fix(editor): stop large SQL paste from freezing the editor (#1654)

* fix(editor): stop large SQL paste from freezing the editor

* perf(editor): suspend syntax highlighting and inline AI for documents over 2MB

* perf(editor): stop the hidden minimap rebuilding line storage on every edit

* perf(editor): avoid O(n) Unicode comparison of query text during SwiftUI diffs

* perf(editor): idle the hidden fold ribbon and use NSString equality in binding sync

* perf(editor): box query text in a reference so SwiftUI compares a pointer not the whole string

* refactor(editor): single source for the large-document threshold and flatten query equality

Author: datlechin

CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Refreshing a table now reloads its data even when the previous load is still running; before, the refresh was silently dropped and the grid kept stale rows. (#1637)
 - Cmd+R on a table now reloads its rows instead of failing with a query error; the refresh was sending the database a stray cancel that aborted its own freshly-issued reload.
 - SQL autocomplete now suggests tables after JOIN. It detects the clause at the cursor across multi-join and multi-clause queries, so columns no longer appear where a table is expected, and tables lead the list. (#1646)
+- Large SQL scripts no longer freeze the editor or pin the CPU. Pasting is faster, and above 2 MB the editor suspends syntax highlighting and inline AI so typing, scrolling, and deleting stay responsive. (#1652)
 
 ### Security
 

LocalPackages/CodeEditSourceEditor/Sources/CodeEditSourceEditor/Gutter/GutterView.swift

@@ -78,6 +78,9 @@ public class GutterView: NSView {
     public var showFoldingRibbon: Bool = true {
         didSet {
             foldingRibbon.isHidden = !showFoldingRibbon
+            if showFoldingRibbon {
+                foldingRibbon.model?.refresh()
+            }
         }
     }
 

LocalPackages/CodeEditSourceEditor/Sources/CodeEditSourceEditor/Highlighting/Highlighter.swift

@@ -12,6 +12,14 @@ import SwiftTreeSitter
 import CodeEditLanguages
 import OSLog
 
+/// Thresholds for degrading language services on large documents.
+public enum EditorHighlighting {
+    /// Documents longer than this (UTF-16 character count) are not syntax highlighted by default. Above it the
+    /// per-edit re-parse and re-highlight cost dominates, so the editor stops highlighting to keep typing, scrolling,
+    /// and deleting responsive, the same way DataGrip and VS Code degrade large files.
+    public static let maxHighlightableCharacters = 2_000_000
+}
+
 /// This class manages fetching syntax highlights from providers, and applying those styles to the editor.
 /// Multiple highlight providers can be used to style the editor.
 ///
@@ -81,7 +89,7 @@ class Highlighter: NSObject {
     /// Counts upwards to provide unique IDs for new highlight providers.
     private var providerIdCounter: Int
 
-    public var maxHighlightableLength: Int = 5_000_000
+    public var maxHighlightableLength: Int = EditorHighlighting.maxHighlightableCharacters
 
     // MARK: - Init
 

LocalPackages/CodeEditSourceEditor/Sources/CodeEditSourceEditor/LineFolding/Model/LineFoldModel.swift

@@ -57,6 +57,11 @@ class LineFoldModel: NSObject, NSTextStorageDelegate, ObservableObject {
         foldCache.folds(in: range)
     }
 
+    /// Recomputes folds for the whole document. Used to catch up after the ribbon has been hidden and is shown again.
+    func refresh() {
+        textChangedStreamContinuation.yield()
+    }
+
     func textStorage(
         _ textStorage: NSTextStorage,
         didProcessEditing editedMask: NSTextStorageEditActions,
@@ -67,6 +72,9 @@ class LineFoldModel: NSObject, NSTextStorageDelegate, ObservableObject {
             return
         }
         foldCache.storageUpdated(editedRange: editedRange, changeInLength: delta)
+        // Recalculating folds walks the whole document. Skip it while the ribbon is hidden; `refresh()` rebuilds when
+        // it is shown again.
+        guard foldView?.isHidden != true else { return }
         textChangedStreamContinuation.yield()
     }
 

