生成数据库自增不重复ID的方法

Posted 2021-01-17 hanstar

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var list = new HashSet<string>(101);
            for (int i = 0; i < 100; i++)
            {
                var task = Task.Factory.StartNew((m =>
                {
                    var id = McidGenerator.NewMcid();
                    list.Add(id);
                    Console.WriteLine($"序号：{(int)m + 1}  线程ID:{Thread.CurrentThread.ManagedThreadId} 生成的MCID:{id}");
                }), i);
            }
            Thread.Sleep(10000);
            var n = 1;
            foreach (var li in list.OrderBy(i=>i))
            {
                
                Console.WriteLine($"序号：{(int)n + 1} 生成的MCID:{li}");
                n++;
            }
            Console.ReadLine();
        }
    }

    public static class McidGenerator
    {
        private const int MaxId = 9;
        private static bool _allNew = true;
        private static int _incrementId = 0;
        private static DateTimeOffset _current = DateTimeOffset.Now;
        private static readonly object SequenceLock = new object();

        public static string NewMcid()
        {
            lock (SequenceLock)
            {
                var now = DateTimeOffset.Now;
                if (_allNew)
                {
                    _allNew = false;
                    _current = now;
                    return now.ToString("yyyyMMddHHmmssfffff") + _incrementId;
                }

                if (Convert.ToDateTime(_current.ToString("yyyy-MM-dd HH:mm:ss.fffff")) == Convert.ToDateTime(now.ToString("yyyy-MM-dd HH:mm:ss.fffff")))
                {
                    _incrementId++;
                    _current = now;
                    return now.ToString("yyyyMMddHHmmssfffff") + _incrementId;
                }

                _incrementId++;
                _incrementId = _incrementId > MaxId ? 0 : _incrementId;
                _current = now;
                return now.ToString("yyyyMMddHHmmssfffff") + _incrementId;
            }
        }
    }
}