Rewrite keyvalue item header with byte-aligned field layout#12
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brayniac merged 3 commits intopelikan-io:mainfrom Apr 18, 2026
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Adopt crucible's BasicHeader design for ItemHeader: Old: [magic:4?][vlen|klen:4 (packed u32)][flags:1] = 5 bytes (9 with magic) New: [klen:1][flags:1][vlen:4][magic:4?] = 6 bytes (10 with magic) Each field is now directly byte-addressable — no cross-word bit manipulation for klen/vlen access. The flags byte packs is_numeric (1 bit) and olen (6 bits) without shift/mask across word boundaries. Also rewrites value.rs (Value/OwnedValue enums) with same API surface. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The magic sentinel is more useful at the start — if you hit garbage while scanning segment memory, you detect it before interpreting klen/flags/vlen as valid fields. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Rename the `magic` feature to `integrity` across all crates. When enabled (default in keyvalue), the item header includes: - 2-byte magic sentinel (0xCA, 0xFE) at the front - 4-byte CRC32 at the end, covering the full item Header layout: Without integrity: [klen:1][flags:1][vlen:4] = 6 bytes With integrity: [magic:2][klen:1][flags:1][vlen:4][crc32:4] = 12 bytes The CRC32 uses crc32fast which auto-detects SSE4.2 (x86_64) and ARM CRC instructions for hardware-accelerated computation. The checksum covers magic + klen + flags + vlen + optional + key + value, with the CRC field zeroed during calculation. CRC is recomputed after wrapping_add/saturating_sub mutations. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
[klen:1][flags:1][vlen:4]= 6 bytes (12 with magic and checksum)integrityfeature which is on by default[vlen|klen:4][flags:1]layout that required cross-word bit manipulationklenis a single byte read,vlenis a direct u32value.rs(Value/OwnedValue) anditem/header.rswith clean codeitem/raw.rsto useis_numeric()instead of the oldvalue_type()enum