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Auto merge of #9176 - bholley:hoist_traversal, r=SimonSapin

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Hoist traversal code into style/

This should be the last major hoisting necessary to use the style system standalone. \o/

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This commit is contained in:
bors-servo 2016-01-08 13:57:39 +05:30
commit ddc3b7942e
11 changed files with 516 additions and 406 deletions
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10
components/layout/context.rs
View file

@ -128,16 +128,6 @@ impl<'a> LayoutContext<'a> {
self.cached_local_layout_context.font_context.borrow_mut()
}
#[inline(always)]
pub fn applicable_declarations_cache(&self) -> RefMut<ApplicableDeclarationsCache> {
self.local_context().applicable_declarations_cache.borrow_mut()
}
#[inline(always)]
pub fn style_sharing_candidate_cache(&self) -> RefMut<StyleSharingCandidateCache> {
self.local_context().style_sharing_candidate_cache.borrow_mut()
}
pub fn get_or_request_image(&self, url: Url, use_placeholder: UsePlaceholder)
-> Option<Arc<Image>> {
// See if the image is already available

7
components/layout/layout_task.rs
View file

@ -38,7 +38,7 @@ use msg::ParseErrorReporter;
use msg::compositor_msg::Epoch;
use msg::constellation_msg::{ConstellationChan, Failure, PipelineId};
use net_traits::image_cache_task::{ImageCacheChan, ImageCacheResult, ImageCacheTask};
use parallel::{self, WorkQueueData};
use parallel;
use profile_traits::mem::{self, Report, ReportKind, ReportsChan};
use profile_traits::time::{TimerMetadataFrameType, TimerMetadataReflowType};
use profile_traits::time::{self, TimerMetadata, profile};
@ -67,6 +67,7 @@ use style::computed_values::{filter, mix_blend_mode};
use style::context::{SharedStyleContext, StylistWrapper};
use style::dom::{TDocument, TElement, TNode};
use style::media_queries::{Device, MediaType};
use style::parallel::WorkQueueData;
use style::selector_matching::{Stylist, USER_OR_USER_AGENT_STYLESHEETS};
use style::stylesheets::{CSSRuleIteratorExt, Stylesheet};
use traversal::RecalcStyleAndConstructFlows;
@ -1025,11 +1026,11 @@ impl LayoutTask {
// Perform CSS selector matching and flow construction.
match self.parallel_traversal {
None => {
sequential::traverse_dom_preorder::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
sequential::traverse_dom::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
node, &shared_layout_context);
}
Some(ref mut traversal) => {
parallel::traverse_dom_preorder::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
parallel::traverse_dom::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
node, &shared_layout_context, traversal);
}
}

