Currently drain() is called twise -- first time from
storage_service::drain() (on shutdown), second via
batchlog_manager::stop(). The routine is unintentinally re-entrable,
because:
- explicit check for not aborting the abort source twise
- breaking semaphore can be done multiple times
- co-await-ing of the _started future works because the future is shared
That's not extremely elegant, better to make the drain() bail out early
if it was already called.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
38d0ea0916