Our LSA cache is implemented as an auto_unlink Boost intrusive list, meaning
that elements of the list unlink themselves from the list automatically on
destruction. Some parts of the code rely on that, and don't unlink them
manually.
However, this precludes accurate bookkeeping about the cache. Elements only have
access to themselves and their neighbours, not to any bookkeeping context.
Therefore, a destructor cannot update the relevant metadata.
In this patch, we fix this by adding explicit unlink calls to places where it
would be done by a destructor. In a following patch, we will add an assert to
the destructor to check that every element is unlinked before destruction.
This reverts commit e0670f0bb5, reversing
changes made to 605ee74c39. It causes failures
in debug mode in
database_test.test_database_with_data_in_sstables_is_a_mutation_source_plain,
though with low probability.
Fixes#10780Reopens#652.
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
Some tests will create two cache_tracker instances because of one
being embedded in the sstable test env.
This would lead to double registration of metrics, which raises run
time error. Avoid by not registering metrics in prometheus in tests at
all.
