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Improve buffering of Razor output in MVC 

These changes are aimed at significantly improving the performance of
MVC/Razor when a large amount of content is in play or a large number of
TagHelpers are used.

A few issues addressed:

- Buffer sync writes after a flush has occurred so that we can write them
  asyncronously. The issue is that an IHtmlContent can only do sync
  writes. This is very bad for Kestrel in general. Doing these writes
  async is better for our overall perf, and the buffer that we use for it
  is from the pool.

- 'Flatten' ViewBuffers when possible. A page with lots of TagHelpers can
  end up renting a ViewBuffer and only write 2-3 things into it. When a
  ViewBuffer sees another ViewBuffer we can either steal its pages, or
  copy data out and 'return' its pages. This lets us use 3-4 buffers for a
  large Razor page instead of hundreds.
This commit is contained in:
Ryan Nowak 2016-01-12 12:39:38 -08:00
parent 6f885c7113
commit 434da683fc
12 changed files with 841 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/Microsoft.AspNetCore.Mvc.Razor/RazorTextWriter.cs
View File

@ -98,15 +98,9 @@ namespace Microsoft.AspNetCore.Mvc.Razor
/// <inheritdoc />
public override void Write(IHtmlContent value)
{
var htmlTextWriter = TargetWriter as HtmlTextWriter;
if (htmlTextWriter == null)
{
value.WriteTo(TargetWriter, HtmlEncoder);
}
else
{
htmlTextWriter.Write(value);
}
// Perf: We don't special case 'TargetWriter is HtmlTextWriter' here, because want to delegate to the
// IHtmlContent if it wants to 'flatten' itself or not. This is an important optimization for TagHelpers.
value.WriteTo(TargetWriter, HtmlEncoder);
}
/// <inheritdoc />

6
src/Microsoft.AspNetCore.Mvc.Razor/RazorView.cs
View File

@ -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.Buffers;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
@ -233,7 +234,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor
if (bodyWriter.IsBuffering)
{
// Only copy buffered content to the Output if we're currently buffering.
await bodyWriter.Buffer.WriteToAsync(context.Writer, _htmlEncoder);
using (var writer = _bufferScope.CreateWriter(context.Writer))
{
await bodyWriter.Buffer.WriteToAsync(writer, _htmlEncoder);
}
}
}

16
src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/IViewBufferScope.cs
View File

@ -1,6 +1,8 @@
// 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.IO;
namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
{
/// <summary>
@ -13,5 +15,19 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
/// </summary>
/// <returns>The <see cref="ViewBufferValue[]"/>.</returns>
ViewBufferValue[] GetSegment();
/// <summary>
/// Returns a <see cref="ViewBufferValue[]"/> that can be reused.
/// </summary>
/// <param name="segment">The <see cref="ViewBufferValue[]"/>.</param>
void ReturnSegment(ViewBufferValue[] segment);
/// <summary>
/// Creates a <see cref="ViewBufferTextWriter"/> that will delegate to the provided
/// <paramref name="writer"/>.
/// </summary>
/// <param name="writer">The <see cref="TextWriter"/>.</param>
/// <returns>A <see cref="ViewBufferTextWriter"/>.</returns>
ViewBufferTextWriter CreateWriter(TextWriter writer);
}
}

61
src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/MemoryPoolViewBufferScope.cs
View File

