The namespace usage in this directory is very inconsistent, with files
and classes scattered in:
* global namespace
* namespace compaction
* namespace sstables
With cases, where all three used in the same file. This code used to
live in sstables/ and some of it still retains namespace sstables as a
heritage of that time. The mismatch between the dir (future module) and
the namespace used is confusing, so finish the migration and move all
code in compaction/ to namespace compaction too.
This patch, although large, is mechanic and only the following kind of
changes are made:
* replace namespace sstable {} with namespace compaction {}
* add namespace compaction {}
* drop/add sstables::
* drop/add compaction::
* move around forward-declarations so they are in the correct namespace
context
This refactoring revealed some awkward leftover coupling between
sstables and compaction, in sstables/sstable_set.cc, where the
make_sstable_set() methods of compaction strategies are implemented.
This patch addes incremental_repair support in compaction.
- The sstables are split into repaired and unrepaired set.
- Repaired and unrepaired set compact sperately.
- The repaired_at from sstable and sstables_repaired_at from
system.tablets table are used to decide if a sstable is repaired or
not.
- Different compactions tasks, e.g., minor, major, scrub, split, are
serialized with tablet repair.
This will allow upcoming work to gently produce a sstable set for
each compaction group view. Example: repaired and unrepaired.
Locking strategy for compaction's sstable selection:
Since sstable retrieval path became futurized, tasks in compaction
manager will now hold the write lock (compaction_state::lock)
when retrieving the sstable list, feeding them into compaction
strategy, and finally registering selected sstables as compacting.
The last step prevents another concurrent task from picking the
same sstable. Previously, all those steps were atomic, but
we have seen stall in that area in large installations, so
futurization of that area would come sooner or later.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Since there will be only one physical sstable set, it makes sense to move
backlog tracker to replica::compaction_group. With incremental repair,
it still makes sense to compute backlog accounting both logical sets,
since the compound backlog influences the overall read amplification,
and the total backlog across repaired and unrepaired sets can help
driving decisions like giving up on incremental repair when unrepaired
set is almost as large as the repaired set, causing an amplification
of 2.
Also it's needed for correctness because a sstable can move quickly
across the logical sets, and having one tracker for each logical
set could cause the sstable to not be erased in the old set it
belonged to;
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Since table_state is a view to a compaction group, it makes sense
to rename it as so.
With upcoming incremental repair, each replica::compaction_group
will be actually two compaction groups, so there will be two
views for each replica::compaction_group.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
This hourly reevaluation is there to help tablets that have very low
write activity, which can go a long time without flushing a memtable,
and it's important to reevaluate compaction as data can get expired.
Today it can happen that we reevaluate a table that is being compacted
actively, which is waste of cpu as the reevaluation will happen anyway
when there are changes to sstable set. This waste can be amplified with
a significant tablet count in a given shard.
Eventually, we could make the revaluation time per table based on
expiration histogram, but until we get there, let's avoid this waste
by only reevaluating tables that are compaction idle for more than 1h.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closesscylladb/scylladb#18280
So that replacing it will destroy the previous tracker
and unregister it before assigning the new one and
then registering it.
This is safer than assiging it in place.
With that, the move assignment operator is not longer
used and can be deleted.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
When perform_cleanup adds sstables to sstables_requiring_cleanup,
also save the owned_ranges_ptr in the compaction_state so
it could be used by other compaction types like
regular, reshape, or major compaction.
When the exhausted sstables are released, check
if sstables_requiring_cleanup is empty, and if it is,
clear also the owned_ranges_ptr.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
