This call will block until all pending watch/notify callbacks have
been executed and the queue is empty. It should usually be called
after shutting down any watches before shutting down the ioctx or
librados to ensure that any callbacks do not misuse the ioctx (for
example by calling rados_notify_ack after the ioctx has been
destroyed).
Flush watch/notify callbacks
This call will block until all pending watch/notify callbacks have been executed and the queue is empty. It should usually be called after shutting down any watches before shutting down the ioctx or librados to ensure that any callbacks do not misuse the ioctx (for example by calling rados_notify_ack after the ioctx has been destroyed).
@param cluster the cluster handle