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Actually fix the CopyToAsync this time (#24609) 

* Actually fix the CopyToAsync this time
- Hard code the 4K buffer length for CopyToAsync
- Write a test this time :D
This commit is contained in:
David Fowler 2020-08-05 21:11:57 -07:00 committed by GitHub
parent a28c2b62dc
commit ed5034eb8e
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2 changed files with 39 additions and 8 deletions
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7
src/Http/WebUtilities/src/FileBufferingReadStream.cs
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@ -363,6 +363,11 @@ namespace Microsoft.AspNetCore.WebUtilities
public override Task CopyToAsync(Stream destination, int bufferSize, CancellationToken cancellationToken)
{
// Set a minimum buffer size of 4K since the base Stream implementation has weird behavior when the stream is
// seekable *and* the length is 0 (it passes in a buffer size of 1).
// See https://github.com/dotnet/runtime/blob/222415c56c9ea73530444768c0e68413eb374f5d/src/libraries/System.Private.CoreLib/src/System/IO/Stream.cs#L164-L184
bufferSize = Math.Max(4096, bufferSize);
// If we're completed buffered then copy from the underlying source
if (_completelyBuffered)
{
@ -372,7 +377,7 @@ namespace Microsoft.AspNetCore.WebUtilities
async Task CopyToAsyncImpl()
{
// At least a 4K buffer
byte[] buffer = _bytePool.Rent(Math.Min(bufferSize, 4096));
byte[] buffer = _bytePool.Rent(bufferSize);
try
{
while (true)

40
src/Http/WebUtilities/test/FileBufferingReadStreamTests.cs
View File

@ -5,7 +5,6 @@ using System;
using System.Buffers;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Moq;
using Xunit;
@ -353,39 +352,49 @@ namespace Microsoft.AspNetCore.WebUtilities
[Fact]
public async Task CopyToAsyncWorks()
{
var data = Enumerable.Range(0, 1024).Select(b => (byte)b).Reverse().ToArray();
// 4K is the lower bound on buffer sizes
var bufferSize = 4096;
var mostExpectedWrites = 8;
var data = Enumerable.Range(0, bufferSize * mostExpectedWrites).Select(b => (byte)b).ToArray();
var inner = new MemoryStream(data);
using var stream = new FileBufferingReadStream(inner, 1024 * 1024, bufferLimit: null, GetCurrentDirectory());
var withoutBufferMs = new MemoryStream();
var withoutBufferMs = new NumberOfWritesMemoryStream();
await stream.CopyToAsync(withoutBufferMs);
var withBufferMs = new MemoryStream();
var withBufferMs = new NumberOfWritesMemoryStream();
stream.Position = 0;
await stream.CopyToAsync(withBufferMs);
Assert.Equal(data, withoutBufferMs.ToArray());
Assert.Equal(mostExpectedWrites, withoutBufferMs.NumberOfWrites);
Assert.Equal(data, withBufferMs.ToArray());
Assert.InRange(withBufferMs.NumberOfWrites, 1, mostExpectedWrites);
}
[Fact]
public async Task CopyToAsyncWorksWithFileThreshold()
{
var data = Enumerable.Range(0, 1024).Select(b => (byte)b).Reverse().ToArray();
// 4K is the lower bound on buffer sizes
var bufferSize = 4096;
var mostExpectedWrites = 8;
var data = Enumerable.Range(0, bufferSize * mostExpectedWrites).Select(b => (byte)b).Reverse().ToArray();
var inner = new MemoryStream(data);
using var stream = new FileBufferingReadStream(inner, 100, bufferLimit: null, GetCurrentDirectory());
var withoutBufferMs = new MemoryStream();
var withoutBufferMs = new NumberOfWritesMemoryStream();
await stream.CopyToAsync(withoutBufferMs);
var withBufferMs = new MemoryStream();
var withBufferMs = new NumberOfWritesMemoryStream();
stream.Position = 0;
await stream.CopyToAsync(withBufferMs);
Assert.Equal(data, withoutBufferMs.ToArray());
Assert.Equal(mostExpectedWrites, withoutBufferMs.NumberOfWrites);
Assert.Equal(data, withBufferMs.ToArray());
Assert.InRange(withBufferMs.NumberOfWrites, 1, mostExpectedWrites);
}
[Fact]
@ -486,5 +495,22 @@ namespace Microsoft.AspNetCore.WebUtilities
{
return AppContext.BaseDirectory;
}
private class NumberOfWritesMemoryStream : MemoryStream
{
public int NumberOfWrites { get; set; }
public override void Write(byte[] buffer, int offset, int count)
{
NumberOfWrites++;
base.Write(buffer, offset, count);
}
public override void Write(ReadOnlySpan<byte> source)
{
NumberOfWrites++;
base.Write(source);
}
}
}
}