disk index: break ref_count u64 into reserved bits #30997
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brooksprumo
approved these changes
Mar 30, 2023
| @@ -365,7 +365,7 @@ mod tests { | |||
| let v = (0..count) | |||
| .map(|x| (x as usize, x as usize /*thread_rng().gen::<usize>()*/)) | |||
| .collect::<Vec<_>>(); | |||
| let rc = thread_rng().gen::<RefCount>(); | |||
| let rc = thread_rng().gen_range(0, RefCount::MAX >> 2); | |||
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I'd recommend adding a comment here why we're shifting right. May help the next brave soul. (Can be done in a subsequent PR.)
Codecov Report
@@ Coverage Diff @@
## master #30997 +/- ##
=========================================
- Coverage 81.5% 81.5% -0.1%
=========================================
Files 728 728
Lines 205471 205479 +8
=========================================
- Hits 167554 167534 -20
- Misses 37917 37945 +28 |
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Problem
See #30711
Summary of Changes
We can use extra bits inside of
RefCountto store bits likeOccupiedinside a disk index or data bucket. We can also use them as an enum tag for more complicated implementations such as storing a single slot list entry insideIndexEntryand not using the data file at all.Fixes #