@ -4,6 +4,7 @@
using System;
using System.Buffers;
using System.Collections.Generic;
using System.IO;
namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
{
@ -13,18 +14,25 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
public class MemoryPoolViewBufferScope : IViewBufferScope, IDisposable
{
public static readonly int SegmentSize = 512;
private readonly ArrayPool<ViewBufferValue> _pool;
private readonly ArrayPool<ViewBufferValue> _viewBufferPool;
private readonly ArrayPool<char> _charPool;
private List<ViewBufferValue[]> _available;
private List<ViewBufferValue[]> _leased;
private bool _disposed;
/// <summary>
/// Initializes a new instance of <see cref="MemoryPoolViewBufferScope"/>.
/// </summary>
/// <param name="pool">The <see cref="ArrayPool{ViewBufferValue}"/> for creating
/// <see cref="ViewBufferValue"/> instances.</param>
public MemoryPoolViewBufferScope(ArrayPool<ViewBufferValue> pool)
/// <param name="viewBufferPool">
/// The <see cref="ArrayPool{ViewBufferValue}"/> for creating <see cref="ViewBufferValue"/> instances.
/// </param>
/// <param name="charPool">
/// The <see cref="ArrayPool{char}"/> for creating <see cref="ViewBufferTextWriter"/> instances.
/// </param>
public MemoryPoolViewBufferScope(ArrayPool<ViewBufferValue> viewBufferPool, ArrayPool<char> charPool)
{
_pool = pool;
_viewBufferPool = viewBufferPool;
_charPool = charPool;
}
/// <inheritdoc />
@ -42,20 +50,57 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
ViewBufferValue[] segment = null;
// Reuse pages that have been returned before going back to the memory pool.
if (_available != null && _available.Count > 0)
{
segment = _available[_available.Count - 1];
_available.RemoveAt(_available.Count - 1);
return segment;
}
try
{
segment = _pool.Rent(SegmentSize);
segment = _viewBufferPool.Rent(SegmentSize);
_leased.Add(segment);
}
catch when (segment != null)
{
_pool.Return(segment);
_viewBufferPool.Return(segment);
throw;
}
return segment;
}
/// <inheritdoc />
public void ReturnSegment(ViewBufferValue[] segment)
{
if (segment == null)
{
throw new ArgumentNullException(nameof(segment));
}
Array.Clear(segment, 0, segment.Length);
if (_available == null)
{
_available = new List<ViewBufferValue[]>();
}
_available.Add(segment);
}
/// <inheritdoc />
public ViewBufferTextWriter CreateWriter(TextWriter writer)
{
if (writer == null)
{
throw new ArgumentNullException(nameof(writer));
}
return new ViewBufferTextWriter(_charPool, writer);
}
/// <inheritdoc />
public void Dispose()
{
@ -70,7 +115,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
for (var i = 0; i < _leased.Count; i++)
{
_pool.Return(_leased[i]);
_viewBufferPool.Return(_leased[i]);
}
_leased.Clear();

111
src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewBuffer.cs
View File

