Polling Service - C#

问题:

Will anobody be able to help me?

I am creating a windows service that connects to a sql database and checks a date in the table and compares it to todays date and updates a field in that database for eg if the date is equal to todays date then the field will be set to true.

The problem I am having is that when i start the service it does not do that but when i do it in a normal form it works perfectly.

My code is below:

//System.Timers
Timer timer = new Timer();
protected override void OnStart(string[] args)
{
    timer.Elapsed += new ElapsedEventHandler(OnElapsedTime);
    timer.Interval = 60000;
    timer.Enabled = true;
}

private void OnElapsedTime(object source, ElapsedEventArgs e)
{
    int campid = 0;
    var campRes = new ROS.Process.CampaignServiceController().GetCampainInfo();

    foreach (var s in campRes)
    {
        campid = s.CampaignId;

        if (s.CampEndDate.Date < DateTime.Today.Date)
        {
            //WriteDataToFile("Not Active : " + campid.ToString());
            new ROS.Process.CampaignServiceController().SetCampainStatusFalse(campid);
        }
        else
        {
            //WriteDataToFile("Active : " + campid.ToString());
            new ROS.Process.CampaignServiceController().SetCampainStatusTrue(campid);
        }
    }
}

回答1:

Another way of doing this would be to wait on an event rather then using a timer.

i.e.

    public class PollingService
    {
        private Thread _workerThread;
        private AutoResetEvent _finished;
        private const int _timeout = 60*1000;

        public void StartPolling()
        {
            _workerThread = new Thread(Poll);
            _finished = new AutoResetEvent(false);
            _workerThread.Start();
        }

        private void Poll()
        {
            while (!_finished.WaitOne(_timeout))
            {
                //do the task
            }
        }

        public void StopPolling()
        {
            _finished.Set();
            _workerThread.Join();
        }
    }

In your Service

    public partial class Service1 : ServiceBase
    {
        private readonly PollingService _pollingService = new PollingService();
        public Service1()
        {
            InitializeComponent();
        }

        protected override void OnStart(string[] args)
        {
            _pollingService.StartPolling();
        }

        protected override void OnStop()
        {
            _pollingService.StopPolling();
        }

    }

回答2:

Set Timer.AutoReset = true. otherwise it will do its work only one time. but it's better to work with threading in windows services.

[edit] ah, yes. autoreset is true in default. I put this too in my code: GC.KeepAlive( myTimer ); so the gc won't remove it if it is inactive.