LocalPackages/CodeEditSourceEditor/Sources/CodeEditSourceEditor/Minimap/MinimapView.swift

@@ -72,6 +72,18 @@ public class MinimapView: FlippedNSView {
         scrollView.visibleRect.height - scrollView.contentInsets.vertical
     }
 
+    /// Suspends the minimap's line storage updates while it is hidden so it does not rebuild on every edit. When the
+    /// minimap becomes visible again, its line storage is rebuilt to catch up on the edits it skipped.
+    override public var isHidden: Bool {
+        didSet {
+            guard isHidden != oldValue else { return }
+            layoutManager?.processesEdits = !isHidden
+            if !isHidden {
+                layoutManager?.reset()
+            }
+        }
+    }
+
     // MARK: - Init
 
     /// Creates a minimap view with the text view to track, and an initial theme.

LocalPackages/CodeEditSourceEditor/Sources/CodeEditSourceEditor/SourceEditor/TextBindingSync.swift

@@ -77,7 +77,9 @@ final class TextBindingSync {
     /// tree-sitter state for the old document and highlighting never recovers.
     func applyRepresentableText(_ newValue: String, controller: TextViewController) {
         guard !phase.isEditorChangePending else { return }
-        guard newValue != lastSyncedText else { return }
+        // Compare with NSString literal equality. The text can be multiple megabytes and bridged from NSTextStorage,
+        // so Swift's canonical `!=` walks the whole string through Unicode normalization on every representable update.
+        if let lastSyncedText, (newValue as NSString).isEqual(to: lastSyncedText) { return }
 
         writebackTask?.cancel()
         phase.applyRepresentableValue {

LocalPackages/CodeEditSourceEditor/Sources/CodeEditSourceEditor/TreeSitter/TreeSitterClient.swift

@@ -138,6 +138,21 @@ public final class TreeSitterClient: HighlightProviding {
 
     // MARK: - HighlightProviding
 
+    /// Decides whether an edit must be parsed asynchronously to keep the main thread responsive.
+    ///
+    /// The magnitude of an edit is the larger of the replaced range and the inserted length. Keying only on the
+    /// replaced range misses a large paste at the caret, where the replaced range is empty but `delta` is huge, so a
+    /// multi-megabyte insertion into a small document would otherwise run a full re-parse synchronously.
+    /// - Parameters:
+    ///   - editLength: The length of the range being replaced.
+    ///   - delta: The change in length, negative for deletions.
+    ///   - documentLength: The length of the document after the edit.
+    /// - Returns: `true` when the edit should be parsed off the main thread.
+    static func shouldExecuteAsync(editLength: Int, delta: Int, documentLength: Int) -> Bool {
+        let editMagnitude = max(editLength, abs(delta))
+        return editMagnitude > Constants.maxSyncEditLength || documentLength > Constants.maxSyncContentLength
+    }
+
     /// Notifies the highlighter of an edit and in exchange gets a set of indices that need to be re-highlighted.
     /// The returned `IndexSet` should include all indexes that need to be highlighted, including any inserted text.
     /// - Parameters:
@@ -161,9 +176,11 @@ public final class TreeSitterClient: HighlightProviding {
             return self?.applyEdit(edit: edit) ?? IndexSet()
         }
 
-        let longEdit = range.length > Constants.maxSyncEditLength
-        let longDocument = textView.documentRange.length > Constants.maxSyncContentLength
-        let execAsync = longEdit || longDocument
+        let execAsync = Self.shouldExecuteAsync(
+            editLength: range.length,
+            delta: delta,
+            documentLength: textView.documentRange.length
+        )
 
         if !execAsync || forceSyncOperation {
             let result = executor.execSync(operation)

LocalPackages/CodeEditSourceEditor/Tests/CodeEditSourceEditorTests/Highlighting/HighlighterTests.swift

