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SimonCropp merged 2 commits into from
Jun 27, 2026
Merged

Align stream wrappers with the dotnet 11 implementation (follow up to #562) #563

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Align stream wrappers with the dotnet 11 implementation (follow-up to…
SimonCropp Jun 27, 2026
894697a
Update Directory.Build.props
SimonCropp Jun 27, 2026
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84 changes: 42 additions & 42 deletions assemblySize.include.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,51 +2,51 @@

| | Empty Assembly | With Polyfill | Diff | Ensure | ArgumentExceptions | StringInterpolation | Nullability |
|----------------|----------------|---------------|-----------|-----------|--------------------|---------------------|-------------|
| netstandard2.0 | 8.0KB | 347.5KB | +339.5KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| netstandard2.1 | 8.5KB | 302.0KB | +293.5KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| net461 | 8.5KB | 346.5KB | +338.0KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| net462 | 7.0KB | 350.0KB | +343.0KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| net47 | 7.0KB | 349.5KB | +342.5KB | +9.0KB | +6.5KB | +9.5KB | +14.0KB |
| net471 | 8.5KB | 349.0KB | +340.5KB | +9.0KB | +6.0KB | +9.0KB | +13.5KB |
| net472 | 8.5KB | 347.5KB | +339.0KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| net48 | 8.5KB | 347.5KB | +339.0KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| net481 | 8.5KB | 347.5KB | +339.0KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netcoreapp2.0 | 9.0KB | 323.5KB | +314.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netcoreapp2.1 | 9.0KB | 304.5KB | +295.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netcoreapp2.2 | 9.0KB | 304.5KB | +295.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netcoreapp3.0 | 9.5KB | 297.0KB | +287.5KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| netcoreapp3.1 | 9.5KB | 295.5KB | +286.0KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| net5.0 | 9.5KB | 259.0KB | +249.5KB | +9.0KB | +6.5KB | +9.5KB | +14.0KB |
| net6.0 | 10.0KB | 201.0KB | +191.0KB | +10.0KB | +6.5KB | +512bytes | +3.5KB |
| net7.0 | 10.0KB | 163.5KB | +153.5KB | +9.0KB | +5.5KB | +512bytes | +3.0KB |
| net8.0 | 9.5KB | 135.0KB | +125.5KB | +8.0KB | | +512bytes | +3.0KB |
| net9.0 | 9.5KB | 88.5KB | +79.0KB | +8.5KB | | +512bytes | +3.5KB |
| net10.0 | 10.0KB | 66.0KB | +56.0KB | +9.0KB | | +512bytes | +3.5KB |
| net11.0 | 10.0KB | 27.0KB | +17.0KB | +9.0KB | | +1.0KB | +3.5KB |
| netstandard2.0 | 8.0KB | 351.5KB | +343.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netstandard2.1 | 8.5KB | 306.0KB | +297.5KB | +8.5KB | +6.0KB | +9.0KB | +13.5KB |
| net461 | 8.5KB | 350.0KB | +341.5KB | +9.0KB | +6.5KB | +9.5KB | +14.0KB |
| net462 | 7.0KB | 353.5KB | +346.5KB | +9.0KB | +6.5KB | +9.5KB | +13.5KB |
| net47 | 7.0KB | 353.5KB | +346.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| net471 | 8.5KB | 352.5KB | +344.0KB | +9.0KB | +6.5KB | +9.5KB | +14.0KB |
| net472 | 8.5KB | 351.5KB | +343.0KB | +9.0KB | +6.0KB | +9.0KB | +13.5KB |
| net48 | 8.5KB | 351.5KB | +343.0KB | +9.0KB | +6.0KB | +9.0KB | +13.5KB |
| net481 | 8.5KB | 351.5KB | +343.0KB | +9.0KB | +6.0KB | +9.0KB | +13.5KB |
| netcoreapp2.0 | 9.0KB | 327.5KB | +318.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netcoreapp2.1 | 9.0KB | 308.0KB | +299.0KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| netcoreapp2.2 | 9.0KB | 308.0KB | +299.0KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| netcoreapp3.0 | 9.5KB | 301.0KB | +291.5KB | +9.0KB | +6.5KB | +9.0KB | +13.5KB |
| netcoreapp3.1 | 9.5KB | 299.0KB | +289.5KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| net5.0 | 9.5KB | 263.0KB | +253.5KB | +9.0KB | +6.5KB | +9.0KB | +14.0KB |
| net6.0 | 10.0KB | 205.0KB | +195.0KB | +9.5KB | +6.5KB | +512bytes | +3.0KB |
| net7.0 | 10.0KB | 167.0KB | +157.0KB | +9.5KB | +5.5KB | +1.0KB | +3.5KB |
| net8.0 | 9.5KB | 138.5KB | +129.0KB | +8.5KB | +512bytes | +512bytes | +3.5KB |
| net9.0 | 9.5KB | 92.5KB | +83.0KB | +8.5KB | | +512bytes | +3.5KB |
| net10.0 | 10.0KB | 70.0KB | +60.0KB | +9.0KB | | +512bytes | +3.5KB |
| net11.0 | 10.0KB | 31.5KB | +21.5KB | +9.0KB | | +512bytes | +3.5KB |


