blevesearch / bleve / 28786286841

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Build Type

push

github

Committed by web-flow

Commit Message

MB-72716: Fix miscalculation of rollback points (#2370)

- We currently mark any bolt snapshot that is beyond the expiry window,
but within the retention window as `live` and pass it on to the time
series mechanism that will protect/retain the number of snapshots
configured in scorch - `NumSnapshotsToKeep`
- However when computing the extended boundary, we skip over the first
snapshot that was after the expiry window. We basically ignore it and
continue to track more snapshots up to the cutoff time determined by the
first expired snapshot's boundary checkpoint.Fixed this issue and added
a unit test.

```text
B                      L E                     T
+----------------------+-+---------------------+
|    Retention Window  + |    Expiry Window    |
+----------------------+-+---------------------+ ---> time


- N  = Number Of Snapshots to keep
- D  = Rollback Sampling Interval 
- R  = Rollback Retention Factor
- T  = Current timestamp
- C  = Current set of checkpoints
- E  = Expiry timestamp    = T - [(N - 1) * D]
- B  = Boundary Checkpoint = f(C, R, Lt)
- L  = First expired snapshot
- Lt = L's timestamp
- Nr = Number of snapshots in the retention window
- Ne = Number of snapshots in the expiry window

If (Nr >= N && Ne == 0 && Lt < E):
Then 
    persisted snapshots = [{Nr} - L}]
    protected snapshots ∩ L = ∅
```
- `rollbackRetentionFactor` config validation was broken and errored on
valid input instead of invalid. Corrected the condition and added a `0 ≤
r ≤ 1` bounds check.
- Retention settings weren't applied when loading existing snapshots on
open, because we opened boltDB before rollback settings were parsed from
config. This resulted in the first set of checkpoints to have a
timestamp of 0, due to which the rollback points used before the restart
were lost. Fixed this issue and added a unit test as well.
- Removed a redundant `closeCh` select after handing a persist off to
the introducer, the introducer always completes and closes applies t... (continued)

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