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Fix log divergence bug #508

Merged
merged 5 commits into from
Feb 12, 2025
Merged

Fix log divergence bug #508

merged 5 commits into from
Feb 12, 2025

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kjnilsson
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@kjnilsson kjnilsson commented Feb 4, 2025

When a follower with uncommitted entries in a prior term when it
was leader receives certain append entry rpc combinations it would
incorrectly increment and evalaute the leader's commit index and
in some cases apply uncommitted entries.

This commit ensures that the commit index is only incremented and
evaluated if the local log's last index is validated against
the leaders's log.

Also handle the case where a snapshot with an index lower than
the follower's last applied index would cause the replication
to this follower to stop.

@kjnilsson kjnilsson force-pushed the handle-lower-index-snapshot branch 3 times, most recently from 13212ab to 882d698 Compare February 10, 2025 10:06
@kjnilsson kjnilsson changed the title handle snapshot with lower index Fix log divergence bug Feb 10, 2025
@kjnilsson kjnilsson force-pushed the handle-lower-index-snapshot branch 6 times, most recently from 038961d to ead3c57 Compare February 12, 2025 10:50
@kjnilsson kjnilsson marked this pull request as ready for review February 12, 2025 10:50
When a follower with uncommitted entries in a prior term when it
was leader receives certain append entry rpc combinations it would
incorrectly increment and evalaute the leader's commit index and
in some cases apply uncommitted entries.

This commit ensures that the commit index is only incremented and
evaluated _if_ the local log's last index is validated against
the leaders's log.

Also handle the case where a snapshot with an index lower than
the follower's last applied index would cause the replication
to this follower to stop.
@kjnilsson kjnilsson force-pushed the handle-lower-index-snapshot branch from ead3c57 to 4168a59 Compare February 12, 2025 10:52
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@the-mikedavis the-mikedavis left a comment

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I think this looks good, I just found a few typos

kjnilsson and others added 3 commits February 12, 2025 15:33
Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
@kjnilsson kjnilsson merged commit 3aa50f2 into main Feb 12, 2025
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@michaelklishin michaelklishin modified the milestones: 2.16.2, 2.15.2 Feb 12, 2025
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@kjnilsson do we want to ship it in a 2.15.2 for RabbitMQ 4.0.x?

kjnilsson added a commit that referenced this pull request Feb 12, 2025
* Fix log divergence bug.

When a follower with uncommitted entries in a prior term when it
was leader receives certain append entry rpc combinations it would
incorrectly increment and evalaute the leader's commit index and
in some cases apply uncommitted entries.

This commit ensures that the commit index is only incremented and
evaluated _if_ the local log's last index is validated against
the leaders's log.

Also handle the case where a snapshot with an index lower than
the follower's last applied index would cause the replication
to this follower to stop.

* reset open segment counter on init

* Update src/ra_server.erl

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

* Update src/ra_server.erl

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

* Update src/ra_server.erl

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

---------

Co-authored-by: Michael Davis <mcarsondavis@gmail.com>
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3 participants