PluralKit/PluralKit.Bot/Services/CpuStatService.cs

using System.Diagnostics;

using Serilog;

namespace PluralKit.Bot;

public class CpuStatService
{
    private readonly ILogger _logger;

    public CpuStatService(ILogger logger)
    {
        _logger = logger;
    }

    public double LastCpuMeasure { get; private set; }

    /// <summary>
    ///     Gets the current CPU usage. Estimation takes ~5 seconds (of mostly sleeping).
    /// </summary>
    public async Task<double> EstimateCpuUsage()
    {
        // We get the current processor time, wait 5 seconds, then compare
        // https://medium.com/@jackwild/getting-cpu-usage-in-net-core-7ef825831b8b

        _logger.Debug("Estimating CPU usage...");
        var stopwatch = new Stopwatch();

        stopwatch.Start();
        var cpuTimeBefore = Process.GetCurrentProcess().TotalProcessorTime;

        await Task.Delay(5000);

        stopwatch.Stop();
        var cpuTimeAfter = Process.GetCurrentProcess().TotalProcessorTime;

        var cpuTimePassed = cpuTimeAfter - cpuTimeBefore;
        var timePassed = stopwatch.Elapsed;

        var percent = cpuTimePassed / timePassed;
        _logger.Debug("CPU usage measured as {Percent:P}", percent);
        LastCpuMeasure = percent;
        return percent;
    }
}