Make IHostedServiceAsync

src/Microsoft.AspNetCore.Hosting/Internal/HostedServiceExecutor.cs

@@ -3,6 +3,8 @@
 
 using System;
 using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 
@@ -19,11 +21,11 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             _services = services;
         }
 
-        public void Start()
+        public async Task StartAsync(CancellationToken token)
         {
             try
             {
-                Execute(service => service.Start());
+                await ExecuteAsync(service => service.StartAsync(token));
             }
             catch (Exception ex)
             {
@@ -31,11 +33,11 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             }
         }
 
-        public void Stop()
+        public async Task StopAsync(CancellationToken token)
         {
             try
             {
-                Execute(service => service.Stop());
+                await ExecuteAsync(service => service.StopAsync(token));
             }
             catch (Exception ex)
             {
@@ -43,7 +45,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             }
         }
 
-        private void Execute(Action<IHostedService> callback)
+        private async Task ExecuteAsync(Func<IHostedService, Task> callback)
         {
             List<Exception> exceptions = null;
 
@@ -51,7 +53,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             {
                 try
                 {
-                    callback(service);
+                    await callback(service);
                 }
                 catch (Exception ex)
                 {

src/Microsoft.AspNetCore.Hosting/Internal/WebHost.cs

@@ -123,7 +123,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             _applicationLifetime?.NotifyStarted();
 
             // Fire IHostedService.Start
-            _hostedServiceExecutor.Start();
+            await _hostedServiceExecutor.StartAsync(cancellationToken).ConfigureAwait(false);
 
             _logger.Started();
 
@@ -296,7 +296,10 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             }
 
             // Fire the IHostedService.Stop
-            _hostedServiceExecutor?.Stop();
+            if (_hostedServiceExecutor != null)
+            {
+                await _hostedServiceExecutor.StopAsync(cancellationToken).ConfigureAwait(false);
+            }
 
             // Fire IApplicationLifetime.Stopped
             _applicationLifetime?.NotifyStopped();

src/Microsoft.Extensions.Hosting.Abstractions/IHostedService.cs

@@ -1,6 +1,9 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Threading;
+using System.Threading.Tasks;
+
 namespace Microsoft.Extensions.Hosting
 {
     /// <summary>
@@ -11,11 +14,11 @@ namespace Microsoft.Extensions.Hosting
         /// <summary>
         /// Triggered when the application host is ready to start the service.
         /// </summary>
-        void Start();
+        Task StartAsync(CancellationToken cancellationToken);
 
         /// <summary>
         /// Triggered when the application host is performing a graceful shutdown.
         /// </summary>
-        void Stop();
+        Task StopAsync(CancellationToken cancellationToken);
     }
 }

test/Microsoft.AspNetCore.Hosting.Tests/WebHostTests.cs

@@ -999,14 +999,16 @@ namespace Microsoft.AspNetCore.Hosting
             public bool StopCalled { get; set; }
             public bool DisposeCalled { get; set; }
 
-            public void Start()
+            public Task StartAsync(CancellationToken token)
             {
                 StartCalled = true;
+                return Task.CompletedTask;
             }
 
-            public void Stop()
+            public Task StopAsync(CancellationToken token)
             {
                 StopCalled = true;
+                return Task.CompletedTask;
             }
 
             public void Dispose()
@@ -1028,9 +1030,16 @@ namespace Microsoft.AspNetCore.Hosting
                 _disposing = disposing;
             }
 
-            public void Start() => _started();
-
-            public void Stop() => _stopping();
+            public Task StartAsync(CancellationToken token)
+            {
+                _started();
+                return Task.CompletedTask;
+            }
+            public Task StopAsync(CancellationToken token)
+            {
+                _stopping();
+                return Task.CompletedTask;
+            }
 
             public void Dispose() => _disposing();
         }