Struct DefaultCapacityPolicy 

pub struct DefaultCapacityPolicy {
    pub grow_at: f64,
    pub shrink_at: f64,
    pub min_capacity: usize,
    pub max_capacity: usize,
    pub hysteresis: Duration,
}

Default capacity policy: fill-ratio with hysteresis.

On every scan the sidecar computes fill_ratio = approx_len / total_capacity. If fill_ratio >= grow_at, the policy doubles the capacity (up to max_capacity). If fill_ratio <= shrink_at, the policy halves the capacity (down to min_capacity). Otherwise it returns None.

Suppressed for since_last_morph < hysteresis to prevent thrashing under bursty load. Default hysteresis 100 ms matches the shape-morph policy.

Fields

grow_at: f64

Upper fill-ratio that triggers a grow. Default 0.85.

shrink_at: f64

Lower fill-ratio that triggers a shrink. Default 0.10.

min_capacity: usize

Minimum allowed capacity (pow2 >= 2). Default 64.

max_capacity: usize

Maximum allowed capacity (pow2). Default 65536.

hysteresis: Duration

Cooldown after each morph. Default 100 ms.

Trait Implementations

impl CapacityPolicy for DefaultCapacityPolicy

fn predict(&self, obs: &CapacityPolicyObservation) -> Option<usize>

Predicts the doubled capacity once the fill ratio crosses 75% of the grow threshold, and the halved capacity once it falls under 150% of the shrink threshold - the trend bands in front of the decide thresholds. Deliberately NOT gated on hysteresis: the cooldown window after a morph is exactly the right time to build the next predicted backing.

fn decide(&self, obs: &CapacityPolicyObservation) -> Option<usize>

impl Default for DefaultCapacityPolicy

fn default() -> Self

Returns the “default value” for a type.