Item=(StyleSource, CascadeLevel)>,
{
let mut current = from;
let mut last_level = current.get().level;
for (source, level) in iter {
debug_assert!(last_level <= level, "Not really ordered");
current = current.ensure_child(self.root.downgrade(), source, level);
last_level = level;
}
current
}
@ -169,6 +180,90 @@ impl RuleTree {
pub unsafe fn maybe_gc(&self) {
self.root.maybe_gc();
}
/// Replaces a rule in a given level (if present) for another rule.
///
/// Returns the resulting node that represents the new path.
pub fn update_rule_at_level(&self,
level: CascadeLevel,
pdb: Option<&Arc<RwLock<PropertyDeclarationBlock>>>,
path: StrongRuleNode)
-> StrongRuleNode {
debug_assert!(level.is_unique_per_element());
// TODO(emilio): Being smarter with lifetimes we could avoid a bit of
// the refcount churn.
let mut current = path.clone();
// First walk up until the first less-or-equally specific rule.
let mut children = vec![];
while current.get().level > level {
children.push((current.get().source.clone().unwrap(), current.get().level));
current = current.parent().unwrap().clone();
}
// Then remove the one at the level we want to replace, if any.
//
// NOTE: Here we assume that only one rule can be at the level we're
// replacing.
//
// This is certainly true for HTML style attribute rules, animations and
// transitions, but could not be so for SMIL animations, which we'd need
// to special-case (isn't hard, it's just about removing the `if` and
// special cases, and replacing them for a `while` loop, avoiding the
// optimizations).
if current.get().level == level {
if let Some(pdb) = pdb {
// If the only rule at the level we're replacing is exactly the
// same as `pdb`, we're done, and `path` is still valid.
//
// TODO(emilio): Another potential optimization is the one where
// we can just replace the rule at that level for `pdb`, and
// then we don't need to re-create the children, and `path` is
// also equally valid. This is less likely, and would require an
// in-place mutation of the source, which is, at best, fiddly,
// so let's skip it for now.
let is_here_already = match current.get().source.as_ref() {
Some(&StyleSource::Declarations(ref already_here)) => {
arc_ptr_eq(pdb, already_here)
},
_ => unreachable!("Replacing non-declarations style?"),
};
if is_here_already {
debug!("Picking the fast path in rule replacement");
return path;
}
}
current = current.parent().unwrap().clone();
}
debug_assert!(current.get().level != level,
"Multiple rules should've been replaced?");
// Insert the rule if it's relevant at this level in the cascade.
//
// These optimizations are likely to be important, because the levels
// where replacements apply (style and animations) tend to trigger
// pretty bad styling cases already.
if let Some(pdb) = pdb {
if level.is_important() {
if pdb.read().any_important() {
current = current.ensure_child(self.root.downgrade(),
StyleSource::Declarations(pdb.clone()),
level);
}
} else {
if pdb.read().any_normal() {
current = current.ensure_child(self.root.downgrade(),
StyleSource::Declarations(pdb.clone()),
level);
}
}
}
// Now the rule is in the relevant place, push the children as
// necessary.
self.insert_ordered_rules_from(current, children.into_iter().rev())
}
}
/// The number of RuleNodes added to the free list before we will consider
@ -183,7 +278,7 @@ const RULE_TREE_GC_INTERVAL: usize = 300;
///
/// [1]: https://drafts.csswg.org/css-cascade/#cascade-origin
#[repr(u8)]
#[derive(Eq, PartialEq, Copy, Clone, Debug)]
#[derive(Eq, PartialEq, Copy, Clone, Debug, PartialOrd)]
#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
pub enum CascadeLevel {
/// Normal User-Agent rules.
@ -211,6 +306,18 @@ pub enum CascadeLevel {
}
impl CascadeLevel {
/// Returns whether this cascade level is unique per element, in which case
/// we can replace the path in the cascade without fear.
pub fn is_unique_per_element(&self) -> bool {
match *self {
CascadeLevel::Transitions |
CascadeLevel::Animations |
CascadeLevel::StyleAttributeNormal |
CascadeLevel::StyleAttributeImportant => true,
_ => false,
}
}
/// Returns whether this cascade level represents important rules of some
/// sort.
#[inline]
@ -248,7 +355,7 @@ struct RuleNode {
source: Option<StyleSource>,
/// The cascade level this rule is positioned at.
cascade_level: CascadeLevel,
level: CascadeLevel,
refcount: AtomicUsize,
first_child: AtomicPtr<RuleNode>,
@ -274,13 +381,13 @@ impl RuleNode {
fn new(root: WeakRuleNode,
parent: StrongRuleNode,
source: StyleSource,
cascade_level: CascadeLevel) -> Self {
level: CascadeLevel) -> Self {
debug_assert!(root.upgrade().parent().is_none());
RuleNode {
root: Some(root),
parent: Some(parent),
source: Some(source),
cascade_level: cascade_level,
level: level,
refcount: AtomicUsize::new(1),
first_child: AtomicPtr::new(ptr::null_mut()),
next_sibling: AtomicPtr::new(ptr::null_mut()),
@ -295,7 +402,7 @@ impl RuleNode {
root: None,
parent: None,
source: None,
cascade_level: CascadeLevel::UANormal,
level: CascadeLevel::UANormal,
refcount: AtomicUsize::new(1),
first_child: AtomicPtr::new(ptr::null_mut()),
next_sibling: AtomicPtr::new(ptr::null_mut()),
@ -444,10 +551,10 @@ impl StrongRuleNode {
fn ensure_child(&self,
root: WeakRuleNode,
source: StyleSource,
cascade_level: CascadeLevel) -> StrongRuleNode {
level: CascadeLevel) -> StrongRuleNode {
let mut last = None;
for child in self.get().iter_children() {
if child .get().cascade_level == cascade_level &&
if child .get().level == level &&
child.get().source.as_ref().unwrap().ptr_equals(&source) {
return child;
}
@ -455,9 +562,9 @@ impl StrongRuleNode {
}
let mut node = Box::new(RuleNode::new(root,
self.clone(),
source.clone(),
cascade_level));
self.clone(),
source.clone(),
level));
let new_ptr: *mut RuleNode = &mut *node;
loop {
@ -521,7 +628,7 @@ impl StrongRuleNode {
/// Get the importance that this rule node represents.
pub fn importance(&self) -> Importance {
self.get().cascade_level.importance()
self.get().level.importance()
}
/// Get an iterator for this rule node and its ancestors.