@@ -277,4 +277,51 @@ final class HighlighterTests: XCTestCase {
         textView.insertText("func helloWorld() {\n\tprint(\"Hello World!\")\n}")
         XCTAssertEqual(textView.string, "func helloWorld() {\n\tprint(\"Hello World!\")\n}")
     }
+
+    @MainActor
+    func test_editDoesNotHighlightDocumentOverMaxLength() {
+        let highlightProvider = MockHighlightProvider(queryResponse: { .success([]) })
+        let textView = Mock.textView()
+        textView.frame = NSRect(x: 0, y: 0, width: 1000, height: 1000)
+        textView.setText(String(repeating: "a", count: 64))
+
+        let highlighter = Mock.highlighter(
+            textView: textView,
+            highlightProviders: [highlightProvider],
+            attributeProvider: attributeProvider
+        )
+        highlighter.maxHighlightableLength = 32
+
+        let baseline = highlightProvider.queryCount
+        textView.replaceCharacters(in: NSRange(location: 0, length: 0), with: "b")
+
+        XCTAssertEqual(
+            highlightProvider.queryCount,
+            baseline,
+            "Editing a document over maxHighlightableLength must not query highlights"
+        )
+    }
+
+    @MainActor
+    func test_editHighlightsDocumentUnderMaxLength() {
+        let highlightProvider = MockHighlightProvider(queryResponse: { .success([]) })
+        let textView = Mock.textView()
+        textView.frame = NSRect(x: 0, y: 0, width: 1000, height: 1000)
+        textView.setText("SELECT 1;")
+
+        let highlighter = Mock.highlighter(
+            textView: textView,
+            highlightProviders: [highlightProvider],
+            attributeProvider: attributeProvider
+        )
+        highlighter.maxHighlightableLength = 1_000
+
+        textView.replaceCharacters(in: NSRange(location: 0, length: 0), with: "x")
+
+        XCTAssertGreaterThan(
+            highlightProvider.queryCount,
+            0,
+            "A document under maxHighlightableLength should still be highlighted"
+        )
+    }
 }

LocalPackages/CodeEditSourceEditor/Tests/CodeEditSourceEditorTests/TreeSitterClientTests.swift

@@ -194,4 +194,38 @@ final class TreeSitterClientTests: XCTestCase {
         wait(for: editExpectations + [finalEditExpectation], timeout: 5.0)
     }
 }
+
+final class TreeSitterClientAsyncGateTests: XCTestCase {
+    private var savedEditLength = 0
+    private var savedContentLength = 0
+
+    override func setUp() {
+        savedEditLength = TreeSitterClient.Constants.maxSyncEditLength
+        savedContentLength = TreeSitterClient.Constants.maxSyncContentLength
+        TreeSitterClient.Constants.maxSyncEditLength = 1024
+        TreeSitterClient.Constants.maxSyncContentLength = 1_000_000
+    }
+
+    override func tearDown() {
+        TreeSitterClient.Constants.maxSyncEditLength = savedEditLength
+        TreeSitterClient.Constants.maxSyncContentLength = savedContentLength
+    }
+
+    func test_largePasteAtCaretRunsAsync() {
+        // The replaced range is empty for a caret paste; the inserted length must still force the async path.
+        XCTAssertTrue(TreeSitterClient.shouldExecuteAsync(editLength: 0, delta: 500_000, documentLength: 500_000))
+    }
+
+    func test_smallEditInSmallDocumentRunsSync() {
+        XCTAssertFalse(TreeSitterClient.shouldExecuteAsync(editLength: 4, delta: 4, documentLength: 1_000))
+    }
+
+    func test_largeDocumentRunsAsync() {
+        XCTAssertTrue(TreeSitterClient.shouldExecuteAsync(editLength: 1, delta: 1, documentLength: 2_000_000))
+    }
+
+    func test_largeDeletionRunsAsync() {
+        XCTAssertTrue(TreeSitterClient.shouldExecuteAsync(editLength: 0, delta: -500_000, documentLength: 10))
+    }
+}
 // swiftlint:enable all

