godot-host-test/Game/Metrics/MetricsHandler.cs

using System;
using System.Diagnostics.Metrics;
using System.Reflection;
using GodotHostTest.Interfaces;
using OwofGames.GodotHost;
using R3;

namespace GodotHostTest.Game.Metrics;

public class MetricsHandler(IMeterFactory meterFactory, ITargetEventBus targetEventBus) : IHostLifetime
{
    public static readonly string MeterName;
    private static readonly string? MeterVersion;
    private IDisposable? _disposables;

    static MetricsHandler()
    {
        var assemblyName = Assembly.GetExecutingAssembly().GetName();
        MeterName = assemblyName.Name!;
        MeterVersion = assemblyName.Version?.ToString();
    }

    public void Startup()
    {
        // create meter
        var assemblyName = Assembly.GetExecutingAssembly().GetName();
        var meterName = assemblyName.Name!;
        var meterVersion = assemblyName.Version?.ToString();
        var meter = meterFactory.Create(meterName, meterVersion);

        // create instruments
        var hitTargetsCounter =
            meter.CreateCounter<int>("targets.hit", description: "number of targets hit");
        var missedTargetsCounter =
            meter.CreateCounter<int>("targets.missed", description: "number of targets missed");

        // feed instruments data, and contextually create the disposable to clean up at shutdown time
        _disposables = Disposable.Combine(
            targetEventBus.Hit.Subscribe(_ => hitTargetsCounter.Add(1)),
            targetEventBus.TimedOut.Subscribe(_ => missedTargetsCounter.Add(1)),
            meter
        );
    }

    public void Shutdown()
    {
        _disposables?.Dispose();
        meterFactory.Create("godot-host-test")?.Dispose();
    }
}