Track the restyle root and use it to do less work during the traversal.

MozReview-Commit-ID: A8O3JOpsv4E
This commit is contained in:
Bobby Holley 2017-07-18 18:38:47 -07:00
parent 0534f72925
commit d4aa8e3cef
9 changed files with 132 additions and 68 deletions

View file

@ -185,10 +185,16 @@ pub trait DomTraversal<E: TElement> : Sync {
let should_traverse = Self::element_needs_traversal(
root,
flags,
data.map(|d| &*d),
data.as_mut().map(|d| &**d),
parent_data.as_ref().map(|d| &**d)
);
// If we're not going to traverse at all, we may need to clear some state
// off the root (which would normally be done at the end of recalc_style_at).
if !should_traverse && data.is_some() {
clear_state_after_traversing(root, data.unwrap(), flags);
}
PreTraverseToken(should_traverse)
}
@ -592,6 +598,31 @@ where
);
}
// FIXME(bholley): Make these assertions pass for servo.
if cfg!(feature = "gecko") && cfg!(debug_assertions) && data.styles.is_display_none() {
debug_assert!(!element.has_dirty_descendants());
debug_assert!(!element.has_animation_only_dirty_descendants());
}
debug_assert!(flags.for_animation_only() ||
!flags.contains(ClearDirtyBits) ||
!element.has_animation_only_dirty_descendants(),
"Should have cleared animation bits already");
clear_state_after_traversing(element, data, flags);
context.thread_local.end_element(element);
}
fn clear_state_after_traversing<E>(
element: E,
data: &mut ElementData,
flags: TraversalFlags
)
where
E: TElement,
{
use traversal_flags::*;
// If we are in a forgetful traversal, drop the existing restyle
// data here, since we won't need to perform a post-traversal to pick up
// any change hints.
@ -599,32 +630,16 @@ where
data.clear_restyle_flags_and_damage();
}
// Optionally clear the descendants bits.
if data.styles.is_display_none() {
// When this element is the root of a display:none subtree, we want to clear
// the bits even if the style didn't change (since, if the style did change,
// we'd have already cleared it above).
//
// This keeps the tree in a valid state without requiring the DOM to check
// display:none on the parent when inserting new children (which can be
// moderately expensive). Instead, DOM implementations can unconditionally
// set the dirty descendants bit on any styled parent, and let the traversal
// sort it out.
//
// Note that the NODE_DESCENDANTS_NEED_FRAMES bit should generally only be set
// when appending content beneath an element with a frame (i.e. not
// display:none), so clearing it here isn't strictly necessary, but good
// belt-and-suspenders.
unsafe { element.clear_descendants_bits(); }
} else if flags.for_animation_only() {
if flags.contains(ClearAnimationOnlyDirtyDescendants) {
// Clear dirty bits as appropriate.
if flags.for_animation_only() {
if flags.intersects(ClearDirtyBits | ClearAnimationOnlyDirtyDescendants) {
unsafe { element.unset_animation_only_dirty_descendants(); }
}
} else if flags.contains(ClearDirtyDescendants) {
unsafe { element.unset_dirty_descendants(); }
} else if flags.contains(ClearDirtyBits) {
// The animation traversal happens first, so we don't need to guard against
// clearing the animation bit on the regular traversal.
unsafe { element.clear_dirty_bits(); }
}
context.thread_local.end_element(element);
}
fn compute_style<E>(
@ -855,6 +870,11 @@ where
}
}
}
p.clear_descendants_bits();
if p == root {
// Make sure not to clear NODE_NEEDS_FRAME on the root.
p.clear_descendants_bits();
} else {
p.clear_dirty_bits();
}
}
}