Reduce revision amplication

Author: benaadams

src/Microsoft.AspNetCore.Http.Features/FeatureReferences.cs

@@ -15,6 +15,13 @@ public FeatureReferences(IFeatureCollection collection)
             Revision = collection.Revision;
         }
 
+        public FeatureReferences(IFeatureCollection collection, int featuresVersion)
+        {
+            Collection = collection;
+            Cache = default(TCache);
+            Revision = featuresVersion;
+        }
+
         public IFeatureCollection Collection { get; private set; }
         public int Revision { get; private set; }
 

src/Microsoft.AspNetCore.Http/DefaultHttpContext.cs

@@ -42,9 +42,22 @@ public DefaultHttpContext()
 
         public DefaultHttpContext(IFeatureCollection features)
         {
-            _features = new FeatureReferences<FeatureInterfaces>(features);
-            _request = new DefaultHttpRequest(this);
-            _response = new DefaultHttpResponse(this);
+            var featuresVersion = features.Revision;
+
+            // Speculatively populate always used features for current version
+            _features = new FeatureReferences<FeatureInterfaces>(features, featuresVersion);
+            _request = new DefaultHttpRequest(this, featuresVersion);
+            _response = new DefaultHttpResponse(this, featuresVersion);
+        }
+
+        public void Initialize(IFeatureCollection features)
+        {
+            var featuresVersion = features.Revision;
+
+            // Speculatively populate always used features for current version
+            _features = new FeatureReferences<FeatureInterfaces>(features, featuresVersion);
+            _request.Initialize(features, featuresVersion);
+            _response.Initialize(features, featuresVersion);
         }
 
         private IItemsFeature ItemsFeature =>
@@ -155,13 +168,6 @@ public override void Abort()
         [MethodImpl(MethodImplOptions.NoInlining)]
         private WebSocketManager InitializeWebSocketManager() => (_websockets = new DefaultWebSocketManager(Features));
 
-        public void Initialize(IFeatureCollection features)
-        {
-            _features = new FeatureReferences<FeatureInterfaces>(features);
-            _request.Initialize(features);
-            _response.Initialize(features);
-        }
-
         public void Uninitialize()
         {
             _features = default(FeatureReferences<FeatureInterfaces>);

src/Microsoft.AspNetCore.Http/Internal/DefaultHttpRequest.cs

@@ -18,13 +18,19 @@ public sealed class DefaultHttpRequest : HttpRequest
         private readonly static Func<HttpRequest, IFormFeature> _newFormFeature = r => new FormFeature(r);
         private readonly static Func<IFeatureCollection, IRequestCookiesFeature> _newRequestCookiesFeature = f => new RequestCookiesFeature(f);
 
-        private DefaultHttpContext _context;
+        private readonly DefaultHttpContext _context;
         private FeatureReferences<FeatureInterfaces> _features;
 
-        public DefaultHttpRequest(DefaultHttpContext context)
+        public DefaultHttpRequest(DefaultHttpContext context, int featuresVersion)
         {
             _context = context;
-            _features = new FeatureReferences<FeatureInterfaces>(context.Features);
+            Initialize(context.Features, featuresVersion);
+        }
+
+        public void Initialize(IFeatureCollection features, int featuresVersion)
+        {
+            // Speculatively populate always used features for current version
+            _features = new FeatureReferences<FeatureInterfaces>(features, featuresVersion);
         }
 
         public override HttpContext HttpContext => _context;
@@ -140,11 +146,6 @@ public override Task<IFormCollection> ReadFormAsync(CancellationToken cancellati
             return FormFeature.ReadFormAsync(cancellationToken);
         }
 
-        public void Initialize(IFeatureCollection features)
-        {
-            _features = new FeatureReferences<FeatureInterfaces>(features);
-        }
-
         public void Uninitialize()
         {
             _features = default(FeatureReferences<FeatureInterfaces>);

src/Microsoft.AspNetCore.Http/Internal/DefaultHttpResponse.cs

@@ -15,13 +15,20 @@ public sealed class DefaultHttpResponse : HttpResponse
         private readonly static Func<IFeatureCollection, IHttpResponseFeature> _nullResponseFeature = f => null;
         private readonly static Func<IFeatureCollection, IResponseCookiesFeature> _newResponseCookiesFeature = f => new ResponseCookiesFeature(f);
 
-        private DefaultHttpContext _context;
+        private readonly DefaultHttpContext _context;
         private FeatureReferences<FeatureInterfaces> _features;
 
-        public DefaultHttpResponse(DefaultHttpContext context)
+        public DefaultHttpResponse(DefaultHttpContext context, int featuresVersion)
         {
             _context = context;
-            _features = new FeatureReferences<FeatureInterfaces>(context.Features);
+            Initialize(context.Features, featuresVersion);
+        }
+
+        public void Initialize(IFeatureCollection features, int featuresVersion)
+        {
+            // Speculatively populate always used features for current version
+            _features = new FeatureReferences<FeatureInterfaces>(features, featuresVersion);
+            _features.Cache.Response = (IHttpResponseFeature)features[typeof(IHttpResponseFeature)];
         }
 
         private IHttpResponseFeature HttpResponseFeature =>
@@ -119,11 +126,6 @@ public override void Redirect(string location, bool permanent)
             Headers[HeaderNames.Location] = location;
         }
 
-        public void Initialize(IFeatureCollection features)
-        {
-            _features = new FeatureReferences<FeatureInterfaces>(features);
-        }
-
         public void Uninitialize()
         {
             _features = default(FeatureReferences<FeatureInterfaces>);

test/Microsoft.AspNetCore.Http.Performance/DefaultContextBenchmark.cs

@@ -18,14 +18,15 @@ public class DefaultContextBenchmark
 
         private IHttpContextFactory _contextFactory;
         private IFeatureCollection _features;
+        private int _featuresVersion;
         private HttpContext _context;
         private DefaultHttpResponse _responseDirect;
 
         [Setup]
         public void Setup()
         {
             _features = CreateFeatureCollection();
-
+            _featuresVersion = _features.Revision;
             _contextFactory = new HttpContextFactory(new DefaultObjectPoolProvider(), Options.Create(new FormOptions()));
 
             _context = _contextFactory.Create(_features);
@@ -74,7 +75,7 @@ public void GetResponseBodyUncached()
             for (var i = 0; i < InnerLoopCount; i++)
             {
                 // Reset feature cache
-                _responseDirect.Initialize(_features);
+                _responseDirect.Initialize(_features, _featuresVersion);
                 GetResponseBodyImpl();
             }
         }
@@ -94,7 +95,7 @@ public void GetContentLengthUncached()
             for (var i = 0; i < InnerLoopCount; i++)
             {
                 // Reset feature cache
-                _responseDirect.Initialize(_features);
+                _responseDirect.Initialize(_features, _featuresVersion);
                 GetContentLengthImpl();
             }
         }