On Thu, Feb 12, 2009 at 4:25 AM, Oleg Krupnov <oleg.krup...@gmail.com> wrote: > This seems a trivial question for a multi-threading app, but I haven't > been successful in implementing this in Cocoa. I've got deadlocks and > strange logs for seemingly no reason. > > Here's my problem: There is the main thread that starts a worker > NSOperation to do some job (-[NSOperationQueue addOperation]). In case > if the main thread is asked to start another NSOperation, it must > cancel the current operation, *wait until it exits*, and start another > one. > > What I have tried: the operation object creates and locks an NSLock > object in its -init. When the main thread cancels the operation > (-cancel), it does the following: > > // cancel > [m_operation cancel]; > // wait until operation exits > [[m_operation isCompletedLock] lock]; > > // the operation object eventually checks the -isCancelled flag and > then sends -unlock to the lock, and its thread exits. > > // unlock the lock > [[m_operation isCompletedLock] unlock]; > // release > [m_operation release]; > m_operation = nil;
Yeah, don't do this. Locks are for mutual exclusion *only*. Use NSConditionLock, something like this: #define OPERATION_FINISHED 1 // operation exit [condLock lock]; [condLock unlockWithCondition:OPERATION_FINISHED]; // wait for exit [condLock lockWhenCondition:OPERATION_FINISHED]; [condLock unlock]; Mike _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
