Struct SlotBackoff 

pub struct SlotBackoff { /* private fields */ }

SlotBackoff is a backoff strategy that randomly chooses a time slot to retry.

This is useful when you have multiple tasks that can’t overlap, and each task takes roughly the same amount of time.

The unit represents the time it takes to complete one attempt. Future attempts are divided into time slots, and a random slot is chosen for the retry. The number of slots increases exponentially with each attempt. Initially, there are 4 slots, then 8, then 16, and so on.

Example: Suppose you have 10 tasks that can’t overlap, each taking 1 second. The tasks don’t know about each other and can’t coordinate. Each task randomly picks a time slot to retry. Here’s how it might look:

First round (4 slots):

task id   | 1, 2, 3 | 4, 5, 6 | 7, 8, 9 | 10 |
status    | x, x, ✓ | x, x, ✓ | x, x, ✓ | ✓  |
timeline  | 0s      | 1s      | 2s      | 3s |

Each slot can have one success. Here, tasks 3, 6, 9, and 10 succeed. In the next round, the number of slots doubles (8):

Second round (8 slots):

task id   |  1 |  2 |    | 4, 5 |  7 |  8 |    |    |
status    |  ✓ |  ✓ |    | x, ✓ |  ✓ |  ✓ |    |    |
timeline  | 0s | 1s | 2s | 3s   | 4s | 5s | 6s | 7s |

Most tasks are done now, except for task 4. It will succeed in the next round.

Implementations

impl SlotBackoff

pub fn with_unit(self, unit: u32) -> Self

pub fn attempt(&self) -> u32

pub fn next_backoff(&mut self) -> Duration

Trait Implementations

impl Default for SlotBackoff

fn default() -> Self

Returns the “default value” for a type.