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Elide unnecessary value copying #82

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8e8a9d3
Elide unnecessary value copies
longfin May 15, 2023
9061b57
More copy-less
longfin May 15, 2023
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2 changes: 1 addition & 1 deletion Bencodex.Tests/EncoderTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,7 @@ public void EncodeInteger()
public void EncodeBinary()
{
var buffer = new byte[20];
long size = Encoder.EncodeBinary(new Binary("hello world", Encoding.ASCII), buffer, 2L);
long size = Encoder.EncodeBinary(new Binary("hello world", Encoding.ASCII).ByteArray.AsSpan(), buffer, 2L);
Assert.Equal(14L, size);
AssertEqual(
new byte[20]
Expand Down
29 changes: 14 additions & 15 deletions Bencodex/Decoder.cs
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Expand Up @@ -4,6 +4,7 @@
using System.Globalization;
using System.IO;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Text;
using Bencodex.Misc;
using Bencodex.Types;
Expand All @@ -12,7 +13,6 @@ namespace Bencodex
{
internal sealed class Decoder
{
private readonly byte[] _tinyBuffer = new byte[1];
private readonly Stream _stream;
private readonly IndirectValue.Loader? _indirectValueLoader;
private byte _lastRead;
Expand Down Expand Up @@ -74,7 +74,7 @@ private IValue DecodeValue()
return ReadTextAfterPrefix();

case 0x6c: // 'l'
var indirElements = new List<IndirectValue>();
var indirBuilder = ImmutableArray.CreateBuilder<IndirectValue>();
while (true)
{
byte b = ReadByte() ?? throw new DecodingException(
Expand All @@ -87,17 +87,17 @@ private IValue DecodeValue()
else if (b == indir)
{
Fingerprint fp = DecodeFingerprint();
indirElements.Add(new IndirectValue(fp));
indirBuilder.Add(new IndirectValue(fp));
continue;
}

Back();
IValue element = DecodeValue();
indirElements.Add(new IndirectValue(element));
indirBuilder.Add(new IndirectValue(element));
}

return new Bencodex.Types.List(
indirElements.ToImmutableArray(),
indirBuilder.MoveToImmutable().AsSpan(),
_indirectValueLoader
);

Expand Down Expand Up @@ -255,15 +255,15 @@ private byte[] Read(byte[] buffer)
return _lastRead;
}

int read = _stream.Read(_tinyBuffer, 0, 1);
int read = _stream.ReadByte();
if (read > 0)
{
_lastRead = _tinyBuffer[0];
_lastRead = (byte)read;
}

_offset++;
_didBack = false;
return read == 0 ? (byte?)null : _tinyBuffer[0];
return read == -1 ? (byte?)null : _lastRead;
}

private void Back()
Expand Down Expand Up @@ -363,12 +363,7 @@ Func<string, IFormatProvider, T> converter
)
{
byte[] buffer = ReadDigits(takeMinusSign, delimiter);
var digits = new char[buffer.Length];
for (int i = 0; i < buffer.Length; i++)
{
digits[i] = (char)buffer[i];
}

var digits = Unsafe.As<byte[], char[]>(ref buffer);
return converter(new string(digits), CultureInfo.InvariantCulture);
}

Expand Down Expand Up @@ -399,7 +394,7 @@ Func<string, IFormatProvider, T> converter
private Binary ReadBinary()
{
(byte[] bytes, _) = ReadByteArray();
return new Binary(bytes);
return new Binary(bytes.AsSpan());
}

private Text ReadTextAfterPrefix()
Expand All @@ -409,7 +404,11 @@ private Text ReadTextAfterPrefix()
string textContent;
try
{
#if NETSTANDARD2_0
textContent = Encoding.UTF8.GetString(bytes);
#else
textContent = Encoding.UTF8.GetString(bytes.AsSpan());
#endif
}
catch (ArgumentException e)
{
Expand Down
23 changes: 13 additions & 10 deletions Bencodex/Encoder.cs
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Expand Up @@ -60,7 +60,11 @@ public static void Encode(IValue value, Stream output, IOffloadOptions? offloadO
}

byte[] buffer = Encode(value, offloadOptions);
#if NETSTANDARD2_0
output.Write(buffer, 0, buffer.Length);
#else
output.Write(buffer.AsSpan());
#endif
}

internal static long EstimateLength(IValue value, IOffloadOptions? offloadOptions)
Expand Down Expand Up @@ -145,23 +149,22 @@ internal static long EncodeInteger(in Integer value, byte[] buffer, long offset)
return 1L + digits.Length + 1L;
}

