Read script carets without blocking the UI thread #20523
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| Original file line number | Diff line number | Diff line change |
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| // Copyright (c) Microsoft Corporation. All Rights Reserved. See License.txt in the project root for license information. | ||
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| namespace Microsoft.VisualStudio.FSharp.Editor | ||
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| open System.ComponentModel.Composition | ||
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| open Microsoft.CodeAnalysis.Text | ||
| open Microsoft.VisualStudio.Text.Editor | ||
| open Microsoft.VisualStudio.Utilities | ||
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| open FSharp.Compiler.Text | ||
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| /// The caret of the focused editor on a text buffer, published by the UI thread for the project options | ||
| /// reactor: the UI thread can be blocked waiting for the reactor, so the reactor must never wait for it. | ||
| [<Sealed>] | ||
| type internal FocusedCaret() = | ||
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| // A reference, not an option: the reactor reads it while the UI thread writes, and must never see a torn struct. | ||
| [<VolatileField>] | ||
| let mutable position: Position option = None | ||
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| let lineChanged = Event<unit>() | ||
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| /// None while no editor on the buffer has focus. | ||
| member _.Position = position | ||
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| /// Raised on the UI thread when the caret moves to another line, or focus enters or leaves the buffer's editors. | ||
| member _.LineChanged = lineChanged.Publish | ||
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| member _.Update(newPosition: Position option) = | ||
| let hasLineChanged = | ||
| (position |> Option.map _.Line) <> (newPosition |> Option.map _.Line) | ||
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| position <- newPosition | ||
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| if hasLineChanged then | ||
| lineChanged.Trigger() | ||
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There was a problem hiding this comment. Added in The tracker itself is not tested: it is an |
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| static member TryGet(sourceText: SourceText) = | ||
| match sourceText.Container.TryGetTextBuffer() with | ||
| | null -> ValueNone | ||
| | buffer -> | ||
| match buffer.Properties.TryGetProperty<FocusedCaret>(typeof<FocusedCaret>) with | ||
| | true, caret -> ValueSome caret | ||
| | _ -> ValueNone | ||
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| [<Export(typeof<IWpfTextViewCreationListener>)>] | ||
| [<ContentType(FSharpConstants.FSharpContentTypeName)>] | ||
| [<TextViewRole(PredefinedTextViewRoles.Editable)>] | ||
| type internal FocusedCaretTracker() = | ||
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| let caretOf (textView: ITextView) = | ||
| let caret = textView.Caret.Position.BufferPosition | ||
| let line = caret.GetContainingLine() | ||
| Position.fromZ line.LineNumber (caret.Position - line.Start.Position) | ||
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| interface IWpfTextViewCreationListener with | ||
| member _.TextViewCreated(textView) = | ||
| let focusedCaret = | ||
| textView.TextBuffer.Properties.GetOrCreateSingletonProperty(fun () -> FocusedCaret()) | ||
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| let publish _ = | ||
| focusedCaret.Update(Some(caretOf textView)) | ||
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| let subscriptions = | ||
| [ | ||
| textView.Caret.PositionChanged.Subscribe(fun _ -> | ||
| if textView.HasAggregateFocus then | ||
| publish ()) | ||
| textView.GotAggregateFocus.Subscribe publish | ||
| textView.LostAggregateFocus.Subscribe(fun _ -> focusedCaret.Update None) | ||
| ] | ||
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| if textView.HasAggregateFocus then | ||
| publish () | ||
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| textView.Closed.Add(fun _ -> | ||
| for subscription in subscriptions do | ||
| subscription.Dispose() | ||
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| // The caret belongs to the buffer, which outlives the view. A view closed while it held focus | ||
| // would leave its line published, and the reactor would go on skipping the `#r` on a line no | ||
| // editor is on. A view that does not hold focus published nothing to clear. | ||
