使用eventwaithandle进行调度

Question

Hi im trying to create an implementation of scheduling using the EventWaitHandle class

Take the following example:

// Program 1
static void Main(string[] args)
{
    EventWaitHandle wh = new EventWaitHandle(false,EventResetMode.ManualReset,"MyCrossProcessEventHandle");
    wh.Set();
}

// Program 2
static void Main(string[] args)
{
    EventWaitHandle wh = new EventWaitHandle(false, EventResetMode.ManualReset, "MyCrossProcessEventHandle");

    while (true)
    {
        var span = CalculateSpan();

        wh.WaitOne(span);

        // TODO Implement check, why did execution proceed? 
        // timeout ocurred
        // OR
        // Eventhandle was set
        //
        // if timeout occured
        // break the current iteration loop (And thereby calculate a new timeout)
        //
        // if event.set
        // continue execution




        // SNIP SNIP - More code here
    }
}

private static int CalculateSpan()
{
    DateTime datetoRun = new DateTime(2020,01,01,00,00,00);

    var span = datetoRun - DateTime.Now;

    if (span.TotalMilliseconds >= int.MaxValue)
    {
        return int.MaxValue;
    }

    return (int)span.TotalMilliseconds;
}

READ THE TODO IN THE CODE

Boiled down: So i want to be able to schedule an execution for more than int.MaxValue, and manually force execution cross process

Perhaps an easier way of achieving the exact same scenario?

Answer 1

If all you're after is waiting for a set period of time before doing something you could use:

• Thread.Sleep
  • Not recommended though as this blocks the thread and is generally considered bad practice (unless you're on a separate thread you can block)
• Timer
  • The most common solution as it supports firing a timer event asynchronously so it doesn't interfere with your main thread etc.

You could also just spin up a new thread / Task and wait for a set period before doing something:

Task.Factory.StartNew(() =>
{
   Thread.Sleep(CalculateSpan());
   // Do something here because the time to wait has passed now
});

Answer 2

After reading the documentation (DOH) i found the solution

    // Summary:
    //     Blocks the current thread until the current System.Threading.WaitHandle receives
    //     a signal, using a 32-bit signed integer to specify the time interval.
    //
    // SNIP SNIP
    //
    // Returns:
    //     true if the current instance receives a signal; otherwise, false.
    //
    // SNIP SNIP
    public virtual bool WaitOne(int millisecondsTimeout);