use sizeDiff=1 to represent holes filled #71
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staltz
commented
Apr 20, 2022
| unshiftedBlockIndex = Math.floor( | ||
| state.unshiftedOffset / log.blockSize | ||
| ) | ||
| unshiftedBlockIndex = Math.floor(unshiftedOffset / log.blockSize) |
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These 3 changes are unrelated to the PR problem, they are just nice refactors
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Context: ssbc/jitdb#199
Problem
In my ssb-db2 PR ssbc/ssb-db2#339, I had a
if (sizeDiff > 0) resetIndexes()but this misses a corner case.sizeDiffis only greater than zero if truncation removed at least one block. ButsizeDiff === 0can mean two very different things:We need to rebuild indexes in the 2nd case, but not in the 1st. So we need a way of knowing the difference between these cases.
Solution
Use
sizeDiff === 1as a special case where no blocks have been truncated (the log size remained the same) but some holes have been filled, thus requiring ssb-db2 to rebuild indexes.I think it's safe to say that sizeDiff is 1 byte because the minimum size of a block is 3 bytes because just the "End Of Block" marker takes 2 bytes.