@ -2,9 +2,11 @@
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Buffers;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Html;
@ -35,17 +37,14 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
_bufferScope = bufferScope;
_name = name;
Pages = new List<ViewBufferPage>();
}
/// <summary>
/// Gets the backing buffer.
/// </summary>
public IList<ViewBufferValue[]> BufferSegments { get; private set; }
/// <summary>
/// Gets the count of entries in the last element of <see cref="BufferSegments"/>.
/// </summary>
public int CurrentCount { get; private set; }
public IList<ViewBufferPage> Pages { get; }
/// <inheritdoc />
public IHtmlContentBuilder Append(string unencoded)
@ -67,7 +66,48 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
return this;
}
AppendValue(new ViewBufferValue(content));
// Perf: special case ViewBuffers so we can 'combine' them.
var otherBuffer = content as ViewBuffer;
if (otherBuffer == null)
{
AppendValue(new ViewBufferValue(content));
return this;
}
for (var i = 0; i < otherBuffer.Pages.Count; i++)
{
var otherPage = otherBuffer.Pages[i];
var currentPage = Pages.Count == 0 ? null : Pages[Pages.Count - 1];
// If the other page is less or equal to than half full, let's copy it's to the current page if
// possible.
var isLessThanHalfFull = 2 * otherPage.Count <= otherPage.Capacity;
if (isLessThanHalfFull &&
currentPage != null &&
currentPage.Capacity - currentPage.Count >= otherPage.Count)
{
// We have room, let's copy the items.
Array.Copy(
sourceArray: otherPage.Buffer,
sourceIndex: 0,
destinationArray: currentPage.Buffer,
destinationIndex: currentPage.Count,
length: otherPage.Count);
currentPage.Count += otherPage.Count;
// Now we can return this page, and it can be reused in the scope of this request.
_bufferScope.ReturnSegment(otherPage.Buffer);
}
else
{
// Otherwise, let's just take the the page from the other buffer.
Pages.Add(otherPage);
}
}
otherBuffer.Clear();
return this;
}
@ -86,35 +126,37 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
private void AppendValue(ViewBufferValue value)
{
ViewBufferValue[] segment;
if (BufferSegments == null)
var page = GetCurrentPage();
page.Append(value);
}
private ViewBufferPage GetCurrentPage()
{
ViewBufferPage page;
if (Pages.Count == 0)
{
BufferSegments = new List<ViewBufferValue[]>(1);
segment = _bufferScope.GetSegment();
BufferSegments.Add(segment);
page = new ViewBufferPage(_bufferScope.GetSegment());
Pages.Add(page);
}
else
{
segment = BufferSegments[BufferSegments.Count - 1];
if (CurrentCount == segment.Length)
page = Pages[Pages.Count - 1];
if (page.IsFull)
{
segment = _bufferScope.GetSegment();
BufferSegments.Add(segment);
CurrentCount = 0;
page = new ViewBufferPage(_bufferScope.GetSegment());
Pages.Add(page);
}
}
segment[CurrentCount] = value;
CurrentCount++;
return page;
}
/// <inheritdoc />
public IHtmlContentBuilder Clear()
{
if (BufferSegments != null)
if (Pages != null)
{
CurrentCount = 0;
BufferSegments = null;
Pages.Clear();
}
return this;
@ -123,7 +165,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
/// <inheritdoc />
public void WriteTo(TextWriter writer, HtmlEncoder encoder)
{
if (BufferSegments == null)
if (Pages == null)
{
return;
}
@ -135,14 +177,12 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
return;
}
for (var i = 0; i < BufferSegments.Count; i++)
for (var i = 0; i < Pages.Count; i++)
{
var segment = BufferSegments[i];
var count = i == BufferSegments.Count - 1 ? CurrentCount : segment.Length;
for (var j = 0; j < count; j++)
var page = Pages[i];
for (var j = 0; j < page.Count; j++)
{
var value = segment[j];
var value = page.Buffer[j];
var valueAsString = value.Value as string;
if (valueAsString != null)
@ -169,7 +209,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
/// <returns>A <see cref="Task"/> which will complete once content has been written.</returns>
public async Task WriteToAsync(TextWriter writer, HtmlEncoder encoder)
{
if (BufferSegments == null)
if (Pages == null)
{
return;
}
@ -181,14 +221,12 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
return;
}
for (var i = 0; i < BufferSegments.Count; i++)
for (var i = 0; i < Pages.Count; i++)
{
var segment = BufferSegments[i];
var count = i == BufferSegments.Count - 1 ? CurrentCount : segment.Length;
for (var j = 0; j < count; j++)
var page = Pages[i];
for (var j = 0; j < page.Count; j++)
{
var value = segment[j];
var value = page.Buffer[j];
var valueAsString = value.Value as string;
if (valueAsString != null)
@ -208,6 +246,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
if (valueAsHtmlContent != null)
{
valueAsHtmlContent.WriteTo(writer, encoder);
await writer.FlushAsync();
continue;
}
}

23
src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewBufferPage.cs Normal file
View File

@ -0,0 +1,23 @@
// 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 Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
{
public class ViewBufferPage
{
public ViewBufferPage(ViewBufferValue[] buffer)
{
Buffer = buffer;
}
public ViewBufferValue[] Buffer { get; }
public int Capacity => Buffer.Length;
public int Count { get; set; }
public bool IsFull => Count == Capacity;
public void Append(ViewBufferValue value) => Buffer[Count++] = value;
}
}

211
src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewBufferTextWriter.cs Normal file
View File

