So that we can reliably ignore stale block services in GC (done in
a future commit). To enable this and future-proof this kind of
mechanism (e.g. having `eggsblocks` to mark something as D itself)
I added a new way to register the block service that lets you mask
which flags you're checking. I'll remove the old way once we've
rolled out everywhere.
This started being a problem since the block service update log
entry does not fit in a UDP packet (it's like 100KB). I think this
approach makes more sense anyway. See comment for `getCache()` for
gotchas.
Just check if we're also unable to count the blocks for the disk,
and if yes, assume it's a single file error.
Of course there will be a time period where we will not have detected
the bad disk when counting the blocks (a few minutes at most), but
that's OK -- the scrubber will scrub blocks for that period, and then
stop.
Once <internal-repo/issues/65#issuecomment-24747>
is done, we should use whatever error detection we use for migration
to also distinguish between these errors.
This is in preparation for #44, but more immediately, to better
stop writing to full block services.
The previous strategy of setting a flag was flawed since once
the flag was set it stayed set -- i.e. we would not remove it once
files would be deleted. This consideration should just be integrated
in distributing the block services.
The idea is to drain the socket and do a single RocksDB WAL
write/fsync for all the write requests we have found.
The read requests are immediately executed. The reasoning here is
that currently write requests are _a lot_ slower than the read
requests because fsyncing takes ~500us on fsf1. In the future this
might change.
Since we're at it, we also use batch UDP syscalls in the CDC.
Fixes#119.
This is to save on a ton of writes as jobs stat tons of files.
It would maybe be a bit cleaner to do it in the kmod, but this is
much quicker.
Thanks to @sgrusny for the good idea.
The `tuple` was for when I thought it'd be useful to leave slots
for each request, but we don't need this anymore, and now leading
up to #66 I want to be able to keep vectors of reqs/resps.
Fixes#32. This also involves some reworking of the block request machinery
to make it more robust and faster. The scrubbing is done assuming that
the overwhelming majority of block checking will go through.
