Struct ExactlyOnce 

pub struct ExactlyOnce { /* private fields */ }

A handler for exactly-once delivery.

Implementations

impl ExactlyOnce

pub async fn confirmed_ack(self) -> Result<(), AckError>

Strongly acknowledge the message associated with this handler.

use google_cloud_pubsub::model::Message;
async fn on_message(m: Message, h: ExactlyOnce) {
  match h.confirmed_ack().await {
    Ok(()) => println!("Confirmed ack for message={m:?}. The message will not be redelivered."),
    Err(e) => println!("Failed to confirm ack for message={m:?} with error={e:?}"),
  }
}

If the result is an Ok, the message is guaranteed not to be delivered again.

If the result is an Err, the message may be redelivered, but this is not guaranteed. If no redelivery occurs a sufficient interval after an error, the acknowledgement likely succeeded.

pub async fn confirmed_nack(self) -> Result<(), AckError>

Rejects the message associated with this handler and waits for confirmation.

use google_cloud_pubsub::model::Message;
async fn on_message(m: Message, h: ExactlyOnce) {
  match h.confirmed_nack().await {
    Ok(()) => println!("Confirmed nack for message={m:?}. The message will be redelivered."),
    Err(e) => println!("Failed to confirm nack for message={m:?} with error={e:?}"),
  }
}

If the result is an Ok, the message is guaranteed to be immediately considered for redelivery. If an error occurs, the message will still be redelivered, but it may be held for the remainder of its max_lease_extension.

pub fn delivery_attempt(&self) -> Option<i32>

Returns the delivery attempt count for this message, if available.

Example

fn on_message(h: ExactlyOnce) {
    match h.delivery_attempt() {
        Some(i) => println!("Delivery attempt: {i}"),
        None => println!("Delivery attempt: unknown"),
    }
}

This returns None if dead-letter topics are not configured on the subscription.

Trait Implementations

impl Debug for ExactlyOnce

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

Formats the value using the given formatter.

impl Drop for ExactlyOnce

fn drop(&mut self)

Rejects the message associated with this handler.

The message will be removed from this Subscriber’s lease management. The service will redeliver this message, possibly to another client.