Re: creating multiple NSTimers
Re: creating multiple NSTimers
- Subject: Re: creating multiple NSTimers
- From: Conrad Shultz <email@hidden>
- Date: Fri, 30 Sep 2011 00:19:54 -0700
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On 9/29/11 10:50 PM, Greg Guerin wrote:
> Gordon Apple wrote:
>
>> There must already be an array for the table, so just iterate
>> the
> array every
>> minute or whatever (single repeating timer), compare the times to
>> [NSDate date} and start or shut down whatever has not been
>> started or shut
> down. Much
>> easier than trying to manage timers.
>
> You don't have to iterate the whole array, either. Sort it by
> ascending order of turn-off time. Keep a current position (index).
> If the time of day is less than the turn-off time of the device at
> the current position, do nothing. If time of day >= turn-off time
> of current position, then turn it off and advance position until
> time of day is again less than the turn-off time of device at the
> current position. Only needs one timer, and scales to as large an
> array as you want to keep.
I don't really see how this is superior to keeping the one timer per
remote box.
When the user updates a timer, one is forced to re-sort the array and
reposition the index (under the above implementation).
One would also have to implement the scheme carefully, particularly if
the shut-off code is offloaded onto separate threads, to avoid
potential race conditions arising from a user changing a fire date in
the middle of a shut-off sequence.
And as Graham mentioned, polling is probably less CPU and power
efficient than using timers anyway.
Am I missing something conceptually here? Why are people pushing for
the single timer model? Is there some hidden complexity in a
multi-timer approach that I'm not seeing?
- --
Conrad Shultz
Synthetiq Solutions
www.synthetiqsolutions.com
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