Enum IdempotencyStrategy 

pub enum IdempotencyStrategy<P> {
    Provided,
    Custom(IdempotencyDeriver<P>),
    Uuid,
    None,
}

How an idempotency token is produced when a new event is written.

The variant is evaluated inside OutboxService::add_event before the event is persisted. When an IdempotencyStorageProvider is wired, the produced token is also used to reserve uniqueness up front.

Variants

Provided

Uses the caller-supplied token as-is. Passing None at call site means the event is stored without a token and no reservation is attempted.

Custom(IdempotencyDeriver<P>)

Derives the token by applying the given callback to the event about to be written. See IdempotencyDeriver.

Prefer constructing this variant via IdempotencyStrategy::custom so the Arc wrapping stays an implementation detail.

Uuid

Generates a fresh UUID v7 token at write time. Any caller-supplied token is ignored.

None

Disables idempotency — no token is produced and no reservation is attempted. This is the default.

Implementations

impl<P> IdempotencyStrategy<P>

pub fn custom<F>(f: F) -> Self

where F: Fn(&Event<P>) -> String + Send + Sync + 'static,

Builds an IdempotencyStrategy::Custom from a callback without requiring the caller to wrap it in Arc.

Example

use outbox_core::prelude::*;

let strategy: IdempotencyStrategy<MyEvent> =
    IdempotencyStrategy::custom(|event| event.id.as_uuid().to_string());

impl<P> IdempotencyStrategy<P>

pub fn invoke( &self, provided_token: Option<String>, event: &Event<P>, ) -> Option<String>

Resolves the strategy into a concrete token for the event about to be written.

Behaviour per variant:

• Provided — returns provided_token as-is; None propagates through and means the event will be stored without a token.
• Uuid — generates a fresh UUID v7; provided_token is ignored.
• Custom — passes event to the user-supplied callback and wraps the returned String in Some.
• None — returns None; neither provided_token nor event is used.

Trait Implementations

impl<P: Clone> Clone for IdempotencyStrategy<P>

fn clone(&self) -> IdempotencyStrategy<P>

Returns a duplicate of the value.

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

Performs copy-assignment from source.