Beginner's Guide to Threading in .NET: Part 2 of n

using System;
using System.ComponentModel;
using System.Threading;

namespace ThreadResumePause_StopUsingEventArgs
{

    public delegate void ReportWorkDoneEventhandler(object sender, 
    WorkDoneCancelEventArgs e);
    
    /// <summary>
    /// This class provides a background worker that finds prime numbers, that
    /// are reported to the UI via the ReportWorkDone event. The UI may pause
    /// the worker by calling the Pause() method, and may resume the worker by
    /// calling the Resume() method. The UI may also cancel the worker by setting
    /// the ReportWorkDone events event args Cancel property to true.
    /// </summary>
    public class WorkerThread
    {

        private Thread worker;
        public event ReportWorkDoneEventhandler ReportWorkDone;
        private volatile bool cancel = false;
        private ManualResetEvent trigger = new ManualResetEvent(true);

        //ctor
        public WorkerThread()
        {
            
        }


        //Do the work, start the thread
        public void Start(long primeNumberLoopToFind)
        {
            worker = new Thread(new ParameterizedThreadStart(DoWork));
            worker.Start(primeNumberLoopToFind);
        }


        //Thread start method
        private void DoWork(object data)
        {

            long primeNumberLoopToFind = (long)data;

            int divisorsFound = 0;
            int startDivisor = 1;

            
            for (int i = 0; i < primeNumberLoopToFind; i++)
            {
                //wait for trigger
                trigger.WaitOne();

                divisorsFound = 0;
                startDivisor = 1;

                //check for prime numbers, and if we find one raise
                //the ReportWorkDone event
                while (startDivisor <= i)
                {
                    if (i % startDivisor == 0)
                        divisorsFound++;
                    startDivisor++;
                }
   
                if (divisorsFound == 2)
                {

                    WorkDoneCancelEventArgs e = 
                        new WorkDoneCancelEventArgs(i);
                    OnReportWorkDone(e);
                    cancel = e.Cancel;

                    //check whether thread should carry on, 
                    //perhaps user cancelled it
                    if (cancel)
                        return;
                }
            }
        }


        /// <summary>
        /// make the worker thread wait on the ManualResetEvent
        /// </summary>
        public void Pause()
        {
            trigger.Reset();
        }


        /// <summary>
        /// signal the worker thread, raise signal on 
        /// the ManualResetEvent
        /// </summary>
        public void Resume()
        {
            trigger.Set();
        }


        /// <summary>
        /// Raise the ReportWorkDone event
        /// </summary>
        protected virtual void OnReportWorkDone(WorkDoneCancelEventArgs e) 
        {
            if (ReportWorkDone != null) 
            {
                ReportWorkDone(this, e); 
            }
        }
    }



    //Simple cancellable EventArgs, that also exposes 
    //current prime number found to UI
    public class WorkDoneCancelEventArgs : CancelEventArgs 
    {
        public int PrimeFound { get; private set; }

        public WorkDoneCancelEventArgs(int primeFound)
        {
            this.PrimeFound = primeFound;
        }
    }


}