From 1354d66fb6dbaa732e18c66daf40a6fda20b7b90 Mon Sep 17 00:00:00 2001
From: Hao Kung <haok@microsoft.com>
Date: Mon, 11 May 2015 15:08:40 -0700
Subject: [PATCH] Ensure ConfigureServices is only called once

---
 .../Internal/HostingEngine.cs                 | 11 ++++---
 .../HostingEngineTests.cs                     | 32 +++++++++++++++++++
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/Microsoft.AspNet.Hosting/Internal/HostingEngine.cs b/src/Microsoft.AspNet.Hosting/Internal/HostingEngine.cs
index 48a0069b92..924d336e1d 100644
--- a/src/Microsoft.AspNet.Hosting/Internal/HostingEngine.cs
+++ b/src/Microsoft.AspNet.Hosting/Internal/HostingEngine.cs
@@ -91,11 +91,12 @@ namespace Microsoft.AspNet.Hosting.Internal
 
         private void EnsureApplicationServices()
         {
-            EnsureStartup();
-
-            _applicationServiceCollection.AddInstance<IApplicationLifetime>(_applicationLifetime);
-
-            _applicationServices = Startup.ConfigureServicesDelegate(_applicationServiceCollection);
+            if (_applicationServices == null)
+            {
+                EnsureStartup();
+                _applicationServiceCollection.AddInstance<IApplicationLifetime>(_applicationLifetime);
+                _applicationServices = Startup.ConfigureServicesDelegate(_applicationServiceCollection);
+            }
         }
 
         private void EnsureStartup()
diff --git a/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs b/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs
index 6c613adcf7..6ad8ab0b87 100644
--- a/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs
+++ b/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs
@@ -291,6 +291,38 @@ namespace Microsoft.AspNet.Hosting
             Assert.Same(requestIdentifierFeature, httpContext.GetFeature<IRequestIdentifierFeature>());
         }
 
+        [Fact]
+        public void HostingEngine_InvokesConfigureMethodsOnlyOnce()
+        {
+            var engine = CreateBuilder()
+                .UseServer(this)
+                .UseStartup<CountStartup>()
+                .Build();
+            using (engine.Start())
+            {
+                var services = engine.ApplicationServices;
+                var services2 = engine.ApplicationServices;
+                Assert.Equal(1, CountStartup.ConfigureCount);
+                Assert.Equal(1, CountStartup.ConfigureServicesCount);
+            }
+        }
+
+        public class CountStartup
+        {
+            public static int ConfigureServicesCount;
+            public static int ConfigureCount;
+
+            public void ConfigureServices(IServiceCollection services)
+            {
+                ConfigureServicesCount++;
+            }
+
+            public void Configure(IApplicationBuilder app)
+            {
+                ConfigureCount++;
+            }
+        }
+
         private IHostingEngine CreateHostingEngine(RequestDelegate requestDelegate)
         {
             var applicationBuilder = new Mock<IApplicationBuilder>();