using System.Diagnostics;
    using System.Threading;
    using System.Threading.Tasks;
    using Microsoft.Data.SqlClient;
    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.Hosting;
    using RepoDb;

    public class MemLeakingService : BackgroundService
    {
        private readonly string connectionString;

        public MemLeakingService(IConfiguration configuration)
        {
            this.connectionString = configuration.GetConnectionString("Database");
        }

        protected override async Task ExecuteAsync(CancellationToken token)
        {
            Console.WriteLine($"SqlClient version: {FileVersionInfo.GetVersionInfo(typeof(SqlCommand).Assembly.Location).ProductVersion}");

            while (true)
            {
                const string sql = "SELECT n FROM (VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) v(n)";
                using (var sqlConnection = new SqlConnection(this.connectionString))
                {
                    await sqlConnection.ExecuteQueryAsync(sql, cancellationToken: token).ConfigureAwait(false);
                }

                GC.Collect(); // for demonstration only; removing this line does not change output
                Console.WriteLine($"Lost registrations: {CountLostSqlCommands(token)}");
            }
        }

        static int CountLostSqlCommands(CancellationToken token)
        {
            var cts = (CancellationTokenSource)typeof(CancellationToken).GetField("_source", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)!.GetValue(token)!;
            var registrationsField = typeof(CancellationTokenSource).GetField("_registrations", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)!;
            var registrations = registrationsField.GetValue(cts);
            if (registrations == null)
                return 0;
            var callbacksProperty = registrationsField.FieldType.GetField("Callbacks", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public)!;
            var callbackNode = callbacksProperty.GetValue(registrations);
            var callbackNodeType = callbacksProperty.FieldType;
            var nextProperty = callbackNodeType.GetField("Next", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public)!;
            var stateProperty = callbackNodeType.GetField("CallbackState", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public)!;
            int lostSqlCommands = 0;
            while (callbackNode != null)
            {
                var callbackState = stateProperty.GetValue(callbackNode);
                if (typeof(SqlCommand) == callbackState?.GetType())
                {
                    lostSqlCommands += 1;
                }
                callbackNode = nextProperty.GetValue(callbackNode);
            }
            return lostSqlCommands;
        }
    }