Bug 250345

Summary:	AX: Isolated trees queued for destruction will not be cleaned up unless an AX client requests an attribute from a wrapper in the destroyed tree
Product:	WebKit	Reporter:	Tyler Wilcock <tyler_w>
Component:	Accessibility	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	andresg_22, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	Other
Hardware:	Unspecified
OS:	Unspecified

Description Tyler Wilcock 2023-01-09 16:13:52 PST

Currently, isolated trees are cleaned up like so:

  1. AXObjectCache::~AXObjectCache() calls AXIsolatedTree::removeTreeForPageID(*m_pageID)
  2. AXIsolatedTree::removeTreeForPageID calls AXIsolatedTree::queueForDestruction
  3. AXIsolatedTree::queueForDestruction sets m_queuedForDestruction to true
  4. The next time AXIsolatedTree::applyPendingChanges() is called, the tree is destroyed if m_queuedForDestruction is true

Because this relies on AXIsolatedTree::applyPendingChanges() being called organically (i.e. an AX client requesting an attribute from a wrapper that is part of the soon-to-be-destroyed tree), it's possible we could never clean up a tree queued for destruction. AXIsolatedTree::queueForDestruction should probably set some internal timer to clean the tree up so we don't rely on AX clients requesting data from a soon-to-be-destroyed wrapper.

Comment 1 Radar WebKit Bug Importer 2023-01-09 16:14:04 PST

<rdar://problem/104050266>