@ -0,0 +1,211 @@
// 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.Buffers;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Threading.Tasks;
namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
{
public class ViewBufferTextWriter : TextWriter
{
public const int PageSize = 1024;
private readonly TextWriter _inner;
private readonly List<char[]> _pages;
private readonly ArrayPool<char> _pool;
private int _currentPage;
private int _currentIndex; // The next 'free' character
public ViewBufferTextWriter(ArrayPool<char> pool, TextWriter inner)
{
_pool = pool;
_inner = inner;
_pages = new List<char[]>();
}
public override Encoding Encoding => _inner.Encoding;
public override void Flush()
{
// Don't do anything. We'll call FlushAsync.
}
public override async Task FlushAsync()
{
if (_pages.Count == 0)
{
return;
}
for (var i = 0; i <= _currentPage; i++)
{
var page = _pages[i];
var count = i == _currentPage ? _currentIndex : page.Length;
if (count > 0)
{
await _inner.WriteAsync(page, 0, count);
}
}
// Return all but one of the pages. This way if someone writes a large chunk of
// content, we can return those buffers and avoid holding them for the whole
// page's lifetime.
for (var i = _pages.Count - 1; i > 0; i--)
{
var page = _pages[i];
try
{
_pages.RemoveAt(i);
}
finally
{
_pool.Return(page);
}
}
_currentPage = 0;
_currentIndex = 0;
}
public override void Write(char value)
{
var page = GetCurrentPage();
page[_currentIndex++] = value;
}
public override void Write(char[] buffer)
{
Write(buffer, 0, buffer.Length);
}
public override void Write(char[] buffer, int index, int count)
{
while (count > 0)
{
var page = GetCurrentPage();
var copyLength = Math.Min(count, page.Length - _currentIndex);
Debug.Assert(copyLength > 0);
Array.Copy(
buffer,
index,
page,
_currentIndex,
copyLength);
_currentIndex += copyLength;
index += copyLength;
count -= copyLength;
}
}
public override void Write(string value)
{
var index = 0;
var count = value.Length;
while (count > 0)
{
var page = GetCurrentPage();
var copyLength = Math.Min(count, page.Length - _currentIndex);
Debug.Assert(copyLength > 0);
value.CopyTo(
index,
page,
_currentIndex,
copyLength);
_currentIndex += copyLength;
index += copyLength;
count -= copyLength;
}
}
public override Task WriteAsync(char value)
{
return _inner.WriteAsync(value);
}
public override Task WriteAsync(char[] buffer, int index, int count)
{
return _inner.WriteAsync(buffer, index, count);
}
public override Task WriteAsync(string value)
{
return _inner.WriteAsync(value);
}
private char[] GetCurrentPage()
{
char[] page = null;
if (_pages.Count == 0)
{
Debug.Assert(_currentPage == 0);
Debug.Assert(_currentIndex == 0);
try
{
page = _pool.Rent(PageSize);
_pages.Add(page);
}
catch when (page != null)
{
_pool.Return(page);
throw;
}
return page;
}
Debug.Assert(_pages.Count > _currentPage);
page = _pages[_currentPage];
if (_currentIndex == page.Length)
{
// Current page is full.
_currentPage++;
_currentIndex = 0;
if (_pages.Count == _currentPage)
{
try
{
page = _pool.Rent(PageSize);
_pages.Add(page);
}
catch when (page != null)
{
_pool.Return(page);
throw;
}
}
}
return page;
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
for (var i = 0; i < _pages.Count; i++)
{
_pool.Return(_pages[i]);
}
_pages.Clear();
}
}
}

26
src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewBufferValue.cs
View File

