Generate repetitive TransportConnection FeatureCollection code (#2548)

src/Kestrel.Core/Internal/Http/HttpProtocol.FeatureCollection.cs

@@ -2,8 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections;
-using System.Collections.Generic;
 using System.IO;
 using System.Net;
 using System.Threading;
@@ -16,8 +14,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    public partial class HttpProtocol : IFeatureCollection,
+    public partial class HttpProtocol : IHttpRequestFeature,
-                                        IHttpRequestFeature,
                                         IHttpResponseFeature,
                                         IHttpConnectionFeature,
                                         IHttpRequestLifetimeFeature,
@@ -29,53 +26,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
     {
         // NOTE: When feature interfaces are added to or removed from this HttpProtocol class implementation,
         // then the list of `implementedFeatures` in the generated code project MUST also be updated.
-        // See also: tools/Microsoft.AspNetCore.Server.Kestrel.GeneratedCode/HttpProtocolFeatureCollection.cs
+        // See also: tools/CodeGenerator/HttpProtocolFeatureCollection.cs
-
-        private int _featureRevision;
-
-        private List<KeyValuePair<Type, object>> MaybeExtra;
-
-        public void ResetFeatureCollection()
-        {
-            FastReset();
-            MaybeExtra?.Clear();
-            _featureRevision++;
-        }
-
-        private object ExtraFeatureGet(Type key)
-        {
-            if (MaybeExtra == null)
-            {
-                return null;
-            }
-            for (var i = 0; i < MaybeExtra.Count; i++)
-            {
-                var kv = MaybeExtra[i];
-                if (kv.Key == key)
-                {
-                    return kv.Value;
-                }
-            }
-            return null;
-        }
-
-        private void ExtraFeatureSet(Type key, object value)
-        {
-            if (MaybeExtra == null)
-            {
-                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
-            }
-
-            for (var i = 0; i < MaybeExtra.Count; i++)
-            {
-                if (MaybeExtra[i].Key == key)
-                {
-                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
-                    return;
-                }
-            }
-            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
-        }
 
         string IHttpRequestFeature.Protocol
         {
@@ -175,9 +126,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
         bool IHttpResponseFeature.HasStarted => HasResponseStarted;
 
-        bool IFeatureCollection.IsReadOnly => false;
-
-        int IFeatureCollection.Revision => _featureRevision;
 
         IPAddress IHttpConnectionFeature.RemoteIpAddress
         {
@@ -277,10 +225,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             OnCompleted(callback, state);
         }
 
-        IEnumerator<KeyValuePair<Type, object>> IEnumerable<KeyValuePair<Type, object>>.GetEnumerator() => FastEnumerable().GetEnumerator();
-
-        IEnumerator IEnumerable.GetEnumerator() => FastEnumerable().GetEnumerator();
-
         void IHttpRequestLifetimeFeature.Abort()
         {
             Abort(new ConnectionAbortedException());

src/Kestrel.Core/Internal/Http/HttpProtocol.Generated.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 
 using Microsoft.AspNetCore.Http.Features;
@@ -10,7 +11,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Core.Features;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
-    public partial class HttpProtocol
+    public partial class HttpProtocol : IFeatureCollection
     {
         private static readonly Type IHttpRequestFeatureType = typeof(IHttpRequestFeature);
         private static readonly Type IHttpResponseFeatureType = typeof(IHttpResponseFeature);
@@ -56,6 +57,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
         private object _currentIHttpBodyControlFeature;
         private object _currentIHttpSendFileFeature;
 
+        private int _featureRevision;
+
+        private List<KeyValuePair<Type, object>> MaybeExtra;
+
         private void FastReset()
         {
             _currentIHttpRequestFeature = this;
@@ -67,7 +72,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _currentIHttpMinRequestBodyDataRateFeature = this;
             _currentIHttpMinResponseDataRateFeature = this;
             _currentIHttpBodyControlFeature = this;
-            
+
             _currentIServiceProvidersFeature = null;
             _currentIHttpAuthenticationFeature = null;
             _currentIQueryFeature = null;
@@ -82,6 +87,53 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             _currentIHttpSendFileFeature = null;
         }
 
+        // Internal for testing
+        internal void ResetFeatureCollection()
+        {
+            FastReset();
+            MaybeExtra?.Clear();
+            _featureRevision++;
+        }
+
+        private object ExtraFeatureGet(Type key)
+        {
+            if (MaybeExtra == null)
+            {
+                return null;
+            }
+            for (var i = 0; i < MaybeExtra.Count; i++)
+            {
+                var kv = MaybeExtra[i];
+                if (kv.Key == key)
+                {
+                    return kv.Value;
+                }
+            }
+            return null;
+        }
+
+        private void ExtraFeatureSet(Type key, object value)
+        {
+            if (MaybeExtra == null)
+            {
+                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+            }
+
+            for (var i = 0; i < MaybeExtra.Count; i++)
+            {
+                if (MaybeExtra[i].Key == key)
+                {
+                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
+                    return;
+                }
+            }
+            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
+        }
+
+        bool IFeatureCollection.IsReadOnly => false;
+
+        int IFeatureCollection.Revision => _featureRevision;
+
         object IFeatureCollection.this[Type key]
         {
             get
@@ -182,7 +234,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             set
             {
                 _featureRevision++;
-                
+
                 if (key == IHttpRequestFeatureType)
                 {
                     _currentIHttpRequestFeature = value;
@@ -274,99 +326,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             }
         }
 
-        void IFeatureCollection.Set<TFeature>(TFeature feature) 
-        {
-            _featureRevision++;
-            if (typeof(TFeature) == typeof(IHttpRequestFeature))
-            {
-                _currentIHttpRequestFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpResponseFeature))
-            {
-                _currentIHttpResponseFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpRequestIdentifierFeature))
-            {
-                _currentIHttpRequestIdentifierFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IServiceProvidersFeature))
-            {
-                _currentIServiceProvidersFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpRequestLifetimeFeature))
-            {
-                _currentIHttpRequestLifetimeFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpConnectionFeature))
-            {
-                _currentIHttpConnectionFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpAuthenticationFeature))
-            {
-                _currentIHttpAuthenticationFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IQueryFeature))
-            {
-                _currentIQueryFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IFormFeature))
-            {
-                _currentIFormFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpUpgradeFeature))
-            {
-                _currentIHttpUpgradeFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttp2StreamIdFeature))
-            {
-                _currentIHttp2StreamIdFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IResponseCookiesFeature))
-            {
-                _currentIResponseCookiesFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IItemsFeature))
-            {
-                _currentIItemsFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(ITlsConnectionFeature))
-            {
-                _currentITlsConnectionFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpWebSocketFeature))
-            {
-                _currentIHttpWebSocketFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(ISessionFeature))
-            {
-                _currentISessionFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpMaxRequestBodySizeFeature))
-            {
-                _currentIHttpMaxRequestBodySizeFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpMinRequestBodyDataRateFeature))
-            {
-                _currentIHttpMinRequestBodyDataRateFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpMinResponseDataRateFeature))
-            {
-                _currentIHttpMinResponseDataRateFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpBodyControlFeature))
-            {
-                _currentIHttpBodyControlFeature = feature;
-            }
-            else if (typeof(TFeature) == typeof(IHttpSendFileFeature))
-            {
-                _currentIHttpSendFileFeature = feature;
-            }
-            else
-            {
-                ExtraFeatureSet(typeof(TFeature), feature);
-            }
-        }
-
         TFeature IFeatureCollection.Get<TFeature>()
         {
             TFeature feature = default;
@@ -458,7 +417,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             {
                 feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
             }
-            
+
             if (feature == null)
             {
                 feature = ConnectionFeatures.Get<TFeature>();
@@ -467,100 +426,197 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             return feature;
         }
 
