On Dec 9, 2011, at 1:11 AM, Uli Kusterer wrote: > On 09.12.2011, at 07:55, Ken Thomases wrote: >> On Dec 8, 2011, at 11:18 PM, Abdul Sowayan wrote: >>> The above will still work in an ARC environment. It is rather inefficient, >>> however. For details please check the "Double Check Locking Optimization >>> pattern": >>> http://www.cs.wustl.edu/~schmidt/PDF/DC-Locking.pdf >> >> Double-checked locking is broken. It is an anti-pattern in many languages, >> including the C family under most common implementations. Don't use it. >> Google it if you want to confirm. One reference: >> <http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html>. > > > Is this an issue that just exists when you want to write against ANSI C, or > is this an actual, practical concern when writing on the Mac, for MacOS or > iOS? Does anyone have information on the actual memory model implemented in > Mac C, ObjC and C++ compilers that reinforce this? > > Just trying to figure out whether I have to change a lot of existing Mac and > iOS code now, or whether it suffices to be aware of the problem and not write > it in new code and stuff that gets ported.
Why not just use dispatch_once? Charles_______________________________________________ Cocoa-dev mailing list ([email protected]) 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
