fis/fis/KeyLockEngine.cs

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

namespace fis
{
    internal interface IKeyLockEngine
    {
        Task InvokeAsync(string key, Func<Task> action);
    }

    internal class SpinLockEngine : IKeyLockEngine
    {
        private const int LockeCount = 0x12fd; //素数，减少hash冲突，值越大冲突概率越小，但占用内存越大
        private static readonly int[] Locks = new int[LockeCount];

        public async Task InvokeAsync(string key, Func<Task> action)
        {
            int index = (key.GetHashCode() & 0x7fffffff) % LockeCount;

            // 尝试0变1,进入对应index的临界状态;
            while (Interlocked.CompareExchange(ref Locks[index], 1, 0) == 1)
            {
                Thread.Sleep(1);
                ////可也以计数方式.每X次尝试失败则睡眠1,否则睡眠0
                //Thread.Sleep(((++count) | 0x000f) == 0 ? 1 : 0);
            }

            try
            {
                await action();
            }
            finally
            {
                Thread.VolatileWrite(ref Locks[index], 0);
            }
        }
    }
}