Program.cs

// <copyright file="Program.cs" company="OpenTelemetry Authors">
// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// </copyright>

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Metrics;
using OpenTelemetry;
using OpenTelemetry.Metrics;

public class Program
{
    private static readonly Meter MyMeter = new Meter("MyCompany.MyProduct.MyLibrary", "1.0");
    private static readonly Histogram<long> MyHistogram = MyMeter.CreateHistogram<long>("MyHistogram");

    static Program()
    {
        var process = Process.GetCurrentProcess();

        MyMeter.CreateObservableCounter("Thread.CpuTime", () => GetThreadCpuTime(process), "ms");

        MyMeter.CreateObservableGauge("Thread.State", () => GetThreadState(process));
    }

    public static void Main(string[] args)
    {
        using var meterProvider = Sdk.CreateMeterProviderBuilder()
            .AddMeter("MyCompany.MyProduct.MyLibrary")
            .AddConsoleExporter()
            .Build();

        var random = new Random();
        for (int i = 0; i < 1000; i++)
        {
            MyHistogram.Record(random.Next(1, 1000));
        }
    }

    private static IEnumerable<Measurement<double>> GetThreadCpuTime(Process process)
    {
        foreach (ProcessThread thread in process.Threads)
        {
            yield return new(thread.TotalProcessorTime.TotalMilliseconds, new("ProcessId", process.Id), new("ThreadId", thread.Id));
        }
    }

    private static IEnumerable<Measurement<int>> GetThreadState(Process process)
    {
        foreach (ProcessThread thread in process.Threads)
        {
            yield return new((int)thread.ThreadState, new("ProcessId", process.Id), new("ThreadId", thread.Id));
        }
    }
}