Method random_layer

nodedb-vector/src/codec_index/graph.rs:107–111

Assign a random layer per the HNSW exponential distribution. Capped at `MAX_LAYER_CAP` to prevent pathological draws from inflating `max_layer`.

(&mut self)

    /// Capped at `MAX_LAYER_CAP` to prevent pathological draws from inflating
    /// `max_layer`.
    pub fn random_layer(&mut self) -> usize {
        let r = self.rng.next_f64().max(f64::MIN_POSITIVE);
        let layer = (-r.ln() * self.level_mult as f64).floor() as usize;
        layer.min(MAX_LAYER_CAP)
    }

    /// Return a reference to the quantized payload at `idx`, if present and
    /// not deleted.