This allows us to have ensure_data() and clear_data() functions on the TElement
trait, instead of hacking around it adding methods in random traits.
This also allows us to do some further cleanup, which I'd rather do in a
followup.
While we're at it, we also eliminate the 'unknown' dom depth for the
bloom filter. Computing depth has negligible cost relative to the
amount of work we do setting up the bloom filter at a given depth.
Doing it once per traversal should be totally fine.
I originally separated the elimination of unknown dom depth from the
traversal changes, but I got bloom filter crashes on the intermediate
patch, presumably because I didn't properly fix the sequential traversal
for this case. Given that the final state is green, I just decided to
squash and move on.
This way we'll be able to take different paths for the sequential and parallel
traversals in some concrete cases.
This is a preliminar patch to fix bug 1332525.
Actually, I think most of the functions in DOMTraversalContext deserve a nice
comment, but that's probably fine as a followup, I want to land the require-docs
thing now.
It turns out that it's problematic to embed ThreadLocalStyleContext within
LayoutContext, because parameterizing the former on TElement (which we do
in the next patch) infects all the traversal stuff with the trait parameters,
which we don't really want.
In general, it probably makes sense to use separate scoped TLS types for
the separate DOM and Flow tree passes, so we can add a different ScopedTLS
type for the Flow pass if we ever need it.
We also reorder the |scope| and |shared| parameters in parallel.rs, because
it aligns more with the order in style/parallel.rs. I did this when I was
adding a TLS parameter to all these functions, which I realized we don't need
for now.
This allows us to get rid of a bunch of lifetimes and simplify a lot of code. It
also lets us get rid of that nasty lifetime transmute, which is awesome.
The situation with thread-local contexts is still suboptimal, but we fix that in
subsequent patches.
The primary idea of this patch is to ditch the rigid enum of Previous/Current
styles, and replace it with a series of indicators for the various types of
work that needs to be performed (expanding snapshots, rematching, recascading,
and damage processing). This loses us a little bit of sanity checking (since
the up-to-date-ness of our style is no longer baked into the type system), but
gives us a lot more flexibility that we'll need going forward (especially when
we separate matching from cascading). We also eliminate get_styling_mode in
favor of a method on the traversal.
This patch does a few other things as ridealongs:
* Temporarily eliminates the handling for transfering ownership of styles to the
frame. We'll need this again at some point, but for now it's causing too much
complexity for a half-implemented feature.
* Ditches TRestyleDamage, which is no longer necessary post-crate-merge, and is
a constant source of compilation failures from either needing to be imported
or being unnecessarily imported (which varies between gecko and servo).
* Expands Snapshots for the traversal root, which was missing before.
* Fixes up the skip_root stuff to avoid visiting the skipped root.
* Unifies parallel traversal and avoids spawning for a single work item.
* Adds an explicit pre_traverse step do any pre-processing and determine whether
we need to traverse at all.
MozReview-Commit-ID: IKhLAkAigXE
I realized that I fixed this issue incorrectly when the test failed before. Our design
document specifies that restyle hints must be expanded by the parent before traversing
children, so that we can properly apply LaterSiblings restyle hints. This includes
parents that do not themselves need processing (StylingMode::Traverse).
So we need to preprocess children even in the case where we don't restyle the parent.
On the flip side, we do in fact know whether a child needs processing before enqueuing
it, so we can skip the conservative visit I added before.
MozReview-Commit-ID: AEiRzdsN0h5
We also make sure that an element never has an ElementData with ElementDataStyles::Uninitialized,
and eagerly call prepare_for_styling whenever an ElementData is instantiated.
MozReview-Commit-ID: 9YP6eSmdMt0
