Replace the per-chunk query cache from []Result slices to fixed-size
bitmaps (ChunkBitmap: [16]uint64 = 128 bytes per entry). Each bit
indicates whether the corresponding item in the chunk matched.
This reduces cache memory by 86 times in testing:
- Old []Result cache: ~22KB per chunk per query (for 500 matches)
- New bitmap cache: ~262 bytes per chunk per query (fixed)
With the reduced per-entry cost, queryCacheMax is raised from
chunkSize/5 to chunkSize/2, allowing broader queries (up to 50% match
rate) to be cached while still using far less memory.
Junegunn Choi
2f27a3ede2