There's nothing specific to scylla in the lister
classes, they could (and maybe should) be part of
the seastar library.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
The database.hh is the central recursive-headers knot -- it has ~50
includes. This patch leaves only 34 (it remains the champion though).
Similar thing for database.cc.
Both changes help the latter compile ~4% faster :)
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20210414183107.30374-1-xemul@scylladb.com>
When moving a sstable between directories, we would like to
be able to crash at any point during the algorithm with a
clear way to either roll the operation forwards or backwards.
To achieve that, define sstable::create_links_common that accepts
a `mark_for_removal` flag, implementing the following algorithm:
1. link src.toc to dst.temp_toc.
until removed, the destination sstable is marked for removal.
2. link all src components to dst.
crashing here will leave dst with both temp_toc and toc.
3.
a. if mark_for_removal is unset then just remove dst.temp_toc.
this is commit the destination sstable and complete create_links.
b. if mark_for_removal is set then move dst.temp_toc to src.temp_toc.
this will atomically toggle recovery after crash from roll-back
to roll-forward.
here too, crashing at this point will leave src with both
temp_toc and toc.
Adjust the unit test for the revised algorithm.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Handle the case where create_link is replayed after crashing in the middle.
In particular, if we restart when moving sstables from staging to the base dir,
right after create_links completes, and right before deleting the source links,
we end up with seemingly 2 valid sstables, one still in staging and the other
already in the base table directory, both are hard linked to the same inodes.
Make create_links idempotent so it can replay the operation safely if crashed and
restarted at any point of its operation.
Add unit tests for replay after partial create_links that is expected to succeed,
and a test for replay when an sstable exist in the destination that is not
hard-linked to the source sstable; create_links is expected to fail in this case.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
