Instead of fixed during the start of replication. To this end, create
term_flush_lsn watch channel similar to commit_lsn one. This allows to continue
recovery streaming if new data appears.
This is a full switch, fs io operations are also tokio ones, working through
thread pool. Similar to pageserver, we have multiple runtimes for easier `top`
usage and isolation.
Notable points:
- Now that guts of safekeeper.rs are full of .await's, we need to be very
careful not to drop task at random point, leaving timeline in unclear
state. Currently the only writer is walreceiver and we don't have top
level cancellation there, so we are good. But to be safe probably we should
add a fuse panicking if task is being dropped while operation on a timeline
is in progress.
- Timeline lock is Tokio one now, as we do disk IO under it.
- Collecting metrics got a crutch: since prometheus Collector is
synchronous, it spawns a thread with current thread runtime collecting data.
- Anything involving closures becomes significantly more complicated, as
async fns are already kinda closures + 'async closures are unstable'.
- Main thread now tracks other main tasks, which got much easier.
- The only sync place left is initial data loading, as otherwise clippy
complains on timeline map lock being held across await points -- which is
not bad here as it happens only in single threaded runtime of main thread.
But having it sync doesn't hurt either.
I'm concerned about performance of thread pool io offloading, async traits and
many await points; but we can try and see how it goes.
fixes https://github.com/neondatabase/neon/issues/3036
fixes https://github.com/neondatabase/neon/issues/3966
It should make remote_consistent_lsn commonly up-to-date on non actively writing
projects, which removes spike or pageserver -> safekeeper reconnections on
storage nodes restart.
Refactors walsenders out of timeline.rs to makes it less convoluted into
separate WalSenders with its own lock, but otherwise having the same structure.
Tracking of in-memory remote_consistent_lsn is also moved there as it is mainly
received from pageserver.
State of walsender (feedback) is also restructured to be cleaner; now it is
either PageserverFeedback or StandbyFeedback(StandbyReply, HotStandbyFeedback),
but not both.
This is the the feedback originating from pageserver, so change previous
confusing names to
s/ReplicationFeedback/PageserverFeedback
s/ps_writelsn/last_receive_lsn
s/ps_flushlsn/disk_consistent_lsn
s/ps_apply_lsn/remote_consistent_lsn
I haven't changed on the wire format to keep compatibility. However,
understanding of new field names is added to compute, so once all computes
receive this patch we can change the wire names as well. Safekeepers/pageservers
are deployed roughly at the same time and it is ok to live without feedbacks
during the short period, so this is not a problem there.
1) Remove allocation and data copy during each message read. Instead, parsing
functions now accept BytesMut from which data they form messages, with
pointers (e.g. in CopyData) pointing directly into BytesMut buffer. Accordingly,
move ConnectionError containing IO error subtype into framed.rs providing this
and leave in pq_proto only ProtocolError.
2) Remove anyhow from pq_proto.
3) Move FeStartupPacket out of FeMessage. Now FeStartupPacket::parse returns it
directly, eliminating dead code where user wants startup packet but has to match
for others.
proxy stream.rs is adapted to framed.rs with minimal changes. It also benefits
from framed.rs improvements described above.
- Add support for splitting async postgres_backend into read and write halfes.
Safekeeper needs this for bidirectional streams. To this end, encapsulate
reading-writing postgres messages to framed.rs with split support without any
additional changes (relying on BufRead for reading and BytesMut out buffer for
writing).
- Use async postgres_backend throughout safekeeper (and in proxy auth link
part).
- In both safekeeper COPY streams, do read-write from the same thread/task with
select! for easier error handling.
- Tidy up finishing CopyBoth streams in safekeeper sending and receiving WAL
-- join split parts back catching errors from them before returning.
Initially I hoped to do that read-write without split at all, through polling
IO:
https://github.com/neondatabase/neon/pull/3522
However that turned out to be more complicated than I initially expected
due to 1) borrow checking and 2) anon Future types. 1) required Rc<Refcell<...>>
which is Send construct just to satisfy the checker; 2) can be workaround with
transmute. But this is so messy that I decided to leave split.
