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Stop storing depth per-node in the sequential traversal.

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This has two advantages:
* It allows us to store nodes in the same format that the parallel traversal uses.
* It allows us to double the size of the sequential work queue without increasing
  the storage, which allows us to have WORK_UNIT_MAX * 2 entries before heap-
  allocating, which is about what we want for adaptive mode.

MozReview-Commit-ID: 6VQwGfTQgct
This commit is contained in:
Bobby Holley 2017-08-24 10:44:00 -07:00
parent 7fa6e35583
commit 2908b52c7b
1 changed files with 16 additions and 10 deletions
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26
components/style/sequential.rs
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@ -7,13 +7,12 @@
#![deny(missing_docs)]
use context::{StyleContext, ThreadLocalStyleContext};
use dom::{TElement, TNode};
use dom::{SendNode, TElement, TNode};
use parallel::WORK_UNIT_MAX;
use std::collections::VecDeque;
use time;
use traversal::{DomTraversal, PerLevelTraversalData, PreTraverseToken};
struct WorkItem<N: TNode>(N, usize);
/// Do a sequential DOM traversal for layout or styling, generic over `D`.
pub fn traverse_dom<E, D>(traversal: &D,
root: E,
@ -27,29 +26,36 @@ pub fn traverse_dom<E, D>(traversal: &D,
debug_assert!(!traversal.is_parallel());
debug_assert!(token.should_traverse());
let mut discovered = VecDeque::<WorkItem<E::ConcreteNode>>::with_capacity(16);
let mut discovered =
VecDeque::<SendNode<E::ConcreteNode>>::with_capacity(WORK_UNIT_MAX * 2);
let mut tlc = ThreadLocalStyleContext::new(traversal.shared_context());
let mut context = StyleContext {
shared: traversal.shared_context(),
thread_local: &mut tlc,
};
let root_depth = root.depth();
discovered.push_back(WorkItem(root.as_node(), root_depth));
// Process the nodes breadth-first, just like the parallel traversal does.
// This helps keep similar traversal characteristics for the style sharing
// cache.
while let Some(WorkItem(node, depth)) = discovered.pop_front() {
let mut depth = root.depth();
let mut nodes_remaining_at_current_depth = 1;
discovered.push_back(unsafe { SendNode::new(root.as_node()) });
while let Some(node) = discovered.pop_front() {
let mut children_to_process = 0isize;
let traversal_data = PerLevelTraversalData { current_dom_depth: depth };
traversal.process_preorder(&traversal_data, &mut context, node, |n| {
traversal.process_preorder(&traversal_data, &mut context, *node, |n| {
children_to_process += 1;
discovered.push_back(WorkItem(n, depth + 1));
discovered.push_back(unsafe { SendNode::new(n) });
});
traversal.handle_postorder_traversal(&mut context, root.as_node().opaque(),
node, children_to_process);
*node, children_to_process);
nodes_remaining_at_current_depth -= 1;
if nodes_remaining_at_current_depth == 0 {
depth += 1;
nodes_remaining_at_current_depth = discovered.len();
}
}
// Dump statistics to stdout if requested.