Tracking Observation with Bits
This is a test of different ways to track whether an item has been observed or not. The original impetus came from writing a graph algorithm that required monitoring whether a node or arc had been visited or not. The naive approach was to use an array<bool>. I wanted to see if there was a way using just raw bits though since a smaller algorithm would likely perform better.
My current results on my machine are the following.
BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000
AMD Ryzen 9 3900X, 1 CPU, 24 logical and 12 physical cores
.NET SDK=6.0.101
[Host] : .NET 6.0.1 (6.0.121.56705), X64 RyuJIT DEBUG
DefaultJob : .NET 6.0.1 (6.0.121.56705), X64 RyuJIT
| Method | Mean | Error | StdDev | Median | Gen 0 | Allocated |
|----------------- |-----------:|----------:|----------:|-----------:|----------:|-------------:|
| SetTracker | 8,758.0 us | 170.92 us | 222.24 us | 8,788.5 us | 4781.2500 | 40,000,008 B |
| HashSetTracker | 5,361.9 us | 105.70 us | 154.93 us | 5,314.5 us | - | 68 B |
| BoolArrayTracker | 4,979.5 us | 92.54 us | 86.56 us | 4,994.3 us | - | 84 B |
| Int64Tracker | 728.8 us | 14.51 us | 17.82 us | 731.7 us | - | - |
| SpanInt64Tracker | 3,052.4 us | 60.16 us | 95.42 us | 3,100.9 us | - | 2 B |
This test run was for tracking up to 64 different items. If you need to track more than 64 items, I recommend the SpanIndex type since it is able to handle an arbitrary number of items and performs better than the naive array<bool> method.
I welcome all suggestions and Pull requests if you have suggestions for how to improve the performance.