Instead of taking a set of functions with different periods, take a
single function that is called on every tick. The periodicity can be
implemented easily on the user side.
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
seastar::later() was recently deprecated and replaced with two
alternatives: a cheap seastar::yield() and an expensive (but more
powerful) seastar::check_for_io_immediately(), that corresponds to
the original later().
This patch replaces all later() calls with the weaker yield(). In
all cases except one, it's unambiguously correct. In one case
(test/perf scheduling_latency_measurer::stop()) it's not so ambiguous,
since check_for_io_immediately() will additionally force a poll and
so will cause more work to be done (but no additional tasks to be
executed). However, I think that any measurement that relies on
the measuring the work on the last tick to be inaccurate (you need
thousands of ticks to get any amount of confidence in the
measurement) that in the end it doesn't matter what we pick.
Tests: unit (dev)
Closes#9904
Use AppendReg instead of ExReg for the state machine.
Use a generator which generates a sequence of append operations with
unique integers.
This implies that the result of every operation uniquely identifies the
operation (since it contains the appended integer, and different
operations use different integers) and all operations that must have
happened before it (since it contains the previous state of the append
register), which allows us to reconstruct the "current state" of the
register according to the results of operations coming from Raft calls,
giving us an on-line linearizability checker with O(1) amortized
complexity on each operation completion.
We also perform a simple liveness check at the end of the test by
ensuring that a leader becomes eventually elected and that we can
successfully execute a call.