148
components/layout/parallel.rs
View file

@ -11,28 +11,23 @@
use context::{LayoutContext, SharedLayoutContext};
use flow::{self, Flow, MutableFlowUtils, PostorderFlowTraversal, PreorderFlowTraversal};
use flow_ref::{self, FlowRef};
use gfx::display_list::OpaqueNode;
use profile_traits::time::{self, TimerMetadata, profile};
use std::mem;
use std::sync::atomic::{AtomicIsize, Ordering};
use style::dom::UnsafeNode;
use traversal::PostorderNodeMutTraversal;
use style::dom::{TNode, UnsafeNode};
use style::parallel::{CHUNK_SIZE, WorkQueueData};
use style::parallel::{run_queue_with_custom_work_data_type};
use traversal::{AssignBSizesAndStoreOverflow, AssignISizes, BubbleISizes};
use traversal::{BuildDisplayList, ComputeAbsolutePositions};
use traversal::{DomTraversal, DomTraversalContext};
use traversal::{BuildDisplayList, ComputeAbsolutePositions, PostorderNodeMutTraversal};
use util::opts;
use util::workqueue::{WorkQueue, WorkUnit, WorkerProxy};
use wrapper::LayoutNode;
const CHUNK_SIZE: usize = 64;
pub struct WorkQueueData(usize, usize);
pub use style::parallel::traverse_dom;
#[allow(dead_code)]
fn static_assertion(node: UnsafeNode) {
unsafe {
let _: UnsafeFlow = ::std::intrinsics::transmute(node);
let _: UnsafeNodeList = ::std::intrinsics::transmute(node);
}
}
@ -55,18 +50,8 @@ pub fn borrowed_flow_to_unsafe_flow(flow: &Flow) -> UnsafeFlow {
}
}
pub type UnsafeNodeList = (Box<Vec<UnsafeNode>>, OpaqueNode);
pub type UnsafeFlowList = (Box<Vec<UnsafeNode>>, usize);
pub type ChunkedDomTraversalFunction =
extern "Rust" fn(UnsafeNodeList,
&mut WorkerProxy<SharedLayoutContext, UnsafeNodeList>);
pub type DomTraversalFunction =
extern "Rust" fn(OpaqueNode, UnsafeNode,
&mut WorkerProxy<SharedLayoutContext, UnsafeNodeList>);
pub type ChunkedFlowTraversalFunction =
extern "Rust" fn(UnsafeFlowList, &mut WorkerProxy<SharedLayoutContext, UnsafeFlowList>);
@ -232,104 +217,6 @@ impl<'a> ParallelPreorderFlowTraversal for ComputeAbsolutePositions<'a> {
impl<'a> ParallelPostorderFlowTraversal for BuildDisplayList<'a> {}
/// A parallel top-down DOM traversal.
#[inline(always)]
fn top_down_dom<'ln, N, T>(unsafe_nodes: UnsafeNodeList,
proxy: &mut WorkerProxy<SharedLayoutContext, UnsafeNodeList>)
where N: LayoutNode<'ln>, T: DomTraversal<'ln, N> {
let shared_layout_context = proxy.user_data();
let layout_context = LayoutContext::new(shared_layout_context);
let traversal_context = DomTraversalContext {
layout_context: &layout_context,
root: unsafe_nodes.1,
};
let mut discovered_child_nodes = Vec::new();
for unsafe_node in *unsafe_nodes.0 {
// Get a real layout node.
let node = unsafe { N::from_unsafe(&unsafe_node) };
// Perform the appropriate traversal.
T::process_preorder(&traversal_context, node);
let child_count = node.children_count();
// Reset the count of children.
{
let data = node.mutate_data().unwrap();
data.parallel.children_count.store(child_count as isize,
Ordering::Relaxed);
}
// Possibly enqueue the children.
if child_count != 0 {
for kid in node.children() {
discovered_child_nodes.push(kid.to_unsafe())
}
} else {
// If there were no more children, start walking back up.
bottom_up_dom::<N, T>(unsafe_nodes.1, unsafe_node, proxy)
}
}
for chunk in discovered_child_nodes.chunks(CHUNK_SIZE) {
proxy.push(WorkUnit {
fun: top_down_dom::<N, T>,
data: (box chunk.iter().cloned().collect(), unsafe_nodes.1),
});
}
}
/// Process current node and potentially traverse its ancestors.
///
/// If we are the last child that finished processing, recursively process
/// our parent. Else, stop. Also, stop at the root.
///
/// Thus, if we start with all the leaves of a tree, we end up traversing
/// the whole tree bottom-up because each parent will be processed exactly
/// once (by the last child that finishes processing).
///
/// The only communication between siblings is that they both
/// fetch-and-subtract the parent's children count.
fn bottom_up_dom<'ln, N, T>(root: OpaqueNode,
unsafe_node: UnsafeNode,
proxy: &mut WorkerProxy<SharedLayoutContext, UnsafeNodeList>)
where N: LayoutNode<'ln>, T: DomTraversal<'ln, N> {
let shared_layout_context = proxy.user_data();
let layout_context = LayoutContext::new(shared_layout_context);
let traversal_context = DomTraversalContext {
layout_context: &layout_context,
root: root,
};
// Get a real layout node.
let mut node = unsafe { N::from_unsafe(&unsafe_node) };
loop {
// Perform the appropriate operation.
T::process_postorder(&traversal_context, node);
let parent = match node.layout_parent_node(traversal_context.root) {
None => break,
Some(parent) => parent,
};
let parent_data = unsafe {
&*parent.borrow_data_unchecked().unwrap()
};
if parent_data
.parallel
.children_count
.fetch_sub(1, Ordering::Relaxed) != 1 {
// Get out of here and find another node to work on.
break
}
// We were the last child of our parent. Construct flows for our parent.
node = parent;
}
}
fn assign_inline_sizes(unsafe_flows: UnsafeFlowList,
proxy: &mut WorkerProxy<SharedLayoutContext, UnsafeFlowList>) {
let shared_layout_context = proxy.user_data();
@ -372,31 +259,6 @@ fn build_display_list(unsafe_flow: UnsafeFlow,
build_display_list_traversal.run_parallel(unsafe_flow);
}
fn run_queue_with_custom_work_data_type<To, F>(
queue: &mut WorkQueue<SharedLayoutContext, WorkQueueData>,
callback: F,
shared_layout_context: &SharedLayoutContext)
where To: 'static + Send, F: FnOnce(&mut WorkQueue<SharedLayoutContext, To>) {
let queue: &mut WorkQueue<SharedLayoutContext, To> = unsafe {
mem::transmute(queue)
};
callback(queue);
queue.run(shared_layout_context);
}
pub fn traverse_dom_preorder<'ln, N, T>(
root: N,
shared_layout_context: &SharedLayoutContext,
queue: &mut WorkQueue<SharedLayoutContext, WorkQueueData>)
where N: LayoutNode<'ln>, T: DomTraversal<'ln, N> {
run_queue_with_custom_work_data_type(queue, |queue| {
queue.push(WorkUnit {
fun: top_down_dom::<N, T>,
data: (box vec![root.to_unsafe()], root.opaque()),
});
}, shared_layout_context);
}
pub fn traverse_flow_tree_preorder(
root: &mut FlowRef,
profiler_metadata: Option<TimerMetadata>,

