Amortize Stream Costs

src/Microsoft.AspNet.Server.Kestrel/Http/Frame.cs

@@ -57,6 +57,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
 
         internal FrameRequestStream _requestBody;
         internal FrameResponseStream _responseBody;
+        internal FrameDuplexStream _duplexStream;
 
         protected bool _responseStarted;
         protected bool _keepAlive;
@@ -86,6 +87,9 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
             _localEndPoint = localEndPoint;
             _prepareRequest = prepareRequest;
             _pathBase = context.ServerAddress.PathBase;
+            _requestBody = new FrameRequestStream();
+            _responseBody = new FrameResponseStream(this);
+            _duplexStream = new FrameDuplexStream(_requestBody, _responseBody);
 
             FrameControl = this;
             Reset();

src/Microsoft.AspNet.Server.Kestrel/Http/FrameOfT.cs

@@ -64,11 +64,9 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
                     {
                         var messageBody = MessageBody.For(HttpVersion, _requestHeaders, this);
                         _keepAlive = messageBody.RequestKeepAlive;
-                        _requestBody = new FrameRequestStream(messageBody);
+                        RequestBody = _requestBody.StartAcceptingReads(messageBody);
-                        RequestBody = _requestBody;
+                        ResponseBody = _responseBody.StartAcceptingWrites();
-                        _responseBody = new FrameResponseStream(this);
+                        DuplexStream = _duplexStream;
-                        ResponseBody = _responseBody;
-                        DuplexStream = new FrameDuplexStream(RequestBody, ResponseBody);
 
                         _abortedCts = null;
                         _manuallySetRequestAbortToken = null;

src/Microsoft.AspNet.Server.Kestrel/Http/FrameRequestStream.cs

@@ -10,12 +10,12 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
 {
     public class FrameRequestStream : Stream
     {
-        private readonly MessageBody _body;
+        private MessageBody _body;
         private StreamState _state;
 
-        public FrameRequestStream(MessageBody body)
+        public FrameRequestStream()
         {
-            _body = body;
+            _state = StreamState.Closed;
         }
 
         public override bool CanRead { get { return true; } }
@@ -112,18 +112,30 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
             throw new NotImplementedException();
         }
 
+        public Stream StartAcceptingReads(MessageBody body)
+        {
+            // Only start if not aborted
+            if (_state == StreamState.Closed)
+            {
+                _state = StreamState.Open;
+                _body = body;
+            }
+            return this;
+        }
+
         public void StopAcceptingReads()
         {
             // Can't use dispose (or close) as can be disposed too early by user code
             // As exampled in EngineTests.ZeroContentLengthNotSetAutomaticallyForCertainStatusCodes
-            _state = StreamState.Disposed;
+            _state = StreamState.Closed;
+            _body = null;
         }
 
         public void Abort()
         {
             // We don't want to throw an ODE until the app func actually completes.
             // If the request is aborted, we throw an IOException instead.
-            if (_state != StreamState.Disposed)
+            if (_state != StreamState.Closed)
             {
                 _state = StreamState.Aborted;
             }
@@ -135,7 +147,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
             {
                 case StreamState.Open:
                     return;
-                case StreamState.Disposed:
+                case StreamState.Closed:
                     throw new ObjectDisposedException(nameof(FrameRequestStream));
                 case StreamState.Aborted:
                     throw new IOException("The request has been aborted.");
@@ -145,7 +157,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
         private enum StreamState
         {
             Open,
-            Disposed,
+            Closed,
             Aborted
         }
     }

src/Microsoft.AspNet.Server.Kestrel/Http/FrameResponseStream.cs

@@ -16,6 +16,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
         public FrameResponseStream(FrameContext context)
         {
             _context = context;
+            _state = StreamState.Closed;
         }
 
         public override bool CanRead => false;
@@ -77,18 +78,29 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
             return _context.FrameControl.WriteAsync(new ArraySegment<byte>(buffer, offset, count), cancellationToken);
         }
 
+        public Stream StartAcceptingWrites()
+        {
+            // Only start if not aborted
+            if (_state == StreamState.Closed)
+            {
+                _state = StreamState.Open;
+            }
+
+            return this;
+        }
+
         public void StopAcceptingWrites()
         {
             // Can't use dispose (or close) as can be disposed too early by user code
             // As exampled in EngineTests.ZeroContentLengthNotSetAutomaticallyForCertainStatusCodes
-            _state = StreamState.Disposed;
+            _state = StreamState.Closed;
         }
 
         public void Abort()
         {
             // We don't want to throw an ODE until the app func actually completes.
             // If the request is aborted, we throw an IOException instead.
-            if (_state != StreamState.Disposed)
+            if (_state != StreamState.Closed)
             {
                 _state = StreamState.Aborted;
             }
@@ -100,7 +112,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
             {
                 case StreamState.Open:
                     return;
-                case StreamState.Disposed:
+                case StreamState.Closed:
                     throw new ObjectDisposedException(nameof(FrameResponseStream));
                 case StreamState.Aborted:
                     throw new IOException("The request has been aborted.");
@@ -110,7 +122,7 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
         private enum StreamState
         {
             Open,
-            Disposed,
+            Closed,
             Aborted
         }
     }

test/Microsoft.AspNet.Server.KestrelTests/MessageBodyTests.cs

@@ -21,7 +21,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         {
             var input = new TestInput();
             var body = MessageBody.For("HTTP/1.0", new Dictionary<string, StringValues>(), input.FrameContext);
-            var stream = new FrameRequestStream(body);
+            var stream = new FrameRequestStream().StartAcceptingReads(body);
 
             input.Add("Hello", true);
 
@@ -39,7 +39,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         {
             var input = new TestInput();
             var body = MessageBody.For("HTTP/1.0", new Dictionary<string, StringValues>(), input.FrameContext);
-            var stream = new FrameRequestStream(body);
+            var stream = new FrameRequestStream().StartAcceptingReads(body);
 
             input.Add("Hello", true);
 
@@ -57,7 +57,7 @@ namespace Microsoft.AspNet.Server.KestrelTests
         {
             var input = new TestInput();
             var body = MessageBody.For("HTTP/1.0", new Dictionary<string, StringValues>(), input.FrameContext);
-            var stream = new FrameRequestStream(body);
+            var stream = new FrameRequestStream().StartAcceptingReads(body);
 
             // Input needs to be greater than 4032 bytes to allocate a block not backed by a slab.
             var largeInput = new string('a', 8192);