//引入命名空间
using System;
using System.Threading;

public class Example
{
   [ThreadStatic] static double previous = 0.0;
   [ThreadStatic] static double sum = 0.0;
   [ThreadStatic] static int calls = 0;
   [ThreadStatic] static bool abnormal;
   static int totalNumbers = 0;
   static CountdownEvent countdown;
   private static Object lockObj;
   Random rand;
   
   public Example()
   { 
      rand = new Random();
      lockObj = new Object();
      countdown = new CountdownEvent(1);
   } 

   public static void Main()
   {
      Example ex = new Example();
      Thread.CurrentThread.Name = "Main";
      ex.Execute();
      countdown.Wait();
      Console.WriteLine("{0:N0} random numbers were generated.", totalNumbers);
   }

   private void Execute()
   {   
      for (int threads = 1; threads <= 10; threads++)
      {
         Thread newThread = new Thread(new ThreadStart(this.GetRandomNumbers));
         countdown.AddCount();
         newThread.Name = threads.ToString();
         newThread.Start();
      }
      this.GetRandomNumbers();
   }

   private void GetRandomNumbers()
   {
      double result = 0.0;

      for (int ctr = 0; ctr < 2000000; ctr++)
      {
         lock (lockObj) {
            result = rand.NextDouble();
            calls++;
            Interlocked.Increment(ref totalNumbers);
            // We should never get the same random number twice.
            if (result == previous) {
               abnormal = true;
               break;
            }
            else {
               previous = result;
               sum += result;
            }   
         }
      }
      // get last result
      if (abnormal)
         Console.WriteLine("Result is {0} in {1}", previous, Thread.CurrentThread.Name);
       
      Console.WriteLine("Thread {0} finished random number generation.", Thread.CurrentThread.Name);
      Console.WriteLine("Sum = {0:N4}, Mean = {1:N4}, n = {2:N0}\n", sum, sum/calls, calls);        
      countdown.Signal();
   }
}