Use AsyncBatchingWorkQueue instead of TaskQueue

src/Features/LanguageServer/Protocol/Features/Diagnostics/DiagnosticService.cs

@@ -9,6 +9,7 @@
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Collections;
 using Microsoft.CodeAnalysis.Common;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Host.Mef;
@@ -19,12 +20,13 @@
 namespace Microsoft.CodeAnalysis.Diagnostics
 {
     [Export(typeof(IDiagnosticService)), Shared]
-    internal partial class DiagnosticService : IDiagnosticService
+    internal partial class DiagnosticService : IDiagnosticService, IDisposable
     {
         private const string DiagnosticsUpdatedEventName = "DiagnosticsUpdated";
 
         private readonly EventMap _eventMap = new();
-        private readonly TaskQueue _eventQueue;
+        private readonly CancellationTokenSource _eventQueueCancellation = new();
+        private readonly AsyncBatchingWorkQueue<(BatchOperation operation, IDiagnosticUpdateSource source, ImmutableArray<DiagnosticsUpdatedArgs> argsCollection)> _eventQueue;
 
         private readonly object _gate = new();
         private readonly Dictionary<IDiagnosticUpdateSource, Dictionary<Workspace, Dictionary<object, Data>>> _map = [];
@@ -43,7 +45,17 @@ public DiagnosticService(
             _updateSources = [];
 
             // queue to serialize events.
-            _eventQueue = new TaskQueue(listenerProvider.GetListener(FeatureAttribute.DiagnosticService), TaskScheduler.Default);
+            _eventQueue = new AsyncBatchingWorkQueue<(BatchOperation operation, IDiagnosticUpdateSource source, ImmutableArray<DiagnosticsUpdatedArgs> argsCollection)>(
+                delay: TimeSpan.Zero,
+                ProcessEventsBatchAsync,
+                listenerProvider.GetListener(FeatureAttribute.DiagnosticService),
+                _eventQueueCancellation.Token);
+        }
+
+        private enum BatchOperation
+        {
+            DiagnosticsUpdated,
+            DiagnosticsCleared,
         }
 
         public event EventHandler<ImmutableArray<DiagnosticsUpdatedArgs>> DiagnosticsUpdated
@@ -59,41 +71,59 @@ public event EventHandler<ImmutableArray<DiagnosticsUpdatedArgs>> DiagnosticsUpd
             }
         }
 
-        private void RaiseDiagnosticsUpdated(IDiagnosticUpdateSource source, ImmutableArray<DiagnosticsUpdatedArgs> argsCollection)
+        void IDisposable.Dispose()
         {
-            var ev = _eventMap.GetEventHandlers<EventHandler<ImmutableArray<DiagnosticsUpdatedArgs>>>(DiagnosticsUpdatedEventName);
-
-            _eventQueue.ScheduleTask(DiagnosticsUpdatedEventName, () =>
-            {
-                var updatedArgsCollection = UpdateDataMap(source, argsCollection);
-                if (updatedArgsCollection.IsEmpty)
-                {
-                    // there is no change, nothing to raise events for.
-                    return;
-                }
-
-                ev.RaiseEvent(static (handler, arg) => handler(arg.source, arg.updatedArgsCollection), (source, updatedArgsCollection));
-            }, CancellationToken.None);
+            _eventQueueCancellation.Cancel();
         }
 
-        private void RaiseDiagnosticsCleared(IDiagnosticUpdateSource source)
+        private ValueTask ProcessEventsBatchAsync(ImmutableSegmentedList<(BatchOperation operation, IDiagnosticUpdateSource source, ImmutableArray<DiagnosticsUpdatedArgs> argsCollection)> batch, CancellationToken cancellationToken)
         {
             var ev = _eventMap.GetEventHandlers<EventHandler<ImmutableArray<DiagnosticsUpdatedArgs>>>(DiagnosticsUpdatedEventName);
 
-            _eventQueue.ScheduleTask(DiagnosticsUpdatedEventName, () =>
+            foreach (var (operation, source, argsCollection) in batch)
             {
-                using var argsBuilder = TemporaryArray<DiagnosticsUpdatedArgs>.Empty;
+                if (operation == BatchOperation.DiagnosticsUpdated)
+                {
+                    var updatedArgsCollection = UpdateDataMap(source, argsCollection);
+                    if (updatedArgsCollection.IsEmpty)
+                    {
+                        // there is no change, nothing to raise events for.
+                        continue;
+                    }
+
+                    ev.RaiseEvent(static (handler, arg) => handler(arg.source, arg.updatedArgsCollection), (source, updatedArgsCollection));
+                }
+                else if (operation == BatchOperation.DiagnosticsCleared)
+                {
+                    using var argsBuilder = TemporaryArray<DiagnosticsUpdatedArgs>.Empty;
+
+                    if (!ClearDiagnosticsReportedBySource(source, ref argsBuilder.AsRef()))
+                    {
+                        // there is no change, nothing to raise events for.
+                        continue;
+                    }
 
-                if (!ClearDiagnosticsReportedBySource(source, ref argsBuilder.AsRef()))
+                    // don't create event listener if it haven't created yet. if there is a diagnostic to remove
+                    // listener should have already created since all events are done in the serialized queue
+                    ev.RaiseEvent(static (handler, arg) => handler(arg.source, arg.args), (source, args: argsBuilder.ToImmutableAndClear()));
+                }
+                else
                 {
-                    // there is no change, nothing to raise events for.
-                    return;
+                    throw ExceptionUtilities.UnexpectedValue(operation);
                 }
+            }
 
-                // don't create event listener if it haven't created yet. if there is a diagnostic to remove
-                // listener should have already created since all events are done in the serialized queue
-                ev.RaiseEvent(static (handler, arg) => handler(arg.source, arg.args), (source, args: argsBuilder.ToImmutableAndClear()));
-            }, CancellationToken.None);
+            return ValueTaskFactory.CompletedTask;
+        }
+
+        private void RaiseDiagnosticsUpdated(IDiagnosticUpdateSource source, ImmutableArray<DiagnosticsUpdatedArgs> argsCollection)
+        {
+            _eventQueue.AddWork((BatchOperation.DiagnosticsUpdated, source, argsCollection));
+        }
+
+        private void RaiseDiagnosticsCleared(IDiagnosticUpdateSource source)
+        {
+            _eventQueue.AddWork((BatchOperation.DiagnosticsCleared, source, ImmutableArray<DiagnosticsUpdatedArgs>.Empty));
         }
 
         private ImmutableArray<DiagnosticsUpdatedArgs> UpdateDataMap(IDiagnosticUpdateSource source, ImmutableArray<DiagnosticsUpdatedArgs> argsCollection)