C# - Alternative to System.Timers.Timer, to call a function at a specific time.

Question

Hello everybody.

I want to call a specific function on my C# application at a specific time. At first i thought about using a Timer (System.Time.Timer), but that soon became impossible to use. Why?

Simple. The Timer Class requires a Interval in milliseconds, but considering that i might want the function to be executed, lets says in a week that would mean:

• 7 Days = 168 hours;
• 168 Hours = 10,080 minutes;
• 10,080 Minutes = 6,048,000 seconds;
• 6,048,000 Seconds = 6,048,000,000 milliseconds;
• So the Interval would be 6,048,000,000;

Now lets remember that the Interval accepted data type is int, and as we know int range goes from -2,147,483,648 to 2,147,483,647.

That makes Timer useless in this case once we cannot set a Interval bigger that 2,147,483,647 milliseconds.

---

So i need a solution where i could specify when the function should be called. Something like this:

solution.ExecuteAt = "30-04-2010 15:10:00";
solution.Function = "functionName";
solution.Start();

So when the System Time would reach "30-04-2010 15:10:00" the function would be executed in the application.

How can this problem be solved?

Thanks just by taking the time to read my question. But if you could provide me with some help i would be most grateful.

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Additional Info: What these functions will do?

• Getting climate information and based on that info:
  • Starting / Shutting down other Applications (most of them Console Based);
  • Sending custom Commands to those Console Applications;
  • Power down, Rebooting, Sleep, Hibernate the computer;
  • And if possible schedule the BIOS to Power Up the Computer;

EDIT:

It would seem that the Interval accepted data type is double, however if you set a value bigger that an int to the Interval, and call Start() it throws a exception [0, Int32.MaxValue].

EDIT 2:

Jørn Schou-Rode suggested using Ncron to handle the scheduling tasks, and at first look this seems a good solution, but i would like to hear about some who as worked with it.

Answer 1

I would recommend that you just write a program that deals with the business part of it and then execute that program when necessary by using Windows Task Scheduler.

Answer 2

Your "Start()" method should spawn a thread that wakes up at a defined interval, checks the time, and if you haven't reached the desired time, goes back to sleep.

Answer 3

You can use the System.Threading.Timer class, which provides a constructor accepting an interval expressed as an Int64, which should be enough for your needs.

Now for the other stuff :

• You can start/stop/configure program using the Process class (I don't really get what you call "custom commands")
• You cannot restart or shut down or control the local BIOS using native .NET classes. Rebooting / restarting is possible through Interop (calling native Windows API from .NET), and scheduling the BIOS is just impossible. Or maybe with a special server motherboard ? I don't know..

Answer 4

You could write some sort of wrapper class for a Timer which takes a DateTime instance. Then you perform the following steps:

1. Determine the difference between DateTime.Now and the desired time.
2. If the difference (in milliseconds) is larger than the maximum allowed value for the Timer.Interval property, set the Interval to the maximum allowed value (i.e. double.MaxValue or whatever) and start it.
3. Now, when the timer elapses the first time, you simply go back to step 1.

At some time, the difference will be smaller than the maximum allowed value for the Interval property, and then you could fire an event in your wrapper which ultimately calls the desired method.

Answer 5

Use the System.Threading.Timer:

    var timer = new System.Threading.Timer(delegate { }, // Pass here a delegate to the method
        null,
        TimeSpan.FromDays(7), // Execute Method after 7 days.
        TimeSpan.Zero);

Answer 6

The class System.Threading.Timer has the same limitation too (it would throw an ArgumentOutOfRangeException according to MSDN).

