So the update items are already sorted before doing the concurrent dispatch. It's kind of brute force approach to lose order by inserting delta updates in any order and then re-sort all of them again later by enumerating through all potential objects. Also the code cannot assume the versions are integers (see descendingVersionComparator usage earlier in the file).

A simpler approach I think is just to opportunistically add the delta item before the dispatch. Remove it if we need to mark the delta as ignored (by finding the firstIndex() and then remove()). That will have to be synchronized in the DispatchQueue.main.async. No need to re-sort again.

Oh yeah, this is much nicer!

I ended up using removeAll() instead of firstIndex()+remove().

I test on the Retcon appcast again, and also tried artificially making some deltas not have a signature; both the ordering and filtering seem to work.

OK, changes applied.

Works for me locally. Merging. Thanks!

Great! Thank you for making these final changes, I was a bit busy.