Re: Background Process?
Re: Background Process?
- Subject: Re: Background Process?
- From: Kyle Sluder <email@hidden>
- Date: Tue, 10 Mar 2009 22:19:49 -0400
On Tue, Mar 10, 2009 at 9:49 PM, Roland King <email@hidden> wrote:
> Could you expand on that a bit please? My mental picture of the runloop has
> always been more like a select() which does nothing unless there is
> something to do. Not that I ever quite sorted out in my own mind how an
> NSTimer fits is something you can select() on. Does the runloop actually
> poll a whole lot even when it has nothing to do?
While NSTimers are not normal input sources, the frameworks are free
to add any input source to the runloop that they wish. And in order
for your timer to fire, you need to keep the runloop awake, using at
least a dummy input source. See "Timers" in "Timer Programming Topics
for Cocoa":
"A timer is not a real-time mechanism; it fires only when one of the
run loop modes to which the timer has been added is running and able
to check if the timer’s firing time has passed."
http://developer.apple.com/documentation/Cocoa/Conceptual/Timers/Articles/timerConcepts.html#//apple_ref/doc/uid/20000806
So your process will need to remain awake, which means that the
processor needs to be that much more active.
--Kyle Sluder
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