LocalPackages/CodeEditTextView/Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager+Edits.swift

@@ -35,6 +35,7 @@ extension TextLayoutManager: NSTextStorageDelegate {
         range editedRange: NSRange,
         changeInLength delta: Int
     ) {
+        guard processesEdits else { return }
         guard editedMask.contains(.editedCharacters) else {
             if editedMask.contains(.editedAttributes) && delta == 0 {
                 invalidateLayoutForRange(editedRange)
@@ -80,42 +81,44 @@ extension TextLayoutManager: NSTextStorageDelegate {
     /// - Parameter range: The range of the string that was inserted into the text storage.
     private func insertNewLines(for range: NSRange) {
         guard !range.isEmpty, let string = textStorage?.substring(from: range) as? NSString else { return }
-        // Loop through each line being inserted, inserting & splitting where necessary
+        // Loop through each line being inserted, inserting & splitting where necessary. Each line is described by its
+        // length and whether it ends in a line break rather than a materialized substring, so a large paste does not
+        // allocate one bridged `String` per line just to test its terminator.
         var index = 0
         while let nextLine = string.getNextLine(startingAt: index) {
-            let lineRange = NSRange(start: index, end: nextLine.max)
-            applyLineInsert(string.substring(with: lineRange) as NSString, at: range.location + index)
+            applyLineInsert(length: nextLine.max - index, endsInLineBreak: true, at: range.location + index)
             index = nextLine.max
         }
 
         if index < string.length {
             // Get the last line.
-            applyLineInsert(string.substring(from: index) as NSString, at: range.location + index)
+            applyLineInsert(length: string.length - index, endsInLineBreak: false, at: range.location + index)
         }
     }
 
     /// Applies a line insert to the internal line storage tree.
     /// - Parameters:
-    ///   - insertedString: The string being inserted.
+    ///   - length: The length of the line being inserted.
+    ///   - endsInLineBreak: Whether the inserted line is terminated by a line break.
     ///   - location: The location the string is being inserted into.
-    private func applyLineInsert(_ insertedString: NSString, at location: Int) {
-        if LineEnding(line: insertedString as String) != nil {
+    private func applyLineInsert(length: Int, endsInLineBreak: Bool, at location: Int) {
+        if endsInLineBreak {
             if location == lineStorage.length {
                 // Insert a new line at the end of the document, need to insert a new line 'cause there's nothing to
                 // split. Also, append the new text to the last line.
-                lineStorage.update(atOffset: location, delta: insertedString.length, deltaHeight: 0.0)
+                lineStorage.update(atOffset: location, delta: length, deltaHeight: 0.0)
                 lineStorage.insert(
                     line: TextLine(),
-                    atOffset: location + insertedString.length,
+                    atOffset: location + length,
                     length: 0,
                     height: estimateLineHeight()
                 )
             } else {
                 // Need to split the line inserting into and create a new line with the split section of the line
                 guard let linePosition = lineStorage.getLine(atOffset: location) else { return }
-                let splitLocation = location + insertedString.length
+                let splitLocation = location + length
                 let splitLength = linePosition.range.max - location
-                let lineDelta = insertedString.length - splitLength // The difference in the line being edited
+                let lineDelta = length - splitLength // The difference in the line being edited
                 if lineDelta != 0 {
                     lineStorage.update(atOffset: location, delta: lineDelta, deltaHeight: 0.0)
                 }
@@ -128,7 +131,7 @@ extension TextLayoutManager: NSTextStorageDelegate {
                 )
             }
         } else {
-            lineStorage.update(atOffset: location, delta: insertedString.length, deltaHeight: 0.0)
+            lineStorage.update(atOffset: location, delta: length, deltaHeight: 0.0)
         }
     }
 }