consumer: shard transitions account for delete-then-create race #315
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If a shard assignment is removed (for example, because its FAILED) and is then immediately re-created by the allocation coordinator, we previously could fail to notice that the prior local shard was invalidated and should be re-created. Account for this by additionally monitoring the CreateRevision of assignments and treating an assignment of the same or higher slot, with a differing CreateRevision, as being a novel assignment which requires a novel local shard to be boot-strapped. Fixes #314
saterus
approved these changes
Feb 2, 2022
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| } else if p.Raw.CreateRevision == asn.Raw.CreateRevision { | ||
| // Assignment value was updated but the assignment itself is unchanged. |
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I'm not sure I understand this case. How would the assignment value be updated without creating a new revision?
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see the etcd spec. CreateRevision is separately tracked from ModRevision.
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If a shard assignment is removed (for example, because its FAILED)
and is then immediately re-created by the allocation coordinator,
we previously could fail to notice that the prior local shard was
invalidated and should be re-created.
Account for this by additionally monitoring the CreateRevision of
assignments and treating an assignment of the same or higher slot,
with a differing CreateRevision, as being a novel assignment which
requires a novel local shard to be boot-strapped.
Fixes #314
This change is