From 2329125d7f76c8e9c0f8bc1d6c9b4477900fde58 Mon Sep 17 00:00:00 2001
From: Christopher Prosser <4368756+ProsserCJ@users.noreply.github.com>
Date: Wed, 20 Mar 2024 18:37:02 +0000
Subject: [PATCH] Don't log error from background service if host is gracefully
 stopped while still starting

Fixes #98935
---
 .../src/Internal/Host.cs                      |  4 +-
 .../tests/UnitTests/Internal/HostTests.cs     | 43 +++++++++++++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/src/libraries/Microsoft.Extensions.Hosting/src/Internal/Host.cs b/src/libraries/Microsoft.Extensions.Hosting/src/Internal/Host.cs
index 154b4225b00245..e84d2f3a646215 100644
--- a/src/libraries/Microsoft.Extensions.Hosting/src/Internal/Host.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting/src/Internal/Host.cs
@@ -29,7 +29,6 @@ internal sealed class Host : IHost, IAsyncDisposable
         private IEnumerable<IHostedService>? _hostedServices;
         private IEnumerable<IHostedLifecycleService>? _hostedLifecycleServices;
         private bool _hostStarting;
-        private volatile bool _stopCalled;
         private bool _hostStopped;
 
         public Host(IServiceProvider services,
@@ -190,7 +189,7 @@ private async Task TryExecuteBackgroundServiceAsync(BackgroundService background
             {
                 // When the host is being stopped, it cancels the background services.
                 // This isn't an error condition, so don't log it as an error.
-                if (_stopCalled && backgroundTask.IsCanceled && ex is OperationCanceledException)
+                if (_applicationLifetime.ApplicationStopping.IsCancellationRequested && backgroundTask.IsCanceled && ex is OperationCanceledException)
                 {
                     return;
                 }
@@ -217,7 +216,6 @@ private async Task TryExecuteBackgroundServiceAsync(BackgroundService background
         /// </summary>
         public async Task StopAsync(CancellationToken cancellationToken = default)
         {
-            _stopCalled = true;
             _logger.Stopping();
 
             CancellationTokenSource? cts = null;
diff --git a/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/Internal/HostTests.cs b/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/Internal/HostTests.cs
index 23cf84e91621d3..64f9dd8f904118 100644
--- a/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/Internal/HostTests.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/Internal/HostTests.cs
@@ -1487,6 +1487,39 @@ public async Task StartOnBackgroundServiceThatDoesNotCallBase()
             }
         }
 
+        /// <summary>
+        /// Tests that when a BackgroundService is cancelled when stopping a host which has not finished starting, it does not log an error
+        /// </summary>
+        [Fact]
+        public async Task HostNoErrorWhenStartingServiceIsCanceledAsPartOfStop()
+        {
+            TestLoggerProvider logger = new TestLoggerProvider();
+
+            using IHost host = CreateBuilder()
+                .ConfigureLogging(logging =>
+                {
+                    logging.AddProvider(logger);
+                })
+                .ConfigureServices(services =>
+                {
+                    services.AddHostedService<WorkerTemplateService>();
+                    services.AddHostedService<SlowStartService>();
+                })
+                .Build();
+
+            IHostApplicationLifetime lifetime = host.Services.GetRequiredService<IHostApplicationLifetime>();
+            _ = host.StartAsync();
+            lifetime.StopApplication();
+            await Task.Delay(TimeSpan.FromMilliseconds(100));
+            await host.WaitForShutdownAsync();
+
+            foreach (LogEvent logEvent in logger.GetEvents())
+            {
+                Assert.True(logEvent.LogLevel < LogLevel.Error);
+                Assert.NotEqual("BackgroundServiceFaulted", logEvent.EventId.Name);
+            }
+        }
+
         private IHostBuilder CreateBuilder(IConfiguration config = null)
         {
             return new HostBuilder().ConfigureHostConfiguration(builder => builder.AddConfiguration(config ?? new ConfigurationBuilder().Build()));
@@ -1637,5 +1670,15 @@ private class BackgroundServiceDoesNotCallBase : BackgroundService
 
             public override Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
         }
+
+        private class SlowStartService : IHostedService
+        {
+            public async Task StartAsync(CancellationToken cancellationToken)
+            {
+                await Task.Delay(TimeSpan.FromSeconds(10), CancellationToken.None);
+            }
+
+            public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+        }
     }
 }