Re: delay function
Re: delay function
- Subject: Re: delay function
- From: Brendan Younger <email@hidden>
- Date: Tue, 07 Dec 2004 22:29:45 -0600
On Dec 7, 2004, at 9:25 PM, Ricky Sharp wrote:
On Dec 7, 2004, at 9:18 PM, Thomas Davie wrote:
On 8 Dec 2004, at 02:43, Ricky Sharp wrote:
I current have it set to 50 ms which would be just over 6 ticks. I
have yet to fine-tune this. At 8-ticks it seems a bit too high when
comparing it to what the built-in widgets do (e.g. NSButton).
A quick note - you're much better off using an NSTimer to fire an
event when you need to unhighlight your control – that way only the
threads that depend on that control block and the rest of your
computation continues – much better for multitasking.
That's a good tip. I'll definitely revisit this code later to ensure
it's a good citizen. I will especially need it in an upcoming title
which will be using threads to run the AI portion of a game.
While I would agree that a timer is much better general practice for
this sort of thing, you need to remember that NSRunLoop is not exactly
fit for real-time processing. In fact, NSRunLoop will often "cheat"
with timer fire dates and fire just a little early to make sure that
your callback will be called in time. For a UI element, you most
certainly do not want the highlight delay to be variable, which it
certainly will if you use NSTimers. Using +[NSThread sleepUntilDate:]
is the correct call in this case since it will NOT block other threads,
even though sleep() and usleep() might. In fact, +[NSTimer
sleepUntilDate:] actually calls the Mach function thread_switch()
underneath (curse pthreads for not having a pthread_sleep() function!).
If you're curious, add a breakpoint on _NSMilliSleep() (I'm pretty
sure that's the correct name) which you can see in the disassembly just
calls thread_switch(). One final thing to note is that Mach does not
promise that it will be able to sleep a thread for any amount of time;
it may well be that every other thread in the system is blocked on some
resource, but I've yet to actually see this in practice.
Brendan Younger
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