Platform benchmarks optimizations (#1470)

Create writer once per request, reduce the number of calls to .GetSpan and .Advance

Author: adamsitnik

src/BenchmarksApps/Kestrel/PlatformBenchmarks/BenchmarkApplication.HttpConnection.cs

@@ -41,41 +41,50 @@ private async Task ProcessRequestsAsync()
         {
             while (true)
             {
-                var task = Reader.ReadAsync();
-
-                if (!task.IsCompleted)
+                var readResult = await Reader.ReadAsync();
+                
+                if (!HandleRequest(readResult))
                 {
-                    // No more data in the input
-                    await OnReadCompletedAsync();
+                    return;
                 }
 
-                var result = await task;
-                var buffer = result.Buffer;
-                while (true)
+                await Writer.FlushAsync();
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private bool HandleRequest(in ReadResult result)
+        {
+            var buffer = result.Buffer;
+            var writer = GetWriter(Writer);
+
+            while (true)
+            {
+                if (!ParseHttpRequest(ref buffer, result.IsCompleted, out var examined))
                 {
-                    if (!ParseHttpRequest(ref buffer, result.IsCompleted, out var examined))
-                    {
-                        return;
-                    }
+                    return false;
+                }
 
-                    if (_state == State.Body)
-                    {
-                        ProcessRequest();
+                if (_state == State.Body)
+                {
+                    ProcessRequest(ref writer);
 
-                        _state = State.StartLine;
+                    _state = State.StartLine;
 
-                        if (!buffer.IsEmpty)
-                        {
-                            // More input data to parse
-                            continue;
-                        }
+                    if (!buffer.IsEmpty)
+                    {
+                        // More input data to parse
+                        continue;
                     }
-
-                    // No more input or incomplete data, Advance the Reader
-                    Reader.AdvanceTo(buffer.Start, examined);
-                    break;
                 }
+
+                // No more input or incomplete data, Advance the Reader
+                Reader.AdvanceTo(buffer.Start, examined);
+                break;
             }
+
+            writer.Commit();
+            return true;
         }
 
         private bool ParseHttpRequest(ref ReadOnlySequence<byte> buffer, bool isCompleted, out SequencePosition examined)
@@ -157,11 +166,6 @@ public void OnHeadersComplete()
         }
 #endif
 
-        public async ValueTask OnReadCompletedAsync()
-        {
-            await Writer.FlushAsync();
-        }
-
         private static void ThrowUnexpectedEndOfData()
         {
             throw new InvalidOperationException("Unexpected end of data!");

src/BenchmarksApps/Kestrel/PlatformBenchmarks/BenchmarkApplication.cs

@@ -54,26 +54,24 @@ public void OnStartLine(HttpMethod method, HttpVersion version, Span<byte> targe
             _requestType = requestType;
         }
 
-        public void ProcessRequest()
+        private void ProcessRequest(ref BufferWriter<WriterAdapter> writer)
         {
             if (_requestType == RequestType.PlainText)
             {
-                PlainText(Writer);
+                PlainText(ref writer);
             }
             else if (_requestType == RequestType.Json)
             {
-                Json(Writer);
+                Json(ref writer);
             }
             else
             {
-                Default(Writer);
+                Default(ref writer);
             }
         }
 
-        private static void PlainText(PipeWriter pipeWriter)
+        private static void PlainText(ref BufferWriter<WriterAdapter> writer)
         {
-            var writer = GetWriter(pipeWriter);
-
             // HTTP 1.1 OK
             writer.Write(_http11OK);
 
@@ -95,13 +93,10 @@ private static void PlainText(PipeWriter pipeWriter)
 
             // Body
             writer.Write(_plainTextBody);
-            writer.Commit();
         }
 
-        private static void Json(PipeWriter pipeWriter)
+        private static void Json(ref BufferWriter<WriterAdapter> writer)
         {
-            var writer = GetWriter(pipeWriter);
-
             // HTTP 1.1 OK
             writer.Write(_http11OK);
 
@@ -124,13 +119,10 @@ private static void Json(PipeWriter pipeWriter)
 
             // Body
             writer.Write(jsonPayload);
-            writer.Commit();
         }
 
-        private static void Default(PipeWriter pipeWriter)
+        private static void Default(ref BufferWriter<WriterAdapter> writer)
         {
-            var writer = GetWriter(pipeWriter);
-
             // HTTP 1.1 OK
             writer.Write(_http11OK);
 
@@ -145,7 +137,6 @@ private static void Default(PipeWriter pipeWriter)
 
             // End of headers
             writer.Write(_crlf);
-            writer.Commit();
         }
 
         private enum RequestType

src/BenchmarksApps/Kestrel/PlatformBenchmarks/BufferWriter.cs

@@ -17,7 +17,7 @@ public BufferWriter(T output)
         {
             _buffered = 0;
             _output = output;
-            _span = output.GetSpan();
+            _span = output.GetSpan(sizeHint: 16 * 160);
         }
 
         public Span<byte> Span => _span;

src/BenchmarksApps/Kestrel/PlatformBenchmarks/IHttpConnection.cs

@@ -11,7 +11,7 @@ public interface IHttpConnection : IHttpHeadersHandler, IHttpRequestLineHandler
     {
         PipeReader Reader { get; set; }
         PipeWriter Writer { get; set; }
+
         Task ExecuteAsync();
-        ValueTask OnReadCompletedAsync();
     }
 }