Currently, when finishing db::view::calculate_affected_clustering_ranges
we deoverlap, transform and copy all ranges prepared before. This
is all done within a single continuation and can cause stalls.
We fix this by adding yields after each transform and moving elements
to the final vector one by one instead of copying them all at the end.
After this change, the longest continuation in this code will be
deoverlapping the initial ranges (and one transform). While it has
a relatively high computational complexity (we sort all ranges), it
should execute quickly because we're operating on views there and
we don't need to copy the actual bytes. If we encounter a stall there,
we'll need to implement an asynchronous `deoverlap` method.
Fixesscylladb/scylladb#21843Closesscylladb/scylladb#21846
37a25d3af4