Enum TierEvict 

pub enum TierEvict {
    Spill {
        slot: usize,
        key: u64,
        depth: usize,
    },
    Drop {
        slot: usize,
        depth: usize,
    },
}

2026-09-26: Outcome of crate::prefix_cache::PrefixCache::evict_snapshot_to_tier.

The depth gate (min_tokens, which the model engine derives from METRALE_SSM_SPILL_MIN_TOKENS) is applied when the victim is chosen, so a shallow victim’s entry is removed rather than left findable with no stored bytes. Either arm returns the victim’s slot for the caller to free.

Variants

Spill

2026-09-26: The entry is marked spilled and stays findable; the caller moves the bytes to the tier.

Fields

slot: usize

2026-09-26: The victim’s snapshot slot: spill from it, then free it.

key: u64

2026-09-26: Tier key: the entry’s prefix hash.

depth: usize

2026-09-26: Victim depth in tokens.

Drop

2026-09-26: Shallower than min_tokens: the entry was removed, and tier_spills was not incremented.

Fields

slot: usize

2026-09-26: The victim’s snapshot slot, for the caller to free.

depth: usize

2026-09-26: Victim depth in tokens.

Implementations

impl TierEvict

pub fn slot(&self) -> usize

2026-09-26: The victim’s slot, whichever arm was taken.

Trait Implementations

impl Clone for TierEvict

fn clone(&self) -> TierEvict

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TierEvict

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

Formats the value using the given formatter.

impl PartialEq for TierEvict

fn eq(&self, other: &TierEvict) -> 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 Copy for TierEvict

impl Eq for TierEvict

impl StructuralPartialEq for TierEvict