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Use ContravariantLifetime in LayoutNode.

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Since ContravariantLifetime uses no storage, this will reduce the size
of a LayoutNode from 3 words to 2.
This commit is contained in:
Cameron Zwarich 2014-05-14 14:59:34 -07:00
parent 99a0dabc1a
commit e9a6430d88
2 changed files with 8 additions and 8 deletions
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6
src/components/main/layout/parallel.rs
View file

@ -37,7 +37,7 @@ fn static_assertion(node: UnsafeLayoutNode) {
/// Memory representation that is at least as large as UnsafeLayoutNode, as it must be
/// safely transmutable to and from that type to accommodate the type-unsafe parallel work
/// queue usage that stores both flows and nodes.
pub type PaddedUnsafeFlow = (uint, uint, uint);
pub type PaddedUnsafeFlow = (uint, uint);
trait UnsafeFlowConversions {
fn to_flow(&self) -> UnsafeFlow;
@ -46,13 +46,13 @@ trait UnsafeFlowConversions {
impl UnsafeFlowConversions for PaddedUnsafeFlow {
fn to_flow(&self) -> UnsafeFlow {
let (vtable, ptr, _padding) = *self;
let (vtable, ptr) = *self;
(vtable, ptr)
}
fn from_flow(flow: &UnsafeFlow) -> PaddedUnsafeFlow {
let &(vtable, ptr) = flow;
(vtable, ptr, 0)
(vtable, ptr)
}
}

10
src/components/main/layout/wrapper.rs
View file

@ -48,6 +48,7 @@ use servo_util::namespace;
use servo_util::namespace::Namespace;
use std::cast;
use std::cell::{Ref, RefMut};
use std::kinds::marker::ContravariantLifetime;
use style::{PropertyDeclarationBlock, TElement, TNode, AttrSelector, SpecificNamespace};
use style::{AnyNamespace};
use style::computed_values::{content, display};
@ -133,8 +134,8 @@ pub struct LayoutNode<'a> {
/// The wrapped node.
node: JS<Node>,
/// Being chained to a value prevents `LayoutNode`s from escaping.
pub chain: &'a (),
/// Being chained to a ContravariantLifetime prevents `LayoutNode`s from escaping.
pub chain: ContravariantLifetime<'a>,
}
impl<'ln> Clone for LayoutNode<'ln> {
@ -192,10 +193,9 @@ impl<'ln> TLayoutNode for LayoutNode<'ln> {
impl<'ln> LayoutNode<'ln> {
/// Creates a new layout node, scoped to the given closure.
pub unsafe fn with_layout_node<R>(node: JS<Node>, f: <'a> |LayoutNode<'a>| -> R) -> R {
let heavy_iron_ball = ();
f(LayoutNode {
node: node,
chain: &heavy_iron_ball,
chain: ContravariantLifetime,
})
}
@ -708,7 +708,7 @@ pub trait PostorderNodeMutTraversal {
/// Opaque type stored in type-unsafe work queues for parallel layout.
/// Must be transmutable to and from LayoutNode/ThreadsafeLayoutNode/PaddedUnsafeFlow.
pub type UnsafeLayoutNode = (uint, uint, uint);
pub type UnsafeLayoutNode = (uint, uint);
pub fn layout_node_to_unsafe_layout_node(node: &LayoutNode) -> UnsafeLayoutNode {
unsafe {