+        void IFeatureCollection.Set<TFeature>(TFeature feature)
+        {
+            _featureRevision++;
+            if (typeof(TFeature) == typeof(IHttpRequestFeature))
+            {
+                _currentIHttpRequestFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpResponseFeature))
+            {
+                _currentIHttpResponseFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpRequestIdentifierFeature))
+            {
+                _currentIHttpRequestIdentifierFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IServiceProvidersFeature))
+            {
+                _currentIServiceProvidersFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpRequestLifetimeFeature))
+            {
+                _currentIHttpRequestLifetimeFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpConnectionFeature))
+            {
+                _currentIHttpConnectionFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpAuthenticationFeature))
+            {
+                _currentIHttpAuthenticationFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IQueryFeature))
+            {
+                _currentIQueryFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IFormFeature))
+            {
+                _currentIFormFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpUpgradeFeature))
+            {
+                _currentIHttpUpgradeFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttp2StreamIdFeature))
+            {
+                _currentIHttp2StreamIdFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IResponseCookiesFeature))
+            {
+                _currentIResponseCookiesFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IItemsFeature))
+            {
+                _currentIItemsFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(ITlsConnectionFeature))
+            {
+                _currentITlsConnectionFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpWebSocketFeature))
+            {
+                _currentIHttpWebSocketFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(ISessionFeature))
+            {
+                _currentISessionFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpMaxRequestBodySizeFeature))
+            {
+                _currentIHttpMaxRequestBodySizeFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpMinRequestBodyDataRateFeature))
+            {
+                _currentIHttpMinRequestBodyDataRateFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpMinResponseDataRateFeature))
+            {
+                _currentIHttpMinResponseDataRateFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpBodyControlFeature))
+            {
+                _currentIHttpBodyControlFeature = feature;
+            }
+            else if (typeof(TFeature) == typeof(IHttpSendFileFeature))
+            {
+                _currentIHttpSendFileFeature = feature;
+            }
+            else
+            {
+                ExtraFeatureSet(typeof(TFeature), feature);
+            }
+        }
+
         private IEnumerable<KeyValuePair<Type, object>> FastEnumerable()
         {
             if (_currentIHttpRequestFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpRequestFeatureType, _currentIHttpRequestFeature as IHttpRequestFeature);
+                yield return new KeyValuePair<Type, object>(IHttpRequestFeatureType, _currentIHttpRequestFeature);
             }
             if (_currentIHttpResponseFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpResponseFeatureType, _currentIHttpResponseFeature as IHttpResponseFeature);
+                yield return new KeyValuePair<Type, object>(IHttpResponseFeatureType, _currentIHttpResponseFeature);
             }
             if (_currentIHttpRequestIdentifierFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpRequestIdentifierFeatureType, _currentIHttpRequestIdentifierFeature as IHttpRequestIdentifierFeature);
+                yield return new KeyValuePair<Type, object>(IHttpRequestIdentifierFeatureType, _currentIHttpRequestIdentifierFeature);
             }
             if (_currentIServiceProvidersFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IServiceProvidersFeatureType, _currentIServiceProvidersFeature as IServiceProvidersFeature);
+                yield return new KeyValuePair<Type, object>(IServiceProvidersFeatureType, _currentIServiceProvidersFeature);
             }
             if (_currentIHttpRequestLifetimeFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpRequestLifetimeFeatureType, _currentIHttpRequestLifetimeFeature as IHttpRequestLifetimeFeature);
+                yield return new KeyValuePair<Type, object>(IHttpRequestLifetimeFeatureType, _currentIHttpRequestLifetimeFeature);
             }
             if (_currentIHttpConnectionFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpConnectionFeatureType, _currentIHttpConnectionFeature as IHttpConnectionFeature);
+                yield return new KeyValuePair<Type, object>(IHttpConnectionFeatureType, _currentIHttpConnectionFeature);
             }
             if (_currentIHttpAuthenticationFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpAuthenticationFeatureType, _currentIHttpAuthenticationFeature as IHttpAuthenticationFeature);
+                yield return new KeyValuePair<Type, object>(IHttpAuthenticationFeatureType, _currentIHttpAuthenticationFeature);
             }
             if (_currentIQueryFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IQueryFeatureType, _currentIQueryFeature as IQueryFeature);
+                yield return new KeyValuePair<Type, object>(IQueryFeatureType, _currentIQueryFeature);
             }
             if (_currentIFormFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IFormFeatureType, _currentIFormFeature as IFormFeature);
+                yield return new KeyValuePair<Type, object>(IFormFeatureType, _currentIFormFeature);
             }
             if (_currentIHttpUpgradeFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpUpgradeFeatureType, _currentIHttpUpgradeFeature as IHttpUpgradeFeature);
+                yield return new KeyValuePair<Type, object>(IHttpUpgradeFeatureType, _currentIHttpUpgradeFeature);
             }
             if (_currentIHttp2StreamIdFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttp2StreamIdFeatureType, _currentIHttp2StreamIdFeature as IHttp2StreamIdFeature);
+                yield return new KeyValuePair<Type, object>(IHttp2StreamIdFeatureType, _currentIHttp2StreamIdFeature);
             }
             if (_currentIResponseCookiesFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IResponseCookiesFeatureType, _currentIResponseCookiesFeature as IResponseCookiesFeature);
+                yield return new KeyValuePair<Type, object>(IResponseCookiesFeatureType, _currentIResponseCookiesFeature);
             }
             if (_currentIItemsFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IItemsFeatureType, _currentIItemsFeature as IItemsFeature);
+                yield return new KeyValuePair<Type, object>(IItemsFeatureType, _currentIItemsFeature);
             }
             if (_currentITlsConnectionFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(ITlsConnectionFeatureType, _currentITlsConnectionFeature as ITlsConnectionFeature);
+                yield return new KeyValuePair<Type, object>(ITlsConnectionFeatureType, _currentITlsConnectionFeature);
             }
             if (_currentIHttpWebSocketFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpWebSocketFeatureType, _currentIHttpWebSocketFeature as IHttpWebSocketFeature);
+                yield return new KeyValuePair<Type, object>(IHttpWebSocketFeatureType, _currentIHttpWebSocketFeature);
             }
             if (_currentISessionFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(ISessionFeatureType, _currentISessionFeature as ISessionFeature);
+                yield return new KeyValuePair<Type, object>(ISessionFeatureType, _currentISessionFeature);
             }
             if (_currentIHttpMaxRequestBodySizeFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpMaxRequestBodySizeFeatureType, _currentIHttpMaxRequestBodySizeFeature as IHttpMaxRequestBodySizeFeature);
+                yield return new KeyValuePair<Type, object>(IHttpMaxRequestBodySizeFeatureType, _currentIHttpMaxRequestBodySizeFeature);
             }
             if (_currentIHttpMinRequestBodyDataRateFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpMinRequestBodyDataRateFeatureType, _currentIHttpMinRequestBodyDataRateFeature as IHttpMinRequestBodyDataRateFeature);
+                yield return new KeyValuePair<Type, object>(IHttpMinRequestBodyDataRateFeatureType, _currentIHttpMinRequestBodyDataRateFeature);
             }
             if (_currentIHttpMinResponseDataRateFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpMinResponseDataRateFeatureType, _currentIHttpMinResponseDataRateFeature as IHttpMinResponseDataRateFeature);
+                yield return new KeyValuePair<Type, object>(IHttpMinResponseDataRateFeatureType, _currentIHttpMinResponseDataRateFeature);
             }
             if (_currentIHttpBodyControlFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpBodyControlFeatureType, _currentIHttpBodyControlFeature as IHttpBodyControlFeature);
+                yield return new KeyValuePair<Type, object>(IHttpBodyControlFeatureType, _currentIHttpBodyControlFeature);
             }
             if (_currentIHttpSendFileFeature != null)
             {
-                yield return new KeyValuePair<Type, object>(IHttpSendFileFeatureType, _currentIHttpSendFileFeature as IHttpSendFileFeature);
+                yield return new KeyValuePair<Type, object>(IHttpSendFileFeatureType, _currentIHttpSendFileFeature);
             }
 
