Today, we're completely blind about the progress of view updating
on Staging files. We don't know how long it will take, nor how much
progress we've made.
This patch adds visibility with a new metric that will inform
the number of bytes to be processed from Staging files.
Before any work is done, the metric tell us the total size to be
processed. As view updating progresses, the metric value is
expected to decrease, unless work is being produced faster than
we can consume them.
We're piggybacking on sstables::read_monitor, which allows the
progress metric to be updated whenever the SSTable reader makes
progress.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closes#11751
ec79ac46c9