mirror of
https://github.com/mozilla/gecko-dev.git
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133841fd02
Source-Repo: https://github.com/servo/servo Source-Revision: aeb7ab867f6d0d0df049329ebb55231c1e092805 --HG-- extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear extra : subtree_revision : 6a948927d7a2f65447b2f8fd65477fb66b3d3f13
296 lines
11 KiB
Rust
296 lines
11 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! The context within which style is calculated.
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#![deny(missing_docs)]
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use animation::Animation;
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use app_units::Au;
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use bloom::StyleBloom;
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use data::ElementData;
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use dom::{OpaqueNode, TNode, TElement, SendElement};
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use error_reporting::ParseErrorReporter;
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use euclid::Size2D;
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use matching::StyleSharingCandidateCache;
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use parking_lot::RwLock;
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use properties::ComputedValues;
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use selectors::matching::ElementSelectorFlags;
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use servo_config::opts;
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use std::collections::HashMap;
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use std::env;
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use std::fmt;
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use std::ops::Add;
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use std::sync::{Arc, Mutex};
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use std::sync::mpsc::Sender;
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use stylist::Stylist;
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use thread_state;
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use time;
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use timer::Timer;
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/// This structure is used to create a local style context from a shared one.
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pub struct ThreadLocalStyleContextCreationInfo {
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new_animations_sender: Sender<Animation>,
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}
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impl ThreadLocalStyleContextCreationInfo {
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/// Trivially constructs a `ThreadLocalStyleContextCreationInfo`.
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pub fn new(animations_sender: Sender<Animation>) -> Self {
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ThreadLocalStyleContextCreationInfo {
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new_animations_sender: animations_sender,
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}
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}
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}
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/// Which quirks mode is this document in.
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///
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/// See: https://quirks.spec.whatwg.org/
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#[derive(PartialEq, Eq, Copy, Clone, Hash, Debug)]
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#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
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pub enum QuirksMode {
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/// Quirks mode.
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Quirks,
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/// Limited quirks mode.
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LimitedQuirks,
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/// No quirks mode.
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NoQuirks,
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}
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/// A shared style context.
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///
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/// There's exactly one of these during a given restyle traversal, and it's
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/// shared among the worker threads.
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pub struct SharedStyleContext {
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/// The current viewport size.
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pub viewport_size: Size2D<Au>,
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/// The CSS selector stylist.
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pub stylist: Arc<Stylist>,
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/// The animations that are currently running.
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pub running_animations: Arc<RwLock<HashMap<OpaqueNode, Vec<Animation>>>>,
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/// The list of animations that have expired since the last style recalculation.
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pub expired_animations: Arc<RwLock<HashMap<OpaqueNode, Vec<Animation>>>>,
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///The CSS error reporter for all CSS loaded in this layout thread
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pub error_reporter: Box<ParseErrorReporter + Sync>,
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/// Data needed to create the thread-local style context from the shared one.
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pub local_context_creation_data: Mutex<ThreadLocalStyleContextCreationInfo>,
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/// The current timer for transitions and animations. This is needed to test
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/// them.
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pub timer: Timer,
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/// The QuirksMode state which the document needs to be rendered with
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pub quirks_mode: QuirksMode,
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/// The default computed values to use for elements with no rules
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/// applying to them.
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pub default_computed_values: Arc<ComputedValues>,
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}
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/// Information about the current element being processed. We group this together
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/// into a single struct within ThreadLocalStyleContext so that we can instantiate
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/// and destroy it easily at the beginning and end of element processing.
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struct CurrentElementInfo {
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/// The element being processed. Currently we use an OpaqueNode since we only
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/// use this for identity checks, but we could use SendElement if there were
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/// a good reason to.
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element: OpaqueNode,
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/// Whether the element is being styled for the first time.
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is_initial_style: bool,
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}
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/// Statistics gathered during the traversal. We gather statistics on each thread
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/// and then combine them after the threads join via the Add implementation below.
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#[derive(Default)]
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pub struct TraversalStatistics {
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/// The total number of elements traversed.
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pub elements_traversed: u32,
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/// The number of elements where has_styles() went from false to true.
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pub elements_styled: u32,
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/// The number of elements for which we performed selector matching.
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pub elements_matched: u32,
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/// The number of cache hits from the StyleSharingCache.
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pub styles_shared: u32,
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/// Time spent in the traversal, in milliseconds.
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pub traversal_time_ms: f64,
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}
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/// Implementation of Add to aggregate statistics across different threads.
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impl<'a> Add for &'a TraversalStatistics {
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type Output = TraversalStatistics;
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fn add(self, other: Self) -> TraversalStatistics {
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debug_assert!(self.traversal_time_ms == 0.0 && other.traversal_time_ms == 0.0,
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"traversal_time_ms should be set at the end by the caller");
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TraversalStatistics {
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elements_traversed: self.elements_traversed + other.elements_traversed,
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elements_styled: self.elements_styled + other.elements_styled,
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elements_matched: self.elements_matched + other.elements_matched,
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styles_shared: self.styles_shared + other.styles_shared,
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traversal_time_ms: 0.0,
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}
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}
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}
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/// Format the statistics in a way that the performance test harness understands.
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/// See https://bugzilla.mozilla.org/show_bug.cgi?id=1331856#c2
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impl fmt::Display for TraversalStatistics {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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debug_assert!(self.traversal_time_ms != 0.0, "should have set traversal time");
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try!(writeln!(f, "[PERF] perf block start"));
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try!(writeln!(f, "[PERF],elements_traversed,{}", self.elements_traversed));
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try!(writeln!(f, "[PERF],elements_styled,{}", self.elements_styled));
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try!(writeln!(f, "[PERF],elements_matched,{}", self.elements_matched));
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try!(writeln!(f, "[PERF],styles_shared,{}", self.styles_shared));
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try!(writeln!(f, "[PERF],traversal_time_ms,{}", self.traversal_time_ms));
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writeln!(f, "[PERF] perf block end")
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}
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}
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lazy_static! {
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/// Whether to dump style statistics, computed statically. We use an environmental
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/// variable so that this is easy to set for Gecko builds, and matches the
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/// mechanism we use to dump statistics on the Gecko style system.