             if (MaybeExtra != null)
             {
-                foreach(var item in MaybeExtra)
+                foreach (var item in MaybeExtra)
                 {
                     yield return item;
                 }
             }
         }
+
+        IEnumerator<KeyValuePair<Type, object>> IEnumerable<KeyValuePair<Type, object>>.GetEnumerator() => FastEnumerable().GetEnumerator();
+
+        IEnumerator IEnumerable.GetEnumerator() => FastEnumerable().GetEnumerator();
     }
 }

src/Kestrel.Transport.Abstractions/Internal/TransportConnection.FeatureCollection.cs

@@ -0,0 +1,91 @@
+// 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.Buffers;
+using System.Collections.Generic;
+using System.IO.Pipelines;
+using System.Net;
+using System.Threading;
+using Microsoft.AspNetCore.Connections.Features;
+using Microsoft.AspNetCore.Http.Features;
+
+namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal
+{
+    public partial class TransportConnection : IHttpConnectionFeature,
+                                               IConnectionIdFeature,
+                                               IConnectionTransportFeature,
+                                               IConnectionItemsFeature,
+                                               IMemoryPoolFeature,
+                                               IApplicationTransportFeature,
+                                               ITransportSchedulerFeature,
+                                               IConnectionLifetimeFeature,
+                                               IBytesWrittenFeature
+    {
+        // NOTE: When feature interfaces are added to or removed from this TransportConnection class implementation,
+        // then the list of `features` in the generated code project MUST also be updated.
+        // See also: tools/CodeGenerator/TransportConnectionFeatureCollection.cs
+
+        string IHttpConnectionFeature.ConnectionId
+        {
+            get => ConnectionId;
+            set => ConnectionId = value;
+        }
+
+        IPAddress IHttpConnectionFeature.RemoteIpAddress
+        {
+            get => RemoteAddress;
+            set => RemoteAddress = value;
+        }
+
+        IPAddress IHttpConnectionFeature.LocalIpAddress
+        {
+            get => LocalAddress;
+            set => LocalAddress = value;
+        }
+
+        int IHttpConnectionFeature.RemotePort
+        {
+            get => RemotePort;
+            set => RemotePort = value;
+        }
+
+        int IHttpConnectionFeature.LocalPort
+        {
+            get => LocalPort;
+            set => LocalPort = value;
+        }
+
+        MemoryPool<byte> IMemoryPoolFeature.MemoryPool => MemoryPool;
+
+        IDuplexPipe IConnectionTransportFeature.Transport
+        {
+            get => Transport;
+            set => Transport = value;
+        }
+
+        IDuplexPipe IApplicationTransportFeature.Application
+        {
+            get => Application;
+            set => Application = value;
+        }
+
+        IDictionary<object, object> IConnectionItemsFeature.Items
+        {
+            get => Items;
+            set => Items = value;
+        }
+
+        PipeScheduler ITransportSchedulerFeature.InputWriterScheduler => InputWriterScheduler;
+        PipeScheduler ITransportSchedulerFeature.OutputReaderScheduler => OutputReaderScheduler;
+
+        CancellationToken IConnectionLifetimeFeature.ConnectionClosed
+        {
+            get => ConnectionClosed;
+            set => ConnectionClosed = value;
+        }
+
+        void IConnectionLifetimeFeature.Abort() => Abort();
+
+        long IBytesWrittenFeature.TotalBytesWritten => TotalBytesWritten;
+    }
+}

src/Kestrel.Transport.Abstractions/Internal/TransportConnection.Generated.cs

@@ -1,25 +1,16 @@
-using System;
+// Copyright (c) .NET Foundation. All rights reserved.
-using System.Buffers;
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.IO.Pipelines;
+
-using System.Net;
-using System.Threading;
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.Http.Features;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal
 {
-    public partial class TransportConnection : IFeatureCollection,
+    public partial class TransportConnection : IFeatureCollection
-                                               IHttpConnectionFeature,
-                                               IConnectionIdFeature,
-                                               IConnectionTransportFeature,
-                                               IConnectionItemsFeature,
-                                               IMemoryPoolFeature,
-                                               IApplicationTransportFeature,
-                                               ITransportSchedulerFeature,
-                                               IConnectionLifetimeFeature,
-                                               IBytesWrittenFeature
     {
         private static readonly Type IHttpConnectionFeatureType = typeof(IHttpConnectionFeature);
         private static readonly Type IConnectionIdFeatureType = typeof(IConnectionIdFeature);
@@ -45,6 +36,28 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal
 
         private List<KeyValuePair<Type, object>> MaybeExtra;
 
