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Introduce ScopedBuffer #415

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merged 8 commits into from
Feb 23, 2024
Merged

Introduce ScopedBuffer #415

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b0a5fe8
Add ScopedBuffer
iamcarbon Feb 22, 2024
215881d
Use scoped buffer (part 1)
iamcarbon Feb 22, 2024
8ad19dc
Optimize BplistReader.HandleDict
iamcarbon Feb 22, 2024
e76716a
Validate GetString parameters
iamcarbon Feb 22, 2024
a436552
Remove unused using statements
iamcarbon Feb 22, 2024
52c9b1f
Use NET8_0_OR_GREATER
iamcarbon Feb 22, 2024
337d235
Unify GetString logic
iamcarbon Feb 23, 2024
50d44e8
Clarify count range
iamcarbon Feb 23, 2024
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11 changes: 2 additions & 9 deletions MetadataExtractor/Formats/Apple/BplistReader.cs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,5 @@
// Copyright (c) Drew Noakes and contributors. All Rights Reserved. Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.

using System.Buffers;

namespace MetadataExtractor.Formats.Apple;

/// <summary>
Expand Down Expand Up @@ -123,12 +121,9 @@ static object HandleInt(ref BufferReader reader, byte marker)

static Dictionary<byte, byte> HandleDict(ref BufferReader reader, byte count)
{
var keyRefs = ArrayPool<byte>.Shared.Rent(count);
Span<byte> keyRefs = stackalloc byte[count]; // <= 255
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Could we convert the comment into a Debug.Assert(count <= 255) instead? It provides a little more safety and is clearer as far as documenting intent.

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I updated the comment to be clearer (count is an unsigned byte, with a safe range) -- no need for an assert. The comment saves a second when auditing the stackalloc call sites.


for (int j = 0; j < count; j++)
{
keyRefs[j] = reader.GetByte();
}
reader.GetBytes(keyRefs);

Dictionary<byte, byte> map = [];

Expand All @@ -137,8 +132,6 @@ static Dictionary<byte, byte> HandleDict(ref BufferReader reader, byte count)
map.Add(keyRefs[j], reader.GetByte());
}

ArrayPool<byte>.Shared.Return(keyRefs);

return map;
}

Expand Down
16 changes: 6 additions & 10 deletions MetadataExtractor/IO/BufferReader.Indexed.cs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
// Copyright (c) Drew Noakes and contributors. All Rights Reserved. Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.

using System.Buffers;
using System.Buffers.Binary;

namespace MetadataExtractor.IO;
Expand Down Expand Up @@ -178,6 +177,9 @@ public readonly double GetDouble64(int index)

public readonly string GetString(int index, int bytesRequested, Encoding encoding)
{
if (bytesRequested < 0)
throw new ArgumentOutOfRangeException(nameof(bytesRequested), "Must be 0 or greater");
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// This check is important on .NET Framework
if (bytesRequested is 0)
{
Expand All @@ -193,17 +195,11 @@ public readonly string GetString(int index, int bytesRequested, Encoding encodin
}
else
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Do we need the else block any more? Looks like the size check could be moved into a ternary conditional and the two blocks collapsed into one, as you've done elsewhere in the PR.

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unified the logic across all the readers. much tidier.

{
byte[] bytes = ArrayPool<byte>.Shared.Rent(bytesRequested);

Span<byte> span = bytes.AsSpan(0, bytesRequested);

GetBytes(index, span);

var s = encoding.GetString(span);
using var buffer = new ScopedBuffer(bytesRequested);

ArrayPool<byte>.Shared.Return(bytes);
GetBytes(index, buffer);

return s;
return encoding.GetString(buffer);
}
}

Expand Down
14 changes: 8 additions & 6 deletions MetadataExtractor/IO/BufferReader.Sequential.cs
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Expand Up @@ -114,17 +114,19 @@ public ulong GetUInt64()

public string GetString(int bytesRequested, Encoding encoding)
{
// This check is important on .NET Framework
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if (bytesRequested < 0)
throw new ArgumentOutOfRangeException(nameof(bytesRequested), "Must be 0 or greater");

if (bytesRequested is 0)
return "";

Span<byte> bytes = bytesRequested <= 256
? stackalloc byte[bytesRequested]
: new byte[bytesRequested];
using var buffer = bytesRequested <= 256
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? new ScopedBuffer(stackalloc byte[bytesRequested])
: new ScopedBuffer(bytesRequested);

