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Use ArrayVec and tweak the SmallVec sizes.

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MozReview-Commit-ID: 1tEZiPdp9WQ
This commit is contained in:
Bobby Holley 2017-06-09 12:10:37 -07:00
parent c6d0ef5e9f
commit fe7191568c
1 changed files with 24 additions and 16 deletions
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40
components/style/parallel.rs
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@ -22,6 +22,7 @@
#![deny(missing_docs)]
use arrayvec::ArrayVec;
use context::TraversalStatistics;
use dom::{OpaqueNode, SendNode, TElement, TNode};
use rayon;
@ -39,11 +40,9 @@ use traversal::{DomTraversal, PerLevelTraversalData, PreTraverseToken};
/// been measured and could potentially be tuned.
pub const WORK_UNIT_MAX: usize = 16;
/// A list of node pointers.
///
/// We make the inline storage size WORK_UNIT_MAX so that we can collect chunks
/// into this structure without heap-allocating.
type NodeList<N> = SmallVec<[SendNode<N>; WORK_UNIT_MAX]>;
/// A set of nodes, sized to the work unit. This gets copied when sent to other
/// threads, so we keep it compact.
type WorkUnit<N> = ArrayVec<[SendNode<N>; WORK_UNIT_MAX]>;
/// Entry point for the parallel traversal.
#[allow(unsafe_code)]
@ -56,7 +55,10 @@ pub fn traverse_dom<E, D>(traversal: &D,
{
let dump_stats = traversal.shared_context().options.dump_style_statistics;
let start_time = if dump_stats { Some(time::precise_time_s()) } else { None };
let mut nodes = NodeList::<E::ConcreteNode>::new();
// Set up the SmallVec. We need to move this, and in most cases this is just
// one node, so keep it small.
let mut nodes = SmallVec::<[SendNode<E::ConcreteNode>; 8]>::new();
debug_assert!(traversal.is_parallel());
// Handle Gecko's eager initial styling. We don't currently support it
@ -87,7 +89,8 @@ pub fn traverse_dom<E, D>(traversal: &D,
pool.install(|| {
rayon::scope(|scope| {
traverse_nodes(nodes,
let nodes = nodes;
traverse_nodes(&*nodes,
DispatchMode::TailCall,
root,
traversal_data,
@ -152,7 +155,12 @@ fn top_down_dom<'a, 'scope, E, D>(nodes: &'a [SendNode<E::ConcreteNode>],
D: DomTraversal<E>,
{
debug_assert!(nodes.len() <= WORK_UNIT_MAX);
let mut discovered_child_nodes = NodeList::<E::ConcreteNode>::new();
// Collect all the children of the elements in our work unit. This will
// contain the combined children of up to WORK_UNIT_MAX nodes, which may
// be numerous. As such, we store it in a large SmallVec to minimize heap-
// spilling, and never move it.
let mut discovered_child_nodes = SmallVec::<[SendNode<E::ConcreteNode>; 128]>::new();
{
// Scope the borrow of the TLS so that the borrow is dropped before
// a potential recursive call when we pass TailCall.
@ -176,7 +184,7 @@ fn top_down_dom<'a, 'scope, E, D>(nodes: &'a [SendNode<E::ConcreteNode>],
let children = mem::replace(&mut discovered_child_nodes, Default::default());
let mut traversal_data_copy = traversal_data.clone();
traversal_data_copy.current_dom_depth += 1;
traverse_nodes(children,
traverse_nodes(&*children,
DispatchMode::NotTailCall,
root,
traversal_data_copy,
@ -206,7 +214,7 @@ fn top_down_dom<'a, 'scope, E, D>(nodes: &'a [SendNode<E::ConcreteNode>],
// on this thread by passing TailCall.
if !discovered_child_nodes.is_empty() {
traversal_data.current_dom_depth += 1;
traverse_nodes(discovered_child_nodes,
traverse_nodes(&discovered_child_nodes,
DispatchMode::TailCall,
root,
traversal_data,
@ -230,7 +238,7 @@ impl DispatchMode {
}
#[inline]
fn traverse_nodes<'a, 'scope, E, D>(nodes: NodeList<E::ConcreteNode>,
fn traverse_nodes<'a, 'scope, E, D>(nodes: &[SendNode<E::ConcreteNode>],
mode: DispatchMode,
root: OpaqueNode,
traversal_data: PerLevelTraversalData,
@ -253,18 +261,18 @@ fn traverse_nodes<'a, 'scope, E, D>(nodes: NodeList<E::ConcreteNode>,
// In the common case, our children fit within a single work unit, in which
// case we can pass the SmallVec directly and avoid extra allocation.
if nodes.len() <= WORK_UNIT_MAX {
let work = nodes.iter().cloned().collect::<WorkUnit<E::ConcreteNode>>();
if may_dispatch_tail {
top_down_dom(&nodes, root, traversal_data, scope, pool, traversal, tls);
top_down_dom(&work, root, traversal_data, scope, pool, traversal, tls);
} else {
scope.spawn(move |scope| {
let nodes = nodes;
top_down_dom(&nodes, root, traversal_data, scope, pool, traversal, tls);
let work = work;
top_down_dom(&work, root, traversal_data, scope, pool, traversal, tls);
});
}
} else {
for chunk in nodes.chunks(WORK_UNIT_MAX) {
let nodes = chunk.iter().cloned().collect::<NodeList<E::ConcreteNode>>();
debug_assert!(!nodes.spilled());
let nodes = chunk.iter().cloned().collect::<WorkUnit<E::ConcreteNode>>();
let traversal_data_copy = traversal_data.clone();
scope.spawn(move |scope| {
let n = nodes;