Apple

-Morgan

On Sat, Jan 8, 2011 at 6:17 PM, Kyle Sluder <email@hidden> wrote:

On Fri, Jan 7, 2011 at 6:41 PM, Morgan Packard <email@hidden> wrote:
> Your post has scared me a bit, since I've been using Objective-C
> extensively. I've been getting some conflicting bits of advice regarding
> whether it's appropriate to call objective-c code from the RemoteIO
> callback. Do you have more specific ideas about what was causing your
> glitches? Was it the non-cached selector calls described
> here http://lists.apple.com/archives/cocoa-dev/2006/feb/msg01735.html, or
> perhaps something else involving locks?

The advice is quite clear: do not call objc_msgSend from your render
callback or anything that gets called by it. This means no calling
Objective-C methods using [foo bar] syntax.

Calling cached IMPs is fine, but only if those IMPs don't themselves
call objc_msgSend.

Under the current runtime, there's a very small chance that calling
objc_msgSend will cause glitches. But since the number of things you
need to do in a render callback is so small and well-defined, there's
very little reason to be using Objective-C anyway.

Render callbacks are very much a "get in, get it done, get out"
situation. If your current architecture will not function without the
dynamic features of Objective-C, that's a good indication that it's
too complicated to fit into a render callback in the first place.

--Kyle Sluder

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References:
	>Re: RemoteIO glitches - cured by propListener audio route change?! (From: jhno <email@hidden>)
	>Re: RemoteIO glitches - cured by propListener audio route change?! (From: Morgan Packard <email@hidden>)
	>Re: RemoteIO glitches - cured by propListener audio route change?! (From: Kyle Sluder <email@hidden>)