Revert "Undo use of pipewriter in FileBufferingWriteStream (#21833)"

This reverts commit 48261fd.

Author: pranavkm

src/Http/WebUtilities/ref/Microsoft.AspNetCore.WebUtilities.netcoreapp.cs

@@ -77,6 +77,8 @@ protected override void Dispose(bool disposing) { }
         [System.Diagnostics.DebuggerStepThroughAttribute]
         public override System.Threading.Tasks.ValueTask DisposeAsync() { throw null; }
         [System.Diagnostics.DebuggerStepThroughAttribute]
+        public System.Threading.Tasks.Task DrainBufferAsync(System.IO.Pipelines.PipeWriter destination, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) { throw null; }
+        [System.Diagnostics.DebuggerStepThroughAttribute]
         public System.Threading.Tasks.Task DrainBufferAsync(System.IO.Stream destination, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) { throw null; }
         public override void Flush() { }
         public override System.Threading.Tasks.Task FlushAsync(System.Threading.CancellationToken cancellationToken) { throw null; }

src/Http/WebUtilities/src/FileBufferingWriteStream.cs

@@ -6,6 +6,7 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
+using System.IO.Pipelines;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Internal;
@@ -185,8 +186,25 @@ public async Task DrainBufferAsync(Stream destination, CancellationToken cancell
             // unspooled content. Copy the FileStream content first when available.
             if (FileStream != null)
             {
-                await FileStream.FlushAsync(cancellationToken);
+                // We make a new stream for async reads from disk and async writes to the destination
+                await using var readStream = new FileStream(FileStream.Name, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite, bufferSize: 1, useAsync: true);
+
+                await readStream.CopyToAsync(destination, cancellationToken);
+
+                // This is created with delete on close
+                await FileStream.DisposeAsync();
+                FileStream = null;
+            }
 
+            await PagedByteBuffer.MoveToAsync(destination, cancellationToken);
+        }
+
+        public async Task DrainBufferAsync(PipeWriter destination, CancellationToken cancellationToken = default)
+        {
+            // When not null, FileStream always has "older" spooled content. The PagedByteBuffer always has "newer"
+            // unspooled content. Copy the FileStream content first when available.
+            if (FileStream != null)
+            {
                 // We make a new stream for async reads from disk and async writes to the destination
                 await using var readStream = new FileStream(FileStream.Name, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite, bufferSize: 1, useAsync: true);
 

src/Http/WebUtilities/test/FileBufferingWriteStreamTests.cs

@@ -371,24 +371,6 @@ public async Task DrainBufferAsync_WithContentInDisk_CopiesContentFromMemoryStre
             Assert.Equal(0, bufferingStream.Length);
         }
 
-        [Fact]
-        public async Task DrainBufferAsync_IncludesContentPossiblyBufferedByFileStream()
-        {
-            // We want to ensure that the FileStream (which has a 1-byte buffer) flushes prior to the other read stream reading input.
-            // Arrange
-            var input = new byte[] { 3, };
-            using var bufferingStream = new FileBufferingWriteStream(0, tempFileDirectoryAccessor: () => TempDirectory);
-            bufferingStream.Write(input, 0, input.Length);
-            var memoryStream = new MemoryStream();
-
-            // Act
-            await bufferingStream.DrainBufferAsync(memoryStream, default);
-
-            // Assert
-            Assert.Equal(input, memoryStream.ToArray());
-            Assert.Equal(0, bufferingStream.Length);
-        }
-
         public void Dispose()
         {
             try

src/Mvc/Mvc.Formatters.Xml/src/XmlSerializerOutputFormatter.cs

@@ -261,7 +261,7 @@ public override async Task WriteResponseBodyAsync(OutputFormatterWriteContext co
                 if (fileBufferingWriteStream != null)
                 {
                     response.ContentLength = fileBufferingWriteStream.Length;
-                    await fileBufferingWriteStream.DrainBufferAsync(response.Body);
+                    await fileBufferingWriteStream.DrainBufferAsync(response.BodyWriter);
                 }
             }
             finally

src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonOutputFormatter.cs

@@ -153,7 +153,7 @@ public override async Task WriteResponseBodyAsync(OutputFormatterWriteContext co
                 if (fileBufferingWriteStream != null)
                 {
                     response.ContentLength = fileBufferingWriteStream.Length;
-                    await fileBufferingWriteStream.DrainBufferAsync(response.Body);
+                    await fileBufferingWriteStream.DrainBufferAsync(response.BodyWriter);
                 }
             }
             finally

src/Mvc/test/Mvc.FunctionalTests/JsonOutputFormatterTestBase.cs

@@ -154,17 +154,15 @@ public virtual async Task Formatting_DictionaryType()
             Assert.Equal(expected, await response.Content.ReadAsStringAsync());
         }
 
-        [Theory]
-        [InlineData(65 * 1024)]
-        [InlineData(2 * 1024 * 1024)]
-        public virtual async Task Formatting_LargeObject(int size)
+        [Fact]
+        public virtual async Task Formatting_LargeObject()
         {
             // Arrange
-            var expectedName = "This is long so we can test large objects " + new string('a', size);
+            var expectedName = "This is long so we can test large objects " + new string('a', 1024 * 65);
             var expected = $"{{\"id\":10,\"name\":\"{expectedName}\",\"streetName\":null}}";
 
             // Act
-            var response = await Client.GetAsync($"/JsonOutputFormatter/{nameof(JsonOutputFormatterController.LargeObjectResult)}/{size}");
+            var response = await Client.GetAsync($"/JsonOutputFormatter/{nameof(JsonOutputFormatterController.LargeObjectResult)}");
 
             // Assert
             await response.AssertStatusCodeAsync(HttpStatusCode.OK);

src/Mvc/test/WebSites/FormatterWebSite/Controllers/JsonOutputFormatterController.cs

@@ -44,12 +44,12 @@ public ActionResult<Dictionary<string, string>> DictionaryResult() =>
                 ["Key3"] = null,
             };
 
-        [HttpGet("{size:int}")]
-        public ActionResult<SimpleModel> LargeObjectResult(int size) =>
+        [HttpGet]
+        public ActionResult<SimpleModel> LargeObjectResult() =>
             new SimpleModel
             {
                 Id = 10,
-                Name = "This is long so we can test large objects " + new string('a', size),
+                Name = "This is long so we can test large objects " + new string('a', 1024 * 65),
             };
 
         [HttpGet]