31
components/layout/sequential.rs
View file

@ -12,36 +12,13 @@ use flow::{self, Flow, ImmutableFlowUtils, InorderFlowTraversal, MutableFlowUtil
use flow_ref::{self, FlowRef};
use fragment::FragmentBorderBoxIterator;
use generated_content::ResolveGeneratedContent;
use traversal::PostorderNodeMutTraversal;
use style::dom::TNode;
use style::traversal::DomTraversalContext;
use traversal::{AssignBSizesAndStoreOverflow, AssignISizes};
use traversal::{BubbleISizes, BuildDisplayList, ComputeAbsolutePositions};
use traversal::{DomTraversal, DomTraversalContext};
use traversal::{BubbleISizes, BuildDisplayList, ComputeAbsolutePositions, PostorderNodeMutTraversal};
use util::opts;
use wrapper::LayoutNode;
pub fn traverse_dom_preorder<'ln, N, T>(root: N,
shared_layout_context: &SharedLayoutContext)
where N: LayoutNode<'ln>,
T: DomTraversal<'ln, N> {
fn doit<'a, 'ln, N, T>(context: &'a DomTraversalContext<'a>, node: N)
where N: LayoutNode<'ln>, T: DomTraversal<'ln, N> {
T::process_preorder(context, node);
for kid in node.children() {
doit::<N, T>(context, kid);
}
T::process_postorder(context, node);
}
let layout_context = LayoutContext::new(shared_layout_context);
let traversal_context = DomTraversalContext {
layout_context: &layout_context,
root: root.opaque(),
};
doit::<N, T>(&traversal_context, root);
}
pub use style::sequential::traverse_dom;
pub fn resolve_generated_content(root: &mut FlowRef, shared_layout_context: &SharedLayoutContext) {
fn doit(flow: &mut Flow, level: u32, traversal: &mut ResolveGeneratedContent) {

