Use string.GetHashCode in ROM

[Shane32]

https://docs.microsoft.com/en-us/dotnet/api/system.memoryextensions.equals?view=net-6.0#system-memoryextensions-equals(system-readonlyspan((system-char))-system-readonlyspan((system-char))-system-stringcomparison)

https://docs.microsoft.com/en-us/dotnet/api/system.string.gethashcode?view=net-6.0#system-string-gethashcode(system-readonlyspan((system-char)))

Should both be faster than existing implementations. Need IFDEF check for both.

[Shane32]

MemoryExtensions.Equals just calls SequenceEqual, so no need to use that.

[Shane32]

However, the GetHashCode method looks to be extremely optimized and a good hash. See this "Marvin" class which is used by the method:

https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/Marvin.cs

[sungam3r]

As I said it does not work. See MemoryTests.GetHashCode_Issue . Both net5/net6 tests failed. Such implementation of hash is simply not suitable for our purposes.
"abcabc".AsMemory().Slice(0, 3).GetHashCode() should be equal to "abcabc".AsMemory().Slice(3, 3).GetHashCode() Otherwise, all dictionaries with ROM keys in GraphQL.NET are stopped working correctly.

[sungam3r]

See #203

[Shane32]

As I said it does not work. See MemoryTests.GetHashCode_Issue . Both net5/net6 tests failed. Such implementation of hash is simply not suitable for our purposes. "abcabc".AsMemory().Slice(0, 3).GetHashCode() should be equal to "abcabc".AsMemory().Slice(3, 3).GetHashCode() Otherwise, all dictionaries with ROM keys in GraphQL.NET are stopped working correctly.

I understand. The suggestion here is to use string.GetHashCode, not ReadOnlyMemory.GetHashCode. It is only available on .NET 6.

string.GetHashCode("abcabc".AsMemory().Slice(0, 3).Span) equals string.GetHashCode("abcabc".AsMemory().Slice(3, 3).Span)

[sungam3r]

🤦 done