> >> On 27 Jul 2016, at 09:33, Trygve Inda <cocoa...@xericdesign.com> wrote: >> >> >> >> If the worker thread calls window.imageRep = myResult; it is possible that >> the main thread is in the middle of a call like: >> >> [[window.imageRep] >> drawInRect:fromRect:operation:fraction:respectFlipped:hints:] >> >> So when the setter (called from the worker thread) replaces the old imageRep >> with a new one, the old one's retain count goes to zero and it will >> disappear. >> >> I know atomic makes the call safe as far as a vaild value is concerned, but >> the main thread could call window.imageRep and get a valid value (because it >> is atomic), but before it is able to use this value, the worker thread calls >> the setter which causes the imageRep obtained by the main thread to be >> released. > > No it couldn’t - because when the main thread calls window.imageRep it gets a > reference which, whether it assigns it to a variable or just uses it in in a > chained call (like you have above with drawInRect:.) is retained by the main > thread during the life of that variable or during the call. So it doesn’t > matter if the worker thread replaces it after the call to window.imageRep, the > main thread’s reference remains valid and usable and is only released when > it’s finished with it and only then gets deallocated (if nothing else is > referencing it) >
How is it retained by the main thread without an explicit retain call? I would be no different than a main thread calling: someVar [[MyObj alloc] init] [someVar doSomething]; If a worker thread were able to call [someVar release] between these two lines, the doSomething call could fail. _______________________________________________ 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
