Scheduled Event

[pjama]

I was wondering what the best method to execute a sub-function at scheduled times of the day (ie. 4:00:00 AM and 4:00:00 PM)

My program consists of a timed-loop structure counting different machine states, and it needs to log the data to file and restart the count twice daily.

The way I have it now, in every loop cycle, it checks if the time = 4:00:00. However, I doubt this is the best way to do it, and I would greatly appreciate any suggestions.

-Phil

[jpdrolet]

I was wondering what the best method to execute a sub-function at scheduled times of the day (ie. 4:00:00 AM and 4:00:00 PM)

My program consists of a timed-loop structure counting different machine states, and it needs to log the data to file and restart the count twice daily.

The way I have it now, in every loop cycle, it checks if the time = 4:00:00.  However, I doubt this is the best way to do it, and I would greatly appreciate any suggestions.

-Phil

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Polling is fine. However, be careful when comparing to exactly 4:00:00 e.g. if the system is busy and the loop only execute at 4:00:01 (skipping 4:00:00) , you'll miss the condition. Maybe time >= 4:00:00 is better.

If you do not want to poll, you can have a parallel process generate an event when it is time to log. For example you wait for a dummy notification with the timeout set to expired at 4:00:00. There is no polling and when the wait times out, execute your log.

[pjama]

You can see why I dont want to poll; the exact second could be missed. So far I've put my program as 'Time-Critical' execution. The problem with doing >=4:00:00 is that it would log every second after 4 o'clock, until it reaches midnight again.

I'm writing to ask what you meant to "have a parallel process generate an event." How would I go about creating a notification, etc?

Thanks,

-Phil

[FLX]

You can see why I dont want to poll; the exact second could be missed.

[didierj]

  So far I've put my program as 'Time-Critical' execution.

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Even with "Time-Critical" your app isn't proof of missing 4:00:00. The only way to be sure not to miss a time would require you to run a real-time operating system.

On Windoze (probably Unix and Mac also) you have always tasks from the system that can have a higher priority than your LV "Time-Critical" process. A temporary high network, Harddisk traffic or complicate screen build up (streaming or rendering) can freeze your computer for several seconds. On W2k/XP systems theese are rare occasions, but if your network switch destroys itself (happend to me: while I was copying big file to a network drive a network switch collapsed, my computer was freezed for more than 15 mins)

So far, the best method is the notification method.

Didier