1 //Copyright (C) Microsoft Corporation.  All rights reserved.  2  3 using System;  4 using System.Threading;  5  6 // The Fibonacci class provides an interface for using an auxiliary  7 // thread to perform the lengthy Fibonacci(N) calculation.  8 // N is provided to the Fibonacci constructor, along with an  9 // event that the object signals when the operation is complete. 10 // The result can then be retrieved with the FibOfN property. 11 public class Fibonacci 12 {
   13     public Fibonacci(int n, ManualResetEvent doneEvent) 14     {
   15         _n = n; 16         _doneEvent = doneEvent; 17     } 18 19     // Wrapper method for use with thread pool. 20     public void ThreadPoolCallback(Object threadContext) 21     {
   22         int threadIndex = (int)threadContext; 23         Console.WriteLine("thread {0} started...", threadIndex); 24         _fibOfN = Calculate(_n); 25         Console.WriteLine("thread {0} result calculated...", threadIndex); 26         _doneEvent.Set(); 27     } 28 29     // Recursive method that calculates the Nth Fibonacci number. 30     public int Calculate(int n) 31     {
   32         if (n <= 1) 33         {
   34             return n; 35         } 36         else 37         {
   38             return Calculate(n - 1) + Calculate(n - 2); 39         } 40     } 41 42     public int N { get { return _n; } } 43     private int _n; 44 45     public int FibOfN { get { return _fibOfN; } } 46     private int _fibOfN; 47 48     ManualResetEvent _doneEvent; 49 } 50 51 public class ThreadPoolExample 52 {
   53     static void Main44() 54     {
   55         const int FibonacciCalculations = 10; 56 57         // One event is used for each Fibonacci object 58         var doneEvents = new ManualResetEvent[FibonacciCalculations]; 59         var fibArray = new Fibonacci[FibonacciCalculations]; 60         var r = new Random(); 61 62         // Configure and launch threads using ThreadPool: 63         Console.WriteLine("launching {0} tasks...", FibonacciCalculations); 64         for (int i = 0; i < FibonacciCalculations; i++) 65         {
   66             doneEvents[i] = new ManualResetEvent(false); 67             var f = new Fibonacci(r.Next(20, 40), doneEvents[i]); 68             fibArray[i] = f; 69             ThreadPool.QueueUserWorkItem(f.ThreadPoolCallback, i); 70         } 71 72         // Wait for all threads in pool to calculation... 73         WaitHandle.WaitAll(doneEvents); 74         Console.WriteLine("Calculations complete."); 75 76         // Display the results... 77         for (int i = 0; i < FibonacciCalculations; i++) 78         {
   79             Fibonacci f = fibArray[i]; 80             Console.WriteLine("Fibonacci({0}) = {1}", f.N, f.FibOfN); 81         } 82     } 83 }