### Assembly Sizes with EmbedUntrackedSources

| | Empty Assembly | With Polyfill | Diff | Ensure | ArgumentExceptions | StringInterpolation | Nullability |
|----------------|----------------|---------------|-----------|-----------|--------------------|---------------------|-------------|
| netstandard2.0 | 8.0KB | 507.8KB | +499.8KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| netstandard2.1 | 8.5KB | 436.6KB | +428.1KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| net461 | 8.5KB | 507.8KB | +499.3KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| net462 | 7.0KB | 511.3KB | +504.3KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| net47 | 7.0KB | 510.6KB | +503.6KB | +16.7KB | +8.2KB | +14.4KB | +19.4KB |
| net471 | 8.5KB | 509.7KB | +501.2KB | +16.7KB | +7.7KB | +13.9KB | +18.9KB |
| net472 | 8.5KB | 507.2KB | +498.7KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| net48 | 8.5KB | 507.2KB | +498.7KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| net481 | 8.5KB | 507.2KB | +498.7KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netcoreapp2.0 | 9.0KB | 473.2KB | +464.2KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netcoreapp2.1 | 9.0KB | 442.8KB | +433.8KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netcoreapp2.2 | 9.0KB | 442.8KB | +433.8KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netcoreapp3.0 | 9.5KB | 426.5KB | +417.0KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| netcoreapp3.1 | 9.5KB | 425.0KB | +415.5KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| net5.0 | 9.5KB | 370.3KB | +360.8KB | +16.7KB | +8.2KB | +14.4KB | +19.4KB |
| net6.0 | 10.0KB | 292.3KB | +282.3KB | +17.7KB | +8.2KB | +1.1KB | +4.2KB |
| net7.0 | 10.0KB | 236.2KB | +226.2KB | +16.6KB | +6.9KB | +1.1KB | +3.7KB |
| net8.0 | 9.5KB | 192.7KB | +183.2KB | +15.5KB | +299bytes | +1.1KB | +3.7KB |
| net9.0 | 9.5KB | 125.2KB | +115.7KB | +16.0KB | | +1.1KB | +4.2KB |
| net10.0 | 10.0KB | 94.4KB | +84.4KB | +16.5KB | | +1.1KB | +4.2KB |
| net11.0 | 10.0KB | 41.3KB | +31.3KB | +16.5KB | | +1.6KB | +4.2KB |
| netstandard2.0 | 8.0KB | 513.0KB | +505.0KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netstandard2.1 | 8.5KB | 441.7KB | +433.2KB | +16.2KB | +7.7KB | +13.9KB | +18.9KB |
| net461 | 8.5KB | 512.5KB | +504.0KB | +16.7KB | +8.2KB | +14.4KB | +19.4KB |
| net462 | 7.0KB | 516.0KB | +509.0KB | +16.7KB | +8.2KB | +14.4KB | +18.9KB |
| net47 | 7.0KB | 515.8KB | +508.8KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| net471 | 8.5KB | 514.4KB | +505.9KB | +16.7KB | +8.2KB | +14.4KB | +19.4KB |
| net472 | 8.5KB | 512.4KB | +503.9KB | +16.7KB | +7.7KB | +13.9KB | +18.9KB |
| net48 | 8.5KB | 512.4KB | +503.9KB | +16.7KB | +7.7KB | +13.9KB | +18.9KB |
| net481 | 8.5KB | 512.4KB | +503.9KB | +16.7KB | +7.7KB | +13.9KB | +18.9KB |
| netcoreapp2.0 | 9.0KB | 478.4KB | +469.4KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netcoreapp2.1 | 9.0KB | 447.4KB | +438.4KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| netcoreapp2.2 | 9.0KB | 447.4KB | +438.4KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| netcoreapp3.0 | 9.5KB | 431.6KB | +422.1KB | +16.7KB | +8.2KB | +13.9KB | +18.9KB |
| netcoreapp3.1 | 9.5KB | 429.6KB | +420.1KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| net5.0 | 9.5KB | 375.4KB | +365.9KB | +16.7KB | +8.2KB | +13.9KB | +19.4KB |
| net6.0 | 10.0KB | 297.4KB | +287.4KB | +17.2KB | +8.2KB | +1.1KB | +3.7KB |
| net7.0 | 10.0KB | 240.8KB | +230.8KB | +17.1KB | +6.9KB | +1.6KB | +4.2KB |
| net8.0 | 9.5KB | 197.3KB | +187.8KB | +16.0KB | +811bytes | +1.1KB | +4.2KB |
| net9.0 | 9.5KB | 130.3KB | +120.8KB | +16.0KB | | +1.1KB | +4.2KB |
| net10.0 | 10.0KB | 99.5KB | +89.5KB | +16.5KB | | +1.1KB | +4.2KB |
| net11.0 | 10.0KB | 46.9KB | +36.9KB | +16.5KB | | +1.1KB | +4.2KB |
2 changes: 1 addition & 1 deletion src/Directory.Build.props
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@
<Project>
<PropertyGroup>
<NoWarn>CS1591;NETSDK1138;NU1901;NU1902;NU1903;CA1822;CA1847;CA1861;NU1510;NU1608;NU1109</NoWarn>
<Version>10.11.0</Version>
<Version>10.11.1</Version>
<AssemblyVersion>1.0.0</AssemblyVersion>
<PackageTags>Polyfill</PackageTags>
<DisableImplicitNamespaceImports>true</DisableImplicitNamespaceImports>
Expand Down
162 changes: 149 additions & 13 deletions src/Polyfill/ReadOnlySequenceStream.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ namespace System.Buffers;
using System.IO;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;

