Enum IdempotencyStrategy 

pub enum IdempotencyStrategy<P>
where
    P: Debug + Clone + Serialize,
{
    Provided,
    Custom(fn(&Event<P>) -> String),
    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(fn(&Event<P>) -> String)

Derives the token by applying the given function to the event about to be written. The add_event callback get_event must return Some for this variant — otherwise the service panics.

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>

where P: Debug + Clone + Serialize,

pub fn invoke<F>( &self, provided_token: Option<String>, get_event: F, ) -> Option<String>

where F: FnOnce() -> Option<Event<P>>,

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 — invokes get_event, passes the resulting Event to the user-supplied function, and wraps the returned String in Some.
• None — returns None; neither provided_token nor get_event is used.

get_event is only evaluated for the Custom branch, so callers can pass || None for every other strategy.

Panics

Panics if the strategy is set to Custom, but the provided get_event closure returns None. The panic message is "Strategy is Custom, but no Event context provided".

Trait Implementations

impl<P> Clone for IdempotencyStrategy<P>

where P: Debug + Clone + Serialize + Clone,

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.