Don't hold onto Roslyn projects longer than necessary

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/ProjectSystem/Extensions.cs

@@ -0,0 +1,31 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+#if !NET
+using System;
+#endif
+
+using System.Diagnostics;
+using Microsoft.AspNetCore.Razor.Utilities;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.AspNetCore.Razor.ProjectSystem;
+
+internal static class Extensions
+{
+    /// <summary>
+    /// Returns <see langword="true"/> if this <see cref="ProjectKey"/> matches the given <see cref="Project"/>.
+    /// </summary>
+    public static bool Matches(this ProjectKey projectKey, Project project)
+    {
+        // In order to perform this check, we are relying on the fact that Id will always end with a '/',
+        // because it is guaranteed to be normalized. However, CompilationOutputInfo.AssemblyPath will
+        // contain the assembly file name, which AreDirectoryPathsEquivalent will shave off before comparing.
+        // So, AreDirectoryPathsEquivalent will return true when Id is "C:/my/project/path/"
+        // and the assembly path is "C:\my\project\path\assembly.dll"
+
+        Debug.Assert(projectKey.Id.EndsWith('/'), $"This method can't be called if {nameof(projectKey.Id)} is not a normalized directory path.");
+
+        return FilePathNormalizer.AreDirectoryPathsEquivalent(projectKey.Id, project.CompilationOutputInfo.AssemblyPath);
+    }
+}

src/Razor/src/Microsoft.AspNetCore.Razor.ProjectEngineHost/SolutionExtensions.cs

@@ -0,0 +1,54 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using Microsoft.AspNetCore.Razor;
+using Microsoft.AspNetCore.Razor.ProjectSystem;
+
+namespace Microsoft.CodeAnalysis;
+
+internal static class SolutionExtensions
+{
+    public static bool TryGetProject(this Solution solution, ProjectId projectId, [NotNullWhen(true)] out Project? result)
+    {
+        result = solution.GetProject(projectId);
+        return result is not null;
+    }
+
+    public static Project GetRequiredProject(this Solution solution, ProjectId projectId)
+    {
+        return solution.GetProject(projectId)
+            ?? ThrowHelper.ThrowInvalidOperationException<Project>($"The project {projectId} did not exist in {solution}.");
+    }
+
+    public static bool TryGetDocument(this Solution solution, DocumentId documentId, [NotNullWhen(true)] out Document? result)
+    {
+        result = solution.GetDocument(documentId);
+        return result is not null;
+    }
+
+    public static Document GetRequiredDocument(this Solution solution, DocumentId documentId)
+    {
+        return solution.GetDocument(documentId)
+            ?? ThrowHelper.ThrowInvalidOperationException<Document>($"The document {documentId} did not exist in {solution.FilePath ?? "solution"}.");
+    }
+
+    public static Project? GetProject(this Solution solution, ProjectKey projectKey)
+    {
+        return solution.Projects.FirstOrDefault(project => projectKey.Matches(project));
+    }
+
+    public static bool TryGetProject(this Solution solution, ProjectKey projectKey, [NotNullWhen(true)] out Project? result)
+    {
+        result = solution.GetProject(projectKey);
+        return result is not null;
+    }
+
+    public static Project GetRequiredProject(this Solution solution, ProjectKey projectKey)
+    {
+        return solution.GetProject(projectKey)
+            ?? ThrowHelper.ThrowInvalidOperationException<Project>($"The project {projectKey} did not exist in {solution}.");
+    }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Extensions/SolutionExtensions.cs

@@ -5,7 +5,6 @@
 using System.Collections.Immutable;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
-using Microsoft.AspNetCore.Razor;
 using Microsoft.CodeAnalysis.Razor;
 
 namespace Microsoft.CodeAnalysis;
@@ -30,16 +29,4 @@ public static bool TryGetRazorDocument(this Solution solution, Uri razorDocument
         razorDocument = document;
         return true;
     }
-
-    public static Project GetRequiredProject(this Solution solution, ProjectId projectId)
-    {
-        return solution.GetProject(projectId)
-            ?? ThrowHelper.ThrowInvalidOperationException<Project>($"The projectId {projectId} did not exist in {solution}.");
-    }
-
-    public static Document GetRequiredDocument(this Solution solution, DocumentId documentId)
-    {
-        return solution.GetDocument(documentId)
-            ?? ThrowHelper.ThrowInvalidOperationException<Document>($"The document {documentId} did not exist in {solution.FilePath ?? "solution"}.");
-    }
 }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/Extensions.cs

