servo/components/script/dom/csssupportsrule.rs
JoeDow 6e6ef513a9
Reuse StylesheetContent for inline style sheets with identical content (#38540)
For duplicate style sheets with identical content, `StylesheetContents`
can be reused to avoid redundant parsing of the inline style sheets.
Since duplicate stylesheets is a common case with web components, this
change will significantly improve performance. Additionally, the cache
hit rate of stylo's `CascadeDataCache` can now be significantly
improved.

When shared `StylesheetContents` is modified, copy-on-write will occur
to avoid affecting other sharers. And then updates the references to
`CssRule` or `PropertyDeclarationBlock` stored in the CSSOMs to ensure
that modifications are made only on the new copy.

Signed-off-by: sharpshooter_pt <ibluegalaxy_taoj@163.com>
2025-08-20 12:31:49 +00:00

84 lines
2.6 KiB
Rust

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use std::cell::RefCell;
use dom_struct::dom_struct;
use servo_arc::Arc;
use style::shared_lock::{SharedRwLockReadGuard, ToCssWithGuard};
use style::stylesheets::{CssRuleType, SupportsRule};
use style_traits::ToCss;
use crate::dom::bindings::reflector::reflect_dom_object;
use crate::dom::bindings::root::DomRoot;
use crate::dom::bindings::str::DOMString;
use crate::dom::cssconditionrule::CSSConditionRule;
use crate::dom::cssrule::SpecificCSSRule;
use crate::dom::cssstylesheet::CSSStyleSheet;
use crate::dom::window::Window;
use crate::script_runtime::CanGc;
#[dom_struct]
pub(crate) struct CSSSupportsRule {
cssconditionrule: CSSConditionRule,
#[ignore_malloc_size_of = "Arc"]
#[no_trace]
supportsrule: RefCell<Arc<SupportsRule>>,
}
impl CSSSupportsRule {
fn new_inherited(
parent_stylesheet: &CSSStyleSheet,
supportsrule: Arc<SupportsRule>,
) -> CSSSupportsRule {
let list = supportsrule.rules.clone();
CSSSupportsRule {
cssconditionrule: CSSConditionRule::new_inherited(parent_stylesheet, list),
supportsrule: RefCell::new(supportsrule),
}
}
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
pub(crate) fn new(
window: &Window,
parent_stylesheet: &CSSStyleSheet,
supportsrule: Arc<SupportsRule>,
can_gc: CanGc,
) -> DomRoot<CSSSupportsRule> {
reflect_dom_object(
Box::new(CSSSupportsRule::new_inherited(
parent_stylesheet,
supportsrule,
)),
window,
can_gc,
)
}
/// <https://drafts.csswg.org/css-conditional-3/#the-csssupportsrule-interface>
pub(crate) fn get_condition_text(&self) -> DOMString {
self.supportsrule.borrow().condition.to_css_string().into()
}
pub(crate) fn update_rule(
&self,
supportsrule: Arc<SupportsRule>,
guard: &SharedRwLockReadGuard,
) {
self.cssconditionrule
.update_rules(supportsrule.rules.clone(), guard);
*self.supportsrule.borrow_mut() = supportsrule;
}
}
impl SpecificCSSRule for CSSSupportsRule {
fn ty(&self) -> CssRuleType {
CssRuleType::Supports
}
fn get_css(&self) -> DOMString {
let guard = self.cssconditionrule.shared_lock().read();
self.supportsrule.borrow().to_css_string(&guard).into()
}
}