await server.WasShutDown;

Author: Martin Lercher

sample/SampleServer/Program.cs

@@ -29,8 +29,7 @@ static async Task MainAsync(string[] args)
             server.AddHandler(new TextDocumentHandler(server));
 
             await server.Initialize();
-
-            await new TaskCompletionSource<object>().Task;
+            await server.WasShutDown;
         }
     }
 

src/Lsp/Abstractions/IAwaitableTermination.cs

@@ -0,0 +1,7 @@
+namespace Lsp
+{
+    public interface IAwaitableTermination
+    {
+        System.Threading.Tasks.Task WasShutDown { get; }
+    }
+}

src/Lsp/Handlers/ShutdownHandler.cs

@@ -1,19 +1,24 @@
+using System;
 using System.Threading.Tasks;
 using Lsp.Protocol;
 
 namespace Lsp.Handlers
 {
-    public class ShutdownHandler : IShutdownHandler
+    public class ShutdownHandler : IShutdownHandler, IAwaitableTermination
     {
         public Task Handle()
         {
             ShutdownRequested = true;
             Shutdown?.Invoke(ShutdownRequested);
+            shutdownSource.SetResult(true); // after all event sinks were notified
             return Task.CompletedTask;
         }
 
         public event ShutdownEventHandler Shutdown;
 
         public bool ShutdownRequested { get; private set; }
+
+        private TaskCompletionSource<bool> shutdownSource = new TaskCompletionSource<bool>(TaskContinuationOptions.LongRunning);
+        Task IAwaitableTermination.WasShutDown => shutdownSource.Task;
     }
 }

src/Lsp/LanguageServer.cs

@@ -16,7 +16,7 @@
 
 namespace Lsp
 {
-    public class LanguageServer : ILanguageServer, IInitializeHandler, IInitializedHandler, IDisposable
+    public class LanguageServer : ILanguageServer, IInitializeHandler, IInitializedHandler, IDisposable, IAwaitableTermination
     {
         private readonly Connection _connection;
         private readonly LspRequestRouter _requestRouter;
@@ -250,6 +250,8 @@ public TaskCompletionSource<JToken> GetRequest(long id)
             return _responseRouter.GetRequest(id);
         }
 
+        public Task WasShutDown => ((IAwaitableTermination)_shutdownHandler).WasShutDown;
+
         public void Dispose()
         {
             _connection?.Dispose();