Windows Service to run a function at specified tim

问题:

I wanted to start a Windows service to run a function everyday at specific time.

What method i should consider to implement this? Timer or using threads?

回答1:

(1) On first start, Set _timer.Interval to the amount of milliseconds between the service start and schedule time. This sample set schedule time to 7:00 a.m. as _scheduleTime = DateTime.Today.AddDays(1).AddHours(7);

(2) On Timer_Elapsed, reset _timer.Interval to 24 hours (in milliseconds) if current interval is not 24 hours.

System.Timers.Timer _timer;
DateTime _scheduleTime; 

public WinService()
{
    InitializeComponent();
    _timer = new System.Timers.Timer();
    _scheduleTime = DateTime.Today.AddDays(1).AddHours(7); // Schedule to run once a day at 7:00 a.m.
}

protected override void OnStart(string[] args)
{           
    // For first time, set amount of seconds between current time and schedule time
    _timer.Enabled = true;
    _timer.Interval = _scheduleTime.Subtract(DateTime.Now).TotalSeconds * 1000;                                          
    _timer.Elapsed += new System.Timers.ElapsedEventHandler(Timer_Elapsed);
}

protected void Timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
    // 1. Process Schedule Task
    // ----------------------------------
    // Add code to Process your task here
    // ----------------------------------


    // 2. If tick for the first time, reset next run to every 24 hours
    if (_timer.Interval != 24 * 60 * 60 * 1000)
    {
        _timer.Interval = 24 * 60 * 60 * 1000;
    }  
}

Edit:

Sometimes people want to schedule the service to start at day 0, not tomorrow so they change DateTime.Today.AddDays(0).If they do that and set a time in the past it causes an error setting the Interval with a negative number.

//Test if its a time in the past and protect setting _timer.Interval with a negative number which causes an error.
double tillNextInterval = _scheduleTime.Subtract(DateTime.Now).TotalSeconds * 1000;
if (tillNextInterval < 0) tillNextInterval += new TimeSpan(24, 0, 0).TotalSeconds * 1000;
_timer.Interval = tillNextInterval;

回答2:

Good answer (I used your code), but one problem with this line:

_timer.Interval = _scheduleTime.Subtract(DateTime.Now).TotalSeconds * 1000;

If DateTime.now is later than scheduleTime, you will go negative and this will generate an exception when assigning to timer.Interval.

I used:

if (DateTime.now > scheduleTime)
    scheduleTime = scheduleTime.AddHours(24);

Then do the subtraction.

回答3:

Are you sure, you need a service, that runs only one time per day?

Maybe Windows Task Schedule will be better solution?

回答4:

Use Windows built in Task Scheduler (http://windows.microsoft.com/en-us/windows7/schedule-a-task) or Quartz.net.

Unless ... you have a service that's doing lots of other processing and needs to be running all the time in which case a Timer might be appropriate.

回答5:

private static double scheduledHour = 10;
private static DateTime scheduledTime;

public WinService()
{
     scheduledTime = DateTime.Today.AddHours(scheduledHour);//setting 10 am of today as scheduled time- service start date
}

private void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
      DateTime now = DateTime.Now;
      if (scheduledTime < DateTime.Now)
      {
         TimeSpan span = now - DateTime.Now;
         scheduledTime = scheduledTime.AddMilliseconds(span.Milliseconds).AddDays(1);// this will set scheduled time to 10 am of next day while correcting the milliseconds
         //do the scheduled task here
      }  
}

回答6:

You can do it with a thread and an event; a timer is not necessary.

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

partial class Service : ServiceBase
{
    Thread Thread;

    readonly AutoResetEvent StopEvent;

    public Service()
    {
        InitializeComponent();

        StopEvent = new AutoResetEvent(initialState: false);
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            StopEvent.Dispose();

            components?.Dispose();
        }

        base.Dispose(disposing);
    }

    protected override void OnStart(string[] args)
    {
        Thread = new Thread(ThreadStart);

        Thread.Start(TimeSpan.Parse(args[0]));
    }

    protected override void OnStop()
    {
        if (!StopEvent.Set())
            Environment.FailFast("failed setting stop event");

        Thread.Join();
    }

    void ThreadStart(object parameter)
    {
        while (!StopEvent.WaitOne(Timeout(timeOfDay: (TimeSpan)parameter)))
        {
            // do work here...
        }
    }

    static TimeSpan Timeout(TimeSpan timeOfDay)
    {
        var timeout = timeOfDay - DateTime.Now.TimeOfDay;

        if (timeout < TimeSpan.Zero)
            timeout += TimeSpan.FromDays(1);

        return timeout;
    }
}

回答7:

if it is one in a day, why you don't use task scheduler? windows service is useful when you want run task many time in minute. so if you want to run a program in a specific time, its better to use task scheduler and set event of task scheduler on a specific time in day. I do many thing with task scheduler and its perfect. you can set rout of program in task scheduler and set interval time to run it. if you want to run a program every 5 min in a day still you can use task scheduler and its better way.