There seems to be no .Net Framework class natively adept to circumvent the Int32.MaxValue milliseconds upper bound.

public static class Scheduler
{
    private const long TimerGranularity = 100;

    static Scheduler()
     {
         ScheduleTimer = new Timer(Callback, null, Timeout.Infinite, Timeout.Infinite);
        Tasks = new SortedQueue<Task>();
     }

    private static void Callback(object state)
    {
        var first = Tasks.Peek();
        if(first.ExecuteAt<DateTime.Now)
        {
            Tasks.Dequeue();
            var executionThread = new Thread(() => first.Function());
            executionThread.Start();                
        }
    }

    private static Timer ScheduleTimer { get; set; }

    public static void Start()
    {
        ScheduleTimer.Change(0, TimerGranularity);
    }
    public static void Add(Task task)
    {
        Tasks.Enqueue(task);
    }

    public static SortedQueue<Task> Tasks { get; set; }
}

public class Task : IComparable<Task>
{
    public Func<Boolean> Function { get; set; }

    public DateTime ExecuteAt { get; set; }

    public int CompareTo(Task other)
    {
        return ExecuteAt.CompareTo(other.ExecuteAt);
    }
}

The solution I'd use is something similar to the above example: a class Scheduler that manages all the Tasks (in order to avoid having a timer for each task we are going to schedule).

Tasks are added to the a queue able to perform sorted insertion. Note that SortedQueue<T> is not a type of the .Net Framework but an hypothetical, easy-to-code collection capable of sorted insertion on a comparable type T.

The scheduler awakes every TimerGranularity milliseconds and checks for the first task whose `ExecuteAt' time has been surpassed; then executes it on a separate thread.

Additional effort could be done by creating a list of all surpassed tasks (instead of the first one only); but I left it out for the sake of clarity.

Answer 7

One approach to task scheduling, simliar to that proposed by klausbyskov, is to built your scheduling service on top of an existing .NET scheduling framework/library. Compared to using the Windows Task Scheduler, this has the advantages of (a) allowing several jobs to be defined in the same project and (b) keeping jobs and scheduling logic "together" - i.e. not relying on server settings prone to get lost in system upgrades/replacements.

I know of two open-source projects that offer this kind of functionality:

• "Quartz.NET is a full-featured, open source job scheduling system that can be used from smallest apps to large scale enterprise systems." I have never actually used this framework myself, but from studying the website, I have the impression of a very solid tool, providing many cool features. The fact that there [quartz-net] tag on Stackoverflow might also indicate that it is actually used in the wild.

• "NCron is a light-weight library for building and deploying scheduled background jobs on the .NET server platform." It does not have half as many features as Quartz.NET, and it does not have any tag on Stackoverflow, but the author (yours truly) believes that its low-friction API makes it somewhat easier to get started with.

Building your scheduling service on top of NCron, you can schedule a CleanupJob for weekly execution using a single line of code:

service.Weekly().Run<CleanupJob>();

_{Ok, you will need around three lines of boiler plate code on top of that to actually turn your project into a Windows service, but it sounds more impressive when I claim that it can be done with one line of code ;)}

Answer 8

I am writing a simple application that is making use of nCron scheduling framework. I dont know what i am doing wrong. This is the exception when i am trying to start the service from Service Manager.

Everything is successfully compiled and installed.Here is the exception that i am getting in Eventlog on starting application.

Event Type: Error

Event Source: nCronTestApplication Event Category: None Event ID: 0 Date: 5/18/2010 Time: 8:45:45 PM User: N/A Computer: HAKSIT-02 Description: An unhandled exception has occured. System.IO.FileNotFoundException: Could not load file or assembly 'C5, Version=1.1.0.0, Culture=neutral, PublicKeyToken=06a1b38866503b69' or one of its dependencies. The system cannot find the file specified. File name: 'C5, Version=1.1.0.0, Culture=neutral, PublicKeyToken=06a1b38866503b69' at NCron.Service.SchedulingService..ctor() at NCron.Service.Bootstrap.RunService(Action`1 setupHandler, Boolean debug) WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.**

Any help is highly appreciated.

Answer 9

Hi

I found calculation wrong at first comment, Milliseconds for 7 days should be 604,800,000. Not 7 days = 6,048,000,000 Milliseconds. Because 1 day = 86,400,000 milliseconds