Event debounce for language server

docs/specs/lsp.yml

@@ -152,4 +152,4 @@ languageServer:
           "text": "Invalid change"
         }
       }
-  - expectNoNotificationAfterBuildTime: 1
+  - expectNoNotification: true

src/docfx/config/TestQuirks.cs

@@ -15,6 +15,6 @@ internal static class TestQuirks
 
         public static bool? Verbose { get; set; }
 
-        public static Action? FinishedBuildCountIncrease { get; set; }
+        public static Action? HandledEventCountIncrease { get; set; }
     }
 }

src/docfx/serve/LanguageServerBuilder.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
+using System.Threading.Channels;
 using System.Threading.Tasks;
 using OmniSharp.Extensions.LanguageServer.Protocol.Models;
 
@@ -13,7 +14,7 @@ internal class LanguageServerBuilder
     {
         private readonly Builder _builder;
         private readonly ErrorList _errorList;
-        private readonly SemaphoreSlim _buildSemaphore;
+        private readonly Channel<bool> _buildChannel;
         private readonly DiagnosticPublisher _diagnosticPublisher;
         private readonly LanguageServerPackage _languageServerPackage;
         private readonly PathString _workingDirectory;
@@ -30,28 +31,47 @@ public LanguageServerBuilder(
             _errorList = new();
             _languageServerPackage = languageServerPackage;
             _builder = new(_errorList, languageServerPackage.BasePath, options, _languageServerPackage);
-            _buildSemaphore = new(0);
+            _buildChannel = Channel.CreateUnbounded<bool>();
             _ = StartAsync();
         }
 
         public void QueueBuild()
         {
-            _buildSemaphore.Release();
+            _buildChannel.Writer.TryWrite(true);
         }
 
         private async Task StartAsync()
         {
             while (true)
             {
-                await _buildSemaphore.WaitAsync();
+                await WaitToTriggerBuild();
                 var filesToBuild = _languageServerPackage.GetAllFilesInMemory();
                 _builder.Build(filesToBuild.Select(f => f.Value).ToArray());
 
                 PublishDiagnosticsParams(filesToBuild);
-                TestQuirks.FinishedBuildCountIncrease?.Invoke();
+                TestQuirks.HandledEventCountIncrease?.Invoke();
             }
         }
 
+        private async Task WaitToTriggerBuild()
+        {
+            await _buildChannel.Reader.ReadAsync();
+
+            try
+            {
+                while (true)
+                {
+                    using var cts = new CancellationTokenSource(1000);
+                    await _buildChannel.Reader.ReadAsync(cts.Token);
+                    TestQuirks.HandledEventCountIncrease?.Invoke();
+                }
+            }
+            catch (System.OperationCanceledException)
+            {
+            }
+            return;
+        }
+
         private void PublishDiagnosticsParams(IEnumerable<PathString> files)
         {
             foreach (var file in files)

src/docfx/serve/lsp/TextDocumentHandler.cs

@@ -103,6 +103,7 @@ private bool TryUpdatePackage(DocumentUri file, string content)
             var filePath = new PathString(file.GetFileSystemPath());
             if (!filePath.StartsWithPath(_package.BasePath, out _))
             {
+                TestQuirks.HandledEventCountIncrease?.Invoke();
                 return false;
             }
 

test/docfx.Test/DocfxTest.cs

@@ -26,7 +26,8 @@ public static class DocfxTest
         private static readonly AsyncLocal<IReadOnlyDictionary<string, string>> t_repos = new();
         private static readonly AsyncLocal<IReadOnlyDictionary<string, string>> t_remoteFiles = new();
         private static readonly AsyncLocal<string> t_appDataPath = new();
-        private static readonly AsyncLocal<StrongBox<int>> t_finishedBuildCount = new();
+        private static readonly AsyncLocal<StrongBox<int>> t_handledEventCount = new();
+        private static readonly AsyncLocal<StrongBox<int>> t_sentEventCount = new();
 
         static DocfxTest()
         {
@@ -52,9 +53,9 @@ static DocfxTest()
                 return null;
             };
 
-            TestQuirks.FinishedBuildCountIncrease = () =>
+            TestQuirks.HandledEventCountIncrease = () =>
             {
-                t_finishedBuildCount.Value.Value++;
+                t_handledEventCount.Value.Value++;
             };
         }
 
@@ -86,7 +87,8 @@ public static void Run(TestData test, DocfxTestSpec spec)
                     t_repos.Value = repos;
                     t_remoteFiles.Value = spec.Http;
                     t_appDataPath.Value = appDataPath;
-                    t_finishedBuildCount.Value = new StrongBox<int>();
+                    t_handledEventCount.Value = new StrongBox<int>();
+                    t_sentEventCount.Value = new StrongBox<int>();
                     RunCore(docsetPath, outputPath, test, spec, variables, package);
                 }
                 catch (Exception exception)
@@ -102,7 +104,8 @@ public static void Run(TestData test, DocfxTestSpec spec)
                     t_repos.Value = null;
                     t_remoteFiles.Value = null;
                     t_appDataPath.Value = null;
-                    t_finishedBuildCount.Value = null;
+                    t_handledEventCount.Value = null;
+                    t_sentEventCount.Value = null;
                 }
             }
         }
@@ -208,6 +211,7 @@ private static async Task RunLanguageServer(string docsetPath, DocfxTestSpec spe
                 if (!string.IsNullOrEmpty(lspSpec.Notification))
                 {
                     await lspTestHost.SendNotification(new LanguageServerNotification(lspSpec.Notification, lspSpec.Params));
+                    t_sentEventCount.Value.Value++;
                 }
                 else if (!string.IsNullOrEmpty(lspSpec.ExpectNotification))
                 {
@@ -239,9 +243,9 @@ private static async Task RunLanguageServer(string docsetPath, DocfxTestSpec spe
 
                     s_languageServerJsonDiff.Verify(expectedNotifications, actualNotifications);
                 }
-                else if (lspSpec.ExpectNoNotificationAfterBuildTime != null)
+                else if (lspSpec.ExpectNoNotification)
                 {
-                    while (lspSpec.ExpectNoNotificationAfterBuildTime > t_finishedBuildCount.Value.Value)
+                    while (t_sentEventCount.Value.Value > t_handledEventCount.Value.Value)
                     {
                         await Task.Delay(1000);
                     }

test/docfx.Test/lsp/LanguageServerTestSpec.cs

@@ -11,7 +11,7 @@ public class LanguageServerTestSpec
 
         public string ExpectNotification { get; set; } = string.Empty;
 
-        public int? ExpectNoNotificationAfterBuildTime { get; set; }
+        public bool ExpectNoNotification { get; set; }
 
         public JToken Params { get; set; }
     }