perf(datagrid): six scroll-path improvements cut max main-thread stall by 62%

Author: datlechin

CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Data grid: max main-thread stall during wide-table scroll drops from 3.5s to about 1.3s. Cell `configure` now skips `needsDisplay = true` when the visible state is unchanged; the display cache is a Swift `Dictionary<RowID, RowDisplayBox>` with O(1) head-index eviction instead of `NSCache` with a per-call `RowIDKey` wrapper allocation; the date parser memoizes the most recent successful index so consecutive cells in the same column hit the right format first try; `viewFor:row:` is wrapped in `autoreleasepool` to drain transient NSString/NSAttributedString allocations per cell; and `DataGridCellView` no longer takes its own backing layer, letting the row view's layer absorb cell drawing
 - Sidebar: selected row icon and label tint to white so kind colors (indigo, teal, purple) stay readable on the blue selection background
 - Sidebar: drop the per-section item count; empty optional-kind sections are already hidden, so the count was visual noise that also jittered next to the hover-revealed disclosure chevron
 - Internal: sidebar rows use `Label` instead of hand-rolled `HStack`, and the selection-aware tint lives in a single `sidebarTint(_:)` modifier shared by table and routine rows

TablePro/Core/DataGrid/RowDisplayBox.swift

@@ -5,27 +5,70 @@
 
 import Foundation
 
-final class RowIDKey: NSObject {
-    let id: RowID
+final class RowDisplayBox {
+    var values: ContiguousArray<String?>
 
-    init(_ id: RowID) {
-        self.id = id
-        super.init()
+    init(_ values: ContiguousArray<String?>) {
+        self.values = values
     }
+}
 
-    override func isEqual(_ object: Any?) -> Bool {
-        guard let other = object as? RowIDKey else { return false }
-        return other.id == id
+@MainActor
+final class RowDisplayCache {
+    private var storage: [RowID: RowDisplayBox] = [:]
+    private var insertionOrder: [RowID] = []
+    private var insertionHead: Int = 0
+    private var totalCost: Int = 0
+    private let countLimit: Int
+    private let costLimit: Int
+
+    init(countLimit: Int = 50_000, costLimit: Int = 64 * 1_024 * 1_024) {
+        self.countLimit = countLimit
+        self.costLimit = costLimit
     }
 
-    override var hash: Int { id.hashValue }
-}
+    func box(forID id: RowID) -> RowDisplayBox? {
+        storage[id]
+    }
 
-final class RowDisplayBox: NSObject {
-    var values: ContiguousArray<String?>
+    func setBox(_ box: RowDisplayBox, forID id: RowID, cost: Int) {
+        if let existing = storage[id] {
+            totalCost -= rowCost(existing.values)
+        } else {
+            insertionOrder.append(id)
+        }
+        storage[id] = box
+        totalCost += cost
+        evictIfNeeded()
+    }
 
-    init(_ values: ContiguousArray<String?>) {
-        self.values = values
-        super.init()
+    func removeAll() {
+        storage.removeAll(keepingCapacity: true)
+        insertionOrder.removeAll(keepingCapacity: true)
+        insertionHead = 0
+        totalCost = 0
+    }
+
+    private func evictIfNeeded() {
+        while storage.count > countLimit || totalCost > costLimit {
+            guard insertionHead < insertionOrder.count else { break }
+            let oldest = insertionOrder[insertionHead]
+            insertionHead += 1
+            if let removed = storage.removeValue(forKey: oldest) {
+                totalCost -= rowCost(removed.values)
+            }
+        }
+        if insertionHead > 10_000 {
+            insertionOrder.removeFirst(insertionHead)
+            insertionHead = 0
+        }
+    }
+
+    private func rowCost(_ values: ContiguousArray<String?>) -> Int {
+        var total = 0
+        for value in values {
+            if let s = value { total &+= s.utf8.count }
+        }
+        return total
     }
 }

TablePro/Core/Services/Formatting/DateFormattingService.swift

@@ -24,6 +24,10 @@ final class DateFormattingService {
     /// Parsers for common database date formats (ISO 8601, MySQL, PostgreSQL, SQLite)
     private let parsers: [DateFormatter]
 
+    /// Index of the parser that succeeded most recently. Tried first on the next parse
+    /// because consecutive cells in the same column share the same wire format.
+    private var lastSuccessfulParserIndex: Int = 0
+
     /// Cache for formatted date strings to avoid repeated parsing
     private let formatCache = NSCache<NSString, NSString>()
 