@ -1,6 +1,9 @@
// 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.Diagnostics;
using System.IO;
using System.Text.Encodings.Web;
using Microsoft.AspNetCore.Html;
namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
@ -8,6 +11,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
/// <summary>
/// Encapsulates a string or <see cref="IHtmlContent"/> value.
/// </summary>
[DebuggerDisplay("{DebuggerToString()}")]
public struct ViewBufferValue
{
/// <summary>
@ -32,5 +36,27 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
/// Gets the value.
/// </summary>
public object Value { get; }
private string DebuggerToString()
{
using (var writer = new StringWriter())
{
var valueAsString = Value as string;
if (valueAsString != null)
{
writer.Write(valueAsString);
return writer.ToString();
}
var valueAsContent = Value as IHtmlContent;
if (valueAsContent != null)
{
valueAsContent.WriteTo(writer, HtmlEncoder.Default);
return writer.ToString();
}
return "(null)";
}
}
}
}

9
test/Microsoft.AspNetCore.Mvc.Razor.Test/RazorTextWriterTest.cs
View File

@ -62,7 +62,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
writer.Write(2.718m);
// Assert
Assert.Null(buffer.BufferSegments);
Assert.Null(buffer.Pages);
foreach (var item in expected)
{
unbufferedWriter.Verify(v => v.Write(item), Times.Once());
@ -90,7 +90,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
await writer.WriteLineAsync(buffer1);
// Assert
Assert.Null(buffer.BufferSegments);
unbufferedWriter.Verify(v => v.Write('x'), Times.Once());
unbufferedWriter.Verify(v => v.Write(buffer1, 1, 2), Times.Once());
unbufferedWriter.Verify(v => v.Write(buffer1, 0, 4), Times.Once());
@ -117,7 +116,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
await writer.WriteLineAsync("gh");
// Assert
Assert.Null(buffer.BufferSegments);
unbufferedWriter.Verify(v => v.Write("a"), Times.Once());
unbufferedWriter.Verify(v => v.WriteLine("ab"), Times.Once());
unbufferedWriter.Verify(v => v.WriteAsync("ef"), Times.Once());
@ -160,7 +158,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
writer.WriteLine(3L);
// Assert
Assert.Null(buffer.BufferSegments);
unbufferedWriter.Verify(v => v.Write("False"), Times.Once());
unbufferedWriter.Verify(v => v.Write("1.1"), Times.Once());
unbufferedWriter.Verify(v => v.Write("3"), Times.Once());
@ -227,8 +224,8 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
private static object[] GetValues(ViewBuffer buffer)
{
return buffer.BufferSegments
.SelectMany(c => c)
return buffer.Pages
.SelectMany(c => c.Buffer)
.Select(d => d.Value)
.TakeWhile(d => d != null)
.ToArray();

16
test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Internal/TestViewBufferScope.cs
View File

@ -1,6 +1,10 @@
// 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;
namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
{
public class TestViewBufferScope : IViewBufferScope
@ -13,6 +17,18 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
_bufferSize = bufferSize;
}
public IList<ViewBufferValue[]> ReturnedBuffers { get; } = new List<ViewBufferValue[]>();
public ViewBufferValue[] GetSegment() => new ViewBufferValue[_bufferSize];
public void ReturnSegment(ViewBufferValue[] segment)
{
ReturnedBuffers.Add(segment);
}
public ViewBufferTextWriter CreateWriter(TextWriter writer)
{
return new ViewBufferTextWriter(ArrayPool<char>.Shared, writer);
}
}
}

252
test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Internal/ViewBufferTest.cs
View File