Expand All @@ -46,15 +47,22 @@ sealed class ReadOnlySequenceStream :
Stream
{
ReadOnlySequence<byte> sequence;
// Incremental cursor into the sequence's segments, kept in sync with the absolute position.
// Advancing from this cursor avoids re-walking the segment list from the start on every read.
SequencePosition cursor;
long position;
bool disposed;

/// <summary>
/// Initializes a new instance of the <see cref="ReadOnlySequenceStream"/> class over the specified <see cref="ReadOnlySequence{Byte}"/>.
/// </summary>
//Link: https://learn.microsoft.com/en-us/dotnet/api/system.buffers.readonlysequencestream.-ctor?view=net-11.0
public ReadOnlySequenceStream(ReadOnlySequence<byte> source) =>
public ReadOnlySequenceStream(ReadOnlySequence<byte> source)
{
sequence = source;
cursor = source.Start;
position = 0;
}

/// <inheritdoc/>
public override bool CanRead => !disposed;
Expand Down Expand Up @@ -91,7 +99,7 @@ public override long Position
throw new ArgumentOutOfRangeException(nameof(value));
}

position = value;
MoveTo(value);
}
}

Expand All @@ -106,14 +114,15 @@ public override int Read(byte[] buffer, int offset, int count)
return 0;
}

var remaining = sequence.Slice(position);
var remaining = sequence.Slice(cursor);
var toRead = (int)Math.Min(remaining.Length, count);
if (toRead <= 0)
{
return 0;
}

remaining.Slice(0, toRead).CopyTo(buffer.AsSpan(offset, toRead));
cursor = sequence.GetPosition(toRead, cursor);
position += toRead;
return toRead;
}
Expand All @@ -128,7 +137,8 @@ public override int ReadByte()
return -1;
}

var result = sequence.Slice(position, 1).First.Span[0];
var result = sequence.Slice(cursor, 1).First.Span[0];
cursor = sequence.GetPosition(1, cursor);
position++;
return result;
}
Expand All @@ -137,20 +147,14 @@ public override int ReadByte()
public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
{
GuardRange(buffer, offset, count);
ThrowIfDisposed();

if (cancellationToken.IsCancellationRequested)
{
return Task.FromCanceled<int>(cancellationToken);
}

try
{
return Task.FromResult(Read(buffer, offset, count));
}
catch (Exception exception)
{
return Task.FromException<int>(exception);
}
return Task.FromResult(Read(buffer, offset, count));
}

