>> > > Thanks, Ken. The reason I'm using a custom operation queue instead of GCD is > that I need to permit only exclusive access to the device (e.g., to obtain > its status requires writing to it), but allow other operations enqueued to > use the device, not just the status checks. So I have an NSOperationQueue > that has maxConcurrentOperationCount set to 1, but I need a status-check > operation to be automatically queued up 1 minute after the last one has run. > > So, if the device is accessed otherwise the status checks won't interfere > with that because only 1 operation can be active in the queue, thus > everything stays well ordered and exclusive access is permitted to all, one > at a time. I just can't figure a way to have the status check operation > trigger another one to be magically enqueued 60 seconds later. > > -Carl
Quite a few ways to skin that cat. Make every operation complete by adding a cleanup operation block to the queue. Have that block do nothing for 60 seconds but check the number of operations in the queue on a regular basis, if the number of operations rises above one, exit, if it gets to 60 seconds, perform cleanup. Wasteful but easy. Make a dispatch_timer, just one, have the start of every operation set the timer to the distant future, at the end set it to 60 seconds, have the dispatch_timer toss the cleanup block on your queue. Or do a dispatch_test_cancel() at the start of the block, and set the timer to 60 seconds and dispatch_resume() at the end of the block, either works. 60 seconds after the last block finished executing, your cleanup block will run. _______________________________________________ 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
