Enum EventError 

pub enum EventError {
    Retry(String),
    DeadLetter(String),
}

What the mesh should do with a failed message. Handlers may keep returning Result<(), String> (strings convert to EventError::Retry) or return EventError directly to decide the message’s fate:

#[EventPattern("order.confirmed")]
async fn on_confirmed(ctx: EventContext) -> Result<(), EventError> {
    let order: Order = ctx
        .payload()
        .map_err(EventError::DeadLetter)?; // malformed: retrying won't help
    warehouse.reserve(&order).await
        .map_err(|e| EventError::Retry(e.to_string()))      // transient
}

Variants

Retry(String)

Transient failure (downstream 5xx, lock contention): nack → bounded retries → dead-letter at max_retries.

DeadLetter(String)

Permanent failure (malformed payload, violated business invariant): dead-letter immediately — burning the retry budget on a poison message only delays the alert.

Trait Implementations

impl Debug for EventError

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

Formats the value using the given formatter.

impl Display for EventError

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

Formats the value using the given formatter.

impl Error for EventError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<&str> for EventError

fn from(s: &str) -> Self

Converts to this type from the input type.

impl From<String> for EventError

fn from(s: String) -> Self

Converts to this type from the input type.