firing an event at specific time or interval

[Aussie Rules]

Hi,

I want to be able to to have an event fired within my application at a
certain time on certain days (such as 2am Monday, Wednesday and Friday) as
well as other timers that fire an event based on a time interval (such as
every 3 minutes).

Out of the box there is the old timer1, which would cover the second
scenario, but is there a way to have the first timer done?

There maybe upto 50 different timers within the application.

Thanks

 

[Stephany Young]

The first thing you need to do is determine how little tolerance you can
live with for your 'forward' time-based events. For example, will it be
absolutely critical that they are fired at the exact time or will it be
alright if they are fired at a point up to 'some small time span' after the
nomintaed time (say, 1 minute)?

If it is the former then you are going to have jump through some hoops.

If it is the latter then it is relatively simple by implementing something
like:

Set the interval for your timer to the desired value,
(say 60000 - 1 minute)

Instantiate a queue object (preferably a generic one).
Enqueue a DateTime object for each required 'trigger point'.
Each 'trigger point' will represent it's next occurrence,
(e.g., 2 AM on Friday 23 May 2008).

When the Tick event for the timer fires, Peek the first
object in the queue.
If DateTime.Now >= 'the object' then DeQueue the object
and 'fire' the appropriate event.

In your 'event' EnQueue a new DateTime object for the next
occurrence of the required 'trigger point',
(e.g., 2 AM on Friday 30 May 2008).

When the application is termintaed, the content of the queue could be
persisted to a file and when the application is instantiated, the queue
could be repopulated from the file, so the whole mechanism can survive
restarts etc.

 

[Just_a_fan]

Funny how long it took Microsoft to decide that this was the way to do
it. They had multiple timers instead of one timer that serviced a time
sorted queue.

We all had to be careful not to use too many timers. There were 16 and
that was it! Try to use a 17th one and your program was history. And
you have no idea how many were in use. What a stupid idea!!

"The IRQ is in use." -- Really, WHAT IRQ???

"The file cannot be found." -- If you would just tell me the filename, I
COULD HELP!

"An unexpected error has occurred." -- ALL errors are unexpected. HELP
ME with some indication of what the error is! Oh, I see, you won't.
Thanks?

There are stronger answers to these STILL EXISTING error messages but
they are not fit to type here.

Mike