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Revert portal hierarchy mutation tracker launch crash #10018

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Merged
austinywang merged 2 commits into from
Aug 12, 2026
Merged

Revert portal hierarchy mutation tracker launch crash #10018

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b36930d
Revert "Fix portal mutation tracker launch crash (#10008)"
austinywang Aug 11, 2026
127dcc7
Revert "Portal: invalidate the split-divider hit-test cache on nested…
austinywang Aug 11, 2026
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34 changes: 7 additions & 27 deletions Sources/BrowserWindowPortal.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -226,7 +226,7 @@ final class WindowBrowserHostView: NSView {
private var cachedSidebarDividerX: CGFloat?
private var sidebarDividerMissCount = 0
private var cachedSplitDividerRegions: [DividerRegion]?
private weak var cachedSplitDividerRootView: NSView?
private var cachedSplitDividerRootSubviewIds: [ObjectIdentifier]?
private let splitDividerCacheInvalidator = PortalSplitDividerCacheInvalidator()
private var splitDividerResizeObserver: NSObjectProtocol?
private var trackingArea: NSTrackingArea?
Expand Down Expand Up @@ -1034,23 +1034,15 @@ final class WindowBrowserHostView: NSView {
return (pageFrame, inspectorFrame)
}
private func splitDividerRegions() -> [DividerRegion] {
guard let rootView = dividerSearchRootView() else {
invalidateSplitDividerRegionCache()
return []
}
if let regions = cachedSplitDividerRegions,
cachedSplitDividerRootView === rootView,
splitDividerCacheInvalidator.isHierarchyCurrent(for: rootView),
PortalSplitDividerRegion.allLive(regions) {
return regions
}
guard let rootView = dividerSearchRootView() else { cachedSplitDividerRegions = []; cachedSplitDividerRootSubviewIds = nil; return [] }
let rootSubviewIds = rootView.subviews.map { ObjectIdentifier($0) }
if let regions = cachedSplitDividerRegions, cachedSplitDividerRootSubviewIds == rootSubviewIds, PortalSplitDividerRegion.allLive(regions) { return regions }
let collected = PortalSplitDividerRegion.collect(in: rootView, hostView: self)
cachedSplitDividerRegions = collected.regions
cachedSplitDividerRootView = rootView
cachedSplitDividerRootSubviewIds = rootSubviewIds
splitDividerCacheInvalidator.observe(
rootView: rootView,
geometryViews: collected.geometryObservedViews,
hierarchyNodes: collected.hierarchyNodes
structureViews: collected.structureObservedViews
) { [weak self] in
guard let self else { return }
self.invalidateSplitDividerRegionCache()
Expand All @@ -1061,7 +1053,7 @@ final class WindowBrowserHostView: NSView {

private func invalidateSplitDividerRegionCache() {
cachedSplitDividerRegions = nil
cachedSplitDividerRootView = nil
cachedSplitDividerRootSubviewIds = nil
splitDividerCacheInvalidator.invalidate()
}

Expand Down Expand Up @@ -1759,18 +1751,6 @@ final class WindowBrowserSlotView: NSView {
overlayContainer.addSubview(dropZoneOverlayView, positioned: .above, relativeTo: nil)
}

var previousPriority = Int.min
var needsReordering = false
for subview in subviews {
let priority = interactionLayerPriority(of: subview)
if priority < previousPriority {
needsReordering = true
break
}
previousPriority = priority
}
guard needsReordering else { return }

let context = Unmanaged.passUnretained(self).toOpaque()
sortSubviews({ lhs, rhs, context in
guard let context else { return .orderedSame }
Expand Down
251 changes: 10 additions & 241 deletions Sources/PortalSplitDividerCacheInvalidator.swift
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,258 +1,25 @@
import AppKit
import ObjectiveC

private typealias PortalSubviewComparator = @convention(c) (
NSView,
NSView,
UnsafeMutableRawPointer?
) -> ComparisonResult

private extension NSView {
@objc(cmux_portalAddSubview:)
func cmux_portalAddSubview(_ subview: NSView) {
PortalViewHierarchyMutationTracker.prepareForInsertion(
parentView: self,
insertedView: subview,
previousWindow: subview.window
)
cmux_portalAddSubview(subview)
}

@objc(cmux_portalAddSubview:positioned:relativeTo:)
func cmux_portalAddSubview(
_ subview: NSView,
positioned place: NSWindow.OrderingMode,
relativeTo otherView: NSView?
) {
PortalViewHierarchyMutationTracker.prepareForInsertion(
parentView: self,
insertedView: subview,
previousWindow: subview.window
)
cmux_portalAddSubview(subview, positioned: place, relativeTo: otherView)
}

