1597348 - Purge interrupted flex items' cached measurements during the same frametree-walk that we use to mark their ancestors as dirty

Status: RESOLVED FIXED

(Core :: Layout: Flexbox, enhancement, P3)

Description

[Daniel Holbert [:dholbert]]

Right now, if some flex item gets interrupted via interruptible reflow, we purge all of the flex-item-measurements for its flex container (i.e. we purge all of its siblings' measurements). This may be unnecessary, e.g. if only the last item was interrupted.

We can do this cache-purging more surgically by doing it in the same frametree-walk where we mark the interrupted frame's ancestors as having a dirty child. We should purge any cached-flex-measurement for the interrupted frame and for all of its ancestors that are flex items. (That should be all the cache-purging that's necessary.)

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: Bug 1597348: When reflow is interrupted, purge flex items' cached measurements during the same traversal that we use to mark ancestor-chain as dirty. r?emilio

This means we no longer have any use for the frame state bit
"NS_STATE_FLEX_MEASUREMENTS_INTERRUPTED". Now, if a flex container
has N children and only the last child is interrupted, we'll only
purge the last child's measurement (and we'll do it promptly at the
end of the whole interrupted reflow).

Depends on D53670

Comment 2

[Daniel Holbert [:dholbert]]

Patch is still rebuilding locally [frame state bit creation/destruction invalidates the whole build], so not requesting review yet.

But feel free to take a look if you like; I think this is approximately ready for review. :)

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3ec96c0dd696
When reflow is interrupted, purge flex items' cached measurements during the same traversal that we use to mark ancestor-chain as dirty. r=emilio

Comment 4

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/3ec96c0dd696