@ -1,6 +1,7 @@
// 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.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
@ -24,9 +25,9 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
buffer.Append("Hello world");
// Assert
var segment = Assert.Single(buffer.BufferSegments);
Assert.Equal(1, buffer.CurrentCount);
Assert.Equal("Hello world", segment[0].Value);
var page = Assert.Single(buffer.Pages);
Assert.Equal(1, page.Count);
Assert.Equal("Hello world", page.Buffer[0].Value);
}
[Fact]
@ -40,9 +41,9 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
buffer.AppendHtml(content);
// Assert
var segment = Assert.Single(buffer.BufferSegments);
Assert.Equal(1, buffer.CurrentCount);
Assert.Same(content, segment[0].Value);
var page = Assert.Single(buffer.Pages);
Assert.Equal(1, page.Count);
Assert.Same(content, page.Buffer[0].Value);
}
[Fact]
@ -56,14 +57,14 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
buffer.AppendHtml(value);
// Assert
var segment = Assert.Single(buffer.BufferSegments);
Assert.Equal(1, buffer.CurrentCount);
var htmlString = Assert.IsType<HtmlString>(segment[0].Value);
var page = Assert.Single(buffer.Pages);
Assert.Equal(1, page.Count);
var htmlString = Assert.IsType<HtmlString>(page.Buffer[0].Value);
Assert.Equal("Hello world", htmlString.ToString());
}
[Fact]
public void Append_CreatesNewSegments_WhenCurrentSegmentIsFull()
public void Append_CreatesNewPages_WhenCurrentPageIsFull()
{
// Arrange
var buffer = new ViewBuffer(new TestViewBufferScope(), "some-name");
@ -78,12 +79,12 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
buffer.Append("world");
// Assert
Assert.Equal(2, buffer.CurrentCount);
Assert.Collection(buffer.BufferSegments,
segment => Assert.Equal(expected, segment.Select(v => v.Value)),
segment =>
Assert.Equal(2, buffer.Pages.Count);
Assert.Collection(buffer.Pages,
page => Assert.Equal(expected, page.Buffer.Select(v => v.Value)),
page =>
{
var array = segment;
var array = page.Buffer;
Assert.Equal("Hello", array[0].Value);
Assert.Equal("world", array[1].Value);
});
@ -106,9 +107,9 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
buffer.Append("world");
// Assert
var segment = Assert.Single(buffer.BufferSegments);
Assert.Equal(1, buffer.CurrentCount);
Assert.Equal("world", segment[0].Value);
var page = Assert.Single(buffer.Pages);
Assert.Equal(1, page.Count);
Assert.Equal("world", page.Buffer[0].Value);
}
[Fact]
@ -224,5 +225,220 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
// Assert
Assert.Equal(expected, writer.ToString());
}
[Fact]
public void AppendHtml_ViewBuffer_TakesPage_IfOriginalIsEmpty()
{
// Arrange
var scope = new TestViewBufferScope(4);
var original = new ViewBuffer(scope, "original");
var other = new ViewBuffer(scope, "other");
other.Append("Hi");
var page = other.Pages[0];
// Act
original.AppendHtml(other);
// Assert
Assert.Empty(other.Pages); // Page was taken
Assert.Same(page, Assert.Single(original.Pages));
}
[Fact]
public void AppendHtml_ViewBuffer_TakesPage_IfCurrentPageInOriginalIsFull()
{
// Arrange
var scope = new TestViewBufferScope(4);
var original = new ViewBuffer(scope, "original");
var other = new ViewBuffer(scope, "other");
for (var i = 0; i < 4; i++)
{
original.Append($"original-{i}");
}
other.Append("Hi");
var page = other.Pages[0];
// Act
original.AppendHtml(other);
// Assert
Assert.Empty(other.Pages); // Page was taken
Assert.Equal(2, original.Pages.Count);
Assert.Same(page, original.Pages[1]);
}
[Fact]
public void AppendHtml_ViewBuffer_TakesPage_IfCurrentPageDoesNotHaveCapacity()
{
// Arrange
var scope = new TestViewBufferScope(4);
var original = new ViewBuffer(scope, "original");
var other = new ViewBuffer(scope, "other");