@objc(cmux_portalSetSubviews:)
func cmux_portalSetSubviews(_ newSubviews: [NSView]) {
let replacementState = PortalViewHierarchyMutationTracker.subviewsBeforeReplacement(
parentView: self,
newSubviews: newSubviews
)
cmux_portalSetSubviews(newSubviews)
guard let replacementState else { return }
PortalViewHierarchyMutationTracker.recordSubviewsReplacement(
parentView: self,
newSubviews: newSubviews,
replacementState: replacementState
)
}

@objc func cmux_portalRemoveFromSuperview() {
let oldSuperview = superview
let previousWindow = window
cmux_portalRemoveFromSuperview()
if let oldSuperview {
PortalViewHierarchyMutationTracker.recordRemoval(
parentView: oldSuperview,
removedView: self,
previousWindow: previousWindow
)
}
}

@objc func cmux_portalRemoveFromSuperviewWithoutNeedingDisplay() {
let oldSuperview = superview
let previousWindow = window
cmux_portalRemoveFromSuperviewWithoutNeedingDisplay()
if let oldSuperview {
PortalViewHierarchyMutationTracker.recordRemoval(
parentView: oldSuperview,
removedView: self,
previousWindow: previousWindow
)
}
}

@objc func cmux_portalReplaceSubview(_ oldView: NSView, with newView: NSView) {
let parentWindow = window
let newViewPreviousWindow = newView.window
cmux_portalReplaceSubview(oldView, with: newView)
PortalViewHierarchyMutationTracker.recordReplacement(
parentView: self,
oldView: oldView,
newView: newView,
newViewPreviousWindow: newViewPreviousWindow,
parentWindow: parentWindow
)
}

@objc func cmux_portalSortSubviews(
_ compare: PortalSubviewComparator,
context: UnsafeMutableRawPointer?
) {
let parentWindow = window
let sortState = PortalViewHierarchyMutationTracker.subviewOrderBeforeSort(
parentView: self,
parentWindow: parentWindow
)
cmux_portalSortSubviews(compare, context: context)
guard let sortState else { return }
PortalViewHierarchyMutationTracker.recordSortIfNeeded(
parentView: self,
sortState: sortState
)
}
}

private extension NSSplitView {
@objc(cmux_portalAddArrangedSubview:)
func cmux_portalAddArrangedSubview(_ view: NSView) {
let mutationState = PortalViewHierarchyMutationTracker.arrangedSubviewsBeforeMutation(
splitView: self
)
cmux_portalAddArrangedSubview(view)
guard let mutationState else { return }
PortalViewHierarchyMutationTracker.recordArrangedSubviewsMutation(
splitView: self,
mutationState: mutationState
)
}

@objc(cmux_portalInsertArrangedSubview:atIndex:)
func cmux_portalInsertArrangedSubview(_ view: NSView, at index: Int) {
let mutationState = PortalViewHierarchyMutationTracker.arrangedSubviewsBeforeMutation(
splitView: self
)
cmux_portalInsertArrangedSubview(view, at: index)
guard let mutationState else { return }
PortalViewHierarchyMutationTracker.recordArrangedSubviewsMutation(
splitView: self,
mutationState: mutationState
)
}

@objc(cmux_portalRemoveArrangedSubview:)
func cmux_portalRemoveArrangedSubview(_ view: NSView) {
let mutationState = PortalViewHierarchyMutationTracker.arrangedSubviewsBeforeMutation(
splitView: self
)
cmux_portalRemoveArrangedSubview(view)
guard let mutationState else { return }
PortalViewHierarchyMutationTracker.recordArrangedSubviewsMutation(
splitView: self,
mutationState: mutationState
)
}

@objc(cmux_portalSetArrangesAllSubviews:)
func cmux_portalSetArrangesAllSubviews(_ arrangesAllSubviews: Bool) {
let mutationState = PortalViewHierarchyMutationTracker.arrangedSubviewsBeforeMutation(
splitView: self
)
cmux_portalSetArrangesAllSubviews(arrangesAllSubviews)
guard let mutationState else { return }
PortalViewHierarchyMutationTracker.recordArrangedSubviewsMutation(
splitView: self,
mutationState: mutationState
)
}
}

