From d89f66f150f7a321895a02f77e4f39b1b2398ce6 Mon Sep 17 00:00:00 2001
From: Derek Gray <dgray90@live.com>
Date: Tue, 21 Mar 2017 14:31:01 -0500
Subject: [PATCH] Use a CopyOnWriteDictionary in ApplicationBuilder so branches
 can set their own properties

Fix #783
---
 .../Internal/ApplicationBuilder.cs                   |  2 +-
 .../Microsoft.AspNetCore.Http.csproj                 |  1 +
 .../Internal/ApplicationBuilderTests.cs              | 12 ++++++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.AspNetCore.Http/Internal/ApplicationBuilder.cs b/src/Microsoft.AspNetCore.Http/Internal/ApplicationBuilder.cs
index 6b36842fbb..c4e6fd7f07 100644
--- a/src/Microsoft.AspNetCore.Http/Internal/ApplicationBuilder.cs
+++ b/src/Microsoft.AspNetCore.Http/Internal/ApplicationBuilder.cs
@@ -29,7 +29,7 @@ namespace Microsoft.AspNetCore.Builder.Internal
 
         private ApplicationBuilder(ApplicationBuilder builder)
         {
-            Properties = builder.Properties;
+            Properties = new CopyOnWriteDictionary<string, object>(builder.Properties, EqualityComparer<string>.Default);
         }
 
         public IServiceProvider ApplicationServices
diff --git a/src/Microsoft.AspNetCore.Http/Microsoft.AspNetCore.Http.csproj b/src/Microsoft.AspNetCore.Http/Microsoft.AspNetCore.Http.csproj
index 04e24f5e2c..f0163c501c 100644
--- a/src/Microsoft.AspNetCore.Http/Microsoft.AspNetCore.Http.csproj
+++ b/src/Microsoft.AspNetCore.Http/Microsoft.AspNetCore.Http.csproj
@@ -18,6 +18,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.CopyOnWriteDictionary.Sources" Version="$(AspNetCoreVersion)" PrivateAssets="All" />
     <PackageReference Include="Microsoft.Extensions.ObjectPool" Version="$(AspNetCoreVersion)" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="$(AspNetCoreVersion)" />
     <PackageReference Include="Microsoft.Extensions.TaskCache.Sources" Version="$(AspNetCoreVersion)" PrivateAssets="All" />
diff --git a/test/Microsoft.AspNetCore.Http.Tests/Internal/ApplicationBuilderTests.cs b/test/Microsoft.AspNetCore.Http.Tests/Internal/ApplicationBuilderTests.cs
index 3a1a4b1606..976d9bf7e1 100644
--- a/test/Microsoft.AspNetCore.Http.Tests/Internal/ApplicationBuilderTests.cs
+++ b/test/Microsoft.AspNetCore.Http.Tests/Internal/ApplicationBuilderTests.cs
@@ -19,5 +19,17 @@ namespace Microsoft.AspNetCore.Builder.Internal
             app.Invoke(httpContext);
             Assert.Equal(httpContext.Response.StatusCode, 404);
         }
+
+        [Fact]
+        public void PropertiesDictionaryIsDistinctAfterNew()
+        {
+            var builder1 = new ApplicationBuilder(null);
+            builder1.Properties["test"] = "value1";
+
+            var builder2 = builder1.New();
+            builder2.Properties["test"] = "value2";
+
+            Assert.Equal(builder1.Properties["test"], "value1");
+        }
     }
 }
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