fune/servo/components/script/dom/cssstylesheet.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

114 lines
3.9 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::CSSStyleSheetBinding;
use dom::bindings::codegen::Bindings::CSSStyleSheetBinding::CSSStyleSheetMethods;
use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
use dom::bindings::error::{Error, ErrorResult, Fallible};
use dom::bindings::js::{JS, MutNullableJS, Root};
use dom::bindings::reflector::{reflect_dom_object, DomObject};
use dom::bindings::str::DOMString;
use dom::cssrulelist::{CSSRuleList, RulesSource};
use dom::element::Element;
use dom::stylesheet::StyleSheet;
use dom::window::Window;
use dom_struct::dom_struct;
use std::cell::Cell;
use std::sync::Arc;
use style::shared_lock::SharedRwLock;
use style::stylesheets::Stylesheet as StyleStyleSheet;
#[dom_struct]
pub struct CSSStyleSheet {
stylesheet: StyleSheet,
owner: JS<Element>,
rulelist: MutNullableJS<CSSRuleList>,
#[ignore_heap_size_of = "Arc"]
style_stylesheet: Arc<StyleStyleSheet>,
origin_clean: Cell<bool>,
}
impl CSSStyleSheet {
fn new_inherited(owner: &Element,
type_: DOMString,
href: Option<DOMString>,
title: Option<DOMString>,
stylesheet: Arc<StyleStyleSheet>) -> CSSStyleSheet {
CSSStyleSheet {
stylesheet: StyleSheet::new_inherited(type_, href, title),
owner: JS::from_ref(owner),
rulelist: MutNullableJS::new(None),
style_stylesheet: stylesheet,
origin_clean: Cell::new(true),
}
}
#[allow(unrooted_must_root)]
pub fn new(window: &Window,
owner: &Element,
type_: DOMString,
href: Option<DOMString>,
title: Option<DOMString>,
stylesheet: Arc<StyleStyleSheet>) -> Root<CSSStyleSheet> {
reflect_dom_object(box CSSStyleSheet::new_inherited(owner, type_, href, title, stylesheet),
window,
CSSStyleSheetBinding::Wrap)
}
fn rulelist(&self) -> Root<CSSRuleList> {
self.rulelist.or_init(|| CSSRuleList::new(self.global().as_window(),
self,
RulesSource::Rules(self.style_stylesheet
.rules.clone())))
}
pub fn disabled(&self) -> bool {
self.style_stylesheet.disabled()
}
pub fn set_disabled(&self, disabled: bool) {
if self.style_stylesheet.set_disabled(disabled) {
self.global().as_window().Document().invalidate_stylesheets();
}
}
pub fn shared_lock(&self) -> &SharedRwLock {
&self.style_stylesheet.shared_lock
}
pub fn style_stylesheet(&self) -> &StyleStyleSheet {
&self.style_stylesheet
}
pub fn set_origin_clean(&self, origin_clean: bool) {
self.origin_clean.set(origin_clean);
}
}
impl CSSStyleSheetMethods for CSSStyleSheet {
// https://drafts.csswg.org/cssom/#dom-cssstylesheet-cssrules
fn GetCssRules(&self) -> Fallible<Root<CSSRuleList>> {
if !self.origin_clean.get() {
return Err(Error::Security);
}
Ok(self.rulelist())
}
// https://drafts.csswg.org/cssom/#dom-cssstylesheet-insertrule
fn InsertRule(&self, rule: DOMString, index: u32) -> Fallible<u32> {
if !self.origin_clean.get() {
return Err(Error::Security);
}
self.rulelist().insert_rule(&rule, index, /* nested */ false)
}
// https://drafts.csswg.org/cssom/#dom-cssstylesheet-deleterule
fn DeleteRule(&self, index: u32) -> ErrorResult {
if !self.origin_clean.get() {
return Err(Error::Security);
}
self.rulelist().remove_rule(index)
}
}