backoff

Documentation

Overview

Package backoff computes retry delays with jitter.

Jitter matters here beyond the usual load-smoothing argument: every follower in every cluster polls the same row, and an unjittered retry period makes them converge into a synchronised herd that all wake, all read, and all contend at the same instant.

Index

• func Jitter(d time.Duration, jitter float64, randFloat func() float64) time.Duration
• type Backoff
  • func New(base, max time.Duration, factor, jitter float64, randFloat func() float64) *Backoff
  • func (b *Backoff) Next() time.Duration
  • func (b *Backoff) Reset()

Functions

func Jitter

func Jitter(d time.Duration, jitter float64, randFloat func() float64) time.Duration

Jitter returns d reduced by a random fraction of up to jitter. It is used for the steady-state polling interval, which does not grow but still must not be synchronised across participants.

Types

type Backoff

type Backoff struct {
	// contains filtered or unexported fields
}

Backoff produces an exponentially growing, jittered delay. The zero value is not usable; construct one with New.

func New

func New(base, max time.Duration, factor, jitter float64, randFloat func() float64) *Backoff

New returns a Backoff that starts at base, multiplies by factor per attempt, and is capped at max. jitter is the fraction of the computed delay that is randomly subtracted, in [0, 1]: 0.2 yields a delay in [0.8d, d].

randFloat supplies values in [0, 1) and may be nil, in which case the global source is used. Tests inject it to make delays deterministic.

func (*Backoff) Next

func (b *Backoff) Next() time.Duration

Next returns the delay for the current attempt and advances the sequence.

func (*Backoff) Reset

func (b *Backoff) Reset()

Reset returns the sequence to its first attempt. It is called whenever an operation succeeds.