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static ref DUMP_STYLE_STATISTICS: bool = {
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match env::var("DUMP_STYLE_STATISTICS") {
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Ok(s) => !s.is_empty(),
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Err(_) => false,
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}
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};
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}
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impl TraversalStatistics {
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/// Returns whether statistics dumping is enabled.
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pub fn should_dump() -> bool {
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*DUMP_STYLE_STATISTICS || opts::get().style_sharing_stats
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}
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/// Computes the traversal time given the start time in seconds.
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pub fn compute_traversal_time(&mut self, start: f64) {
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self.traversal_time_ms = (time::precise_time_s() - start) * 1000.0;
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}
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}
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/// A task to be run in sequential mode on the parent (non-worker) thread. This
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/// is used by the style system to queue up work which is not safe to do during
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/// the parallel traversal.
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pub enum SequentialTask<E: TElement> {
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/// Sets selector flags. This is used when we need to set flags on an
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/// element that we don't have exclusive access to (i.e. the parent).
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SetSelectorFlags(SendElement<E>, ElementSelectorFlags),
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}
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impl<E: TElement> SequentialTask<E> {
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/// Executes this task.
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pub fn execute(self) {
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use self::SequentialTask::*;
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debug_assert!(thread_state::get() == thread_state::LAYOUT);
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match self {
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SetSelectorFlags(el, flags) => {
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unsafe { el.set_selector_flags(flags) };
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}
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}
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}
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/// Creates a task to set the selector flags on an element.
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pub fn set_selector_flags(el: E, flags: ElementSelectorFlags) -> Self {
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use self::SequentialTask::*;
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SetSelectorFlags(unsafe { SendElement::new(el) }, flags)
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}
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}
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/// A thread-local style context.
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///
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/// This context contains data that needs to be used during restyling, but is
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/// not required to be unique among worker threads, so we create one per worker
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/// thread in order to be able to mutate it without locking.
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pub struct ThreadLocalStyleContext<E: TElement> {
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/// A cache to share style among siblings.
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pub style_sharing_candidate_cache: StyleSharingCandidateCache<E>,
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/// The bloom filter used to fast-reject selector-matching.
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pub bloom_filter: StyleBloom<E>,
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/// A channel on which new animations that have been triggered by style
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/// recalculation can be sent.
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pub new_animations_sender: Sender<Animation>,
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/// A set of tasks to be run (on the parent thread) in sequential mode after
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/// the rest of the styling is complete. This is useful for infrequently-needed
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/// non-threadsafe operations.
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pub tasks: Vec<SequentialTask<E>>,
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/// Statistics about the traversal.
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pub statistics: TraversalStatistics,
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/// Information related to the current element, non-None during processing.
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current_element_info: Option<CurrentElementInfo>,
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}
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impl<E: TElement> ThreadLocalStyleContext<E> {
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/// Creates a new `ThreadLocalStyleContext` from a shared one.
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pub fn new(shared: &SharedStyleContext) -> Self {
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ThreadLocalStyleContext {
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style_sharing_candidate_cache: StyleSharingCandidateCache::new(),
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bloom_filter: StyleBloom::new(),
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new_animations_sender: shared.local_context_creation_data.lock().unwrap().new_animations_sender.clone(),
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tasks: Vec::new(),
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statistics: TraversalStatistics::default(),
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current_element_info: None,
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}
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}
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/// Notes when the style system starts traversing an element.
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pub fn begin_element(&mut self, element: E, data: &ElementData) {
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debug_assert!(self.current_element_info.is_none());
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self.current_element_info = Some(CurrentElementInfo {
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element: element.as_node().opaque(),
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is_initial_style: !data.has_styles(),
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});
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}
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/// Notes when the style system finishes traversing an element.
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pub fn end_element(&mut self, element: E) {
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debug_assert!(self.current_element_info.is_some());
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debug_assert!(self.current_element_info.as_ref().unwrap().element ==
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element.as_node().opaque());
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self.current_element_info = None;
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}
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/// Returns true if the current element being traversed is being styled for
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/// the first time.
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///
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/// Panics if called while no element is being traversed.
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pub fn is_initial_style(&self) -> bool {
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self.current_element_info.as_ref().unwrap().is_initial_style
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}
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}
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impl<E: TElement> Drop for ThreadLocalStyleContext<E> {
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fn drop(&mut self) {
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debug_assert!(self.current_element_info.is_none());
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// Execute any enqueued sequential tasks.
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debug_assert!(thread_state::get() == thread_state::LAYOUT);
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for task in self.tasks.drain(..) {
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task.execute();
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}
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}
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}
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/// A `StyleContext` is just a simple container for a immutable reference to a
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/// shared style context, and a mutable reference to a local one.
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pub struct StyleContext<'a, E: TElement + 'a> {
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/// The shared style context reference.
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pub shared: &'a SharedStyleContext,
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/// The thread-local style context (mutable) reference.
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pub thread_local: &'a mut ThreadLocalStyleContext<E>,
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}
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/// Why we're doing reflow.
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#[derive(PartialEq, Copy, Clone, Debug)]
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pub enum ReflowGoal {
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/// We're reflowing in order to send a display list to the screen.
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ForDisplay,
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/// We're reflowing in order to satisfy a script query. No display list will be created.
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ForScriptQuery,
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}
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