Struct ChunkKey 

pub struct ChunkKey {
    pub sstable: u64,
    pub chunk_index: u64,
    pub aux: u64,
}

Authoritative cache key: an SSTable identity hash and a chunk discriminator.

chunk_index carries whichever authoritative offset the wiring site uses — a real chunk index (windowed scan, BTI target chunk) or an index-resolved block_offset (BIG point read). Sites keep separate key namespaces by folding a site salt into sstable (design D4), so numerically-overlapping values from different sites never collide.

Fields

sstable: u64

Stable hash of the SSTable’s file_path (+ generation), optionally XORed with a per-site namespace salt.

chunk_index: u64

Authoritative chunk index or index-resolved offset within sstable.

aux: u64

Extra discriminant for a size-dependent range read. The chunk-index sites (BTI, windowed scan) decompress a whole compression chunk whose bytes are fully determined by chunk_index, so they use aux = 0. The BIG point-read path (get_cached_data) reads an index-resolved (block_offset, size) byte range whose decompressed content depends on BOTH the offset AND the length: two reads at the same block_offset with different size decompress different input and MUST NOT alias. aux carries size for that path so the key is complete (roborev #1567), and because (u64 offset, u32 size) cannot be packed into one u64 without loss, aux is a first-class key field, not folded into chunk_index.

Implementations

impl ChunkKey

pub fn new(sstable: u64, chunk_index: u64) -> Self

Construct a key from an sstable identity hash and a chunk discriminator (whole-chunk sites; aux = 0).

pub fn with_aux(sstable: u64, chunk_index: u64, aux: u64) -> Self

Construct a key with an extra discriminant (aux) for a size-dependent range read (the BIG point-read path keys aux = size).

Trait Implementations

impl Clone for ChunkKey

fn clone(&self) -> ChunkKey

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ChunkKey

impl Debug for ChunkKey

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for ChunkKey

impl Hash for ChunkKey

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ChunkKey

fn eq(&self, other: &ChunkKey) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for ChunkKey