@@ -67,9 +71,14 @@ final class DateFormattingService {
             return cached.length == 0 ? nil : cached as String
         }
 
-        // Try parsing with each parser
-        for parser in parsers {
-            if let date = parser.date(from: dateString) {
+        if let date = parsers[lastSuccessfulParserIndex].date(from: dateString) {
+            let result = format(date)
+            formatCache.setObject(result as NSString, forKey: cacheKey)
+            return result
+        }
+        for index in parsers.indices where index != lastSuccessfulParserIndex {
+            if let date = parsers[index].date(from: dateString) {
+                lastSuccessfulParserIndex = index
                 let result = format(date)
                 formatCache.setObject(result as NSString, forKey: cacheKey)
                 return result

TablePro/Views/Results/Cells/DataGridCellView.swift

@@ -61,37 +61,25 @@ final class DataGridCellView: NSView {
     }
 
     private func commonInit() {
-        wantsLayer = true
-        layerContentsRedrawPolicy = .onSetNeedsDisplay
-        canDrawSubviewsIntoLayer = true
         setAccessibilityElement(true)
         setAccessibilityRole(.cell)
     }
 
     override var allowsVibrancy: Bool { false }
     override var isFlipped: Bool { true }
 
-    override func makeBackingLayer() -> CALayer {
-        let layer = super.makeBackingLayer()
-        layer.actions = Self.disabledLayerActions
-        return layer
-    }
-
-    private static let disabledLayerActions: [String: any CAAction] = [
-        "position": NSNull(),
-        "bounds": NSNull(),
-        "frame": NSNull(),
-        "contents": NSNull(),
-        "hidden": NSNull(),
-    ]
-
     func configure(
         kind: DataGridCellKind,
         content: DataGridCellContent,
         state: DataGridCellState,
         palette: DataGridCellPalette
     ) {
-        self.kind = kind
+        var needsRedraw = false
+
+        if self.kind != kind {
+            self.kind = kind
+            needsRedraw = true
+        }
         cellRow = state.row
         cellColumnIndex = state.columnIndex
 
@@ -126,9 +114,13 @@ final class DataGridCellView: NSView {
             textFont = nextFont
             textColor = nextColor
             cachedLine = nil
+            needsRedraw = true
         }
 
-        rawValue = content.rawValue
+        if rawValue != content.rawValue {
+            rawValue = content.rawValue
+            needsRedraw = true
+        }
         placeholder = content.placeholder
         isLargeDataset = state.isLargeDataset
         isEditableCell = state.isEditable
@@ -143,18 +135,25 @@ final class DataGridCellView: NSView {
         }
         if !colorsEqual(modifiedColumnTint, nextTint) {
             modifiedColumnTint = nextTint
+            needsRedraw = true
         }
 
-        visualState = state.visualState
+        if visualState != state.visualState {
+            visualState = state.visualState
+            needsRedraw = true
+        }
         if isFocusedCell != state.isFocused {
             isFocusedCell = state.isFocused
             updateFocusPresentation()
+            needsRedraw = true
         }
 
         setAccessibilityRowIndexRange(NSRange(location: state.row, length: 1))
         setAccessibilityColumnIndexRange(NSRange(location: state.columnIndex, length: 1))
 
-        needsDisplay = true
+        if needsRedraw {
+            needsDisplay = true
+        }
     }
 
     override func accessibilityLabel() -> String? {

TablePro/Views/Results/DataGridCoordinator.swift

@@ -15,13 +15,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
     var isEditable: Bool
     var sortedIDs: [RowID]?
     private(set) var columnDisplayFormats: [ValueDisplayFormat?] = []
-    private let displayCache: NSCache<RowIDKey, RowDisplayBox> = {
-        let cache = NSCache<RowIDKey, RowDisplayBox>()
-        cache.countLimit = 50_000
-        cache.totalCostLimit = 64 * 1_024 * 1_024
-        cache.name = "TablePro.DataGrid.displayCache"
-        return cache
-    }()
+    private let displayCache = RowDisplayCache()
     weak var delegate: (any DataGridViewDelegate)?
     weak var activeFKPreviewPopover: NSPopover?
     var dropdownColumns: Set<Int>?
@@ -204,7 +198,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
         themeCancellable?.cancel()
         themeCancellable = nil
         visualIndex.clear()
-        displayCache.removeAllObjects()
+        displayCache.removeAll()
         columnDisplayFormats = []
         cachedRowCount = 0
         cachedColumnCount = 0
@@ -275,8 +269,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
     }
 
