Optimize db.clear() and db.iterator()
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vweevers
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Sep 12, 2021
vweevers
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db.clear() by doing it nativelydb.clear() and db.iterator()
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Relevant benchmarks are in Level/bench#29. |
Because this uses an iterator under the hood, it also refactors shared code between `db.iterator()` and `db.clear()`.
By using `emplace_back()`, reusing the `std::vector` cache between `iterator.next()` calls, and not advancing the iterator prematurely. That last one only matters for single reads (i.e. the first `next()` call or one made after seeking) and it doesn't improve performance compared to the previous release, just undoes a mistake in b815bea.
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Squashed. The test failure can be ignored: |
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Closes #680. To be (partially) squashed before merge; I separated this into small refactoring commits for easier review.
By doing
db.clear()natively, without crossing the C++/JS boundary for every key, it's 27x faster. That's compared tomaster, shown as "baseline" in the graphs.After further refactoring and tweaking,
db.iterator()also became slightly faster. I also fixed an edge case where adb.close()would never call its callback if aiterator().next()was in progress and thatnext()call errored.