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From "Hunsberger, Peter" <Peter.Hunsber...@stjude.org>
Subject RE: CommandManager issues [was Re: Releasing 2.1.1?]
Date Mon, 01 Sep 2003 15:14:05 GMT
Giacomo Pati <giacomo@apache.org> writes:

<snip/>

> First, if you look at the Cornerstone Scheduler you'll see 
> that the ability to define repeated tasks are somehow 
> limited. Business apps can easily request administration 
> tasks to be run twice a day on work days. To define this with 
> the Cornerstone Scheduler you'll need to add 10 'cron' 
> entries to it. This is why I'd like to extend it using the 
> unix cron direction to define ranges and list of timing 
> aspects. But then you're faced with the problem of defining 
> sleep time for efficient use (which you need to be able to 
> cooperate in the Cornerstone Scheduler machinery).
> 
> The unix cron daemon runs every minute to check if there are 
> any jobs to run. It checks initially creating bitsets for the 
> minute, hour, day, month, and weekday definition for each 
> task. This makes it easy to check whether a task has to be 
> launched. I still haven't found an algorithm (and I think 
> there isn't an easy one available) to determine the sleep 
> time until the next task is due.

I did this once upon a time, I think in C code.  As I recall it's
basically the equivalent of building a Map of tasks and the calculated
delta time until they need to be executed next and then using the
minimum of these deltas. I don't think it's all that complex?  This
could be a little problematic if the delta's are in the same order of
magnitude as the time to calculate them :-), but that certainly doesn't
seem to be the case here....

<snip/>


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