Struct BackoffPolicy 

pub struct BackoffPolicy {
    pub max_attempts: Option<u32>,
    pub backoff: Backoff,
}

The built-in ReconnectPolicy: a Backoff curve plus an optional cap on consecutive attempts.

A dropped connection is the normal case, not the exceptional one: brokers are restarted for upgrades, failed over, and partitioned from their clients by the network in between. The default therefore retries forever, on the theory that a worker process which outlives its broker’s restart is worth more than one which exits and waits for a supervisor.

use queuey_rabbitmq::BackoffPolicy;

// Give up after ten tries instead of retrying forever.
let policy = BackoffPolicy::default().max_attempts(Some(10));
assert_eq!(policy.max_attempts, Some(10));

Set RabbitMqOptions::reconnect to None to turn reconnection off entirely and get the original fail-fast behaviour back.

Fields

max_attempts: Option<u32>

How many consecutive attempts to make before giving up, or None to keep trying indefinitely.

Defaults to None. The count is of consecutive failures: it resets the moment a connection succeeds, so a process that reconnects once an hour for a year never exhausts a limit of three. Some(0) never reconnects at all, which is RabbitMqOptions::reconnect(None) the long way round.

backoff: Backoff

Delay between attempts, as a function of how many have failed.

Defaults to exponential with full jitter: 500ms base, doubling, capped at 30 seconds. Jitter matters more here than in a job backoff: every worker in a fleet loses its connection at the same instant when a broker goes down, and an unjittered backoff would have all of them knock on the door in lockstep for as long as the outage lasts.

Implementations

impl BackoffPolicy

pub fn max_attempts(self, attempts: Option<u32>) -> Self

Limit the number of consecutive attempts, or None for no limit.

pub fn backoff(self, backoff: Backoff) -> Self

Replace the delay schedule between attempts.

Trait Implementations

impl Clone for BackoffPolicy

fn clone(&self) -> BackoffPolicy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BackoffPolicy

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

Formats the value using the given formatter.

impl Default for BackoffPolicy

fn default() -> Self

Returns the “default value” for a type.

impl ReconnectPolicy for BackoffPolicy

fn next_delay(&self, attempt: Attempt<'_>) -> Option<Duration>

The first attempt after a drop is immediate; the rest follow the curve.

A failover is often complete in the time it took the client to notice, so waiting out a backoff before even trying would add that delay to the common case. Backoff::delay_for takes the 1-based attempt that just failed, which is exactly the failure count.