for (var i = 0; i < 3; i++)
{
original.Append($"original-{i}");
}
// With two items, we'd try to copy the items, but there's no room in the current page.
// So we just take over the page.
for (var i = 0; i < 2; i++)
{
other.Append($"other-{i}");
}
var page = other.Pages[0];
// Act
original.AppendHtml(other);
// Assert
Assert.Empty(other.Pages); // Page was taken
Assert.Equal(2, original.Pages.Count);
Assert.Same(page, original.Pages[1]);
}
[Fact]
public void AppendHtml_ViewBuffer_CopiesItems_IfCurrentPageHasRoom()
{
// Arrange
var scope = new TestViewBufferScope(4);
var original = new ViewBuffer(scope, "original");
var other = new ViewBuffer(scope, "other");
for (var i = 0; i < 2; i++)
{
original.Append($"original-{i}");
}
// With two items, this is half full so we try to copy the items.
for (var i = 0; i < 2; i++)
{
other.Append($"other-{i}");
}
var page = other.Pages[0];
// Act
original.AppendHtml(other);
// Assert
Assert.Empty(other.Pages); // Other is cleared
Assert.Contains(page.Buffer, scope.ReturnedBuffers); // Buffer was returned
Assert.Collection(
Assert.Single(original.Pages).Buffer,
item => Assert.Equal("original-0", item.Value),
item => Assert.Equal("original-1", item.Value),
item => Assert.Equal("other-0", item.Value),
item => Assert.Equal("other-1", item.Value));
}
[Fact]
public void AppendHtml_ViewBuffer_CanAddToTakenPage()
{
// Arrange
var scope = new TestViewBufferScope(4);
var original = new ViewBuffer(scope, "original");
var other = new ViewBuffer(scope, "other");
for (var i = 0; i < 3; i++)
{
original.Append($"original-{i}");
}
// More than half full, so we take the page
for (var i = 0; i < 3; i++)
{
other.Append($"other-{i}");
}
var page = other.Pages[0];
original.AppendHtml(other);
// Act
original.Append("after-merge");
// Assert
Assert.Empty(other.Pages); // Other is cleared
Assert.Equal(2, original.Pages.Count);
Assert.Collection(
original.Pages[0].Buffer,
item => Assert.Equal("original-0", item.Value),
item => Assert.Equal("original-1", item.Value),
item => Assert.Equal("original-2", item.Value),
item => Assert.Null(item.Value));
Assert.Collection(
original.Pages[1].Buffer,
item => Assert.Equal("other-0", item.Value),
item => Assert.Equal("other-1", item.Value),
item => Assert.Equal("other-2", item.Value),
item => Assert.Equal("after-merge", item.Value));
}
[Fact]
public void AppendHtml_ViewBuffer_MultiplePages()
{
// Arrange
var scope = new TestViewBufferScope(4);
var original = new ViewBuffer(scope, "original");
var other = new ViewBuffer(scope, "other");
for (var i = 0; i < 2; i++)
{
original.Append($"original-{i}");
}
for (var i = 0; i < 9; i++)
{
other.Append($"other-{i}");
}
var pages = new List<ViewBufferPage>(other.Pages);
// Act
original.AppendHtml(other);
// Assert
Assert.Empty(other.Pages); // Other is cleared
Assert.Equal(4, original.Pages.Count);
Assert.Collection(
original.Pages[0].Buffer,
item => Assert.Equal("original-0", item.Value),
item => Assert.Equal("original-1", item.Value),
item => Assert.Null(item.Value),
item => Assert.Null(item.Value));
Assert.Collection(
original.Pages[1].Buffer,
item => Assert.Equal("other-0", item.Value),
item => Assert.Equal("other-1", item.Value),
item => Assert.Equal("other-2", item.Value),
item => Assert.Equal("other-3", item.Value));
Assert.Collection(
original.Pages[2].Buffer,
item => Assert.Equal("other-4", item.Value),
item => Assert.Equal("other-5", item.Value),
item => Assert.Equal("other-6", item.Value),
item => Assert.Equal("other-7", item.Value));
Assert.Collection(
original.Pages[3].Buffer,
item => Assert.Equal("other-8", item.Value),
item => Assert.Null(item.Value),
item => Assert.Null(item.Value),
item => Assert.Null(item.Value));
}
}
}

