29b795709b
Currently, maybe_switch_to_new_writer resets _current_writer only in a continuation after closing the current writer. This leaves a window of vulnerability if close() yields, and token_group_based_splitting_mutation_writer::close() is called. Seeing the engaged _current_writer, close() will call _current_writer->close() - which must be called exactly once. Solve this when switching to a new writer by resetting _current_writer before closing it and potentially yielding. Fixes #22715 Signed-off-by: Benny Halevy <bhalevy@scylladb.com> Closes scylladb/scylladb#22922