275
components/layout/traversal.rs
View file

@ -5,142 +5,68 @@
//! Traversals over the DOM and flow trees, running the layout computations.
use construct::FlowConstructor;
use context::LayoutContext;
use context::{LayoutContext, SharedLayoutContext};
use flow::{PostorderFlowTraversal, PreorderFlowTraversal};
use flow::{self, Flow};
use gfx::display_list::OpaqueNode;
use incremental::{BUBBLE_ISIZES, REFLOW, REFLOW_OUT_OF_FLOW, REPAINT, RestyleDamage};
use script::layout_interface::ReflowGoal;
use selectors::bloom::BloomFilter;
use std::cell::RefCell;
use std::mem;
use style::context::StyleContext;
use style::dom::{TRestyleDamage, UnsafeNode};
use style::matching::{ApplicableDeclarations, ElementMatchMethods, MatchMethods, StyleSharingResult};
use style::matching::MatchMethods;
use style::traversal::{DomTraversalContext, STYLE_BLOOM};
use style::traversal::{put_task_local_bloom_filter, recalc_style_at};
use util::opts;
use util::tid::tid;
use wrapper::{LayoutNode, ThreadSafeLayoutNode};
/// Every time we do another layout, the old bloom filters are invalid. This is
/// detected by ticking a generation number every layout.
type Generation = u32;
pub struct RecalcStyleAndConstructFlows<'lc> {
context: LayoutContext<'lc>,
root: OpaqueNode,
}
/// A pair of the bloom filter used for css selector matching, and the node to
/// which it applies. This is used to efficiently do `Descendant` selector
/// matches. Thanks to the bloom filter, we can avoid walking up the tree
/// looking for ancestors that aren't there in the majority of cases.
///
/// As we walk down the DOM tree a task-local bloom filter is built of all the
/// CSS `SimpleSelector`s which are part of a `Descendant` compound selector
/// (i.e. paired with a `Descendant` combinator, in the `next` field of a
/// `CompoundSelector`.
///
/// Before a `Descendant` selector match is tried, it's compared against the
/// bloom filter. If the bloom filter can exclude it, the selector is quickly
/// rejected.
///
/// When done styling a node, all selectors previously inserted into the filter
/// are removed.
///
/// Since a work-stealing queue is used for styling, sometimes, the bloom filter
/// will no longer be the for the parent of the node we're currently on. When
/// this happens, the task local bloom filter will be thrown away and rebuilt.
thread_local!(
static STYLE_BLOOM: RefCell<Option<(Box<BloomFilter>, UnsafeNode, Generation)>> = RefCell::new(None));
/// Returns the task local bloom filter.
///
/// If one does not exist, a new one will be made for you. If it is out of date,
/// it will be cleared and reused.
fn take_task_local_bloom_filter<'ln, N>(parent_node: Option<N>,
root: OpaqueNode,
layout_context: &LayoutContext)
-> Box<BloomFilter>
where N: LayoutNode<'ln> {
STYLE_BLOOM.with(|style_bloom| {
match (parent_node, style_bloom.borrow_mut().take()) {
// Root node. Needs new bloom filter.
(None, _ ) => {
debug!("[{}] No parent, but new bloom filter!", tid());
box BloomFilter::new()
}
// No bloom filter for this thread yet.
(Some(parent), None) => {
let mut bloom_filter = box BloomFilter::new();
insert_ancestors_into_bloom_filter(&mut bloom_filter, parent, root);
bloom_filter
}
// Found cached bloom filter.
(Some(parent), Some((mut bloom_filter, old_node, old_generation))) => {
if old_node == parent.to_unsafe() &&
old_generation == layout_context.shared_context().generation {
// Hey, the cached parent is our parent! We can reuse the bloom filter.
debug!("[{}] Parent matches (={}). Reusing bloom filter.", tid(), old_node.0);
} else {
// Oh no. the cached parent is stale. I guess we need a new one. Reuse the existing
// allocation to avoid malloc churn.
bloom_filter.clear();
insert_ancestors_into_bloom_filter(&mut bloom_filter, parent, root);
}
bloom_filter
},
impl<'lc, 'ln, N: LayoutNode<'ln>> DomTraversalContext<'ln, N> for RecalcStyleAndConstructFlows<'lc> {
type SharedContext = SharedLayoutContext;
#[allow(unsafe_code)]
fn new<'a>(shared: &'a Self::SharedContext, root: OpaqueNode) -> Self {
// FIXME(bholley): This transmutation from &'a to &'lc is very unfortunate, but I haven't
// found a way to avoid it despite spending several days on it (and consulting Manishearth,
// brson, and nmatsakis).
//
// The crux of the problem is that parameterizing DomTraversalContext on the lifetime of
// the SharedContext doesn't work for a variety of reasons [1]. However, the code in
// parallel.rs needs to be able to use the DomTraversalContext trait (or something similar)
// to stack-allocate a struct (a generalized LayoutContext<'a>) that holds a borrowed
// SharedContext, which means that the struct needs to be parameterized on a lifetime.
// Given the aforementioned constraint, the only way to accomplish this is to avoid
// propagating the borrow lifetime from the struct to the trait, but that means that the
// new() method on the trait cannot require the lifetime of its argument to match the
// lifetime of the Self object it creates.
//
// This could be solved with an associated type with an unbound lifetime parameter, but
// that would require higher-kinded types, which don't exist yet and probably aren't coming
// for a while.
//
// So we transmute. :-( This is safe because the DomTravesalContext is stack-allocated on
// the worker thread while processing a WorkUnit, whereas the borrowed SharedContext is
// live for the entire duration of the restyle. This really could _almost_ compile: all
// we'd need to do is change the signature to to |new<'a: 'lc>|, and everything would
// work great. But we can't do that, because that would cause a mismatch with the signature
// in the trait we're implementing, and we can't mention 'lc in that trait at all for the
// reasons described above.
//
// [1] For example, the WorkQueue type needs to be parameterized on the concrete type of
// DomTraversalContext::SharedContext, and the WorkQueue lifetime is similar to that of the
// LayoutTask, generally much longer than that of a given SharedLayoutContext borrow.
let shared_lc: &'lc SharedLayoutContext = unsafe { mem::transmute(shared) };
RecalcStyleAndConstructFlows {
context: LayoutContext::new(shared_lc),
root: root,
}
})
}
fn put_task_local_bloom_filter(bf: Box<BloomFilter>,
unsafe_node: &UnsafeNode,
layout_context: &LayoutContext) {
STYLE_BLOOM.with(move |style_bloom| {
assert!(style_bloom.borrow().is_none(),
"Putting into a never-taken task-local bloom filter");
*style_bloom.borrow_mut() = Some((bf, *unsafe_node, layout_context.shared_context().generation));
})
}
/// "Ancestors" in this context is inclusive of ourselves.