+        private void FastReset()
+        {
+            _currentIHttpConnectionFeature = this;
+            _currentIConnectionIdFeature = this;
+            _currentIConnectionTransportFeature = this;
+            _currentIConnectionItemsFeature = this;
+            _currentIMemoryPoolFeature = this;
+            _currentIApplicationTransportFeature = this;
+            _currentITransportSchedulerFeature = this;
+            _currentIConnectionLifetimeFeature = this;
+            _currentIBytesWrittenFeature = this;
+
+        }
+
+        // Internal for testing
+        internal void ResetFeatureCollection()
+        {
+            FastReset();
+            MaybeExtra?.Clear();
+            _featureRevision++;
+        }
+
         private object ExtraFeatureGet(Type key)
         {
             if (MaybeExtra == null)
@@ -84,125 +97,55 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal
 
         int IFeatureCollection.Revision => _featureRevision;
 
-        string IHttpConnectionFeature.ConnectionId
-        {
-            get => ConnectionId;
-            set => ConnectionId = value;
-        }
-
-        IPAddress IHttpConnectionFeature.RemoteIpAddress
-        {
-            get => RemoteAddress;
-            set => RemoteAddress = value;
-        }
-
-        IPAddress IHttpConnectionFeature.LocalIpAddress
-        {
-            get => LocalAddress;
-            set => LocalAddress = value;
-        }
-
-        int IHttpConnectionFeature.RemotePort
-        {
-            get => RemotePort;
-            set => RemotePort = value;
-        }
-
-        int IHttpConnectionFeature.LocalPort
-        {
-            get => LocalPort;
-            set => LocalPort = value;
-        }
-
-        MemoryPool<byte> IMemoryPoolFeature.MemoryPool => MemoryPool;
-
-        IDuplexPipe IConnectionTransportFeature.Transport
-        {
-            get => Transport;
-            set => Transport = value;
-        }
-
-        IDuplexPipe IApplicationTransportFeature.Application
-        {
-            get => Application;
-            set => Application = value;
-        }
-
-        IDictionary<object, object> IConnectionItemsFeature.Items
-        {
-            get => Items;
-            set => Items = value;
-        }
-
-        CancellationToken IConnectionLifetimeFeature.ConnectionClosed
-        {
-            get => ConnectionClosed;
-            set => ConnectionClosed = value;
-        }
-
-        void IConnectionLifetimeFeature.Abort() => Abort();
-
-        long IBytesWrittenFeature.TotalBytesWritten => TotalBytesWritten;
-
-        PipeScheduler ITransportSchedulerFeature.InputWriterScheduler => InputWriterScheduler;
-        PipeScheduler ITransportSchedulerFeature.OutputReaderScheduler => OutputReaderScheduler;
-
         object IFeatureCollection.this[Type key]
         {
             get
             {
+                object feature = null;
                 if (key == IHttpConnectionFeatureType)
                 {
-                    return _currentIHttpConnectionFeature;
+                    feature = _currentIHttpConnectionFeature;
                 }
-
+                else if (key == IConnectionIdFeatureType)
-                if (key == IConnectionIdFeatureType)
                 {
-                    return _currentIConnectionIdFeature;
+                    feature = _currentIConnectionIdFeature;
                 }
-
+                else if (key == IConnectionTransportFeatureType)
-                if (key == IConnectionTransportFeatureType)
                 {
-                    return _currentIConnectionTransportFeature;
+                    feature = _currentIConnectionTransportFeature;
                 }
-
+                else if (key == IConnectionItemsFeatureType)
-                if (key == IConnectionItemsFeatureType)
                 {
-                    return _currentIConnectionItemsFeature;
+                    feature = _currentIConnectionItemsFeature;
                 }
-
+                else if (key == IMemoryPoolFeatureType)
-                if (key == IMemoryPoolFeatureType)
                 {
-                    return _currentIMemoryPoolFeature;
+                    feature = _currentIMemoryPoolFeature;
                 }
-
+                else if (key == IApplicationTransportFeatureType)
-                if (key == IApplicationTransportFeatureType)
                 {
-                    return _currentIApplicationTransportFeature;
+                    feature = _currentIApplicationTransportFeature;
                 }
-
+                else if (key == ITransportSchedulerFeatureType)
-                if (key == ITransportSchedulerFeatureType)
                 {
-                    return _currentITransportSchedulerFeature;
+                    feature = _currentITransportSchedulerFeature;
                 }
-
+                else if (key == IConnectionLifetimeFeatureType)
-                if (key == IConnectionLifetimeFeatureType)
                 {
-                    return _currentIConnectionLifetimeFeature;
+                    feature = _currentIConnectionLifetimeFeature;
                 }
-
+                else if (key == IBytesWrittenFeatureType)
-                if (key == IBytesWrittenFeatureType)
                 {
-                    return _currentIBytesWrittenFeature;
+                    feature = _currentIBytesWrittenFeature;
                 }
-
+                else if (MaybeExtra != null)
-                if (MaybeExtra != null)
                 {
-                    return ExtraFeatureGet(key);
+                    feature = ExtraFeatureGet(key);
                 }
 
-                return null;
+                return feature;
             }
+
             set
             {
                 _featureRevision++;
@@ -252,142 +195,130 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal
 
