before this change, we only record the exception returned
by `upload_file()`, and rethrow the exception. but the exception
thrown by `update_file()` not populated to its caller. instead, the
exceptional future is ignored on pupose -- we need to perform
the uploads in parallel. this is why the task is not marked fail
even if some of the uploads performed by it fail.
in this change, we
- coroutinize `backup_task_impl::do_backup()`. strictly speaking,
this is not necessary to populate the exception. but, in order
to ensure that the possible exception is captured before the
gate is closed, and to reduce the intentation, the teardown
steps are performed explicitly.
- in addition to note down the exception in the logging message,
we also store it in a local variable, which it rethrown
before this function returns.
Fixesscylladb/scylladb#21248
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21254
9f8adcd207