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Asynchronous Calls:Waiting for Completion 2

Asynchronous Calls:Waiting for Completion 2

/*
A Programmer's Introduction to C# (Second Edition)
by Eric Gunnerson

Publisher: Apress  L.P.
ISBN: 1-893115-62-3
*/
// 29 - Threading and Asynchronous Operations\Asynchronous Calls\Waiting for Completion
// copyright 2000 Eric Gunnerson
using System;
using System.Threading;


public class AsynchronousCallsWaitingforCompletion2
{
    public static double DoCalculation(double value)
    {
        Console.WriteLine("DoCalculation: {0}", value);
        Thread.Sleep(250);
        return(Math.Cos(value));
    }
    
    public static void Main()
    {
        AsyncCaller ac = new AsyncCaller();
        
        ac.CallMathCallback(new AsyncCaller.MathFunctionToCall(DoCalculation));
    }
}

public class AsyncCallTracker
{
    Delegate function;
    AutoResetEvent doneEvent;
    
    public AutoResetEvent DoneEvent
    {
        get
        {
            return(doneEvent);
        }
    }
    
    public Delegate Function
    {
        get
        {
            return(function);
        }
    }
    
    public AsyncCallTracker(Delegate function)
    {
        this.function = function;
        doneEvent = new AutoResetEvent(false);
    }
}

public class AsyncCaller
{
    public delegate double MathFunctionToCall(double arg);
    
    public void MathCallback(IAsyncResult iar)
    {
        AsyncCallTracker callTracker = (AsyncCallTracker) iar.AsyncState;
        MathFunctionToCall func = (MathFunctionToCall) callTracker.Function;
        double result = func.EndInvoke(iar);
        Console.WriteLine("Function value = {0}", result);
        callTracker.DoneEvent.Set();
    }
    
    WaitHandle DoInvoke(MathFunctionToCall mathFunc, double value)
    {
        AsyncCallTracker callTracker = new AsyncCallTracker(mathFunc);
        
        AsyncCallback cb = new AsyncCallback(MathCallback);
        IAsyncResult asyncResult = mathFunc.BeginInvoke(value, cb, callTracker);
        return(callTracker.DoneEvent);
    }
    
    public void CallMathCallback(MathFunctionToCall mathFunc)
    {
        WaitHandle[] waitArray = new WaitHandle[4];
        
        Console.WriteLine("Begin Invoke");
        waitArray[0] = DoInvoke(mathFunc, 0.1);
        waitArray[1] = DoInvoke(mathFunc, 0.5);
        waitArray[2] = DoInvoke(mathFunc, 1.0);
        waitArray[3] = DoInvoke(mathFunc, 3.14159);
        Console.WriteLine("Begin Invoke Done");
        
        Console.WriteLine("Waiting for completion");
        WaitHandle.WaitAll(waitArray, 10000, false);
        Console.WriteLine("Completion achieved");
    }
}


           
       








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