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test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/ViewBufferTextWriterTest.cs Normal file
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// 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;
using System.Threading.Tasks;
using Xunit;
namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
{
public class ViewBufferTextWriterTest
{
private static readonly char[] Content;
static ViewBufferTextWriterTest()
{
Content = new char[4 * ViewBufferTextWriter.PageSize];
for (var i = 0; i < Content.Length; i++)
{
Content[i] = (char)((i % 26) + 'A');
}
}
[Fact]
public async Task Write_Char()
{
// Arrange
var pool = new TestArrayPool();
var inner = new StringWriter();
var writer = new ViewBufferTextWriter(pool, inner);
// Act
for (var i = 0; i < Content.Length; i++)
{
writer.Write(Content[i]);
}
await writer.FlushAsync();
// Assert
Assert.Equal<char>(Content, inner.ToString().ToCharArray());
}
[Fact]
public async Task Write_CharArray()
{
// Arrange
var pool = new TestArrayPool();
var inner = new StringWriter();
var writer = new ViewBufferTextWriter(pool, inner);
// These numbers chosen to hit boundary conditions in buffer lengths
Assert.Equal(4096, Content.Length); // Update these numbers if this changes.
var chunkSizes = new int[] { 3, 1021, 1023, 1023, 1, 1, 1024 };
// Act
var offset = 0;
foreach (var chunkSize in chunkSizes)
{
var chunk = new char[chunkSize];
for (var j = 0; j < chunkSize; j++)
{
chunk[j] = Content[offset + j];
}
writer.Write(chunk);
offset += chunkSize;
}
await writer.FlushAsync();
// Assert
var array = inner.ToString().ToCharArray();
for (var i = 0; i < Content.Length; i++)
{
Assert.Equal(Content[i], array[i]);
}
Assert.Equal<char>(Content, inner.ToString().ToCharArray());
}
[Fact]
public async Task Write_CharArray_Bounded()
{
// Arrange
var pool = new TestArrayPool();
var inner = new StringWriter();
var writer = new ViewBufferTextWriter(pool, inner);
// These numbers chosen to hit boundary conditions in buffer lengths
Assert.Equal(4096, Content.Length); // Update these numbers if this changes.
var chunkSizes = new int[] { 3, 1021, 1023, 1023, 1, 1, 1024 };
// Act
var offset = 0;
foreach (var chunkSize in chunkSizes)
{
writer.Write(Content, offset, chunkSize);
offset += chunkSize;
}
await writer.FlushAsync();
// Assert
Assert.Equal<char>(Content, inner.ToString().ToCharArray());
}
[Fact]
public async Task Write_String()
{
// Arrange
var pool = new TestArrayPool();
var inner = new StringWriter();
var writer = new ViewBufferTextWriter(pool, inner);
// These numbers chosen to hit boundary conditions in buffer lengths
Assert.Equal(4096, Content.Length); // Update these numbers if this changes.
var chunkSizes = new int[] { 3, 1021, 1023, 1023, 1, 1, 1024 };
// Act
var offset = 0;
foreach (var chunkSize in chunkSizes)
{
var chunk = new string(Content, offset, chunkSize);
writer.Write(chunk);
offset += chunkSize;
}
await writer.FlushAsync();
// Assert
Assert.Equal<char>(Content, inner.ToString().ToCharArray());
}
[Fact]
public async Task FlushAsync_ReturnsPages()
{
// Arrange
var pool = new TestArrayPool();
var inner = new StringWriter();
var writer = new ViewBufferTextWriter(pool, inner);
for (var i = 0; i < Content.Length; i++)
{
writer.Write(Content[i]);
}
// Act
await writer.FlushAsync();
// Assert
Assert.Equal(3, pool.Returned.Count);
}
private class TestArrayPool: ArrayPool<char>
{
public IList<char[]> Returned { get; } = new List<char[]>();
public override char[] Rent(int minimumLength)
{
return new char[minimumLength];
}
public override void Return(char[] buffer, bool clearArray = false)
{
Returned.Add(buffer);
}
}
}
}