互斥锁与信号量有什么关系?

添加:好的，所以我可以把互斥锁和信号量分开，我只是想知道这是我的计数器的想法对吗?即Release - 1和WaitOne加1，只有当计数器大于0时，才允许运行。这个说法对吗?

我有一些运行良好的代码:按顺序运行first() second() third()

我只是想知道计数器在信号量是如何工作的?我知道它是反的。Release - 1和WaitOne加1，只有当计数器大于0时，才会允许运行。对吧?

然而，我读了一本关于另一件事的书，互斥锁，书上说互斥锁等待减一，释放加一，所以互斥锁是相反的信号量?对吧?

代码:

using System;
namespace Algorithm.MultiThread
{
    class Semaphore
    {
        System.Threading.Semaphore s1, s2;
        public Semaphore()
        {
            s1 = new System.Threading.Semaphore(1, 5);
            s2 = new System.Threading.Semaphore(1, 5); //initialize as start counter 1
        }
        public void first()
        {
            Console.WriteLine("First");
            s1.Release(); // minus one
        }
        public void second()
        {
            s1.WaitOne(); //add one two times
            s1.WaitOne();
            Console.WriteLine("Second");
            s2.Release();
        }
        public void third()
        {
            s2.WaitOne(); // add one two times
            s2.WaitOne();
            Console.WriteLine("Third");
        }
        public void startnum(object obj)
        {
            int i = (int)obj;
            switch (i)
            {
                case 1:
                    first();
                    break;
                case 2:
                    second();
                    break;
                case 3:
                    third();
                    break;
                default:
                    break;
            }
        }
        public static void test()
        {
            Semaphore s = new Semaphore();
            System.Threading.Thread t1 = new System.Threading.Thread(new System.Threading.ParameterizedThreadStart(s.startnum));
            System.Threading.Thread t2 = new System.Threading.Thread(new System.Threading.ParameterizedThreadStart(s.startnum));
            System.Threading.Thread t3 = new System.Threading.Thread(new System.Threading.ParameterizedThreadStart(s.startnum));
            t1.Start(3);
            t2.Start(2);
            t3.Start(1);
        }
    }
}