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release-24.3: raft: assert on HardState field modifications #133581

Merged
merged 4 commits into from
Oct 28, 2024
Merged

release-24.3: raft: assert on HardState field modifications #133581

merged 4 commits into from
Oct 28, 2024

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@blathers-crl blathers-crl bot commented Oct 28, 2024 •
edited by nvanbenschoten
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Backport 4/4 commits from #133169 on behalf of @nvanbenschoten.

/cc @cockroachdb/release

Informs #125352.

This commit adds setters for the HardState fields (Term, Vote, lead, leadEpoch), allowing us to assert that these fields are only modified in expected ways.

Some bugs that this change could catch:

  • term regressions
  • vote changes
  • lead changes in a single term
  • leadEpoch regressions

The "lead changes in a single term" class of bugs is especially interesting, as we have found two of these in this thread: https://cockroachlabs.slack.com/archives/G01G8LK77DK/p1720274557285239. These are tracked in the following issues, which we may need to address ASAP:

The 2nd, 3rd, and 4th commits in the PR address these issues in raft by not assuming that a MsgSnap as always coming from the leader of Message.Term.

Release note: None

Release justification: needed for leader leases.

@nvanbenschoten
raft: assert on HardState field modifications
17a601b 
Informs #125352.

This commit adds setters for the HardState fields (Term, Vote, lead, leadEpoch),
allowing us to assert that these fields are only modified in expected ways.

Some bugs that this change could catch:
- term regressions
- vote changes
- lead changes in a single term
- leadEpoch regressions

The "lead changes in a single term" class of bugs is especially interesting, as
we have found two of these in this thread: https://cockroachlabs.slack.com/archives/G01G8LK77DK/p1720274557285239.
These are tracked in the following issues, which we may need to address ASAP:
* #127349
* #127348

Release note: None
@nvanbenschoten
raft: use IsMsgFromLeader is stepFollower
a5e2b08 
Group the handling of learning about the leader in stepFollower.

Epic: None
Release note: None
@nvanbenschoten
raft: use IsMsgFromLeader in stepCandidate
b251bfe 
Group the handling of the candidate -> follower state transition
when hearing from the leader while a candidate.

Epic: None
Release note: None
@nvanbenschoten
raft: don't assume MsgSnap comes from leader
f857ddd 
We can't consider MsgSnap to be from the leader of Message.Term until we
address #127348 and #127349.

Epic: None
Release note: None
@blathers-crl blathers-crl bot force-pushed the blathers/backport-release-24.3-133169 branch from 8ff55ab to f857ddd Compare October 28, 2024 18:16
@blathers-crl blathers-crl bot requested a review from a team as a code owner October 28, 2024 18:16
@blathers-crl blathers-crl bot added blathers-backport This is a backport that Blathers created automatically. O-robot Originated from a bot. labels Oct 28, 2024
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blathers-crl bot commented Oct 28, 2024

Thanks for opening a backport.

Please check the backport criteria before merging:

  • Backports should only be created for serious
    issues     or test-only changes.
  • Backports should not break backwards-compatibility.
  • Backports should change as little code as possible.
  • Backports should not change on-disk formats or node communication protocols.
  • Backports should not add new functionality (except as defined
    here).
  • Backports must not add, edit, or otherwise modify cluster versions; or add version gates.
  • All backports must be reviewed by the owning areas TL. For more information as to how that review should be conducted, please consult the backport
    policy    .
If your backport adds new functionality, please ensure that the following additional criteria are satisfied:
  • There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
  • The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
  • New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
  • The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.
  • Your backport must be accompanied by a post to the appropriate Slack
    channel (#db-backports-point-releases or #db-backports-XX-X-release) for awareness and discussion.

Also, please add a brief release justification to the body of your PR to justify this
backport.

@blathers-crl blathers-crl bot added the backport Label PR's that are backports to older release branches label Oct 28, 2024
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@nvanbenschoten nvanbenschoten merged commit 0ea9c22 into release-24.3 Oct 28, 2024
20 of 21 checks passed
@nvanbenschoten nvanbenschoten deleted the blathers/backport-release-24.3-133169 branch October 28, 2024 19:32
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@pav-kv pav-kv pav-kv approved these changes

@arulajmani arulajmani Awaiting requested review from arulajmani

@nvanbenschoten nvanbenschoten Awaiting requested review from nvanbenschoten

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