Bug 262934 – AX: AXIsolatedTree::children() should not re-initialize m_children unless they've changed

• Status: RESOLVED
• Resolution: FIXED
• Component: Accessibility

[Tyler Wilcock]

This shows up heavily on samples for some sites.

[Radar WebKit Bug Importer]

<rdar://problem/116715426>

[Tyler Wilcock]

Created attachment 468141 [details]
Patch

[chris fleizach]

Comment on attachment 468141 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=468141&action=review

> Source/WebCore/accessibility/isolatedtree/AXIsolatedObject.cpp:463
> +    m_childrenIDs = WTFMove(ids);

Can we avoid dirty children if the IDs are same in same order?

[Tyler Wilcock]

(In reply to chris fleizach from comment #3)
> Comment on attachment 468141 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=468141&action=review
> 
> > Source/WebCore/accessibility/isolatedtree/AXIsolatedObject.cpp:463
> > +    m_childrenIDs = WTFMove(ids);
> 
> Can we avoid dirty children if the IDs are same in same order?
I thought about this too...but ended up deciding against it since it forces an O(n) iteration for what is likely a very uncommon case. Additionally, this proposed iteration would have to happen while we hold the m_changeLogLock, potentially increasing lock contention.

[Andres Gonzalez]

(In reply to Tyler Wilcock from comment #2)
> Created attachment 468141 [details]
> Patch

Are we covering the unconnected objects case? We don't update m_pendingchildrenUpdates for those objects.

[Tyler Wilcock]

(In reply to Andres Gonzalez from comment #5)
> (In reply to Tyler Wilcock from comment #2)
> > Created attachment 468141 [details]
> > Patch
> 
> Are we covering the unconnected objects case? We don't update
> m_pendingchildrenUpdates for those objects.
I don't think that's necessary here. The only time we need to mark children as dirty is when AXIsolatedObject::m_childrenIDs changes, which addUnconnectedNode doesn't do.

[EWS]

Committed 269170@main (4d35a6d87939): <https://commits.webkit.org/269170@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 468141 [details].