On Dec 9, 2012, at 6:53 AM, Ken Thomases <k...@codeweavers.com> wrote:
> On Dec 9, 2012, at 1:27 AM, Kyle Sluder wrote: > >> If dispatch_once() really is unsuitable for use with a dispatch_once_t >> stored in Objective-C instance storage, then the correct example in the >> paper I've cited might be a sufficient workaround. > > I thought we had established that, in all sane use cases, an instance > variable once predicate is fine. Hence the hedge. ;-) > The cases where an instance variable once predicate would be unsafe are > exactly the cases where it would be unsafe to access any instance variable, > including the isa pointer. So, if you're using the instance in any way, > you've already assumed conditions that make the once predicate fine. (And, > hopefully, you've more than assumed it, you've ensured it by proper > inter-thread communication of the object pointer.) Yes, but as Greg pointed out the real danger comes from not understanding all the nuances of this, and assuming that dispatch_once is a more powerful synchronization primitive than it really is. --Kyle Sluder _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