         TFeature IFeatureCollection.Get<TFeature>()
         {
+            TFeature feature = default;
             if (typeof(TFeature) == typeof(IHttpConnectionFeature))
             {
-                return (TFeature)_currentIHttpConnectionFeature;
+                feature = (TFeature)_currentIHttpConnectionFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionIdFeature))
             {
-                return (TFeature)_currentIConnectionIdFeature;
+                feature = (TFeature)_currentIConnectionIdFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionTransportFeature))
             {
-                return (TFeature)_currentIConnectionTransportFeature;
+                feature = (TFeature)_currentIConnectionTransportFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionItemsFeature))
             {
-                return (TFeature)_currentIConnectionItemsFeature;
+                feature = (TFeature)_currentIConnectionItemsFeature;
             }
             else if (typeof(TFeature) == typeof(IMemoryPoolFeature))
             {
-                return (TFeature)_currentIMemoryPoolFeature;
+                feature = (TFeature)_currentIMemoryPoolFeature;
             }
             else if (typeof(TFeature) == typeof(IApplicationTransportFeature))
             {
-                return (TFeature)_currentIApplicationTransportFeature;
+                feature = (TFeature)_currentIApplicationTransportFeature;
             }
             else if (typeof(TFeature) == typeof(ITransportSchedulerFeature))
             {
-                return (TFeature)_currentITransportSchedulerFeature;
+                feature = (TFeature)_currentITransportSchedulerFeature;
             }
             else if (typeof(TFeature) == typeof(IConnectionLifetimeFeature))
             {
-                return (TFeature)_currentIConnectionLifetimeFeature;
+                feature = (TFeature)_currentIConnectionLifetimeFeature;
             }
             else if (typeof(TFeature) == typeof(IBytesWrittenFeature))
             {
-                return (TFeature)_currentIBytesWrittenFeature;
+                feature = (TFeature)_currentIBytesWrittenFeature;
             }
             else if (MaybeExtra != null)
             {
-                return (TFeature)ExtraFeatureGet(typeof(TFeature));
+                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
             }
 
-            return default;
+            return feature;
         }
 
-        void IFeatureCollection.Set<TFeature>(TFeature instance)
+        void IFeatureCollection.Set<TFeature>(TFeature feature)
         {
             _featureRevision++;
-
             if (typeof(TFeature) == typeof(IHttpConnectionFeature))
             {
-                _currentIHttpConnectionFeature = instance;
+                _currentIHttpConnectionFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IConnectionIdFeature))
             {
-                _currentIConnectionIdFeature = instance;
+                _currentIConnectionIdFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IConnectionTransportFeature))
             {
-                _currentIConnectionTransportFeature = instance;
+                _currentIConnectionTransportFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IConnectionItemsFeature))
             {
-                _currentIConnectionItemsFeature = instance;
+                _currentIConnectionItemsFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IMemoryPoolFeature))
             {
-                _currentIMemoryPoolFeature = instance;
+                _currentIMemoryPoolFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IApplicationTransportFeature))
             {
-                _currentIApplicationTransportFeature = instance;
+                _currentIApplicationTransportFeature = feature;
             }
             else if (typeof(TFeature) == typeof(ITransportSchedulerFeature))
             {
-                _currentITransportSchedulerFeature = instance;
+                _currentITransportSchedulerFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IConnectionLifetimeFeature))
             {
-                _currentIConnectionLifetimeFeature = instance;
+                _currentIConnectionLifetimeFeature = feature;
             }
             else if (typeof(TFeature) == typeof(IBytesWrittenFeature))
             {
-                _currentIBytesWrittenFeature = instance;
+                _currentIBytesWrittenFeature = feature;
             }
             else
             {
-                ExtraFeatureSet(typeof(TFeature), instance);
+                ExtraFeatureSet(typeof(TFeature), feature);
             }
         }
 
-        IEnumerator<KeyValuePair<Type, object>> IEnumerable<KeyValuePair<Type, object>>.GetEnumerator() => FastEnumerable().GetEnumerator();
-
-        IEnumerator IEnumerable.GetEnumerator() => FastEnumerable().GetEnumerator();
-
         private IEnumerable<KeyValuePair<Type, object>> FastEnumerable()
         {
             if (_currentIHttpConnectionFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IHttpConnectionFeatureType, _currentIHttpConnectionFeature);
             }
-
             if (_currentIConnectionIdFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IConnectionIdFeatureType, _currentIConnectionIdFeature);
             }
-
             if (_currentIConnectionTransportFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IConnectionTransportFeatureType, _currentIConnectionTransportFeature);
             }
-
             if (_currentIConnectionItemsFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IConnectionItemsFeatureType, _currentIConnectionItemsFeature);
             }
-
             if (_currentIMemoryPoolFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IMemoryPoolFeatureType, _currentIMemoryPoolFeature);
             }
-
             if (_currentIApplicationTransportFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IApplicationTransportFeatureType, _currentIApplicationTransportFeature);
             }
-
             if (_currentITransportSchedulerFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(ITransportSchedulerFeatureType, _currentITransportSchedulerFeature);
             }
-
             if (_currentIConnectionLifetimeFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IConnectionLifetimeFeatureType, _currentIConnectionLifetimeFeature);
             }
-
             if (_currentIBytesWrittenFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IBytesWrittenFeatureType, _currentIBytesWrittenFeature);
@@ -401,5 +332,9 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal
                 }
             }
         }
+
+        IEnumerator<KeyValuePair<Type, object>> IEnumerable<KeyValuePair<Type, object>>.GetEnumerator() => FastEnumerable().GetEnumerator();
+
+        IEnumerator IEnumerable.GetEnumerator() => FastEnumerable().GetEnumerator();
     }
 }

src/Kestrel.Transport.Abstractions/Internal/TransportConnection.cs

@@ -1,4 +1,7 @@
-using System.Buffers;
+// 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.Buffers;
 using System.Collections.Generic;
 using System.IO.Pipelines;
 using System.Net;

test/Kestrel.Tests/GeneratedCodeTests.cs

@@ -15,26 +15,31 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
             const string httpHeadersGeneratedPath = "../../../../../src/Kestrel.Core/Internal/Http/HttpHeaders.Generated.cs";
             const string httpProtocolGeneratedPath = "../../../../../src/Kestrel.Core/Internal/Http/HttpProtocol.Generated.cs";
             const string httpUtilitiesGeneratedPath = "../../../../../src/Kestrel.Core/Internal/Infrastructure/HttpUtilities.Generated.cs";
+            const string transportConnectionGeneratedPath = "../../../../../src/Kestrel.Transport.Abstractions/Internal/TransportConnection.Generated.cs";
 
             var testHttpHeadersGeneratedPath = Path.GetTempFileName();
             var testHttpProtocolGeneratedPath = Path.GetTempFileName();
             var testHttpUtilitiesGeneratedPath = Path.GetTempFileName();
+            var testTransportConnectionGeneratedPath = Path.GetTempFileName();
 
             try
             {
                 var currentHttpHeadersGenerated = File.ReadAllText(httpHeadersGeneratedPath);
                 var currentHttpProtocolGenerated = File.ReadAllText(httpProtocolGeneratedPath);
                 var currentHttpUtilitiesGenerated = File.ReadAllText(httpUtilitiesGeneratedPath);
+                var currentTransportConnectionGenerated = File.ReadAllText(transportConnectionGeneratedPath);
 
