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[N4] unwrap StorageKey #4358

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[N4] unwrap StorageKey #4358

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61 changes: 59 additions & 2 deletions src/Neo/SmartContract/KeyBuilder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,6 @@ namespace Neo.SmartContract;
/// </summary>
public class KeyBuilder : IEnumerable
{
public const int PrefixLength = sizeof(int) + sizeof(byte);

private readonly byte[] _cacheData;
private int _keyLength;

Expand Down Expand Up @@ -105,6 +103,65 @@ public KeyBuilder Add<T>(T key) where T : unmanaged
return Add(data);
}

internal static bool TryParse(byte[] data, Type[] types, out int id, out byte prefix, out object[] values)
{
values = Array.Empty<object>();

foreach (var t in types)
{
if (!t.IsValueType || t.IsGenericType)
{
id = default;
prefix = default;
return false;
}
}

if (data.Length < sizeof(int) + 1)
{
id = default;
prefix = default;
return false;
}

id = BinaryPrimitives.ReadInt32LittleEndian(data);
prefix = data[sizeof(int)];

values = new object[types.Length];
int offset = sizeof(int) + 1;

for (int i = 0; i < types.Length; i++)
{
int size = Marshal.SizeOf(types[i]);
if (data.Length < offset + size)
return false;

Span<byte> span = data.AsSpan(offset, size);

if (BitConverter.IsLittleEndian)
span.Reverse();
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@shargon shargon Dec 2, 2025

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@erikzhang we loose performance here, because in regular nodes we always need to reverse each key, before the change this was faster

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@erikzhang erikzhang Dec 2, 2025

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Have you tested it? Approximately how much performance was lost?

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@shargon shargon Dec 2, 2025

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I don't have a benchmark. it depends a lot on the key size, but previously an integer was written directly inverted, and now it requires an extra loop to reverse it. Also, I think a string gets reversed, and it shouldn't; only an integer should be reversed.

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@erikzhang erikzhang Dec 2, 2025

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string is not a value type.


values[i] = ReadStruct(span, types[i]);
offset += size;
}

return true;
}

static object ReadStruct(Span<byte> span, Type t)
{
byte[] buffer = span.ToArray();
var handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
try
{
return Marshal.PtrToStructure(handle.AddrOfPinnedObject(), t)!;
}
finally
{
handle.Free();
}
}

/// <summary>
/// Gets the storage key generated by the builder.
/// </summary>
Expand Down
25 changes: 25 additions & 0 deletions tests/Neo.UnitTests/SmartContract/UT_KeyBuilder.cs
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Expand Up @@ -11,6 +11,7 @@

using Neo.IO;
using Neo.SmartContract;
using System.Reflection;

namespace Neo.UnitTests.SmartContract;

Expand Down Expand Up @@ -42,6 +43,30 @@ public void Test()
Assert.AreEqual("010000000000000001", key.ToArray().ToHexString());
}

[TestMethod]
public void TestTryParse()
{
var key = new KeyBuilder(1, 2);
Assert.AreEqual("0100000002", key.ToArray().ToHexString());

// add int
key = new KeyBuilder(1, 2);
key = key.Add(-1);
key = key.Add(2);
Assert.AreEqual("0100000002ffffffff00000002", key.ToArray().ToHexString());

Assert.IsFalse(KeyBuilder.TryParse([], [typeof(int), typeof(int)], out int id, out byte prefix, out var ret));
Assert.IsFalse(KeyBuilder.TryParse([0, 1, 2, 3, 4, 5], [typeof(int), typeof(int)], out id, out prefix, out ret));
Assert.IsTrue(KeyBuilder.TryParse(key.ToArray(), [typeof(int), typeof(int)], out id, out prefix, out ret));

Assert.AreEqual(1, id);
Assert.AreEqual(2, prefix);
Assert.IsNotNull(ret);
Assert.HasCount(2, ret);
Assert.AreEqual(-1, ret[0]);
Assert.AreEqual(2, ret[1]);
}

[TestMethod]
public void TestAddInt()
{
Expand Down