hashset.cs

using BenchmarkDotNet.Attributes;

namespace HashSetDemo;

public class Benchmarks
{
    private static readonly HashSet<foo1> hashset1 = new HashSet<foo1>();
    private static readonly HashSet<foo2> hashset2 = new HashSet<foo2>();

    [GlobalSetup]
    public void Setup()
    {
        for (int i = 0; i <= 10_000; i++)
        {
            hashset1.Add(new foo1
            {
                Id = i,
                Name = Guid.NewGuid().ToString()
            });
            
            hashset2.Add(new foo2
            {
                Id = i,
                Name = Guid.NewGuid().ToString()
            });
        }
    }
    
    [Benchmark]
    public void HashSetTest1()
    {
        var foo = new foo1
        {
            Id = 1,
        };
        
        for (int i = 0; i < 1_000; i++)
        {
            _ = hashset1.Contains(foo);
        }
    }
    
    [Benchmark]
    public void HashSetTest2()
    {
        for (int i = 0; i < 1_000; i++)
        {
            _ = hashset2.Any(h => h.Id == i);
        }
    }
}

public class foo1
{
    public int Id { get; set; }
    public string Name { get; set; }
    
    public override int GetHashCode()
    {
        return Id;
    }

    public override bool Equals(object obj)
    {
        if (obj is foo1 otherFoo)
        {
            return Id == otherFoo.Id;
        }
        return false;
    }
}

public class foo2
{
    public int Id { get; set; }
    public string Name { get; set; }
}