Fix CTRL+C shutdown error with WebSocket connections

csharp/Platform.Data.Doublets.Gql.Server/GracefulShutdownService.cs

@@ -0,0 +1,41 @@
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Platform.Data.Doublets.Gql.Server
+{
+    public class GracefulShutdownService : IHostedService
+    {
+        private readonly IHostApplicationLifetime _applicationLifetime;
+        private readonly ILogger<GracefulShutdownService> _logger;
+
+        public GracefulShutdownService(IHostApplicationLifetime applicationLifetime, ILogger<GracefulShutdownService> logger)
+        {
+            _applicationLifetime = applicationLifetime;
+            _logger = logger;
+        }
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            _applicationLifetime.ApplicationStopping.Register(OnApplicationStopping);
+            return Task.CompletedTask;
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            return Task.CompletedTask;
+        }
+
+        private void OnApplicationStopping()
+        {
+            _logger.LogInformation("Application is stopping. Initiating graceful shutdown for WebSocket connections...");
+
+            // Give some time for active connections to close gracefully
+            Thread.Sleep(TimeSpan.FromSeconds(2));
+
+            _logger.LogInformation("Graceful shutdown completed.");
+        }
+    }
+}

csharp/Platform.Data.Doublets.Gql.Server/Program.cs

@@ -1,5 +1,6 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.DependencyInjection;
 using Platform.IO;
 using Serilog;
 using Serilog.Events;
@@ -35,6 +36,13 @@ public static int Main(params string[] args)
         }
 
         public static IHostBuilder CreateHostBuilder(string[] args) => Host.CreateDefaultBuilder(args)
+            .ConfigureServices((context, services) =>
+            {
+                services.Configure<HostOptions>(options =>
+                {
+                    options.ShutdownTimeout = TimeSpan.FromSeconds(30);
+                });
+            })
             .ConfigureWebHostDefaults(webBuilder =>
             {
                 webBuilder.UseSerilog().UseStartup<StartupWithRouting>();

csharp/Platform.Data.Doublets.Gql.Server/StartupWithRouting.cs

@@ -39,6 +39,7 @@ public void ConfigureServices(IServiceCollection services) => services.AddRoutin
             })
             .AddSingleton(sp => Data.CreateLinks())
             .AddSingleton<LinksSchema>()
+            .AddHostedService<GracefulShutdownService>()
             .AddGraphQL((options, provider) =>
             {
                 options.EnableMetrics = Environment.IsDevelopment();