How to make a method accessible to one user at a time in c#

Question

I have got a method that i want only one user can access at a time. I really don't know how to do this.

public static int add(int a, int b)
{
 int c = a+b;
 return c;
}

and i am calling this method when a user enters data into two text boxes and click the submit button on a asp.net webpage. I don't want other users access to be denied. They should be kept in some sort of queue and when method is finished serving one user next user should be served.

Answer 1

Msdn got good explanation, check documentation. Thread Synchronization

Since you have a static method, you need static Object for locking.

public class Calculator
{
    private static System.Object lockThis = new System.Object();

    public static void Add(int a, int b)
    {   
        lock (lockThis)
        {
            return a+b;
        }
    }

}

That lock means, that whenever a Thread accesses that method and it is not locked, it will lock it and run the code. If it is locked it will do nothing until it is unlocked.

Edit: Edited code for your method.