| if textView.HasAggregateFocus then | ||
| focusedCaret.Update None) | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,63 @@ | ||
| // Copyright (c) Microsoft Corporation. All Rights Reserved. See License.txt in the project root for license information. | ||
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| /// What the project options reactor reads off the focused editor, and when it is told to read it again. | ||
| /// Only the line matters: the caret decides which `#r "nuget: …"` line is still being typed, and a script's | ||
| /// references are resolved again once it leaves that line or the editors lose focus. | ||
| module FSharp.Editor.Tests.FocusedCaretTests | ||
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| open Xunit | ||
| open Microsoft.CodeAnalysis.Text | ||
| open Microsoft.VisualStudio.FSharp.Editor | ||
| open FSharp.Compiler.Text | ||
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| let private caretWithRecordedChanges () = | ||
| let caret = FocusedCaret() | ||
| let changes = ResizeArray() | ||
| caret.LineChanged.Add(fun () -> changes.Add caret.Position) | ||
| caret, changes | ||
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| [<Fact>] | ||
| let ``a caret that moves to another line is published as a line change`` () = | ||
| let caret, changes = caretWithRecordedChanges () | ||
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| caret.Update(Some(Position.mkPos 7 0)) | ||
| caret.Update(Some(Position.mkPos 8 4)) | ||
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| Assert.Equal<int list>([ 7; 8 ], [ for position in changes -> position.Value.Line ]) | ||
| Assert.Equal(8, caret.Position.Value.Line) | ||
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| [<Fact>] | ||
| let ``a caret that moves along its line is not a line change`` () = | ||
| let caret, changes = caretWithRecordedChanges () | ||
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| caret.Update(Some(Position.mkPos 7 0)) | ||
| caret.Update(Some(Position.mkPos 7 12)) | ||
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| Assert.Equal(1, changes.Count) | ||
| // The position is still published: the reactor reads the column of the line it skips. | ||
| Assert.Equal(12, caret.Position.Value.Column) | ||
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| [<Fact>] | ||
| let ``editors losing focus is a line change, and the caret is gone`` () = | ||
| let caret, changes = caretWithRecordedChanges () | ||
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| caret.Update(Some(Position.mkPos 7 0)) | ||
| caret.Update None | ||
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| Assert.Equal(2, changes.Count) | ||
| Assert.True(caret.Position.IsNone) | ||
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| [<Fact>] | ||
| let ``no editor has focus twice over is one line change`` () = | ||
| let caret, changes = caretWithRecordedChanges () | ||
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| caret.Update None | ||
| caret.Update None | ||
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| Assert.Empty changes | ||
| Assert.True(caret.Position.IsNone) | ||
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| [<Fact>] | ||
| let ``a text with no editor behind it has no caret`` () = | ||
| // What the reactor sees for a document Visual Studio has not opened a view on. | ||
| Assert.True((FocusedCaret.TryGet(SourceText.From "#r \"nuget: Newtonsoft.Json\"\n")).IsNone) |
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The lifecycle is real but it cannot leave a reference pending, because the suppression and the subscription have the same precondition. FCS skips a
#r "nuget: …"line only when it is given a caret, and a caret can only come from the sameFocusedCaretobject whoseLineChangedthe entry subscribes to. WhenTryGetanswersValueNone— no view yet — no caret is passed, so that computation resolves every reference rather than holding one back, and there is nothing for a later notification to re-resolve. Once the user does type in the view that appears, the text version changes, the entry is dropped byfileStamp <> oldFileStamp, and the recomputation finds the caret and subscribes.What the same lifecycle does break is the other direction, and that is fixed in
1826a7e2a6: the caret lives on the buffer, which outlives the view, so a view closed while it held focus left its line published. Options computed after that were given a caret on a line no editor was on, and the#rthere stayed unresolved until some other view moved a caret.Closednow clears the caret when the view being closed is the one holding focus — a view that does not hold focus published nothing to clear, and a sibling view's caret is left alone.