@@ -1,11 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
-#if !NET
-using System;
-#endif
-
-using System.Diagnostics;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.AspNetCore.Razor.Serialization;
 using Microsoft.AspNetCore.Razor.Utilities;
@@ -22,20 +17,4 @@ public static ProjectKey ToProjectKey(this Project project)
         var intermediateOutputPath = FilePathNormalizer.GetNormalizedDirectoryName(project.CompilationOutputInfo.AssemblyPath);
         return new(intermediateOutputPath);
     }
-
-    /// <summary>
-    /// Returns <see langword="true"/> if this <see cref="ProjectKey"/> matches the given <see cref="Project"/>.
-    /// </summary>
-    public static bool Matches(this ProjectKey projectKey, Project project)
-    {
-        // In order to perform this check, we are relying on the fact that Id will always end with a '/',
-        // because it is guaranteed to be normalized. However, CompilationOutputInfo.AssemblyPath will
-        // contain the assembly file name, which AreDirectoryPathsEquivalent will shave off before comparing.
-        // So, AreDirectoryPathsEquivalent will return true when Id is "C:/my/project/path/"
-        // and the assembly path is "C:\my\project\path\assembly.dll"
-
-        Debug.Assert(projectKey.Id.EndsWith('/'), $"This method can't be called if {nameof(projectKey.Id)} is not a normalized directory path.");
-
-        return FilePathNormalizer.AreDirectoryPathsEquivalent(projectKey.Id, project.CompilationOutputInfo.AssemblyPath);
-    }
 }

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Discovery/IProjectStateUpdater.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using Microsoft.AspNetCore.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.VisualStudio.Razor.Discovery;
+
+internal interface IProjectStateUpdater
+{
+    void EnqueueUpdate(ProjectKey key, ProjectId? id);
+
+    void CancelUpdates();
+}

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Remote/OutOfProcTagHelperResolver.cs → src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Discovery/OutOfProcTagHelperResolver.cs

@@ -17,7 +17,7 @@
 using Microsoft.CodeAnalysis.Razor.Remote;
 using Microsoft.CodeAnalysis.Razor.Workspaces;
 
-namespace Microsoft.VisualStudio.Razor.Remote;
+namespace Microsoft.VisualStudio.Razor.Discovery;
 
 /// <summary>
 ///  Retrieves <see cref="TagHelperDescriptor">tag helpers</see> for a given <see cref="Project"/>

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Discovery/ProjectBuildDetector.TestAccessor.cs

@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Threading;
+using Microsoft.VisualStudio.Shell.Interop;
+using Microsoft.VisualStudio.Threading;
+using Task = System.Threading.Tasks.Task;
+
+namespace Microsoft.VisualStudio.Razor.Discovery;
+
+internal sealed partial class ProjectBuildDetector
+{
+    internal TestAccessor GetTestAccessor() => new(this);
+
+    internal readonly struct TestAccessor(ProjectBuildDetector instance)
+    {
+        public JoinableTask InitializeTask => instance._initializeTask;
+        public Task? OnProjectBuiltTask => instance._projectBuiltTask;
+
+        public Task OnProjectBuiltAsync(IVsHierarchy projectHierarchy, CancellationToken cancellationToken)
+            => instance.OnProjectBuiltAsync(projectHierarchy, cancellationToken);
+    }
+}

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/VsSolutionUpdatesProjectSnapshotChangeTrigger.cs → src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Discovery/ProjectBuildDetector.cs

@@ -3,9 +3,9 @@
 
 using System;
 using System.ComponentModel.Composition;
-using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Microsoft.VisualStudio.Razor.Extensions;
@@ -14,14 +14,14 @@
 using Microsoft.VisualStudio.Threading;
 using Task = System.Threading.Tasks.Task;
 
-namespace Microsoft.VisualStudio.Razor;
+namespace Microsoft.VisualStudio.Razor.Discovery;
 
 [Export(typeof(IRazorStartupService))]
-internal class VsSolutionUpdatesProjectSnapshotChangeTrigger : IRazorStartupService, IVsUpdateSolutionEvents2, IDisposable
+internal sealed partial class ProjectBuildDetector : IRazorStartupService, IVsUpdateSolutionEvents2, IDisposable
 {
     private readonly IServiceProvider _serviceProvider;
     private readonly ProjectSnapshotManager _projectManager;
-    private readonly IProjectWorkspaceStateGenerator _workspaceStateGenerator;
+    private readonly IProjectStateUpdater _projectStateUpdater;
     private readonly IWorkspaceProvider _workspaceProvider;
     private readonly JoinableTaskFactory _jtf;
     private readonly CancellationTokenSource _disposeTokenSource;
@@ -33,16 +33,16 @@ internal class VsSolutionUpdatesProjectSnapshotChangeTrigger : IRazorStartupServ
     private Task? _projectBuiltTask;
 
