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macOS sleep() VS. usleep() VS. [NSThread sleepForTimeInterval:]

Darkroom

Darkroom

Guest
Original poster
Dec 15, 2006
2,445
0
Montréal, Canada
i don't really understand the difference between these 3 functions... assuming i have a program running, with several timers going on in the background for different things, and i execute an IBAction which would execute some stuff and then pause for 2 seconds before redirecting to another method in the class... which of these 3 functions are better to use and why?

Code: 
-(IBAction)start:(id)sender
{
[COLOR="Green"]//do something;
//do something else;[/COLOR]

[NSThread sleepForTimeInterval:2]; [COLOR="green"]//or[/COLOR]
sleep(2); [COLOR="green"]//or[/COLOR]
usleep(2000);

[COLOR="green"]//then redirect to another method within the class[/COLOR]
}

i should probably mention that while "usleep" seems to be an actual function and compiles without error: usleep(<#useconds_t #>), it doesn't work for me at all...
 
K

kpua

macrumors 6502
Jul 25, 2006
294
0
They're essentially all wrappers around nanosleep() and just provide different conveniences.

I think useconds_t is just a typedef for unsigned long or unsigned long long, so passing other integer types won't cause errors.


Haha... sorry. I didn't see the actual question in there—it was too early in the morning. Do what Catfish Man said.
 
Catfish_Man

Catfish_Man

macrumors 68030
Sep 13, 2001
2,579
2
Portland, OR
None of the above. Sleeping the main thread will just lag your program. Instead, schedule an NSTimer to fire two seconds later with the work you need done.
 
iSee

iSee

macrumors 68040
Oct 25, 2004
3,539
272
Darkroom said:
i should probably mention that while "usleep" seems to be an actual function and compiles without error: usleep(<#useconds_t #>), it doesn't work for me at all...
Click to expand...

The parameter of usleep() is in microseconds. That's millionths of a second. So usleep(2000) will sleep for 2 milliseconds (two thousandths of a second)--too fast for a human to perceive. sleep(2) would be equivalent to usleep(2000000).
 
Darkroom

Darkroom

Guest
Original poster
Dec 15, 2006
2,445
0
Montréal, Canada
iSee said:
The parameter of usleep() is in microseconds. That's millionths of a second. So usleep(2000) will sleep for 2 milliseconds (two thousandths of a second)--too fast for a human to perceive. sleep(2) would be equivalent to usleep(2000000).
Click to expand...

ooohhhh! i though it was just my lefts and rights that i got mixed up, now i've got to deal with microseconds and milliseconds too :p... but at least now i know why it wasn't working... thanks for that...
 
Darkroom

Darkroom

Guest
Original poster
Dec 15, 2006
2,445
0
Montréal, Canada
i had noticed that [NSThread sleepForTimeInterval:2]; actually pauses my application instead of just the class it's in, which i had assumed the later would be the case...

after playing around with this function, i had noticed that the spinning beachball would show up if i set it this function to around 5 seconds... strange? yes/no?

i've therefore decided to use [NSThread sleepForTimeInterval:0.5]; instead of using NSTimer - simply because NSTimer gave unexpected/unwanted results in certain situations.
 
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