kvserver,keys: force-flush when needed by split/merge/migrate #136077
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This is a draft. Based on an initial review, and some testing, we can start pulling things out from here for PRs to merge.
Reviewable status:
complete! 0 of 0 LGTMs obtained (waiting on @kvoli and @pav-kv)
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Reviewed 28 of 28 files at r1, all commit messages.
Reviewable status:
pkg/kv/kvserver/kvserverpb/proposer_kv.go line 73 at r1 (raw file):
allowlist.IsProbe = false // probes are trivial, they always get refused in CheckForcedErr allowlist.State = nil allowlist.DoTimelyApplicationToAllReplicas = false
nit: acknowledge this is a draft, for the non-draft PRs we should add a comment here.
pkg/roachpb/metadata.proto line 568 at r1 (raw file):
option (gogoproto.goproto_stringer) = true; optional uint64 index = 1 [(gogoproto.nullable) = false];
nit: we are using a uint64 in the rangecontroller/processor code but we have a typed version available from here, is there a reason for it?
pkg/kv/kvserver/kvflowcontrol/rac2/range_controller.go line 1207 at r1 (raw file):
// quorum or leaseholder requirements may already have ensured that this // replica must force-flush. if rs.scratchEvent.replicaStateInfo.Next <= rc.forceFlushIndex &&
Just double checking my understanding here (bit rusty) about:
if rs.scratchEvent.replicaStateInfo.Next <= rc.forceFlushIndex &&This is Next because (Match,Next) are in-flight and [Next,forceFlushIndex] is the range that needs to be force flushed as a result (ffIndex - match - inflight)?
pkg/kv/kvserver/kvflowcontrol/rac2/range_controller.go line 1531 at r1 (raw file):
// ForceFlushIndexChangedLocked implements RangeController. func (rc *rangeController) ForceFlushIndexChangedLocked(ctx context.Context, index uint64) { rc.forceFlushIndex = index
Is there an invariant we could assert here w.r.t the prior rc.forceFlushIndex? I was thinking an increasing invariant (not strictly), but I'm guessing there's some edge case where it is valid, but I can't think of anything.
pkg/kv/kvserver/kvserverpb/proposer_kv.proto line 267 at r1 (raw file):
// DoTimelyApplicationToAllReplicas is set to true when this proposal needs // to be applied on all replicas for various reasons.
nit: similar disclaimer, we should extend this comment w/ some examples like split, merge etc.
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TFTR!
Reviewable status:
pkg/kv/kvserver/kvflowcontrol/rac2/range_controller.go line 1207 at r1 (raw file):
Previously, kvoli (Austen) wrote…
Just double checking my understanding here (bit rusty) about:
if rs.scratchEvent.replicaStateInfo.Next <= rc.forceFlushIndex &&This is Next because
(Match,Next)are in-flight and [Next,forceFlushIndex] is the range that needs to be force flushed as a result (ffIndex - match - inflight)?
Correct.
I added a comment.
// NB: Next is exclusive and the first entry that has not yet been sent.
// And forceFlushIndex is inclusive. Therefore, [Next, forceFlushIndex]
// needs to have been sent for force-flush to not be needed, and we
// check for non-emptiness of the interval below.
pkg/kv/kvserver/kvflowcontrol/rac2/range_controller.go line 1531 at r1 (raw file):
Previously, kvoli (Austen) wrote…
Is there an invariant we could assert here w.r.t the prior
rc.forceFlushIndex? I was thinking an increasing invariant (not strictly), but I'm guessing there's some edge case where it is valid, but I can't think of anything.
Good point. I added the following in processorImpl since that lives for the lifetime of the Replica struct so can do a stricter check there
if buildutil.CrdbTestBuild && p.forceFlushIndex > index {
panic(errors.AssertionFailedf("force-flush index decreased from %d to %d",
p.forceFlushIndex, index))
}
pkg/kv/kvserver/kvserverpb/proposer_kv.go line 73 at r1 (raw file):
Previously, kvoli (Austen) wrote…
nit: acknowledge this is a draft, for the non-draft PRs we should add a comment here.
Done. This is a bit subtle, at least to me, so I'm glad you asked.
pkg/kv/kvserver/kvserverpb/proposer_kv.proto line 267 at r1 (raw file):
Previously, kvoli (Austen) wrote…
nit: similar disclaimer, we should extend this comment w/ some examples like split, merge etc.
Done
pkg/roachpb/metadata.proto line 568 at r1 (raw file):
Previously, kvoli (Austen) wrote…
nit: we are using a uint64 in the rangecontroller/processor code but we have a typed version available from here, is there a reason for it?
I didn't understand the question, specifically which "typed version" and what is "here", in "typed version available from here". Presumably "here" is not this PR since it is simply using uint64
- ReplicatedEvalResult.DoTimelyApplicationToAllReplicas is added and set in splitTriggerHelper, MergeTrigger, Migrate, Subsume. - The previous setting to true is gated on cluster version V25_1_AddRangeForceFlushKey. - This causes ReplicaState.ForceFlushIndex to be set, and RangeForceFlushKey (a replicated range-id local key) to be written when applying the corresponding batch to the state machine. The index is set to the index of the entry being applied, and is monotonically increasing. - replica_rac2.Processor and rac2.RangeController have ForceFlushIndexChangedLocked methods that are called whenever the Replica sees a change in the force-flush-index. When in pull-mode the rangeController acts on the latest value it has seem to force-flush a replicaSendStream that has a send-queue that has some entries at or equal to the force-flush-index. Fixes cockroachdb#135601 Epic: CRDB-37515 Release note: None
Fixes #135601
Epic: CRDB-37515
Release note: None