     [ImportingConstructor]
-    public VsSolutionUpdatesProjectSnapshotChangeTrigger(
+    public ProjectBuildDetector(
         [Import(typeof(SVsServiceProvider))] IServiceProvider serviceProvider,
         ProjectSnapshotManager projectManager,
-        IProjectWorkspaceStateGenerator workspaceStateGenerator,
+        IProjectStateUpdater projectStateUpdater,
         IWorkspaceProvider workspaceProvider,
         JoinableTaskContext joinableTaskContext)
     {
         _serviceProvider = serviceProvider;
         _projectManager = projectManager;
-        _workspaceStateGenerator = workspaceStateGenerator;
+        _projectStateUpdater = projectStateUpdater;
         _workspaceProvider = workspaceProvider;
         _jtf = joinableTaskContext.Factory;
 
@@ -110,7 +110,7 @@ private void ProjectManager_Changed(object sender, ProjectChangeEventArgs args)
         if (args.IsSolutionClosing)
         {
             // If the solution is closing, cancel all existing updates.
-            _workspaceStateGenerator.CancelUpdates();
+            _projectStateUpdater.CancelUpdates();
         }
     }
 
@@ -123,30 +123,22 @@ private async Task OnProjectBuiltAsync(IVsHierarchy projectHierarchy, Cancellati
         }
 
         var projectKeys = _projectManager.GetProjectKeysWithFilePath(projectFilePath);
+        if (projectKeys.IsEmpty)
+        {
+            return;
+        }
+
+        var workspace = _workspaceProvider.GetWorkspace();
+        var solution = workspace.CurrentSolution;
+
         foreach (var projectKey in projectKeys)
         {
-            if (_projectManager.TryGetProject(projectKey, out var project))
+            if (solution.TryGetProject(projectKey, out var workspaceProject))
             {
-                var workspace = _workspaceProvider.GetWorkspace();
-                var workspaceProject = workspace.CurrentSolution.Projects.FirstOrDefault(wp => wp.ToProjectKey() == project.Key);
-                if (workspaceProject is not null)
-                {
-                    // Trigger a tag helper update by forcing the project manager to see the workspace Project
-                    // from the current solution.
-                    _workspaceStateGenerator.EnqueueUpdate(workspaceProject, project);
-                }
+                // Trigger a tag helper update by forcing the project manager to see the workspace Project
+                // from the current solution.
+                _projectStateUpdater.EnqueueUpdate(projectKey, workspaceProject.Id);
             }
         }
     }
-
-    internal TestAccessor GetTestAccessor() => new(this);
-
-    internal sealed class TestAccessor(VsSolutionUpdatesProjectSnapshotChangeTrigger instance)
-    {
-        public JoinableTask InitializeTask => instance._initializeTask;
-        public Task? OnProjectBuiltTask => instance._projectBuiltTask;
-
-        public Task OnProjectBuiltAsync(IVsHierarchy projectHierarchy, CancellationToken cancellationToken)
-            => instance.OnProjectBuiltAsync(projectHierarchy, cancellationToken);
-    }
 }

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Discovery/ProjectStateChangeDetector.Comparer.cs

@@ -0,0 +1,24 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.VisualStudio.Razor.Discovery;
+
+internal partial class ProjectStateChangeDetector
+{
+    private sealed class Comparer : IEqualityComparer<Work>
+    {
+        public static readonly Comparer Instance = new();
+
+        private Comparer()
+        {
+        }
+
+        public bool Equals(Work x, Work y)
+            => x.Key == y.Key;
+
+        public int GetHashCode(Work obj)
+            => obj.Key.GetHashCode();
+    }
+}

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/Discovery/ProjectStateChangeDetector.TestAccessor.cs

@@ -0,0 +1,45 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Immutable;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.VisualStudio.Razor.Discovery;
+
+internal partial class ProjectStateChangeDetector
+{
+    internal TestAccessor GetTestAccessor() => new(this);
+
+    internal sealed class TestAccessor(ProjectStateChangeDetector instance)
+    {
+        public void CancelExistingWork()
+        {
+            instance._workQueue.CancelExistingWork();
+        }
+
+        public async Task WaitUntilCurrentBatchCompletesAsync()
+        {
+            await instance._workQueue.WaitUntilCurrentBatchCompletesAsync();
+        }
+
+        public Task ListenForWorkspaceChangesAsync(params WorkspaceChangeKind[] kinds)
+        {
+            if (instance._workspaceChangedListener is not null)
+            {
+                throw new InvalidOperationException($"There's already a {nameof(WorkspaceChangedListener)} installed.");
+            }
+
+            var listener = new WorkspaceChangedListener(kinds.ToImmutableArray());
+            instance._workspaceChangedListener = listener;
+
+            return listener.Task;
+        }
+
+        public void WorkspaceChanged(WorkspaceChangeEventArgs e)
+        {
+            instance.Workspace_WorkspaceChanged(instance, e);
+        }
+    }
+}