ack_extension

ack_extension sets how far each background extension of a delivery's lease reaches, from 10 seconds to 10 minutes, 60 seconds by default.

Pub/Sub redelivers a message whose ack deadline passes before it is settled. While a handler works, the client library extends that deadline in the background, each time by this much. A longer extension means fewer calls for a slow handler. A shorter one brings a delivery back sooner when the process dies, because the service redelivers once the last extension runs out. The client clamps the value to the 10 seconds to 10 minutes Pub/Sub accepts. It is independent of the ack deadline configured on the subscription. How long the client keeps extending one delivery is max_lease.

Example

A report takes minutes to render, so each extension reaches five minutes.

Macros

examples/pubsub_subscriptions_flow.rs

/// A report takes minutes to render, so each extension of its lease reaches five minutes.
#[subscriber(
    GooglePubSub::new("flow-reports-workers")
        .create_with_topic("flow-reports")
        .ack_extension(Duration::from_mins(5))
)]
async fn render(report: &Report) -> HandlerOutcome {
    tracing::info!(report.id, "report rendered");
    HandlerOutcome::ack()
}

Manual

examples/manual/pubsub_subscriptions_flow.rs

/// A report takes minutes to render, so each extension of its lease reaches five minutes.
fn reports() -> GooglePubSub {
    GooglePubSub::new("flow-reports-workers")
        .create_with_topic("flow-reports")
        .ack_extension(Duration::from_mins(5))
}