Before this patch, persistent peer_horizon_lsn was always sent to walproposer,
making it initially calculate it equal to max of persistent values and in turn
pulling back the in memory value. Send instead in memory value and take max when
safekeeper sets it.
closes https://github.com/neondatabase/neon/issues/3752
This API is rather pointless, as sane choice anyway requires knowledge of peers
status and leaders lifetime in any case can intersect, which is fine for us --
so manual elections are straightforward. Here, we deterministically choose among
the reasonably caught up safekeepers, shifting by timeline id to spread the
load.
A step towards custom broker https://github.com/neondatabase/neon/issues/2394
With the ability to pass commit_lsn. This allows to perform project WAL recovery
through different (from the original) set of safekeepers (or under different
ttid) by
1) moving WAL files to s3 under proper ttid;
2) explicitly creating timeline on safekeepers, setting commit_lsn to the
latest point;
3) putting the lastest .parital file to the timeline directory on safekeepers, if
desired.
Extend test_s3_wal_replay to exersise this behaviour.
Also extends timeline_status endpoint to return postgres information.
- Split postgres_ffi into two version specific files.
- Preserve pg_version in timeline metadata.
- Use pg_version in safekeeper code. Check for postgres major version mismatch.
- Clean up the code to use DEFAULT_PG_VERSION constant everywhere, instead of hardcoding.
- Parameterize python tests: use DEFAULT_PG_VERSION env and pg_version fixture.
To run tests using a specific PostgreSQL version, pass the DEFAULT_PG_VERSION environment variable:
'DEFAULT_PG_VERSION='15' ./scripts/pytest test_runner/regress'
Currently don't all tests pass, because rust code relies on the default version of PostgreSQL in a few places.
Another preparatory commit for pg15 support:
* generate bindings for both pg14 and pg15;
* update Makefile and CI scripts: now neon build depends on both PostgreSQL versions;
* some code refactoring to decrease version-specific dependencies.
Re-export only things that are used by other modules.
In the future, I'm imagining that we run bindgen twice, for Postgres
v14 and v15. The two sets of bindings would go into separate
'bindings_v14' and 'bindings_v15' modules.
Rearrange postgres_ffi modules.
Move function, to avoid Postgres version dependency in timelines.rs
Move function to generate a logical-message WAL record to postgres_ffi.
To flush inmemory layer eventually when no new data arrives, which helps
safekeepers to suspend activity (stop pushing to the broker). Default 10m should
be ok.
On ProposerElected message receival WAL is truncated at streaming point; this
code expected that, once vote is given for the proposer / term switch happened,
flush_lsn can be advanced only by this proposer (or higher one). However, that
didn't take into account possibility of accumulating written WAL and flushing it
after vote is given -- flushing goes without term checks. Which eventually led
to the violation in question.
ref #2048
- Uncomment accidently `self.keep_alive.abort()` commented line, due to this
task never finished, which blocked launcher.
- Mess up with initialization one more time, to fix offloader trying to back up
segment 0. Now we initialize all required LSNs in handle_elected,
where we learn start LSN for the first time.
- Fix blind attempt to provide safekeeper service file with remote storage
params.
Separate task is launched for each timeline and stopped when timeline doesn't
need offloading. Decision who offloads is done through etcd leader election;
currently there is no pre condition for participating, that's a TODO.
neon_local and tests infrastructure for remote storage in safekeepers added,
along with the test itself.
ref #1009
Co-authored-by: Anton Shyrabokau <ahtoxa@Antons-MacBook-Pro.local>
Make it remember when timeline starts in general and on this safekeeper in
particular (the point might be later on new safekeeper replacing failed one).
Bumps control file and walproposer protocol versions.
While protocol is bumped, also add safekeeper node id to
AcceptorProposerGreeting.
ref #1561
Remove when it is consumed by all of 1) pageserver (remote_consistent_lsn) 2)
safekeeper peers 3) s3 WAL offloading.
In test s3 offloading for now is mocked by directly bumping s3_wal_lsn.
ref #1403
