NRG (2.11): When term matches, simply truncate and store append entry #6073
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MauriceVanVeen
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MauriceVanVeen
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| // Heartbeat, makes sure we commit. | ||
| n.processAppendEntry(aeHeartbeat2, n.aesub) | ||
| require_Equal(t, n.commit, 3) | ||
| } | ||
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| func TestNRGNewLeaderWithIncorrectPtermDoesNotTruncateIfCommitted(t *testing.T) { |
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These two tests that have been removed asserted that n.pterm = n.term could still be executed, resulting in a situation where we should recover from the possibility of having an incorrect pterm.
Since its removal in #6060, these tests should be removed. We should never have this situation occur anymore.
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Signed-off-by: Maurice van Veen <github@mauricevanveen.com>
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neilalexander
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Nov 11, 2024
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LGTM, this is effectively the approach Maurice and I were talking about at the end of last week, where we can avoid having to wait for a heartbeat to apply an entry after a truncation, and additionally where we can prune the log back step-by-step if needed until we can resolve a pterm mismatch.
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If we are leader and store two entries, the first having quorum and being committed/applied and the second not having quorum. A new leader should be able to truncate the second entry.
That was not possible before as the
n.loadEntry(ae.pindex)andn.truncateWAL(eae.pterm, eae.pindex)combination would remove two entries, not just one.We now check if the entry stored at
ae.pindexhas a matching term withae.pterm, if so we can truncate entries past that point and then simply continue storing that append entry. Instead of needing to truncate, stop, get a heartbeat, start catchup, get the same append entry again, store it, get the next entry, stop catchup, etc. In this case we can now just, truncate and store.Signed-off-by: Maurice van Veen github@mauricevanveen.com