Struct ShapeKeyHasher 

pub struct ShapeKeyHasher(/* private fields */);

FNV-1a 64 over a canonical encoding of a model’s decode identity.

Same constants as fuel_dispatch::fkc::revhash and fuel_memory::dlpack_view — offset basis 0xcbf29ce484222325, prime 0x100000001b3. Pinned by known-answer vectors below rather than by cross-checking against those, so a consistent drift in all three cannot pass.

Implementations

impl ShapeKeyHasher

pub fn new() -> Self

pub fn mix_str(&mut self, s: &str) -> &mut Self

Mix a structural discriminant — the model family, a hook’s presence, a mask policy. Prefer a stable literal ("qwen3", "sliding_window") over anything derived from a Debug impl, which is free to change.

pub fn mix_u64(&mut self, v: u64) -> &mut Self

Mix a numeric structural parameter (n_layers, head_dim, a window size, an enum discriminant).

pub fn mix_f64(&mut self, v: f64) -> &mut Self

Mix a float structural parameter (rms_norm_eps). By bit pattern, so NaN and -0.0 need no comparison.

Note this gives +0.0 and -0.0 different keys. That is deliberate and conservative — the cost is a redundant plan rebuild in a case that does not arise, and the alternative (normalizing) is a comparison that has to stay correct forever. Do not “fix” it.

pub fn mix_instance(&mut self, id: ModelInstanceId) -> &mut Self

Mix the model’s identity — the component that separates two models of the same architecture, whose baked weight Consts differ.

There is deliberately no mix_weight(&Arc<T>) here. Folding weight addresses is the obvious cheaper implementation and it is unsound: a session does not pin the model’s weight allocations, so a dropped model frees addresses a later model can be handed. The module docs carry the full sequence. A method that looks like identity and silently isn’t is worse than no method, so it is absent rather than deprecated.

pub fn mix_present(&mut self, present: bool) -> &mut Self

Mix whether an optional hook is present, so a model with it disabled cannot key the same as one with it enabled. The obvious implementation — skipping the mix when absent — has exactly that bug.

pub fn finish(&self) -> u64

Trait Implementations

impl Clone for ShapeKeyHasher

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ShapeKeyHasher

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

Formats the value using the given formatter.

impl Default for ShapeKeyHasher

fn default() -> Self

Returns the “default value” for a type.