GetBytes(bytes);
GetBytes(buffer);

return encoding.GetString(bytes);
return encoding.GetString(buffer);
}

public StringValue GetNullTerminatedStringValue(int maxLengthBytes, Encoding? encoding = null, bool moveToMaxLength = false)
Expand Down
17 changes: 6 additions & 11 deletions MetadataExtractor/IO/IndexedReader.cs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,5 @@
// Copyright (c) Drew Noakes and contributors. All Rights Reserved. Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.


using System.Buffers;
using System.Buffers.Binary;

namespace MetadataExtractor.IO
Expand Down Expand Up @@ -320,6 +318,9 @@ public double GetDouble64(int index)
/// <exception cref="IOException"/>
public string GetString(int index, int bytesRequested, Encoding encoding)
{
if (bytesRequested < 0)
throw new ArgumentOutOfRangeException(nameof(bytesRequested), "Must be 0 or greater");

// This check is important on .NET Framework
if (bytesRequested is 0)
{
Expand All @@ -335,17 +336,11 @@ public string GetString(int index, int bytesRequested, Encoding encoding)
}
else
{
byte[] bytes = ArrayPool<byte>.Shared.Rent(bytesRequested);

Span<byte> span = bytes.AsSpan(0, bytesRequested);

GetBytes(index, span);

var s = encoding.GetString(span);
using var buffer = new ScopedBuffer(bytesRequested);

ArrayPool<byte>.Shared.Return(bytes);
GetBytes(index, buffer);

return s;
return encoding.GetString(buffer);
}
}

Expand Down
43 changes: 43 additions & 0 deletions MetadataExtractor/IO/ScopedBuffer.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,43 @@
// Copyright (c) Drew Noakes and contributors. All Rights Reserved. Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.

using System.Buffers;

namespace MetadataExtractor.IO;

internal ref struct ScopedBuffer
{
private byte[]? _rentedBuffer;
private readonly Span<byte> _span;

public ScopedBuffer(int size)
{
_rentedBuffer = ArrayPool<byte>.Shared.Rent(size);
_span = _rentedBuffer.AsSpan(0, size);
}

public ScopedBuffer(Span<byte> span)
{
_span = span;
}

public readonly Span<byte> Span => _span;

public static implicit operator Span<byte>(ScopedBuffer bufferScope)
{
return bufferScope._span;
}

public static implicit operator ReadOnlySpan<byte>(ScopedBuffer bufferScope)
{
return bufferScope._span;
}

public void Dispose()
{
if (_rentedBuffer is null) return;

ArrayPool<byte>.Shared.Return(_rentedBuffer);

_rentedBuffer = null;
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}
}
16 changes: 6 additions & 10 deletions MetadataExtractor/IO/SequentialReader.cs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
// Copyright (c) Drew Noakes and contributors. All Rights Reserved. Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.

using System.Buffers;
using System.Buffers.Binary;

namespace MetadataExtractor.IO
Expand Down Expand Up @@ -221,6 +220,9 @@ public float GetS15Fixed16()
/// <exception cref="IOException"/>
public string GetString(int bytesRequested, Encoding encoding)
{
if (bytesRequested < 0)
throw new ArgumentOutOfRangeException(nameof(bytesRequested), "Must be 0 or greater");

// This check is important on .NET Framework
if (bytesRequested is 0)
{
Expand All @@ -236,17 +238,11 @@ public string GetString(int bytesRequested, Encoding encoding)
}
else
{
byte[] bytes = ArrayPool<byte>.Shared.Rent(bytesRequested);

Span<byte> span = bytes.AsSpan(0, bytesRequested);

GetBytes(span);

var s = encoding.GetString(span);
using var buffer = new ScopedBuffer(bytesRequested);

ArrayPool<byte>.Shared.Return(bytes);
GetBytes(buffer);

return s;
return encoding.GetString(buffer);
}
}

Expand Down
2 changes: 1 addition & 1 deletion MetadataExtractor/Util/DateUtil.cs
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Expand Up @@ -18,7 +18,7 @@ public static bool IsValidTime(int hours, int minutes, int seconds)
minutes is >= 0 and < 60
&& seconds is >= 0 and < 60;

#if NET8_0 || NETSTANDARD2_1
#if NET8_0_OR_GREATER || NETSTANDARD2_1
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Thanks for fixing this. I searched and couldn't find any other instances.

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Yep, also searched -- and only one I found!

private static readonly DateTime _unixEpoch = DateTime.UnixEpoch;
#else
private static readonly DateTime _unixEpoch = new(1970, 1, 1, 0, 0, 0);
Expand Down
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