From e62787c5f850e26211d55822430416c8d564f626 Mon Sep 17 00:00:00 2001
From: Tudor Stanciu <tudor.stanciu94@gmail.com>
Date: Thu, 10 Oct 2019 01:48:48 +0300
Subject: [PATCH] ServiceBaseLifetimeHost

---
 NDB.Hosting.WindowsService/Class1.cs          |  8 ---
 .../ServiceBaseLifetime.cs                    | 63 +++++++++++++++++++
 .../ServiceBaseLifetimeHostExtensions.cs      | 20 ++++++
 3 files changed, 83 insertions(+), 8 deletions(-)
 delete mode 100644 NDB.Hosting.WindowsService/Class1.cs
 create mode 100644 NDB.Hosting.WindowsService/ServiceBaseLifetime.cs
 create mode 100644 NDB.Hosting.WindowsService/ServiceBaseLifetimeHostExtensions.cs

diff --git a/NDB.Hosting.WindowsService/Class1.cs b/NDB.Hosting.WindowsService/Class1.cs
deleted file mode 100644
index cf38fd2..0000000
--- a/NDB.Hosting.WindowsService/Class1.cs
+++ /dev/null
@@ -1,8 +0,0 @@
-using System;
-
-namespace NDB.Hosting.WindowsService
-{
-    public class Class1
-    {
-    }
-}
diff --git a/NDB.Hosting.WindowsService/ServiceBaseLifetime.cs b/NDB.Hosting.WindowsService/ServiceBaseLifetime.cs
new file mode 100644
index 0000000..c483e97
--- /dev/null
+++ b/NDB.Hosting.WindowsService/ServiceBaseLifetime.cs
@@ -0,0 +1,63 @@
+using Microsoft.Extensions.Hosting;
+using System;
+using System.ServiceProcess;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace NDB.Hosting.WindowsService
+{
+    public class ServiceBaseLifetime : ServiceBase, IHostLifetime
+    {
+        private readonly TaskCompletionSource<object> _delayStart = new TaskCompletionSource<object>();
+
+        public ServiceBaseLifetime(IApplicationLifetime applicationLifetime)
+        {
+            ApplicationLifetime = applicationLifetime ?? throw new ArgumentNullException(nameof(applicationLifetime));
+        }
+
+        private IApplicationLifetime ApplicationLifetime { get; }
+
+        public Task WaitForStartAsync(CancellationToken cancellationToken)
+        {
+            cancellationToken.Register(() => _delayStart.TrySetCanceled());
+            ApplicationLifetime.ApplicationStopping.Register(Stop);
+
+            new Thread(Run).Start(); // Otherwise this would block and prevent IHost.StartAsync from finishing.
+            return _delayStart.Task;
+        }
+
+        private void Run()
+        {
+            try
+            {
+                Run(this); // This blocks until the service is stopped.
+                _delayStart.TrySetException(new InvalidOperationException("Stopped without starting"));
+            }
+            catch (Exception ex)
+            {
+                _delayStart.TrySetException(ex);
+            }
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            Stop();
+            return Task.CompletedTask;
+        }
+
+        // Called by base.Run when the service is ready to start.
+        protected override void OnStart(string[] args)
+        {
+            _delayStart.TrySetResult(null);
+            base.OnStart(args);
+        }
+
+        // Called by base.Stop. This may be called multiple times by service Stop, ApplicationStopping, and StopAsync.
+        // That's OK because StopApplication uses a CancellationTokenSource and prevents any recursion.
+        protected override void OnStop()
+        {
+            ApplicationLifetime.StopApplication();
+            base.OnStop();
+        }
+    }
+}
diff --git a/NDB.Hosting.WindowsService/ServiceBaseLifetimeHostExtensions.cs b/NDB.Hosting.WindowsService/ServiceBaseLifetimeHostExtensions.cs
new file mode 100644
index 0000000..cc46608
--- /dev/null
+++ b/NDB.Hosting.WindowsService/ServiceBaseLifetimeHostExtensions.cs
@@ -0,0 +1,20 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace NDB.Hosting.WindowsService
+{
+    public static class ServiceBaseLifetimeHostExtensions
+    {
+        public static IHostBuilder UseServiceBaseLifetime(this IHostBuilder hostBuilder)
+        {
+            return hostBuilder.ConfigureServices((hostContext, services) => services.AddSingleton<IHostLifetime, ServiceBaseLifetime>());
+        }
+
+        public static Task RunAsServiceAsync(this IHostBuilder hostBuilder, CancellationToken cancellationToken = default)
+        {
+            return hostBuilder.UseServiceBaseLifetime().Build().RunAsync(cancellationToken);
+        }
+    }
+}