115
components/style/traversal.rs
View file

@ -8,7 +8,7 @@
use atomic_refcell::{AtomicRefCell, AtomicRefMut};
use context::{SharedStyleContext, StyleContext, ThreadLocalStyleContext};
use data::{ElementData, ElementStyles, StoredRestyleHint};
use data::{ElementData, ElementStyles, RestyleKind, StoredRestyleHint};
use dom::{NodeInfo, TElement, TNode};
use matching::{MatchMethods, StyleSharingResult};
use restyle_hints::{RESTYLE_DESCENDANTS, RESTYLE_SELF};
@ -453,9 +453,6 @@ pub fn recalc_style_at<E, D>(traversal: &D,
// Computes style, returning true if the inherited styles changed for this
// element.
//
// FIXME(bholley): This should differentiate between matching and cascading,
// since we have separate bits for each now.
fn compute_style<E, D>(_traversal: &D,
traversal_data: &mut PerLevelTraversalData,
context: &mut StyleContext<E>,
@ -466,63 +463,75 @@ fn compute_style<E, D>(_traversal: &D,
{
context.thread_local.statistics.elements_styled += 1;
let shared_context = context.shared;
// Ensure the bloom filter is up to date.
let dom_depth = context.thread_local.bloom_filter
.insert_parents_recovering(element, traversal_data.current_dom_depth);
// Update the dom depth with the up-to-date dom depth.
//
// Note that this is always the same than the pre-existing depth, but it can
// change from unknown to known at this step.
traversal_data.current_dom_depth = Some(dom_depth);
// TODO(emilio): Make cascade_input less expensive to compute in the cases
// we don't need to run selector matching.
let cascade_input = match data.restyle_kind() {
RestyleKind::MatchAndCascade => {
// Check to see whether we can share a style with someone.
let sharing_result = unsafe {
element.share_style_if_possible(&mut context.thread_local.style_sharing_candidate_cache,
shared_context,
&mut data)
};
context.thread_local.bloom_filter.assert_complete(element);
// Check to see whether we can share a style with someone.
let sharing_result = if element.parent_element().is_none() {
StyleSharingResult::CannotShare
} else {
unsafe { element.share_style_if_possible(&mut context.thread_local.style_sharing_candidate_cache,
shared_context, &mut data) }
};
// Otherwise, match and cascade selectors.
match sharing_result {
StyleSharingResult::CannotShare => {
let match_results;
let shareable_element = {
// Perform the CSS selector matching.
context.thread_local.statistics.elements_matched += 1;
let filter = context.thread_local.bloom_filter.filter();
match_results = element.match_element(context, Some(filter));
if match_results.primary_is_shareable() {
Some(element)
} else {
match sharing_result {
StyleSharingResult::StyleWasShared(index) => {
context.thread_local.statistics.styles_shared += 1;
context.thread_local.style_sharing_candidate_cache.touch(index);
None
}
};
let relations = match_results.relations;
StyleSharingResult::CannotShare => {
// Ensure the bloom filter is up to date.
let dom_depth =
context.thread_local.bloom_filter
.insert_parents_recovering(element,
traversal_data.current_dom_depth);
// Perform the CSS cascade.
unsafe {
let shareable = match_results.primary_is_shareable();
element.cascade_node(context, &mut data,
element.parent_element(),
match_results.primary,
match_results.per_pseudo,
shareable);
}
// Update the dom depth with the up-to-date dom depth.
//
// Note that this is always the same than the pre-existing depth,
// but it can change from unknown to known at this step.
traversal_data.current_dom_depth = Some(dom_depth);
// Add ourselves to the LRU cache.
if let Some(element) = shareable_element {
context.thread_local
.style_sharing_candidate_cache
.insert_if_possible(&element, &data.styles().primary.values, relations);
context.thread_local.bloom_filter.assert_complete(element);
// Perform the CSS selector matching.
context.thread_local.statistics.elements_matched += 1;
let filter = context.thread_local.bloom_filter.filter();
Some(element.match_element(context, Some(filter)))
}
}
}
StyleSharingResult::StyleWasShared(index) => {
context.thread_local.statistics.styles_shared += 1;
context.thread_local.style_sharing_candidate_cache.touch(index);
RestyleKind::CascadeWithReplacements(hint) => {
Some(element.cascade_with_replacements(hint, context, &mut data))
}
RestyleKind::CascadeOnly => {
// TODO(emilio): Stop doing this work, and teach cascade_node about
// the current style instead.
Some(element.match_results_from_current_style(&*data))
}
};
if let Some(match_results) = cascade_input {
// Perform the CSS cascade.
let shareable = match_results.primary_is_shareable();
unsafe {
element.cascade_node(context, &mut data,
element.parent_element(),
match_results.primary,
match_results.per_pseudo,
shareable);
}
if shareable {
// Add ourselves to the LRU cache.
context.thread_local
.style_sharing_candidate_cache
.insert_if_possible(&element,
&data.styles().primary.values,
match_results.relations);
}
}