@MainActor
final class PortalSplitDividerCacheInvalidator {
/// AppKit does not document `subviews` as KVO-compliant, and an `NSSplitView`
/// can change its arranged panes without changing `subviews`. Hook both
/// authoritative mutation surfaces once so the window tracker can advance
/// its generation without a pointer-time tree walk.
private static let hierarchyMutationHooksInstalled: Bool = {
let selectorPairs: [(ownerClass: AnyClass, original: Selector, replacement: Selector)] = [
(NSView.self, #selector(NSView.addSubview(_:)), #selector(NSView.cmux_portalAddSubview(_:))),
(
NSView.self,
#selector(NSView.addSubview(_:positioned:relativeTo:)),
#selector(NSView.cmux_portalAddSubview(_:positioned:relativeTo:))
),
(NSView.self, #selector(setter: NSView.subviews), #selector(NSView.cmux_portalSetSubviews(_:))),
(NSView.self, #selector(NSView.removeFromSuperview), #selector(NSView.cmux_portalRemoveFromSuperview)),
(
NSView.self,
#selector(NSView.removeFromSuperviewWithoutNeedingDisplay),
#selector(NSView.cmux_portalRemoveFromSuperviewWithoutNeedingDisplay)
),
(
NSView.self,
#selector(NSView.replaceSubview(_:with:)),
#selector(NSView.cmux_portalReplaceSubview(_:with:))
),
(
NSView.self,
#selector(NSView.sortSubviews(_:context:)),
#selector(NSView.cmux_portalSortSubviews(_:context:))
),
(
NSSplitView.self,
#selector(NSSplitView.addArrangedSubview(_:)),
#selector(NSSplitView.cmux_portalAddArrangedSubview(_:))
),
(
NSSplitView.self,
#selector(NSSplitView.insertArrangedSubview(_:at:)),
#selector(NSSplitView.cmux_portalInsertArrangedSubview(_:at:))
),
(
NSSplitView.self,
#selector(NSSplitView.removeArrangedSubview(_:)),
#selector(NSSplitView.cmux_portalRemoveArrangedSubview(_:))
),
(
NSSplitView.self,
#selector(setter: NSSplitView.arrangesAllSubviews),
#selector(NSSplitView.cmux_portalSetArrangesAllSubviews(_:))
),
]

var methodPairs: [(original: Method, replacement: Method)] = []
for selectors in selectorPairs {
guard let original = class_getInstanceMethod(selectors.ownerClass, selectors.original),
let replacement = class_getInstanceMethod(selectors.ownerClass, selectors.replacement) else {
assertionFailure("Unable to install portal view-hierarchy mutation hook for \(selectors.original)")
return false
}
methodPairs.append((original, replacement))
}
for methods in methodPairs {
method_exchangeImplementations(methods.original, methods.replacement)
}
return true
}()

// Observer tokens are assigned/cleared from main-thread AppKit paths. Swift
// deinit is nonisolated, so the teardown helper needs nonisolated access
// after all main-thread use has ceased.
private nonisolated(unsafe) var observations: [NSKeyValueObservation] = []
private nonisolated(unsafe) var notificationObservers: [NSObjectProtocol] = []
private var hierarchyRegistration: PortalViewHierarchyMutationRegistration?

init() {
_ = Self.hierarchyMutationHooksInstalled
}

deinit {
invalidateObservations()
}

func observe(
rootView: NSView,
geometryViews: [NSView],
hierarchyNodes: [(view: NSView, containsSplitView: Bool)],
structureViews: [NSView],
onChange: @escaping @MainActor () -> Void
) {
invalidate()
let geometryViews = Self.uniqueViews(geometryViews)
hierarchyRegistration = PortalViewHierarchyMutationTracker.register(
rootView: rootView,
hierarchyNodes: hierarchyNodes
)
let subviewObservedViews = Self.uniqueViews(geometryViews + structureViews)

for view in geometryViews {
// These NSView flags are shared; do not restore them per observer or
Expand All @@ -275,6 +42,14 @@ final class PortalSplitDividerCacheInvalidator {
MainActor.assumeIsolated { onChange() }
}
}
// Nested splits can be inserted under known layout containers after cache
// warm-up. Keep this bounded to root/direct/split-related containers, not
// arbitrary descendants such as WebKit or terminal internals.
observations.append(contentsOf: subviewObservedViews.map { view in
view.observe(\.subviews, options: [.new]) { _, _ in
MainActor.assumeIsolated { onChange() }
}
})
}

private static func uniqueViews(_ views: [NSView]) -> [NSView] {
Expand All @@ -287,15 +62,9 @@ final class PortalSplitDividerCacheInvalidator {
}

func invalidate() {
hierarchyRegistration = nil
invalidateObservations()
}

func isHierarchyCurrent(for rootView: NSView) -> Bool {
guard Self.hierarchyMutationHooksInstalled else { return false }
return hierarchyRegistration?.isCurrent(for: rootView) == true
}

private nonisolated func invalidateObservations() {
observations.removeAll()
notificationObservers.forEach(NotificationCenter.default.removeObserver)
Expand Down
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