Previously, some service levels tests requires to sleep in order to
ensure in-memory configuration of service levels was updated.
Now, when we are updating the configuration as the raft log is applied,
doing read barrier (for instance to execute `DROP TABLE IF EXISTS
non_existing_table`) is enough and the sleeps are not needed.
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
This patch is not backward compatible with its original,
but it's considered fine, since the original workload types were not
yet part of any release.
The changes include:
- instead of using 'unspecified' for declaring that there's no workload
type for a particular service level, NULL is used for that purpose;
NULL is the standard way of representing lack of data
- introducing a delete marker, which accompanies NULL and makes it
possible to distinguish between wanting to forcibly reset a workload
type to unspecified and not wanting to change the previous value
- updating the tests accordingly
These changes come in as a single patch, because they're intertwined
with each other and the tests for workload types are already in place;
an attempt to split them proved to be more complicated than it's worth.
Tests: unit(release)
Closes#8763
