Enum Exclusivity 

pub enum Exclusivity {
    Atomic,
    BestEffort,
}

Whether a backend’s write_new is exclusive by construction, or only by a check the backend performs itself.

A consumer reaches for write_new to make a coupled-record mismatch unreachable rather than merely unlikely, and that reasoning is only valid against a backend whose store offers a create-if-absent primitive. So the claim is exposed rather than assumed.

The default is BestEffort: a backend that says nothing understates its guarantee. Overstating it hands a consumer back exactly the race the method exists to remove, which is the more expensive direction to be wrong in.

Variants

Atomic

The underlying store creates-if-absent in one indivisible step, so two concurrent write_new calls cannot both succeed. Exactly one racer establishes the record and every other receives KeystoreError::AlreadyExists.

BestEffort

The backend checks for the key and then writes. Correct when uncontended, but two concurrent calls can both observe absence and both write, so a consumer MUST NOT rely on this to make a coupled mismatch unreachable.

The store offers no create-if-absent primitive — not a defect in the backend, and the reason this is reported rather than hidden.

Trait Implementations

impl Clone for Exclusivity

fn clone(&self) -> Exclusivity

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Exclusivity

impl Debug for Exclusivity

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

Formats the value using the given formatter.

impl Display for Exclusivity

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

Formats the value using the given formatter.

impl Eq for Exclusivity

impl PartialEq for Exclusivity

fn eq(&self, other: &Exclusivity) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Exclusivity