-                CodeGenerator.Program.Run(testHttpHeadersGeneratedPath, testHttpProtocolGeneratedPath, testHttpUtilitiesGeneratedPath);
+                CodeGenerator.Program.Run(testHttpHeadersGeneratedPath, testHttpProtocolGeneratedPath, testHttpUtilitiesGeneratedPath, testTransportConnectionGeneratedPath);
 
                 var testHttpHeadersGenerated = File.ReadAllText(testHttpHeadersGeneratedPath);
                 var testHttpProtocolGenerated = File.ReadAllText(testHttpProtocolGeneratedPath);
                 var testHttpUtilitiesGenerated = File.ReadAllText(testHttpUtilitiesGeneratedPath);
+                var testTransportConnectionGenerated = File.ReadAllText(testTransportConnectionGeneratedPath);
 
                 Assert.Equal(currentHttpHeadersGenerated, testHttpHeadersGenerated, ignoreLineEndingDifferences: true);
                 Assert.Equal(currentHttpProtocolGenerated, testHttpProtocolGenerated, ignoreLineEndingDifferences: true);
                 Assert.Equal(currentHttpUtilitiesGenerated, testHttpUtilitiesGenerated, ignoreLineEndingDifferences: true);
+                Assert.Equal(currentTransportConnectionGenerated, testTransportConnectionGenerated, ignoreLineEndingDifferences: true);
 
             }
             finally
@@ -42,6 +47,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
                 File.Delete(testHttpHeadersGeneratedPath);
                 File.Delete(testHttpProtocolGeneratedPath);
                 File.Delete(testHttpUtilitiesGeneratedPath);
+                File.Delete(testTransportConnectionGeneratedPath);
             }
         }
     }

test/Kestrel.Tests/Kestrel.Tests.csproj

@@ -11,6 +11,10 @@
     <Content Include="..\shared\TestCertificates\*.pfx" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' != 'net461'">
+    <ProjectReference Include="..\..\tools\CodeGenerator\CodeGenerator.csproj" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\Kestrel\Kestrel.csproj" />
     <ProjectReference Include="..\..\src\Kestrel.Transport.Libuv\Kestrel.Transport.Libuv.csproj" />

test/Kestrel.Transport.Libuv.FunctionalTests/Kestrel.Transport.Libuv.FunctionalTests.csproj

@@ -16,10 +16,6 @@
     <Content Include="..\shared\TestCertificates\*.pfx" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFramework)' != 'net461'">
-    <ProjectReference Include="..\..\tools\CodeGenerator\CodeGenerator.csproj" />
-  </ItemGroup>
-
   <ItemGroup>
     <ProjectReference Include="..\..\src\Kestrel\Kestrel.csproj" />
     <ProjectReference Include="..\..\src\Kestrel.Transport.Libuv\Kestrel.Transport.Libuv.csproj" />

test/Kestrel.Transport.Sockets.FunctionalTests/Kestrel.Transport.Sockets.FunctionalTests.csproj

@@ -15,10 +15,6 @@
     <Content Include="..\shared\TestCertificates\*.pfx" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFramework)' != 'net461'">
-    <ProjectReference Include="..\..\tools\CodeGenerator\CodeGenerator.csproj" />
-  </ItemGroup>
-
   <ItemGroup>
     <ProjectReference Include="..\..\src\Kestrel\Kestrel.csproj" />
     <ProjectReference Include="..\..\src\Kestrel.Transport.Sockets\Kestrel.Transport.Sockets.csproj" />

tools/CodeGenerator/CodeGenerator.csproj

@@ -14,8 +14,8 @@
   </ItemGroup>
 
   <PropertyGroup>
-    <StartWorkingDirectory>$(MSBuildThisFileDirectory)..\..\src\Kestrel.Core</StartWorkingDirectory>
+    <StartWorkingDirectory>$(MSBuildThisFileDirectory)..\..\</StartWorkingDirectory>
-    <StartArguments>Internal/Http/HttpHeaders.Generated.cs Internal/Http/HttpProtocol.Generated.cs Internal/Infrastructure/HttpUtilities.Generated.cs</StartArguments>
+    <StartArguments>src/Kestrel.Core/Internal/Http/HttpHeaders.Generated.cs src/Kestrel.Core/Internal/Http/HttpProtocol.Generated.cs src/Kestrel.Core/Internal/Infrastructure/HttpUtilities.Generated.cs src/Kestrel.Transport.Abstractions/Internal/TransportConnection.Generated.cs</StartArguments>
   </PropertyGroup>
 