fn insert_ancestors_into_bloom_filter<'ln, N>(bf: &mut Box<BloomFilter>,
mut n: N,
root: OpaqueNode)
where N: LayoutNode<'ln> {
debug!("[{}] Inserting ancestors.", tid());
let mut ancestors = 0;
loop {
ancestors += 1;
n.insert_into_bloom_filter(&mut **bf);
n = match n.layout_parent_node(root) {
None => break,
Some(p) => p,
};
}
debug!("[{}] Inserted {} ancestors.", tid(), ancestors);
}
#[derive(Copy, Clone)]
pub struct DomTraversalContext<'a> {
pub layout_context: &'a LayoutContext<'a>,
pub root: OpaqueNode,
}
pub trait DomTraversal<'ln, N: LayoutNode<'ln>> {
fn process_preorder<'a>(context: &'a DomTraversalContext<'a>, node: N);
fn process_postorder<'a>(context: &'a DomTraversalContext<'a>, node: N);
}
/// FIXME(bholley): I added this now to demonstrate the usefulness of the new design.
/// This is currently unused, but will be used shortly.
#[allow(dead_code)]
pub struct RecalcStyleOnly;
impl<'ln, N: LayoutNode<'ln>> DomTraversal<'ln, N> for RecalcStyleOnly {
fn process_preorder<'a>(context: &'a DomTraversalContext<'a>, node: N) { recalc_style_at(context, node); }
fn process_postorder<'a>(_: &'a DomTraversalContext<'a>, _: N) {}
}
pub struct RecalcStyleAndConstructFlows;
impl<'ln, N: LayoutNode<'ln>> DomTraversal<'ln, N> for RecalcStyleAndConstructFlows {
fn process_preorder<'a>(context: &'a DomTraversalContext<'a>, node: N) { recalc_style_at(context, node); }
fn process_postorder<'a>(context: &'a DomTraversalContext<'a>, node: N) { construct_flows_at(context, node); }
fn process_preorder(&self, node: N) { recalc_style_at(&self.context, self.root, node); }
fn process_postorder(&self, node: N) { construct_flows_at(&self.context, self.root, node); }
}
/// A bottom-up, parallelizable traversal.
@ -149,107 +75,10 @@ pub trait PostorderNodeMutTraversal<'ln, ConcreteThreadSafeLayoutNode: ThreadSaf
fn process(&mut self, node: &ConcreteThreadSafeLayoutNode) -> bool;
}
/// The recalc-style-for-node traversal, which styles each node and must run before
/// layout computation. This computes the styles applied to each node.
#[inline]
#[allow(unsafe_code)]
fn recalc_style_at<'a, 'ln, N: LayoutNode<'ln>> (context: &'a DomTraversalContext<'a>, node: N) {
// Initialize layout data.
//
// FIXME(pcwalton): Stop allocating here. Ideally this should just be done by the HTML
// parser.
node.initialize_data();
// Get the parent node.
let parent_opt = node.layout_parent_node(context.root);
// Get the style bloom filter.
let mut bf = take_task_local_bloom_filter(parent_opt, context.root, context.layout_context);
let nonincremental_layout = opts::get().nonincremental_layout;
if nonincremental_layout || node.is_dirty() {
// Remove existing CSS styles from nodes whose content has changed (e.g. text changed),
// to force non-incremental reflow.
if node.has_changed() {
let node = node.to_threadsafe();
node.unstyle();
}
// Check to see whether we can share a style with someone.
let style_sharing_candidate_cache =
&mut context.layout_context.style_sharing_candidate_cache();
let sharing_result = match node.as_element() {
Some(element) => {
unsafe {
element.share_style_if_possible(style_sharing_candidate_cache,
parent_opt.clone())
}
},
None => StyleSharingResult::CannotShare,
};
// Otherwise, match and cascade selectors.
match sharing_result {
StyleSharingResult::CannotShare => {
let mut applicable_declarations = ApplicableDeclarations::new();
let shareable_element = match node.as_element() {
Some(element) => {
// Perform the CSS selector matching.
let stylist = unsafe { &*context.layout_context.shared_context().stylist.0 };
if element.match_element(stylist,
Some(&*bf),
&mut applicable_declarations) {
Some(element)
} else {
None
}
},
None => {
if node.has_changed() {
node.set_restyle_damage(N::ConcreteRestyleDamage::rebuild_and_reflow())
}
None
},
};
// Perform the CSS cascade.
unsafe {
node.cascade_node(&context.layout_context.shared.style_context,
parent_opt,
&applicable_declarations,
&mut context.layout_context.applicable_declarations_cache(),
&context.layout_context.shared_context().new_animations_sender);
}
// Add ourselves to the LRU cache.
if let Some(element) = shareable_element {
style_sharing_candidate_cache.insert_if_possible(&element);
}
}
StyleSharingResult::StyleWasShared(index, damage) => {
style_sharing_candidate_cache.touch(index);
node.set_restyle_damage(damage);
}
}
}
let unsafe_layout_node = node.to_unsafe();
// Before running the children, we need to insert our nodes into the bloom
// filter.
debug!("[{}] + {:X}", tid(), unsafe_layout_node.0);
node.insert_into_bloom_filter(&mut *bf);
// NB: flow construction updates the bloom filter on the way up.
put_task_local_bloom_filter(bf, &unsafe_layout_node, context.layout_context);
}
/// The flow construction traversal, which builds flows for styled nodes.
#[inline]
#[allow(unsafe_code)]
fn construct_flows_at<'a, 'ln, N: LayoutNode<'ln>>(context: &'a DomTraversalContext<'a>, node: N) {
fn construct_flows_at<'a, 'ln, N: LayoutNode<'ln>>(context: &'a LayoutContext<'a>, root: OpaqueNode, node: N) {
// Construct flows for this node.
{
let tnode = node.to_threadsafe();
@ -257,7 +86,7 @@ fn construct_flows_at<'a, 'ln, N: LayoutNode<'ln>>(context: &'a DomTraversalCont
// Always reconstruct if incremental layout is turned off.
let nonincremental_layout = opts::get().nonincremental_layout;
if nonincremental_layout || node.has_dirty_descendants() {
let mut flow_constructor = FlowConstructor::new(context.layout_context);
let mut flow_constructor = FlowConstructor::new(context);
if nonincremental_layout || !flow_constructor.repair_if_possible(&tnode) {
flow_constructor.process(&tnode);
debug!("Constructed flow for {:x}: {:x}",
@ -286,9 +115,9 @@ fn construct_flows_at<'a, 'ln, N: LayoutNode<'ln>>(context: &'a DomTraversalCont
});
assert_eq!(old_node, unsafe_layout_node);
assert_eq!(old_generation, context.layout_context.shared_context().generation);
assert_eq!(old_generation, context.shared_context().generation);
match node.layout_parent_node(context.root) {
match node.layout_parent_node(root) {
None => {
debug!("[{}] - {:X}, and deleting BF.", tid(), unsafe_layout_node.0);
// If this is the reflow root, eat the task-local bloom filter.
@ -297,7 +126,7 @@ fn construct_flows_at<'a, 'ln, N: LayoutNode<'ln>>(context: &'a DomTraversalCont
// Otherwise, put it back, but remove this node.
node.remove_from_bloom_filter(&mut *bf);
let unsafe_parent = parent.to_unsafe();
put_task_local_bloom_filter(bf, &unsafe_parent, context.layout_context);
put_task_local_bloom_filter(bf, &unsafe_parent, &context.shared_context());
},
};
}

