Re: Giving the CPU a break...

FROM : Sherm Pendley
DATE : Wed Nov 20 05:00:36 2002

On Monday, November 18, 2002, at 02:04 PM, Buzz Andersen wrote:

> My question is: is there a good way for me to give the CPU a break and
> make the computer more responsive during this loop without compromising
> performance significantly?

Are you sending messages inside of this loop? If so, you could eliminate
some overhead from that, by using NSObject's methodForSelector: to get a
direct pointer to the implementation (that is, an IMP) for the method.

From the example, you'd replace this:

while ( ![target isEqual: someObject] ) {
    ...
}

with this:

BOOL (*test)(id, SEL, id);
test = (BOOL (*)(id, SEL, id))([target methodForSelector:
@selector(isEqual:)];
while ( !test(target, @selector(isEqual:), someObject) ) {
    ...
}

As you can see, the replacement is a bit harder to read. I'd benchmark
both alternatives, to be sure that the added performance is enough to
justify the loss in maintainability.

sherm--

If you listen to a UNIX shell, can you hear the C?
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