static void Main(string[] args)
        {
            var list = new List<int>(new int[] { 1, 2, 3, 5, 8, 10 });
            int insertItem = 9;
            var index = list.BinarySearch(insertItem);
            if (index < 0)
            {
                list.Insert(-index - 1, insertItem);
            }
            Console.WriteLine(index);
            Console.WriteLine(string.Join(",", list));
            Console.ReadKey();
        }

        static void Main(string[] args)
        {
            var list = new List<int>(new int[] { 1, 2, 3, 5, 8, 10 });
            int insertItem = 9;
            var index = list.BinarySearch(insertItem);
            if (index < 0)
            {
                list.Insert(~index, insertItem);
            }
            Console.WriteLine(index);
            Console.WriteLine(string.Join(",", list));
            Console.ReadKey();
        }

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp3
{
    public struct MyStruct
    {
        public MyStruct(int id, decimal level, decimal measurement)
        {
            Id = id;
            Level = level;
            Measurement = measurement;
        }

        public int Id;
        public decimal Level;
        public decimal Measurement;
    }

    class Program
    {
        static Test _test;
        static void Main(string[] args)
        {
            _test = new Test();

            var tokenSource = new CancellationTokenSource();
            var token = tokenSource.Token;
            var task1 = Task.Run(() =>
            {
                while (!token.IsCancellationRequested)
                {
                    OnWrite();
                    Task.Delay(10).Wait();
                }
            });
            var task2 = Task.Run(() =>
            {
                while (!token.IsCancellationRequested)
                {
                    OnRead();
                    Task.Delay(1000).Wait();
                }
            });

            Console.ReadKey();
            tokenSource.Cancel();
            Task.WaitAll(task1, task2);
            foreach (var i in _test.Read())
            {
                Console.WriteLine($"({i.Id:00};{i.Level:0.0000};{i.Measurement:0.0000})");
            }
            Console.ReadKey();
        }

        private static void OnRead()
        {
            decimal result = 0;
            var count = 0;
            foreach (var i in _test.Read())
            {
                result += i.Measurement;
                count++;
            }
            Console.SetCursorPosition(0, 0);
            Console.Write($"{count},{result}");
        }

        static Random _rnd = new Random(0);

        private static void OnWrite()
        {
            var id = _rnd.Next(0, 100);
            var level = (decimal)_rnd.NextDouble();
            var measure = (decimal)_rnd.NextDouble();
            var insertItem = new MyStruct(id, level, measure);
            _test.InsertOrUpdate(insertItem);
        }

        public class Test
        {

            private readonly List<MyStruct> _list;
            private ReaderWriterLockSlim _lock = new ReaderWriterLockSlim();

            public Test()
            {
                _list = new List<MyStruct>();
            }

            public void InsertOrUpdate(MyStruct item)
            {
                _lock.EnterUpgradeableReadLock();
                var index = _list.BinarySearch(item, Comparer<MyStruct>.Create((x, y) => y.Level.CompareTo(x.Level)));
                _lock.EnterWriteLock();
                if (index < 0)
                {
                    _list.Insert(~index, item);
                }
                else
                {
                    _list[index] = item;
                }
                _lock.ExitWriteLock();
                _lock.ExitUpgradeableReadLock();
            }

            public IEnumerable<MyStruct> Read()
            {
                _lock.EnterReadLock();
                foreach (var i in _list)
                {
                    yield return i;
                }
                _lock.ExitReadLock();
            }
        }
    }
}