internal static long EncodeBinary(in Binary value, byte[] buffer, long offset)
internal static long EncodeBinary(in ReadOnlySpan<byte> bin, byte[] buffer, long offset)
{
long len = value.ByteArray.Length;
long len = bin.Length;
long lenStrLength = EncodeDigits(len, buffer, offset);
offset += lenStrLength;
buffer[offset] = 0x3a; // ':'
offset++;

if (offset + len <= int.MaxValue)
long ct = 0;
foreach (byte b in bin)
{
value.ByteArray.CopyTo(buffer, (int)offset);
return lenStrLength + 1L + len;
buffer[offset + ct] = b;
ct++;
}

byte[] b = value.ToByteArray();
Array.Copy(b, 0L, buffer, offset, b.LongLength);
return lenStrLength + 1L + b.LongLength;
return lenStrLength + 1L + ct;
}

internal static long EncodeText(in Text value, byte[] buffer, long offset)
Expand Down Expand Up @@ -240,7 +243,7 @@ long offset
actualBytes += pair.Key switch
{
Text tk => EncodeText(tk, buffer, offset + actualBytes),
Binary bk => EncodeBinary(bk, buffer, offset + actualBytes),
Binary bk => EncodeBinary(bk.ByteArray.AsSpan(), buffer, offset + actualBytes),
{ } k => Encode(k, offloadOptions, buffer, offset + actualBytes),
};
if (offloadOptions is { } oo && !oo.Embeds(pair.Value))
Expand Down Expand Up @@ -322,7 +325,7 @@ long offset
Null _ => EncodeNull(buffer, offset),
Types.Boolean b => EncodeBoolean(b, buffer, offset),
Integer i => EncodeInteger(i, buffer, offset),
Binary bin => EncodeBinary(bin, buffer, offset),
Binary bin => EncodeBinary(bin.ByteArray.AsSpan(), buffer, offset),
Text t => EncodeText(t, buffer, offset),
List l => EncodeList(l, offloadOptions, buffer, offset),
Dictionary d => EncodeDictionary(d, offloadOptions, buffer, offset),
Expand Down
26 changes: 18 additions & 8 deletions Bencodex/Types/Binary.cs
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Expand Up @@ -30,13 +30,24 @@ namespace Bencodex.Types
private readonly int?[] _hashCode;
private readonly ImmutableArray<byte>?[] _digest;

public Binary(ImmutableArray<byte> value)
public Binary(ReadOnlySpan<byte> value)
{
_value = value;
var builder = ImmutableArray.CreateBuilder<byte>(value.Length);
foreach (byte b in value)
{
builder.Add(b);
}

_value = builder.MoveToImmutable();
_hashCode = new int?[1];
_digest = new[] { (ImmutableArray<byte>?)null };
}

public Binary(ImmutableArray<byte> value)
: this(value.AsSpan())
{
}

public Binary(params byte[] value)
: this(value is byte[] bytes
? ImmutableArray.Create(bytes)
Expand Down Expand Up @@ -90,7 +101,7 @@ public Fingerprint Fingerprint
public string Inspection => Inspect(true);

public static implicit operator Binary(ImmutableArray<byte> bytes) =>
new Binary(bytes);
new Binary(bytes.AsSpan());

public static implicit operator ImmutableArray<byte>(Binary binary) =>
binary.ByteArray;
Expand Down Expand Up @@ -179,7 +190,7 @@ byte ParseNibble(char hex)
bytes.Add((byte)(ParseNibble(upper) << 4 | ParseNibble(lower)));
}

return new Binary(bytes.MoveToImmutable());
return new Binary(bytes.MoveToImmutable().AsSpan());
}

#if !NETSTANDARD2_0
Expand Down Expand Up @@ -225,8 +236,7 @@ public static Binary FromBase64(ReadOnlySpan<char> base64)
public static Binary FromBase64(string base64)
{
byte[] bytes = Convert.FromBase64String(base64);
ImmutableArray<byte> moved = Unsafe.As<byte[], ImmutableArray<byte>>(ref bytes);
return new Binary(moved);
return new Binary(bytes.AsSpan());
}

bool IEquatable<ImmutableArray<byte>>.Equals(ImmutableArray<byte> other) =>
Expand Down Expand Up @@ -325,10 +335,10 @@ public byte[] ToByteArray()
{
if (ByteArray.IsDefaultOrEmpty)
{
return new byte[0];
return Array.Empty<byte>();
}

return ByteArray.ToBuilder().ToArray();
return ByteArray.ToArray();
}

/// <summary>
Expand Down
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