MetroHash for .NET

This is a direct port of J. Andrew Rogers' Metro Hash 128 algorithm. Compare https://github.com/jandrewrogers/MetroHash

Implementation

This implements the non-incremental and incremental version of the Metro Hash 128 algorithm. Due to code-sharing between both versions the non-incremental is a bit slower than previously.

Usage

Non-Incremental:

    var hash = MetroHash128.Hash(0, _data, 0, _data.Length);
    MetroHash128.Hash(0, inputSpan, outputSpan);

Incremental:

    var metroHash = new MetroHash128(0);
    metroHash.Update(_data, 0, _data.Length);
    var hash = metroHash.FinalizeHash();
	
    var metroHash = new MetroHash128(0);
    metroHash.Update(dataSpan);
    var hash = metroHash.FinalizeHash();
	
    var metroHash = new MetroHash128(0);
    metroHash.Update(dataSpan);
    metroHash.FinalizeHash(outputSpan); // this version is a bit slower than the one above

Note: The Span versions are considerably slower on netfx as it does not yet support the fast span.

Nuget

https://www.nuget.org/packages/MetroHash

Performance

BenchmarkDotNet=v0.10.14, OS=Windows 10.0.17134
Intel Core i7-4790K CPU 4.00GHz (Haswell), 1 CPU, 8 logical and 4 physical cores
Frequency=3906246 Hz, Resolution=256.0003 ns, Timer=TSC
.NET Core SDK=2.1.300-rtm-008701
  [Host]     : .NET Core 2.1.0-rtm-26502-02 (CoreCLR 4.6.26502.03, CoreFX 4.6.26502.02), 64bit RyuJIT
  DefaultJob : .NET Core 2.1.0-rtm-26502-02 (CoreCLR 4.6.26502.03, CoreFX 4.6.26502.02), 64bit RyuJIT

Method	Mean	Error	StdDev	Gen 0	Allocated
MetroHash128NonIncremental	42.90 ns	0.6105 ns	0.5711 ns	0.0095	40 B
MetroHash128Incremental	65.56 ns	0.1082 ns	0.0904 ns	0.0380	160 B
MetroHash128NonIncrementalSpan	45.46 ns	0.1894 ns	0.1772 ns	-	0 B
MetroHash128IncrementalSpan	85.60 ns	0.0716 ns	0.0598 ns	0.0380	160 B
MetroHash128IncrementalSpanDirectReturn	70.01 ns	0.6243 ns	0.5534 ns	0.0380	160 B

Copyright

C++ Implementation: Copyright (c) 2015 J. Andrew Rogers

C# Implementation: Copyright © MetroHash for .NET Contributors