Best Timer for using in a Windows service

Answer 1

I know this thread is a little old but it came in handy for a specific scenario I had and I thought it worth while to note that there is another reason why System.Threading.Timer might be a good approach. When you have to periodically execute a Job that might take a long time and you want to ensure that the entire waiting period is used between jobs or if you don't want the job to run again before the previous job has finished in the case where the job takes longer than the timer period. You could use the following:

using System;
using System.ServiceProcess;
using System.Threading;

    public partial class TimerExampleService : ServiceBase
    {
        private AutoResetEvent AutoEventInstance { get; set; }
        private StatusChecker StatusCheckerInstance { get; set; }
        private Timer StateTimer { get; set; }
        public int TimerInterval { get; set; }

        public CaseIndexingService()
        {
            InitializeComponent();
            TimerInterval = 300000;
        }

        protected override void OnStart(string[] args)
        {
            AutoEventInstance = new AutoResetEvent(false);
            StatusCheckerInstance = new StatusChecker();

            // Create the delegate that invokes methods for the timer.
            TimerCallback timerDelegate =
                new TimerCallback(StatusCheckerInstance.CheckStatus);

            // Create a timer that signals the delegate to invoke 
            // 1.CheckStatus immediately, 
            // 2.Wait until the job is finished,
            // 3.then wait 5 minutes before executing again. 
            // 4.Repeat from point 2.
            Console.WriteLine("{0} Creating timer.\n",
                DateTime.Now.ToString("h:mm:ss.fff"));
            //Start Immediately but don't run again.
            StateTimer = new Timer(timerDelegate, AutoEventInstance, 0, Timeout.Infinite);
            while (StateTimer != null)
            {
                //Wait until the job is done
                AutoEventInstance.WaitOne();
                //Wait for 5 minutes before starting the job again.
                StateTimer.Change(TimerInterval, Timeout.Infinite);
            }
            //If the Job somehow takes longer than 5 minutes to complete then it wont matter because we will always wait another 5 minutes before running again.
        }

        protected override void OnStop()
        {
            StateTimer.Dispose();
        }
    }

    class StatusChecker
        {

            public StatusChecker()
            {
            }

            // This method is called by the timer delegate.
            public void CheckStatus(Object stateInfo)
            {
                AutoResetEvent autoEvent = (AutoResetEvent)stateInfo;
                Console.WriteLine("{0} Start Checking status.",
                    DateTime.Now.ToString("h:mm:ss.fff"));
                //This job takes time to run. For example purposes, I put a delay in here.
                int milliseconds = 5000;
                Thread.Sleep(milliseconds);
                //Job is now done running and the timer can now be reset to wait for the next interval
                Console.WriteLine("{0} Done Checking status.",
                    DateTime.Now.ToString("h:mm:ss.fff"));
                autoEvent.Set();
            }
        }