fune/servo/components/script/dom/cssconditionrule.rs
Simon Sapin 33a9e6d050 servo: Merge #16014 - Per-process lock for CSSOM objects (from servo:style-ref); r=emilio
<!-- Please describe your changes on the following line: -->

Before this PR, every object reflected in CSSOM is in `Arc<RwLock<_>>` to enable safe (synchronized) mutable aliasing. Acquiring all these locks has significant cost during selector matching:

* https://bugzilla.mozilla.org/show_bug.cgi?id=1311469
* https://bugzilla.mozilla.org/show_bug.cgi?id=1335941
* https://bugzilla.mozilla.org/show_bug.cgi?id=1339703

This PR introduce a mechanism to protect many objects with the same `RwLock` that only needs to be acquired once.

In Stylo, there is one such lock per process (in a `lazy_static`), used for everything.

I non-Stylo Servo, I originally intended to have one such lock per document (for author-origin stylesheets, and one per process for user-agent and user sytlesheets since they’re shared across documents, and never mutated anyway). However I failed to have the same document-specific (or pipeline-specific) `Arc` reachable from both `Document` nodes and `LayoutThread`. Recursively following callers lead me to include this `Arc` in `UnprivilegedPipelineContent`, but that needs to be serializable. So there is a second process-wide lock.

This was previously #15998, closed accidentally.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Source-Repo: https://github.com/servo/servo
Source-Revision: bb54f0a429de0e8b8861f8071b6cf82f73622664

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 851230e57ac8775707df5f0f103be5feac81fc41
2017-03-19 14:31:19 -07:00

61 lines
2.1 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 http://mozilla.org/MPL/2.0/. */
use dom::bindings::codegen::Bindings::CSSConditionRuleBinding::CSSConditionRuleMethods;
use dom::bindings::inheritance::Castable;
use dom::bindings::str::DOMString;
use dom::cssgroupingrule::CSSGroupingRule;
use dom::cssmediarule::CSSMediaRule;
use dom::cssstylesheet::CSSStyleSheet;
use dom::csssupportsrule::CSSSupportsRule;
use dom_struct::dom_struct;
use std::sync::Arc;
use style::shared_lock::{SharedRwLock, Locked};
use style::stylesheets::CssRules as StyleCssRules;
#[dom_struct]
pub struct CSSConditionRule {
cssgroupingrule: CSSGroupingRule,
}
impl CSSConditionRule {
pub fn new_inherited(parent_stylesheet: &CSSStyleSheet,
rules: Arc<Locked<StyleCssRules>>) -> CSSConditionRule {
CSSConditionRule {
cssgroupingrule: CSSGroupingRule::new_inherited(parent_stylesheet, rules),
}
}
pub fn parent_stylesheet(&self) -> &CSSStyleSheet {
self.cssgroupingrule.parent_stylesheet()
}
pub fn shared_lock(&self) -> &SharedRwLock {
self.cssgroupingrule.shared_lock()
}
}
impl CSSConditionRuleMethods for CSSConditionRule {
/// https://drafts.csswg.org/css-conditional-3/#dom-cssconditionrule-conditiontext
fn ConditionText(&self) -> DOMString {
if let Some(rule) = self.downcast::<CSSMediaRule>() {
rule.get_condition_text()
} else if let Some(rule) = self.downcast::<CSSSupportsRule>() {
rule.get_condition_text()
} else {
unreachable!()
}
}
/// https://drafts.csswg.org/css-conditional-3/#dom-cssconditionrule-conditiontext
fn SetConditionText(&self, text: DOMString) {
if let Some(rule) = self.downcast::<CSSMediaRule>() {
rule.set_condition_text(text)
} else if let Some(rule) = self.downcast::<CSSSupportsRule>() {
rule.set_condition_text(text)
} else {
unreachable!()
}
}
}