Enum DiscardPolicy 

pub enum DiscardPolicy {
    New,
    Old,
}

What a bounded bucket does when it reaches max_bytes (NATS-specific).

This is a real semantic choice, not a tuning knob — it decides what the bucket gives up at capacity:

Variants

New

Reject new writes when full, preserving every existing entry (NATS discard:new). Correct for config buckets (certs, configs read as the source of truth) where silently dropping a live value is unacceptable — but it FREEZES writes at capacity (err 10077). Pair it with max_age so the bucket is trimmed before it ever fills.

Old

Evict the oldest messages when full (NATS discard:old): a hard size ceiling that never rejects. Correct for high-churn log buckets whose consumers hold the durable fold (e.g. routing origins): the bucket is a bounded change-feed, not the source of truth, so an evicted entry is recovered from the consumer’s fold (and the CursorExpired resync path), while writers never freeze.

Trait Implementations

impl Clone for DiscardPolicy

fn clone(&self) -> DiscardPolicy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for DiscardPolicy

impl Debug for DiscardPolicy

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

Formats the value using the given formatter.

impl Default for DiscardPolicy

fn default() -> DiscardPolicy

Returns the “default value” for a type.

impl Eq for DiscardPolicy

impl PartialEq for DiscardPolicy

fn eq(&self, other: &DiscardPolicy) -> 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 DiscardPolicy