 </Project>

tools/CodeGenerator/FeatureCollectionGenerator.cs

@@ -0,0 +1,196 @@
+// 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;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace CodeGenerator
+{
+    public static class FeatureCollectionGenerator
+    {
+        public static string GenerateFile(string namespaceName, string className, string[] allFeatures, string[] implementedFeatures, string extraUsings, string fallbackFeatures)
+        {
+            // NOTE: This list MUST always match the set of feature interfaces implemented by TransportConnection.
+            // See also: src/Kestrel/Http/TransportConnection.FeatureCollection.cs
+            var features = allFeatures.Select((type, index) => new KnownFeature
+            {
+                Name = type,
+                Index = index
+            });
+
+            return $@"// 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;
+using System.Collections;
+using System.Collections.Generic;
+{extraUsings}
+
+namespace {namespaceName}
+{{
+    public partial class {className} : IFeatureCollection
+    {{{Each(features, feature => $@"
+        private static readonly Type {feature.Name}Type = typeof({feature.Name});")}
+{Each(features, feature => $@"
+        private object _current{feature.Name};")}
+
+        private int _featureRevision;
+
+        private List<KeyValuePair<Type, object>> MaybeExtra;
+
+        private void FastReset()
+        {{{Each(implementedFeatures, feature => $@"
+            _current{feature} = this;")}
+{Each(allFeatures.Where(f => !implementedFeatures.Contains(f)), feature => $@"
+            _current{feature} = null;")}
+        }}
+
+        // Internal for testing
+        internal void ResetFeatureCollection()
+        {{
+            FastReset();
+            MaybeExtra?.Clear();
+            _featureRevision++;
+        }}
+
+        private object ExtraFeatureGet(Type key)
+        {{
+            if (MaybeExtra == null)
+            {{
+                return null;
+            }}
+            for (var i = 0; i < MaybeExtra.Count; i++)
+            {{
+                var kv = MaybeExtra[i];
+                if (kv.Key == key)
+                {{
+                    return kv.Value;
+                }}
+            }}
+            return null;
+        }}
+
+        private void ExtraFeatureSet(Type key, object value)
+        {{
+            if (MaybeExtra == null)
+            {{
+                MaybeExtra = new List<KeyValuePair<Type, object>>(2);
+            }}
+
+            for (var i = 0; i < MaybeExtra.Count; i++)
+            {{
+                if (MaybeExtra[i].Key == key)
+                {{
+                    MaybeExtra[i] = new KeyValuePair<Type, object>(key, value);
+                    return;
+                }}
+            }}
+            MaybeExtra.Add(new KeyValuePair<Type, object>(key, value));
+        }}
+
+        bool IFeatureCollection.IsReadOnly => false;
+
+        int IFeatureCollection.Revision => _featureRevision;
+
+        object IFeatureCollection.this[Type key]
+        {{
+            get
+            {{
+                object feature = null;{Each(features, feature => $@"
+                {(feature.Index != 0 ? "else " : "")}if (key == {feature.Name}Type)
+                {{
+                    feature = _current{feature.Name};
+                }}")}
+                else if (MaybeExtra != null)
+                {{
+                    feature = ExtraFeatureGet(key);
+                }}
+
+                return feature{(string.IsNullOrEmpty(fallbackFeatures) ? "" : $" ?? {fallbackFeatures}[key]")};
+            }}
+
+            set
+            {{
+                _featureRevision++;
+{Each(features, feature => $@"
+                {(feature.Index != 0 ? "else " : "")}if (key == {feature.Name}Type)
+                {{
+                    _current{feature.Name} = value;
+                }}")}
+                else
+                {{
+                    ExtraFeatureSet(key, value);
+                }}
+            }}
+        }}
+
+        TFeature IFeatureCollection.Get<TFeature>()
+        {{
+            TFeature feature = default;{Each(features, feature => $@"
+            {(feature.Index != 0 ? "else " : "")}if (typeof(TFeature) == typeof({feature.Name}))
+            {{
+                feature = (TFeature)_current{feature.Name};
+            }}")}
+            else if (MaybeExtra != null)
+            {{
+                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
+            }}{(string.IsNullOrEmpty(fallbackFeatures) ? "" : $@"
+
+            if (feature == null)
+            {{
+                feature = {fallbackFeatures}.Get<TFeature>();
+            }}")}
+
+            return feature;
+        }}
+
+        void IFeatureCollection.Set<TFeature>(TFeature feature)
+        {{
+            _featureRevision++;{Each(features, feature => $@"
+            {(feature.Index != 0 ? "else " : "")}if (typeof(TFeature) == typeof({feature.Name}))
+            {{
+                _current{feature.Name} = feature;
+            }}")}
+            else
+            {{
+                ExtraFeatureSet(typeof(TFeature), feature);
+            }}
+        }}
+
+        private IEnumerable<KeyValuePair<Type, object>> FastEnumerable()
+        {{{Each(features, feature => $@"
+            if (_current{feature.Name} != null)
+            {{
+                yield return new KeyValuePair<Type, object>({feature.Name}Type, _current{feature.Name});
+            }}")}
+
+            if (MaybeExtra != null)
+            {{
+                foreach (var item in MaybeExtra)
+                {{
+                    yield return item;
+                }}
+            }}
+        }}
+
+        IEnumerator<KeyValuePair<Type, object>> IEnumerable<KeyValuePair<Type, object>>.GetEnumerator() => FastEnumerable().GetEnumerator();
+
+        IEnumerator IEnumerable.GetEnumerator() => FastEnumerable().GetEnumerator();
+    }}
+}}
+";
+        }
+
+        static string Each<T>(IEnumerable<T> values, Func<T, string> formatter)
+        {
+            return values.Any() ? values.Select(formatter).Aggregate((a, b) => a + b) : "";
+        }
+
+        private class KnownFeature
+        {
+            public string Name;
+            public int Index;
+        }
+    }
+}

tools/CodeGenerator/HttpProtocolFeatureCollection.cs

@@ -1,28 +1,13 @@
 // 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;
-using System.Collections.Generic;
 using System.Linq;
 
 namespace CodeGenerator
 {
-    // This project can output the Class library as a NuGet Package.
-    // To enable this option, right-click on the project and select the Properties menu item. In the Build tab select "Produce outputs on build".
     public class HttpProtocolFeatureCollection
     {
-        static string Each<T>(IEnumerable<T> values, Func<T, string> formatter)
+        public static string GenerateFile()
-        {
-            return values.Select(formatter).Aggregate((a, b) => a + b);
-        }
-
-        public class KnownFeature
-        {
-            public string Name;
-            public int Index;
-        }
-
-        public static string GeneratedFile(string className)
         {
             var alwaysFeatures = new[]
             {
@@ -65,14 +50,10 @@ namespace CodeGenerator
                 .Concat(commonFeatures)
                 .Concat(sometimesFeatures)
                 .Concat(rareFeatures)
-                .Select((type, index) => new KnownFeature
+                .ToArray();
-                {
-                    Name = type,
-                    Index = index
-                });
 
             // NOTE: This list MUST always match the set of feature interfaces implemented by HttpProtocol.
-            // See also: src/Kestrel/Http/HttpProtocol.FeatureCollection.cs
+            // See also: src/Kestrel.Core/Internal/Http/HttpProtocol.FeatureCollection.cs
             var implementedFeatures = new[]
             {
                 "IHttpRequestFeature",
@@ -86,114 +67,18 @@ namespace CodeGenerator
                 "IHttpBodyControlFeature",
             };
 
-            return $@"// Copyright (c) .NET Foundation. All rights reserved.
+            var usings = $@"
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-using System.Collections.Generic;
-
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Http.Features.Authentication;
-using Microsoft.AspNetCore.Server.Kestrel.Core.Features;
+using Microsoft.AspNetCore.Server.Kestrel.Core.Features;";
 
-namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
+            return FeatureCollectionGenerator.GenerateFile(
-{{
+                namespaceName: "Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http",
-    public partial class {className}
+                className: "HttpProtocol",
-    {{{Each(allFeatures, feature => $@"
+                allFeatures: allFeatures,
-        private static readonly Type {feature.Name}Type = typeof({feature.Name});")}
+                implementedFeatures: implementedFeatures,
-{Each(allFeatures, feature => $@"
+                extraUsings: usings,
-        private object _current{feature.Name};")}
+                fallbackFeatures: "ConnectionFeatures");
-
-        private void FastReset()
-        {{{Each(implementedFeatures, feature => $@"
-            _current{feature} = this;")}
-            {Each(allFeatures.Where(f => !implementedFeatures.Contains(f.Name)), feature => $@"
-            _current{feature.Name} = null;")}
-        }}
-
-        object IFeatureCollection.this[Type key]
-        {{
-            get
-            {{
-                object feature = null;{Each(allFeatures, feature => $@"
-                {(feature.Index != 0 ? "else " : "")}if (key == {feature.Name}Type)
-                {{
-                    feature = _current{feature.Name};
-                }}")}
-                else if (MaybeExtra != null)
-                {{
-                    feature = ExtraFeatureGet(key);
-                }}
-
-                return feature ?? ConnectionFeatures[key];
-            }}
-
-            set
-            {{
-                _featureRevision++;
-                {Each(allFeatures, feature => $@"
-                {(feature.Index != 0 ? "else " : "")}if (key == {feature.Name}Type)
-                {{
-                    _current{feature.Name} = value;
-                }}")}
-                else
-                {{
-                    ExtraFeatureSet(key, value);
-                }}
-            }}
-        }}
-
-        void IFeatureCollection.Set<TFeature>(TFeature feature) 
-        {{
-            _featureRevision++;{Each(allFeatures, feature => $@"
-            {(feature.Index != 0 ? "else " : "")}if (typeof(TFeature) == typeof({feature.Name}))
-            {{
-                _current{feature.Name} = feature;
-            }}")}
-            else
-            {{
-                ExtraFeatureSet(typeof(TFeature), feature);
-            }}
-        }}
-
-        TFeature IFeatureCollection.Get<TFeature>()
-        {{
-            TFeature feature = default;{Each(allFeatures, feature => $@"
-            {(feature.Index != 0 ? "else " : "")}if (typeof(TFeature) == typeof({feature.Name}))
-            {{
-                feature = (TFeature)_current{feature.Name};
-            }}")}
-            else if (MaybeExtra != null)
-            {{
-                feature = (TFeature)(ExtraFeatureGet(typeof(TFeature)));
-            }}
-            
-            if (feature == null)
-            {{
-                feature = ConnectionFeatures.Get<TFeature>();
-            }}
-
-            return feature;
-        }}
-
-        private IEnumerable<KeyValuePair<Type, object>> FastEnumerable()
-        {{{Each(allFeatures, feature => $@"
-            if (_current{feature.Name} != null)
-            {{
-                yield return new KeyValuePair<Type, object>({feature.Name}Type, _current{feature.Name} as {feature.Name});
-            }}")}
-
-            if (MaybeExtra != null)
-            {{
-                foreach(var item in MaybeExtra)
-                {{
-                    yield return item;
-                }}
-            }}
-        }}
-    }}
-}}
-";
         }
     }
 }

tools/CodeGenerator/KnownHeaders.cs

@@ -9,8 +9,6 @@ using System.Text;
 
 namespace CodeGenerator
 {
-    // This project can output the Class library as a NuGet Package.
-    // To enable this option, right-click on the project and select the Properties menu item. In the Build tab select "Produce outputs on build".
     public class KnownHeaders
     {
         static string Each<T>(IEnumerable<T> values, Func<T, string> formatter)
@@ -18,11 +16,6 @@ namespace CodeGenerator
             return values.Any() ? values.Select(formatter).Aggregate((a, b) => a + b) : "";
         }
 
-        static string If(bool condition, Func<string> formatter)
-        {
-            return condition ? formatter() : "";
-        }
-
         static string AppendSwitch(IEnumerable<IGrouping<int, KnownHeader>> values, string className) =>
              $@"var pUL = (ulong*)pUB;
                 var pUI = (uint*)pUB;

tools/CodeGenerator/Program.cs

@@ -25,17 +25,27 @@ namespace CodeGenerator
                 Console.Error.WriteLine("Missing path to HttpUtilities.Generated.cs");
                 return 1;
             }
+            else if (args.Length < 4)
+            {
+                Console.Error.WriteLine("Missing path to TransportConnection.Generated.cs");
+                return 1;
+            }
 
-            Run(args[0], args[1], args[2]);
+            Run(args[0], args[1], args[2], args[3]);
 
             return 0;
         }
 
-        public static void Run(string knownHeadersPath, string httpProtocolFeatureCollectionPath, string httpUtilitiesPath)
+        public static void Run(
+            string knownHeadersPath,
+            string httpProtocolFeatureCollectionPath,
+            string httpUtilitiesPath,
+            string transportConnectionFeatureCollectionPath)
         {
             var knownHeadersContent = KnownHeaders.GeneratedFile();
-            var httpProtocolFeatureCollectionContent = HttpProtocolFeatureCollection.GeneratedFile("HttpProtocol");
+            var httpProtocolFeatureCollectionContent = HttpProtocolFeatureCollection.GenerateFile();
             var httpUtilitiesContent = HttpUtilities.HttpUtilities.GeneratedFile();
+            var transportConnectionFeatureCollectionContent = TransportConnectionFeatureCollection.GenerateFile();
 
             var existingKnownHeaders = File.Exists(knownHeadersPath) ? File.ReadAllText(knownHeadersPath) : "";
             if (!string.Equals(knownHeadersContent, existingKnownHeaders))
@@ -54,6 +64,12 @@ namespace CodeGenerator
             {
                 File.WriteAllText(httpUtilitiesPath, httpUtilitiesContent);
             }
+
+            var existingTransportConnectionFeatureCollection = File.Exists(transportConnectionFeatureCollectionPath) ? File.ReadAllText(transportConnectionFeatureCollectionPath) : "";
+            if (!string.Equals(transportConnectionFeatureCollectionContent, existingTransportConnectionFeatureCollection))
+            {
+                File.WriteAllText(transportConnectionFeatureCollectionPath, transportConnectionFeatureCollectionContent);
+            }
         }
     }
 }

tools/CodeGenerator/TransportConnectionFeatureCollection.cs

@@ -0,0 +1,38 @@
+// 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.
+
+namespace CodeGenerator
+{
+    public class TransportConnectionFeatureCollection
+    {
+        public static string GenerateFile()
+        {
+            // NOTE: This list MUST always match the set of feature interfaces implemented by TransportConnection.
+            // See also: src/Kestrel.Transport.Abstractions/Internal/TransportConnection.FeatureCollection.cs
+            var features = new[]
+            {
+                "IHttpConnectionFeature",
+                "IConnectionIdFeature",
+                "IConnectionTransportFeature",
+                "IConnectionItemsFeature",
+                "IMemoryPoolFeature",
+                "IApplicationTransportFeature",
+                "ITransportSchedulerFeature",
+                "IConnectionLifetimeFeature",
+                "IBytesWrittenFeature",
+            };
+
+            var usings = $@"
+using Microsoft.AspNetCore.Connections.Features;
+using Microsoft.AspNetCore.Http.Features;";
+
+            return FeatureCollectionGenerator.GenerateFile(
+                namespaceName: "Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal",
+                className: "TransportConnection",
+                allFeatures: features,
+                implementedFeatures: features,
+                extraUsings: usings,
+                fallbackFeatures: null);
+        }
+    }
+}