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LibWeb: Reduce HashMap thrashing during custom property cascade

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Build the final custom property map right away instead of first making
a temporary pointer-only map. We also precompute the final needed
capacity for the map to avoid incremental rehashing.
This commit is contained in:
Andreas Kling 2022-03-03 13:40:06 +01:00
parent e4fdb40158
commit 205208db11
3 changed files with 23 additions and 25 deletions
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35
Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
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@ -439,7 +439,7 @@ static void set_property_expanding_shorthands(StyleProperties& style, CSS::Prope
style.set_property(property_id, value);
}
bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView property_name, HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>>& dependencies, Vector<StyleComponentValueRule> const& source, Vector<StyleComponentValueRule>& dest, size_t source_start_index, HashMap<FlyString, StyleProperty const*> const& custom_properties) const
bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView property_name, HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>>& dependencies, Vector<StyleComponentValueRule> const& source, Vector<StyleComponentValueRule>& dest, size_t source_start_index, HashMap<FlyString, StyleProperty> const& custom_properties) const
{
// FIXME: Do this better!
// We build a copy of the tree of StyleComponentValueRules, with all var()s replaced with their contents.
@ -456,7 +456,7 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
auto get_custom_property = [&custom_properties](auto& name) -> RefPtr<StyleValue> {
auto it = custom_properties.find(name);
if (it != custom_properties.end())
return it->value->value;
return it->value.value;
return nullptr;
};
@ -532,7 +532,7 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
return true;
}
RefPtr<StyleValue> StyleComputer::resolve_unresolved_style_value(DOM::Element& element, PropertyID property_id, UnresolvedStyleValue const& unresolved, HashMap<FlyString, StyleProperty const*> const& custom_properties) const
RefPtr<StyleValue> StyleComputer::resolve_unresolved_style_value(DOM::Element& element, PropertyID property_id, UnresolvedStyleValue const& unresolved, HashMap<FlyString, StyleProperty> const& custom_properties) const
{
// Unresolved always contains a var(), unless it is a custom property's value, in which case we shouldn't be trying
// to produce a different StyleValue from it.
@ -549,7 +549,7 @@ RefPtr<StyleValue> StyleComputer::resolve_unresolved_style_value(DOM::Element& e
return {};
}
void StyleComputer::cascade_declarations(StyleProperties& style, DOM::Element& element, Vector<MatchingRule> const& matching_rules, CascadeOrigin cascade_origin, Important important, HashMap<FlyString, StyleProperty const*> const& custom_properties) const
void StyleComputer::cascade_declarations(StyleProperties& style, DOM::Element& element, Vector<MatchingRule> const& matching_rules, CascadeOrigin cascade_origin, Important important, HashMap<FlyString, StyleProperty> const& custom_properties) const
{
for (auto const& match : matching_rules) {
for (auto const& property : verify_cast<PropertyOwningCSSStyleDeclaration>(match.rule->declaration()).properties()) {
@ -575,26 +575,29 @@ void StyleComputer::cascade_declarations(StyleProperties& style, DOM::Element& e
}
}
static HashMap<FlyString, StyleProperty const*> cascade_custom_properties(DOM::Element& element, Vector<MatchingRule> const& matching_rules)
static HashMap<FlyString, StyleProperty> const& cascade_custom_properties(DOM::Element& element, Vector<MatchingRule> const& matching_rules)
{
HashMap<FlyString, StyleProperty const*> custom_properties;
size_t needed_capacity = 0;
if (auto* parent_element = element.parent_element())
needed_capacity += parent_element->custom_properties().size();
for (auto const& matching_rule : matching_rules)
needed_capacity += verify_cast<PropertyOwningCSSStyleDeclaration>(matching_rule.rule->declaration()).custom_properties().size();
HashMap<FlyString, StyleProperty> custom_properties;
custom_properties.ensure_capacity(needed_capacity);
if (auto* parent_element = element.parent_element()) {
for (auto const& it : parent_element->custom_properties())
custom_properties.set(it.key, &it.value);
custom_properties.set(it.key, it.value);
}
for (auto const& matching_rule : matching_rules) {
for (auto const& it : verify_cast<PropertyOwningCSSStyleDeclaration>(matching_rule.rule->declaration()).custom_properties()) {
custom_properties.set(it.key, &it.value);
}
for (auto const& it : verify_cast<PropertyOwningCSSStyleDeclaration>(matching_rule.rule->declaration()).custom_properties())
custom_properties.set(it.key, it.value);
}
element.custom_properties().clear();
for (auto& it : custom_properties)
element.add_custom_property(it.key, *it.value);
return custom_properties;
element.set_custom_properties(move(custom_properties));
return element.custom_properties();
}
// https://www.w3.org/TR/css-cascade/#cascading
@ -608,7 +611,7 @@ void StyleComputer::compute_cascaded_values(StyleProperties& style, DOM::Element
sort_matching_rules(matching_rule_set.author_rules);
// Then we resolve all the CSS custom properties ("variables") for this element:
auto custom_properties = cascade_custom_properties(element, matching_rule_set.author_rules);
auto const& custom_properties = cascade_custom_properties(element, matching_rule_set.author_rules);
// Then we apply the declarations from the matched rules in cascade order: