Enum CachePresence 

pub enum CachePresence {
    Present,
    Absent,
    MaybePresent,
}

Three-valued answer for BlobCache::exists.

Today the implementation always returns Present or Absent — it tracks the answer authoritatively. The MaybePresent variant exists in the type so the upcoming Bloom synopsis (#146) can answer “probably yes” without forcing a metadata read, all without breaking the exists contract.

Variants

Present

The cache holds a live entry for this key.

Absent

The cache definitely does not hold this key (negative cache hit).

MaybePresent

A probabilistic synopsis cannot rule the key out without a deeper lookup. Treat as a hit prospect: the caller should fetch.

Trait Implementations

impl Clone for CachePresence

fn clone(&self) -> CachePresence

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CachePresence

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

Formats the value using the given formatter.

impl From<bool> for CachePresence

fn from(present: bool) -> CachePresence

Converts to this type from the input type.

impl PartialEq for CachePresence

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

impl Eq for CachePresence

impl StructuralPartialEq for CachePresence