Add cancellation for textDocument/completion, textDocument/codeAction, textDocument/folding

src/PowerShellEditorServices/PowerShellEditorServices.csproj

@@ -39,7 +39,7 @@
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
     <PackageReference Include="Microsoft.Extensions.FileSystemGlobbing" Version="3.1.2" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="3.1.2" />
-    <PackageReference Include="OmniSharp.Extensions.LanguageServer" Version="0.15.0" />
+    <PackageReference Include="OmniSharp.Extensions.LanguageServer" Version="0.15.1-*" />
     <PackageReference Include="PowerShellStandard.Library" Version="5.1.1" />
     <PackageReference Include="Serilog" Version="2.9.0" />
     <PackageReference Include="Serilog.Extensions.Logging" Version="3.0.1" />

src/PowerShellEditorServices/Services/TextDocument/Handlers/CodeActionHandler.cs

@@ -60,6 +60,11 @@ public void SetCapability(CodeActionCapability capability)
 
         public async Task<CommandOrCodeActionContainer> Handle(CodeActionParams request, CancellationToken cancellationToken)
         {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return new List<CommandOrCodeAction>();
+            }
+
             // On Windows, VSCode still gives us file URIs like "file:///c%3a/...", so we need to escape them
             IReadOnlyDictionary<string, MarkerCorrection> corrections = await _analysisService.GetMostRecentCodeActionsForFileAsync(
                 _workspaceService.GetFile(request.TextDocument.Uri)).ConfigureAwait(false);

src/PowerShellEditorServices/Services/TextDocument/Handlers/CompletionHandler.cs

@@ -24,7 +24,8 @@ namespace Microsoft.PowerShell.EditorServices.Handlers
     internal class CompletionHandler : ICompletionHandler, ICompletionResolveHandler
     {
         const int DefaultWaitTimeoutMilliseconds = 5000;
-        private readonly CompletionItem[] s_emptyCompletionResult = Array.Empty<CompletionItem>();
+        private static readonly CompletionItem[] s_emptyCompletionResult = Array.Empty<CompletionItem>();
+        private readonly SemaphoreSlim _completionLock = AsyncUtils.CreateSimpleLockingSemaphore();
 
         private readonly ILogger _logger;
         private readonly PowerShellContextService _powerShellContextService;
@@ -67,24 +68,39 @@ public async Task<CompletionList> Handle(CompletionParams request, CancellationT
 
             ScriptFile scriptFile = _workspaceService.GetFile(request.TextDocument.Uri);
 
-            CompletionResults completionResults =
-                await GetCompletionsInFileAsync(
-                    scriptFile,
-                    cursorLine,
-                    cursorColumn).ConfigureAwait(false);
+            await _completionLock.WaitAsync().ConfigureAwait(false);
 
-            CompletionItem[] completionItems = s_emptyCompletionResult;
-
-            if (completionResults != null)
+            try
             {
-                completionItems = new CompletionItem[completionResults.Completions.Length];
-                for (int i = 0; i < completionItems.Length; i++)
+                if (cancellationToken.IsCancellationRequested)
                 {
-                    completionItems[i] = CreateCompletionItem(completionResults.Completions[i], completionResults.ReplacedRange, i + 1);
+                    _logger.LogDebug("Completion request canceled for file: {0}", request.TextDocument.Uri);
+                    return new CompletionList(s_emptyCompletionResult);
                 }
-            }
 
-            return new CompletionList(completionItems);
+                CompletionResults completionResults =
+                    await GetCompletionsInFileAsync(
+                        scriptFile,
+                        cursorLine,
+                        cursorColumn).ConfigureAwait(false);
+
+                CompletionItem[] completionItems = s_emptyCompletionResult;
+
+                if (completionResults != null)
+                {
+                    completionItems = new CompletionItem[completionResults.Completions.Length];
+                    for (int i = 0; i < completionItems.Length; i++)
+                    {
+                        completionItems[i] = CreateCompletionItem(completionResults.Completions[i], completionResults.ReplacedRange, i + 1);
+                    }
+                }
+
+                return new CompletionList(completionItems);
+            }
+            finally
+            {
+                _completionLock.Release();
+            }
         }
 
         public bool CanResolve(CompletionItem value)

src/PowerShellEditorServices/Services/TextDocument/Handlers/FoldingRangeHandler.cs

@@ -40,6 +40,11 @@ public TextDocumentRegistrationOptions GetRegistrationOptions()
 
         public Task<Container<FoldingRange>> Handle(FoldingRangeRequestParam request, CancellationToken cancellationToken)
         {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                Task.FromResult(new Container<FoldingRange>());
+            }
+
             // TODO Should be using dynamic registrations
             if (!_configurationService.CurrentSettings.CodeFolding.Enable) { return null; }