llSetAlarmClock function and alarm event
Peter Stindberg
Often you need to have a script perform certain duties at specific times, for example at Midnight. Currently, you need to set a timer at a shorter interval, and check the time until the desired time is reached. I myself have used a variation of the following many times:
- Calculate minutes to full hour
- Set a timer to the full hour
- Change the timer to run hourly
- Check in every timer instance wether the alarm time is reached
Especially if you have a timer running for other tasks as well, this gets cumbersome as you have to make many comparisons in the timer loop.
This is certainly doable - has been done by LSL developers since the dawn of time - but is annoying and confusing for new devs starting with LSL. I would like to suggest an easier solution for this:
llSetAlarmClock(list alarmtimes)
The various alarm times are given in a list as integer parameters:
llSetAlarmClock([2400,0900,1233,1758])
This would set an alarm for Midnight, 9am, 12:33 and 5:58pm SLT time.
When an alarm time is reached, the alarm-event gets triggered:
alarm(integer alarmtime) {}
The alarmtime variable contains the integer representing the alarm time that triggered the event, in the above example e. g. 1233.
An alarm time gets removed from the list by re-submitting the list without the specific time:
llSetAlarmClock([2400,0900,1758])
In this exmaple, the timer for 12:33 gets removed. In order to clear all alarms, an empty list gets submitted:
llSetAlarmClock([])
If the Lab is generous, they could also implement:
list llGetAlarmClock()
This would return the currently set alarms, so the need to keep the list of alarms saved in memory gets removed.
This would simplify wallclock-time based activities a lot, and would especially helpful by inexperienced/new scripters, but also benefit seasoned devs.
Pretty please?
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Bugs Larnia
The more I read it, the more I like it. I'm not sure how the server-side implementation would work, but it would be a great asset.
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Bleuhazenfurfle Resident
A wall-clock version of llSetTimerEvent would be very nice, since llSetTimerEvent is affected by time dilation, which is problematic over long durations… llSetTimerAlarm would be a good name if it shares the same timer, to make that point more clear.
As for multiple timers… They're really not difficult at all, and in any non-trivial case, not notably more so than handling all those keys or integers or whatever tag you choose it to return. Plus, LL will have to impose a limit, and it likely won't be a big one — so if you need a decent number of them, you'll end up having to fall back to what we already do now anyhow. (Plus there's the whole event queue overflow thing if they all happen to come in at the same time.)
There's basically three main multi-timer patterns;
* regular count and divide; fine if one of your timers is (close enough to) a divisor of all the others. (This gets horribly overused, though; for everything that is holy, don't use a 1 second fixed interval timer to run your nightly or even weekly event!!! — yes, I've seen it done more than once.)
* positional list of times with LIST_STAT_MIN; good for a fixed set of timers, if()s to check each for expiry really isn't too bad.
* strided list with llListSort; the granddaddy pattern, you pair the time with a "timer id", and anything else you need — this method can do it all, including implementing a complete multi-llSetTimerEvent replacement, though just re-adding repeated timers each time they fire is generally much better.
The last two methods basically come down to a list of absolute times, from which you find the smallest, and set the next timer event for the difference from then to now (being sure to handle already expired times appropriately — I generally just use a minimum interval of 0.1s between timers). You also lose all these fun tuning options if LL do it for you.
Nelson Jenkins
l'd prefer a function that specifies the hour and minute separately with a return value (like the suggestion below). Or, maybe even simpler to implement and more granular, seconds throughout the day. Using an integer from 0 to 2359 to represent 24-hour time requires a relatively convoluted validation process when you could just say that any integer from 0 to 86399 is valid. I'm not aware of any languages that do that (although most have time structs/classes/whatever in the first place).
Peter Stindberg
Nelson Jenkins I doubt a second-based granularity is necessary, feasible, or even possible. But by all means, if the Lab can pull it off, so be it.
I liked the idea of a list, so you can set multiple timers at once and do not need to save a list of keys (which consumes memory).
Bavid Dailey
i like the idea of having multiple timers , but this seems a bit too complex.
Off the top of my head why not return a key from llSetAlarm and change the list to an integer
key llSetAlarm(integer whenever)
then the alarm event looks like
alarm(key whichalarm)
?
Peter Stindberg
Bavid Dailey Would work as well. I had LSL newcomers in mind, but returning a key is established practice so why not.