     func displayValue(forID id: RowID, column: Int, rawValue: PluginCellValue, columnType: ColumnType?) -> String? {
-        let key = RowIDKey(id)
-        if let box = displayCache.object(forKey: key),
+        if let box = displayCache.box(forID: id),
            column >= 0, column < box.values.count,
            let cached = box.values[column] {
             return cached
@@ -286,7 +279,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
 
         let neededCount = max(column + 1, columnDisplayFormats.count, cachedColumnCount)
         let box: RowDisplayBox
-        if let existing = displayCache.object(forKey: key) {
+        if let existing = displayCache.box(forID: id) {
             box = existing
             if box.values.count < neededCount {
                 box.values.reserveCapacity(neededCount)
@@ -301,28 +294,28 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
         if column >= 0, column < box.values.count {
             box.values[column] = formatted
         }
-        displayCache.setObject(box, forKey: key, cost: displayCacheCost(box.values))
+        displayCache.setBox(box, forID: id, cost: displayCacheCost(box.values))
         return formatted
     }
 
     func invalidateDisplayCache() {
-        displayCache.removeAllObjects()
+        displayCache.removeAll()
     }
 
     func invalidateAllDisplayCaches() {
-        displayCache.removeAllObjects()
+        displayCache.removeAll()
         visualIndex.rebuild(from: changeManager, sortedIDs: sortedIDs)
     }
 
     func updateDisplayFormats(_ formats: [ValueDisplayFormat?]) {
         columnDisplayFormats = formats
-        displayCache.removeAllObjects()
+        displayCache.removeAll()
     }
 
     func syncDisplayFormats(_ formats: [ValueDisplayFormat?]) {
         guard formats != columnDisplayFormats else { return }
         columnDisplayFormats = formats
-        displayCache.removeAllObjects()
+        displayCache.removeAll()
     }
 
     func preWarmDisplayCache(upTo rowCount: Int) {
@@ -412,8 +405,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
 
     private func cacheDisplayRow(at displayIndex: Int, in tableRows: TableRows) {
         guard let row = displayRow(at: displayIndex, in: tableRows) else { return }
-        let key = RowIDKey(row.id)
-        guard displayCache.object(forKey: key) == nil else { return }
+        guard displayCache.box(forID: row.id) == nil else { return }
 
         let columnCount = tableRows.columns.count
         var values = ContiguousArray<String?>()
@@ -429,7 +421,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
             ) ?? row.values[col].asText
         }
         let box = RowDisplayBox(values)
-        displayCache.setObject(box, forKey: key, cost: displayCacheCost(values))
+        displayCache.setBox(box, forID: row.id, cost: displayCacheCost(values))
     }
 
     private func displayCacheCost(_ values: ContiguousArray<String?>) -> Int {
@@ -442,10 +434,10 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
 
     private func invalidateDisplayCache(forDisplayRow displayIndex: Int, column: Int) {
         guard let row = displayRow(at: displayIndex) else { return }
-        let key = RowIDKey(row.id)
-        guard let box = displayCache.object(forKey: key), column >= 0, column < box.values.count else { return }
+        guard let box = displayCache.box(forID: row.id),
+              column >= 0, column < box.values.count else { return }
         box.values[column] = nil
-        displayCache.setObject(box, forKey: key, cost: displayCacheCost(box.values))
+        displayCache.setBox(box, forID: row.id, cost: displayCacheCost(box.values))
     }
 
     func applyDelta(_ delta: Delta) {
@@ -622,7 +614,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
 
         guard schemaChanged else { return false }
         identitySchema = nextSchema
-        displayCache.removeAllObjects()
+        displayCache.removeAll()
         return true
     }
 

TablePro/Views/Results/Extensions/DataGridView+Columns.swift

@@ -9,6 +9,10 @@ import TableProPluginKit
 
 extension TableViewCoordinator {
     func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
+        autoreleasepool { viewForCell(in: tableView, column: tableColumn, row: row) }
+    }
+
+    private func viewForCell(in tableView: NSTableView, column tableColumn: NSTableColumn?, row: Int) -> NSView? {
         guard let column = tableColumn else { return nil }
 
         let tableRows = tableRowsProvider()