Struct ShapeHistory 

pub struct ShapeHistory { /* private fields */ }

Bounded ring buffer of recent dispatch fingerprints. The predictor looks back at most MAX_HISTORY entries.

Implementations

impl ShapeHistory

pub fn new() -> Self

Empty history - no prediction is possible.

pub fn record(&mut self, fingerprint: ShapeFingerprint)

Record a dispatch fingerprint. The predictor uses the most recent MAX_HISTORY entries to predict the next.

pub fn latest(&self) -> Option<&ShapeFingerprint>

Most recent fingerprint, or None if history is empty.

pub fn len(&self) -> usize

Number of entries currently retained.

pub fn is_empty(&self) -> bool

True when no entries have been recorded yet.

pub fn contains(&self, fingerprint: &ShapeFingerprint) -> bool

True when the retained history window contains fingerprint.

This lets backend-side prediction caches evict cloned predicted programs that can no longer be predicted by the bounded history.

pub fn predict_next(&self) -> Option<ShapeFingerprint>

Predict the next dispatch fingerprint. Returns None when the history is too sparse or no pattern matches.

Strategy:

1. If the last two entries are equal, predict another repeat.
2. Otherwise, look for the smallest cycle length N such that every retained entry with an entry N positions earlier matches it. This predicts partial cycles as soon as one lag agrees, e.g. A,B,C,A,B -> C, instead of waiting for A,B,C,A,B,C.
3. No prediction.

Trait Implementations

impl Clone for ShapeHistory

fn clone(&self) -> ShapeHistory

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ShapeHistory

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

Formats the value using the given formatter.

impl Default for ShapeHistory

fn default() -> Self

Returns the “default value” for a type.