12
components/layout/wrapper.rs
View file

@ -275,6 +275,14 @@ impl<'ln> TNode<'ln> for ServoLayoutNode<'ln> {
self.node.next_sibling_ref().map(|node| self.new_with_this_lifetime(&node))
}
}
fn style(&self) -> Ref<Arc<ComputedValues>> {
Ref::map(self.borrow_data().unwrap(), |data| data.style.as_ref().unwrap())
}
fn unstyle(self) {
self.mutate_data().unwrap().style = None;
}
}
impl<'ln> LayoutNode<'ln> for ServoLayoutNode<'ln> {
@ -696,6 +704,8 @@ pub trait ThreadSafeLayoutNode<'ln> : Clone + Copy + Sized {
/// Returns the style results for the given node. If CSS selector matching
/// has not yet been performed, fails.
///
/// Unlike the version on TNode, this handles pseudo-elements.
#[inline]
fn style(&self) -> Ref<Arc<ComputedValues>> {
Ref::map(self.borrow_layout_data().unwrap(), |data| {
@ -709,6 +719,8 @@ pub trait ThreadSafeLayoutNode<'ln> : Clone + Copy + Sized {
}
/// Removes the style from this node.
///
/// Unlike the version on TNode, this handles pseudo-elements.
fn unstyle(self) {
let mut data = self.mutate_layout_data().unwrap();
let style =

