void.cat/VoidCat/Services/InMemoryStatsCollector.cs

using Microsoft.Extensions.Caching.Memory;

namespace VoidCat.Services
{
    public class InMemoryStatsCollector : IStatsCollector
    {
        private static Guid _global = new Guid("{A98DFDCC-C4E1-4D42-B818-912086FC6157}");
        private readonly IMemoryCache _cache;

        public InMemoryStatsCollector(IMemoryCache cache)
        {
            _cache = cache;
        }

        public ValueTask TrackIngress(Guid id, ulong amount)
        {
            Incr(IngressKey(id), amount);
            Incr(IngressKey(_global), amount);
            return ValueTask.CompletedTask;
        }

        public ValueTask TrackEgress(Guid id, ulong amount)
        {
            Incr(EgressKey(id), amount);
            Incr(EgressKey(_global), amount);
            return ValueTask.CompletedTask;
        }

        public ValueTask<Bandwidth> GetBandwidth()
            => ValueTask.FromResult(GetBandwidthInternal(_global));

        public ValueTask<Bandwidth> GetBandwidth(Guid id)
            => ValueTask.FromResult(GetBandwidthInternal(id));

        private Bandwidth GetBandwidthInternal(Guid id)
        {
            var i = _cache.Get(IngressKey(id)) as ulong?;
            var o = _cache.Get(EgressKey(id)) as ulong?;
            return new(i ?? 0UL, o ?? 0UL);
        }

        private void Incr(string k, ulong amount)
        {
            ulong v;
            _cache.TryGetValue(k, out v);
            _cache.Set(k, v + amount);
        }

        private string IngressKey(Guid id) => $"stats:ingress:{id}";
        private string EgressKey(Guid id) => $"stats:egress:{id}";
    }
}