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; The effect is that sometimes it works but sometimes not, and I get logs in the console: *** -[NSLock lock]: deadlock (<NSLock: 0x197a90> '(null)') *** -[NSLock unlock]: lock (<NSLock: 0x197a90> '(null)') unlocked from thread which did not lock it *** Break on _NSLockError() to debug. Is this a valid way of implementing the subject? Am I using NSLock correctly for this purpose? Or if not, can someone please post the correct way of doing this? _______________________________________________ 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