Simplify LSP refresh queue management

src/LanguageServer/Protocol/Handler/AbstractRefreshQueue.cs

@@ -30,8 +30,6 @@ internal abstract class AbstractRefreshQueue :
     private readonly CancellationTokenSource _disposalTokenSource;
     private readonly LspWorkspaceRegistrationService _lspWorkspaceRegistrationService;
 
-    protected bool _isQueueCreated;
-
     protected abstract string GetFeatureAttribute();
     protected abstract bool? GetRefreshSupport(ClientCapabilities clientCapabilities);
     protected abstract string GetWorkspaceRefreshName();
@@ -42,7 +40,6 @@ public AbstractRefreshQueue(
         LspWorkspaceManager lspWorkspaceManager,
         IClientLanguageServerManager notificationManager)
     {
-        _isQueueCreated = false;
         _asyncListener = asynchronousOperationListenerProvider.GetListener(GetFeatureAttribute());
         _lspWorkspaceRegistrationService = lspWorkspaceRegistrationService;
         _disposalTokenSource = new();
@@ -71,7 +68,6 @@ public void Initialize(ClientCapabilities clientCapabilities)
                 equalityComparer: EqualityComparer<DocumentUri?>.Default,
                 asyncListener: _asyncListener,
                 _disposalTokenSource.Token);
-            _isQueueCreated = true;
             _lspWorkspaceRegistrationService.LspSolutionChanged += OnLspSolutionChanged;
         }
     }
@@ -95,16 +91,15 @@ protected virtual void OnLspSolutionChanged(object? sender, WorkspaceChangeEvent
         }
     }
 
+    /// <summary>
+    /// Enqueues a request to refresh the workspace.  If <paramref name="documentUri"/> is null, then the refresh will
+    /// always happen.  If non-null, the refresh will only happen if the client is <em>not</em> tracking that document.
+    /// If the client is tracking the document, no refresh is necessary as the client clearly knows about the change.
+    /// </summary>
     protected void EnqueueRefreshNotification(DocumentUri? documentUri)
-    {
-        if (_isQueueCreated)
-        {
-            Contract.ThrowIfNull(_refreshQueue);
-            _refreshQueue.AddWork(documentUri);
-        }
-    }
+        => _refreshQueue?.AddWork(documentUri);
 
-    private ValueTask FilterLspTrackedDocumentsAsync(
+    private async ValueTask FilterLspTrackedDocumentsAsync(
         LspWorkspaceManager lspWorkspaceManager,
         IClientLanguageServerManager notificationManager,
         ImmutableSegmentedList<DocumentUri?> documentUris,
@@ -117,7 +112,11 @@ private ValueTask FilterLspTrackedDocumentsAsync(
             {
                 try
                 {
-                    return notificationManager.SendRequestAsync(GetWorkspaceRefreshName(), cancellationToken);
+                    // Fire the notification and immediately return.  Refresh notifications are server-wide, and are not
+                    // associated with a particular project/document.  So once we've sent one, we can stop processing
+                    // entirely.
+                    await notificationManager.SendRequestAsync(GetWorkspaceRefreshName(), cancellationToken).ConfigureAwait(false);
+                    return;
                 }
                 catch (Exception ex) when (ex is ObjectDisposedException or ConnectionLostException)
                 {
@@ -128,7 +127,6 @@ private ValueTask FilterLspTrackedDocumentsAsync(
         }
 
         // LSP is already tracking all changed documents so we don't need to send a refresh request.
-        return ValueTask.CompletedTask;
     }
 
     public virtual void Dispose()

src/LanguageServer/Protocol/Handler/SourceGenerators/SourceGeneratorRefreshQueue.cs

@@ -120,27 +120,25 @@ await newProject.GetDependentVersionAsync(_disposalTokenSource.Token).ConfigureA
         }
     }
 
-    private ValueTask RefreshSourceGeneratedDocumentsAsync(
+    private async ValueTask RefreshSourceGeneratedDocumentsAsync(
         CancellationToken cancellationToken)
     {
         var hasOpenSourceGeneratedDocuments = _lspWorkspaceManager.GetTrackedLspText().Keys.Any(uri => uri.ParsedUri?.Scheme == SourceGeneratedDocumentUri.Scheme);
         if (!hasOpenSourceGeneratedDocuments)
         {
             // There are no opened source generated documents - we don't need to bother asking the client to refresh anything.
-            return ValueTask.CompletedTask;
+            return;
         }
 
         try
         {
-            return _notificationManager.SendNotificationAsync(RefreshSourceGeneratedDocumentName, cancellationToken);
+            await _notificationManager.SendNotificationAsync(RefreshSourceGeneratedDocumentName, cancellationToken).ConfigureAwait(false);
         }
         catch (Exception ex) when (ex is ObjectDisposedException or ConnectionLostException)
         {
             // It is entirely possible that we're shutting down and the connection is lost while we're trying to send a notification
             // as this runs outside of the guaranteed ordering in the queue. We can safely ignore this exception.
         }
-
-        return ValueTask.CompletedTask;
     }
 
     public void Dispose()