8
components/style/dom.rs
View file

@ -156,6 +156,14 @@ pub trait TNode<'ln> : Sized + Copy + Clone {
fn prev_sibling(&self) -> Option<Self>;
fn next_sibling(&self) -> Option<Self>;
/// Returns the style results for the given node. If CSS selector matching
/// has not yet been performed, fails.
fn style(&self) -> Ref<Arc<ComputedValues>>;
/// Removes the style from this node.
fn unstyle(self);
}
pub trait TDocument<'ld> : Sized + Copy + Clone {

3
components/style/lib.rs
View file

@ -53,10 +53,13 @@ pub mod dom;
pub mod font_face;
pub mod matching;
pub mod media_queries;
pub mod parallel;
pub mod parser;
pub mod restyle_hints;
pub mod selector_matching;
pub mod sequential;
pub mod stylesheets;
pub mod traversal;
#[macro_use]
#[allow(non_camel_case_types)]
pub mod values;

141
components/style/parallel.rs Normal file
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@ -0,0 +1,141 @@
/* 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/. */
//! Implements parallel traversal over the DOM tree.
//!
//! This code is highly unsafe. Keep this file small and easy to audit.
#![allow(unsafe_code)]
use dom::{OpaqueNode, TNode, UnsafeNode};
use std::mem;
use std::sync::atomic::Ordering;
use traversal::DomTraversalContext;
use util::workqueue::{WorkQueue, WorkUnit, WorkerProxy};
#[allow(dead_code)]
fn static_assertion(node: UnsafeNode) {
unsafe {
let _: UnsafeNodeList = ::std::intrinsics::transmute(node);
}
}
pub type UnsafeNodeList = (Box<Vec<UnsafeNode>>, OpaqueNode);
pub const CHUNK_SIZE: usize = 64;
pub struct WorkQueueData(usize, usize);
pub fn run_queue_with_custom_work_data_type<To, F, SharedContext: Sync>(
queue: &mut WorkQueue<SharedContext, WorkQueueData>,
callback: F,
shared: &SharedContext)
where To: 'static + Send, F: FnOnce(&mut WorkQueue<SharedContext, To>) {
let queue: &mut WorkQueue<SharedContext, To> = unsafe {
mem::transmute(queue)
};
callback(queue);
queue.run(shared);
}
pub fn traverse_dom<'ln, N, C>(root: N,
queue_data: &C::SharedContext,
queue: &mut WorkQueue<C::SharedContext, WorkQueueData>)
where N: TNode<'ln>, C: DomTraversalContext<'ln, N> {
run_queue_with_custom_work_data_type(queue, |queue| {
queue.push(WorkUnit {
fun: top_down_dom::<N, C>,
data: (box vec![root.to_unsafe()], root.opaque()),
});
}, queue_data);
}
/// A parallel top-down DOM traversal.
#[inline(always)]
fn top_down_dom<'ln, N, C>(unsafe_nodes: UnsafeNodeList,
proxy: &mut WorkerProxy<C::SharedContext, UnsafeNodeList>)
where N: TNode<'ln>, C: DomTraversalContext<'ln, N> {
let context = C::new(proxy.user_data(), unsafe_nodes.1);
let mut discovered_child_nodes = Vec::new();
for unsafe_node in *unsafe_nodes.0 {
// Get a real layout node.
let node = unsafe { N::from_unsafe(&unsafe_node) };
// Perform the appropriate traversal.
context.process_preorder(node);
let child_count = node.children_count();
// Reset the count of children.
{
let data = node.mutate_data().unwrap();
data.parallel.children_count.store(child_count as isize,
Ordering::Relaxed);
}
// Possibly enqueue the children.
if child_count != 0 {
for kid in node.children() {
discovered_child_nodes.push(kid.to_unsafe())
}
} else {
// If there were no more children, start walking back up.
bottom_up_dom::<N, C>(unsafe_nodes.1, unsafe_node, proxy)
}
}
for chunk in discovered_child_nodes.chunks(CHUNK_SIZE) {
proxy.push(WorkUnit {
fun: top_down_dom::<N, C>,
data: (box chunk.iter().cloned().collect(), unsafe_nodes.1),
});
}
}
/// Process current node and potentially traverse its ancestors.
///
/// If we are the last child that finished processing, recursively process
/// our parent. Else, stop. Also, stop at the root.
///
/// Thus, if we start with all the leaves of a tree, we end up traversing
/// the whole tree bottom-up because each parent will be processed exactly
/// once (by the last child that finishes processing).
///
/// The only communication between siblings is that they both
/// fetch-and-subtract the parent's children count.
fn bottom_up_dom<'ln, N, C>(root: OpaqueNode,
unsafe_node: UnsafeNode,
proxy: &mut WorkerProxy<C::SharedContext, UnsafeNodeList>)
where N: TNode<'ln>, C: DomTraversalContext<'ln, N> {
let context = C::new(proxy.user_data(), root);
// Get a real layout node.
let mut node = unsafe { N::from_unsafe(&unsafe_node) };
loop {
// Perform the appropriate operation.
context.process_postorder(node);
let parent = match node.layout_parent_node(root) {
None => break,
Some(parent) => parent,
};
let parent_data = unsafe {
&*parent.borrow_data_unchecked().unwrap()
};
if parent_data
.parallel
.children_count
.fetch_sub(1, Ordering::Relaxed) != 1 {
// Get out of here and find another node to work on.
break
}
// We were the last child of our parent. Construct flows for our parent.
node = parent;
}
}