/// <inheritdoc/>
Expand All @@ -166,16 +170,147 @@ public override long Seek(long offset, SeekOrigin origin)
_ => throw new ArgumentException("Invalid seek origin.", nameof(origin))
};

if (offset > long.MaxValue - basePosition)
{
throw new ArgumentOutOfRangeException(nameof(offset));
}

var newPosition = basePosition + offset;
if (newPosition < 0)
{
throw new IOException("An attempt was made to move the position before the beginning of the stream.");
}

position = newPosition;
MoveTo(newPosition);
return position;
}

// Repositions the segment cursor to the given absolute position, advancing forward from the
// current cursor when possible and only walking from the start for backward jumps.
void MoveTo(long value)
{
if (value >= sequence.Length)
{
cursor = sequence.End;
}
else if (value >= position)
{
cursor = sequence.GetPosition(value - position, cursor);
}
else
{
cursor = sequence.GetPosition(value, sequence.Start);
}

position = value;
}

#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
// Stream.CopyTo(Stream, int) only became virtual in netcoreapp2.1/netstandard2.1. On older
// targets it cannot be overridden, so the base implementation (which routes through the
// cursor-based Read above) is used instead.
/// <inheritdoc/>
public override void CopyTo(Stream destination, int bufferSize)
{
GuardCopyTo(destination, bufferSize);
ThrowIfDisposed();

if (position >= sequence.Length)
{
return;
}

foreach (var segment in sequence.Slice(cursor))
{
destination.Write(segment.Span);
}

cursor = sequence.End;
position = sequence.Length;
}
#endif

/// <inheritdoc/>
public override Task CopyToAsync(Stream destination, int bufferSize, CancellationToken cancellationToken)
{
GuardCopyTo(destination, bufferSize);
ThrowIfDisposed();

if (cancellationToken.IsCancellationRequested)
{
return Task.FromCanceled(cancellationToken);
}

if (position >= sequence.Length)
{
return Task.CompletedTask;
}

return CopyToAsyncCore(destination, cancellationToken);
}

async Task CopyToAsyncCore(Stream destination, CancellationToken cancellationToken)
{
foreach (var segment in sequence.Slice(cursor))
{
await WriteSegmentAsync(destination, segment, cancellationToken).ConfigureAwait(false);
}

cursor = sequence.End;
position = sequence.Length;
}

static Task WriteSegmentAsync(Stream destination, ReadOnlyMemory<byte> segment, CancellationToken cancellationToken)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
return destination.WriteAsync(segment, cancellationToken).AsTask();
#else
var array = GetSegmentArray(segment, out var offset, out var count);
return destination.WriteAsync(array, offset, count, cancellationToken);
#endif
}

#if !(NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER)
static byte[] GetSegmentArray(ReadOnlyMemory<byte> segment, out int offset, out int count)
{
if (MemoryMarshal.TryGetArray(segment, out var arraySegment) &&
arraySegment.Array != null)
{
offset = arraySegment.Offset;
count = arraySegment.Count;
return arraySegment.Array;
}

var array = segment.ToArray();
offset = 0;
count = array.Length;
return array;
}
#endif

static void GuardCopyTo(Stream destination, int bufferSize)
{
if (destination == null)
{
throw new ArgumentNullException(nameof(destination));
}

if (bufferSize <= 0)
{
throw new ArgumentOutOfRangeException(nameof(bufferSize));
}

if (!destination.CanWrite)
{
if (destination.CanRead)
{
throw new NotSupportedException("Stream does not support writing.");
}

throw new ObjectDisposedException(null, "Cannot access a closed stream.");
}
}

/// <inheritdoc/>
public override void Flush()
{
Expand All @@ -198,6 +333,7 @@ protected override void Dispose(bool disposing)
{
disposed = true;
sequence = default;
cursor = default;
base.Dispose(disposing);
}

Expand Down
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