[Compatibility] Added INCRBYFLOAT command

[Vijay-Nirmal]

Adding INCRBYFLOAT command to garnet

• Add INCRBYFLOAT command
• Add Test cases
• Add documentation

Question:

Do you guys have any optimal way to double to ASCII byte?

Below is a benchmark with 2 approaches.

NumOfCharInDoubleWithMathAbsRound => Same code as the PR
NumOfCharInDoubleWithDiyFp => Similar code as .Format("{0:0.####}"). Below are the links to the code I used from .dotnet runtime repo
Number.DiyFp.cs
Number.Grisu3.cs - TryRunCounted
NumOfCharInDoubleWithStringFormat => Using doubleValue.ToString("0.###############") and using buffer copy to move the value to input span
NumOfCharInDoubleWithUtf8Formatter => Using Utf8Formatter

Method	Value	Mean	Error	StdDev	Gen0	Allocated
NumOfCharInDoubleWithMathAbsRound	10.23	30.55 ns	0.608 ns	0.769 ns	-	-
NumOfCharInDoubleWithDiyFp	10.23	51.39 ns	1.035 ns	1.346 ns	-	-
NumOfCharInDoubleWithStringFormat	10.23	111.70 ns	2.124 ns	1.986 ns	0.0017	32 B
NumOfCharInDoubleWithUtf8Formatter	10.23	144.58 ns	2.915 ns	2.863 ns	-	-
NumOfCharInDoubleWithMathAbsRound	12.023642000155785	169.63 ns	2.703 ns	2.529 ns	-	-
NumOfCharInDoubleWithDiyFp	12.023642000155785	50.21 ns	0.627 ns	0.586 ns	-	-
NumOfCharInDoubleWithStringFormat	12.023642000155785	109.51 ns	2.095 ns	2.151 ns	0.0029	56 B
NumOfCharInDoubleWithUtf8Formatter	12.023642000155785	185.39 ns	2.528 ns	2.111 ns	-	-
NumOfCharInDoubleWithMathAbsRound	85.98498198191919	159.88 ns	1.536 ns	1.437 ns	-	-
NumOfCharInDoubleWithDiyFp	85.98498198191919	51.27 ns	1.001 ns	1.112 ns	-	-
NumOfCharInDoubleWithStringFormat	85.98498198191919	108.07 ns	2.041 ns	1.909 ns	0.0029	56 B
NumOfCharInDoubleWithUtf8Formatter	85.98498198191919	205.70 ns	3.498 ns	3.272 ns	-	-
NumOfCharInDoubleWithMathAbsRound	152.3645	59.08 ns	1.211 ns	1.295 ns	-	-
NumOfCharInDoubleWithDiyFp	152.3645	56.91 ns	0.915 ns	0.856 ns	-	-
NumOfCharInDoubleWithStringFormat	152.3645	129.73 ns	2.571 ns	2.525 ns	0.0019	40 B
NumOfCharInDoubleWithUtf8Formatter	152.3645	220.38 ns	4.267 ns	4.382 ns	-	-
NumOfCharInDoubleWithMathAbsRound	456621336.22	78.48 ns	1.529 ns	1.761 ns	-	-
NumOfCharInDoubleWithDiyFp	456621336.22	45.34 ns	0.809 ns	0.757 ns	-	-
NumOfCharInDoubleWithStringFormat	456621336.22	135.40 ns	2.678 ns	3.387 ns	0.0024	48 B
NumOfCharInDoubleWithUtf8Formatter	456621336.22	241.70 ns	3.849 ns	3.601 ns	-	-
NumOfCharInDoubleWithMathAbsRound	9.874(...)2E+20 [21]	237.65 ns	3.564 ns	2.976 ns	-	-
NumOfCharInDoubleWithDiyFp	9.874(...)2E+20 [21]	36.29 ns	0.739 ns	0.691 ns	-	-
NumOfCharInDoubleWithStringFormat	9.874(...)2E+20 [21]	120.56 ns	1.948 ns	1.823 ns	0.0033	64 B
NumOfCharInDoubleWithUtf8Formatter	9.874(...)2E+20 [21]	325.66 ns	6.171 ns	5.773 ns	-	-

Even though the dotnet runtime approach does better in most cases in the benchmark, I have not done it as part of this PR because of 2 reasons, 1) it has lots of code and 2) for smaller numbers it always performs worse. If you guys like dotnet's approach, I can change it quickly.

Let me know if you guys have any other ideas, I can implement and compare the performance.

[badrishc]

Why not use Utf8Parser.TryParse? The open PR #631 also uses it.
https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Utf8Parser/Utf8Parser.Float.cs#L63

[badrishc]

Or, double.TryParse(ReadOnlySpan<byte> utf8Text, out double result). This also goes from byte[] to double.

[badrishc]

For other direction, check this:

https://learn.microsoft.com/en-us/dotnet/api/system.buffers.text.utf8formatter.tryformat?view=net-8.0

[badrishc]

might be best to just convert the double to the ROS with a sufficiently large buffer, to know how many bytes it uses. hopefully the conversion will not need to be repeated.

[Vijay-Nirmal]

@badrishc I have added the benchmark results with Utf8Formatter. In my benchmark, it is the slowest option. I've shared below my benchmark method for using Utf8Formatter, please let me know if I made any mistake in my benchmark. Note: We can't use exponential notation.

[Benchmark]
public byte NumOfCharInDoubleWithUtf8Formatter()
{
    Span<byte> buffer = stackalloc byte[327];  // 309 (max digits) + 1 (dot) + 17 (precision)
    Utf8Formatter.TryFormat(Value, buffer, out var bytesWritten, new StandardFormat('f', 17));
    buffer = buffer.Slice(0, bytesWritten).TrimEnd((byte)'0').TrimEnd((byte)'.');
    return buffer[0];
}