28
components/style/sequential.rs Normal file
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@ -0,0 +1,28 @@
/* 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/. */
//! Implements sequential traversal over the DOM tree.
use dom::TNode;
use traversal::DomTraversalContext;
pub fn traverse_dom<'ln, N, C>(root: N,
shared: &C::SharedContext)
where N: TNode<'ln>,
C: DomTraversalContext<'ln, N> {
fn doit<'a, 'ln, N, C>(context: &'a C, node: N)
where N: TNode<'ln>, C: DomTraversalContext<'ln, N> {
context.process_preorder(node);
for kid in node.children() {
doit::<N, C>(context, kid);
}
context.process_postorder(node);
}
let context = C::new(shared, root.opaque());
doit::<N, C>(&context, root);
}

259
components/style/traversal.rs Normal file
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@ -0,0 +1,259 @@
/* 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 context::{LocalStyleContext, SharedStyleContext, StyleContext};
use dom::{OpaqueNode, TNode, TRestyleDamage, UnsafeNode};
use matching::{ApplicableDeclarations, ElementMatchMethods, MatchMethods, StyleSharingResult};
use selectors::bloom::BloomFilter;
use std::cell::RefCell;
use std::mem;
use std::rc::Rc;
use util::opts;
use util::tid::tid;
/// Every time we do another layout, the old bloom filters are invalid. This is
/// detected by ticking a generation number every layout.
pub type Generation = u32;
/// A pair of the bloom filter used for css selector matching, and the node to
/// which it applies. This is used to efficiently do `Descendant` selector
/// matches. Thanks to the bloom filter, we can avoid walking up the tree
/// looking for ancestors that aren't there in the majority of cases.
///
/// As we walk down the DOM tree a task-local bloom filter is built of all the
/// CSS `SimpleSelector`s which are part of a `Descendant` compound selector
/// (i.e. paired with a `Descendant` combinator, in the `next` field of a
/// `CompoundSelector`.
///
/// Before a `Descendant` selector match is tried, it's compared against the
/// bloom filter. If the bloom filter can exclude it, the selector is quickly
/// rejected.
///
/// When done styling a node, all selectors previously inserted into the filter
/// are removed.
///
/// Since a work-stealing queue is used for styling, sometimes, the bloom filter
/// will no longer be the for the parent of the node we're currently on. When
/// this happens, the task local bloom filter will be thrown away and rebuilt.
thread_local!(
pub static STYLE_BLOOM: RefCell<Option<(Box<BloomFilter>, UnsafeNode, Generation)>> = RefCell::new(None));
/// Returns the task local bloom filter.
///
/// If one does not exist, a new one will be made for you. If it is out of date,
/// it will be cleared and reused.
fn take_task_local_bloom_filter<'ln, N>(parent_node: Option<N>,
root: OpaqueNode,
context: &SharedStyleContext)
-> Box<BloomFilter>
where N: TNode<'ln> {
STYLE_BLOOM.with(|style_bloom| {
match (parent_node, style_bloom.borrow_mut().take()) {
// Root node. Needs new bloom filter.
(None, _ ) => {
debug!("[{}] No parent, but new bloom filter!", tid());
box BloomFilter::new()
}
// No bloom filter for this thread yet.
(Some(parent), None) => {
let mut bloom_filter = box BloomFilter::new();
insert_ancestors_into_bloom_filter(&mut bloom_filter, parent, root);
bloom_filter
}
// Found cached bloom filter.
(Some(parent), Some((mut bloom_filter, old_node, old_generation))) => {
if old_node == parent.to_unsafe() &&
old_generation == context.generation {
// Hey, the cached parent is our parent! We can reuse the bloom filter.
debug!("[{}] Parent matches (={}). Reusing bloom filter.", tid(), old_node.0);
} else {
// Oh no. the cached parent is stale. I guess we need a new one. Reuse the existing
// allocation to avoid malloc churn.
bloom_filter.clear();
insert_ancestors_into_bloom_filter(&mut bloom_filter, parent, root);
}
bloom_filter
},
}
})
}
pub fn put_task_local_bloom_filter(bf: Box<BloomFilter>,
unsafe_node: &UnsafeNode,
context: &SharedStyleContext) {
STYLE_BLOOM.with(move |style_bloom| {
assert!(style_bloom.borrow().is_none(),
"Putting into a never-taken task-local bloom filter");
*style_bloom.borrow_mut() = Some((bf, *unsafe_node, context.generation));
})
}
/// "Ancestors" in this context is inclusive of ourselves.
fn insert_ancestors_into_bloom_filter<'ln, N>(bf: &mut Box<BloomFilter>,
mut n: N,
root: OpaqueNode)
where N: TNode<'ln> {
debug!("[{}] Inserting ancestors.", tid());
let mut ancestors = 0;
loop {
ancestors += 1;
n.insert_into_bloom_filter(&mut **bf);
n = match n.layout_parent_node(root) {
None => break,
Some(p) => p,
};
}
debug!("[{}] Inserted {} ancestors.", tid(), ancestors);
}
pub trait DomTraversalContext<'ln, N: TNode<'ln>> {
type SharedContext: Sync + 'static;
fn new<'a>(&'a Self::SharedContext, OpaqueNode) -> Self;
fn process_preorder(&self, node: N);
fn process_postorder(&self, node: N);
}
/// FIXME(bholley): I added this now to demonstrate the usefulness of the new design.
/// This is currently unused, but will be used shortly.
#[allow(dead_code)]
pub struct StandaloneStyleContext<'a> {
pub shared: &'a SharedStyleContext,
cached_local_style_context: Rc<LocalStyleContext>,
}
impl<'a> StandaloneStyleContext<'a> {
pub fn new(_: &'a SharedStyleContext) -> Self { panic!("Not implemented") }
}
impl<'a> StyleContext<'a> for StandaloneStyleContext<'a> {
fn shared_context(&self) -> &'a SharedStyleContext {
&self.shared
}
fn local_context(&self) -> &LocalStyleContext {
&self.cached_local_style_context
}
}
#[allow(dead_code)]
pub struct RecalcStyleOnly<'lc> {
context: StandaloneStyleContext<'lc>,
root: OpaqueNode,
}
impl<'lc, 'ln, N: TNode<'ln>> DomTraversalContext<'ln, N> for RecalcStyleOnly<'lc> {
type SharedContext = SharedStyleContext;
#[allow(unsafe_code)]
fn new<'a>(shared: &'a Self::SharedContext, root: OpaqueNode) -> Self {
// See the comment in RecalcStyleAndConstructFlows::new for an explanation of why this is
// necessary.
let shared_lc: &'lc SharedStyleContext = unsafe { mem::transmute(shared) };
RecalcStyleOnly {
context: StandaloneStyleContext::new(shared_lc),
root: root,
}
}
fn process_preorder(&self, node: N) { recalc_style_at(&self.context, self.root, node); }
fn process_postorder(&self, _: N) {}
}
/// The recalc-style-for-node traversal, which styles each node and must run before
/// layout computation. This computes the styles applied to each node.
#[inline]
#[allow(unsafe_code)]
pub fn recalc_style_at<'a, 'ln, N: TNode<'ln>, C: StyleContext<'a>> (context: &'a C, root: OpaqueNode, node: N) {
// Initialize layout data.
//
// FIXME(pcwalton): Stop allocating here. Ideally this should just be done by the HTML
// parser.
node.initialize_data();
// Get the parent node.
let parent_opt = node.layout_parent_node(root);
// Get the style bloom filter.
let mut bf = take_task_local_bloom_filter(parent_opt, root, context.shared_context());
let nonincremental_layout = opts::get().nonincremental_layout;
if nonincremental_layout || node.is_dirty() {
// Remove existing CSS styles from nodes whose content has changed (e.g. text changed),
// to force non-incremental reflow.
if node.has_changed() {
node.unstyle();
}
// Check to see whether we can share a style with someone.
let style_sharing_candidate_cache =
&mut context.local_context().style_sharing_candidate_cache.borrow_mut();
let sharing_result = match node.as_element() {
Some(element) => {
unsafe {
element.share_style_if_possible(style_sharing_candidate_cache,
parent_opt.clone())
}
},
None => StyleSharingResult::CannotShare,
};
// Otherwise, match and cascade selectors.
match sharing_result {
StyleSharingResult::CannotShare => {
let mut applicable_declarations = ApplicableDeclarations::new();
let shareable_element = match node.as_element() {
Some(element) => {
// Perform the CSS selector matching.
let stylist = unsafe { &*context.shared_context().stylist.0 };
if element.match_element(stylist,
Some(&*bf),
&mut applicable_declarations) {
Some(element)
} else {
None
}
},
None => {
if node.has_changed() {
node.set_restyle_damage(N::ConcreteRestyleDamage::rebuild_and_reflow())
}
None
},
};
// Perform the CSS cascade.
unsafe {
node.cascade_node(&context.shared_context(),
parent_opt,
&applicable_declarations,
&mut context.local_context().applicable_declarations_cache.borrow_mut(),
&context.shared_context().new_animations_sender);
}
// Add ourselves to the LRU cache.
if let Some(element) = shareable_element {
style_sharing_candidate_cache.insert_if_possible(&element);
}
}
StyleSharingResult::StyleWasShared(index, damage) => {
style_sharing_candidate_cache.touch(index);
node.set_restyle_damage(damage);
}
}
}
let unsafe_layout_node = node.to_unsafe();
// Before running the children, we need to insert our nodes into the bloom
// filter.
debug!("[{}] + {:X}", tid(), unsafe_layout_node.0);
node.insert_into_bloom_filter(&mut *bf);
// NB: flow construction updates the bloom filter on the way up.
put_task_local_bloom_filter(bf, &unsafe_layout_node, context.shared_context());
}