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backoff.go
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backoff.go
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package netutil
import (
"math/rand"
"time"
)
// DefaultBackoffConfig uses values specified for backoff in common.
var DefaultBackoffConfig = BackoffConfig{
MaxDelay: 120 * time.Second,
BaseDelay: 1.0 * time.Second,
Factor: 1.6,
Jitter: 0.2,
}
// Backoff defines the methodology for backing off after a call failure.
type Backoff interface {
// Backoff returns the amount of time to wait before the next retry given
// the number of consecutive failures.
Backoff(retries int) time.Duration
}
// BackoffConfig defines the parameters for the default backoff strategy.
type BackoffConfig struct {
// MaxDelay is the upper bound of backoff delay.
MaxDelay time.Duration
// baseDelay is the amount of time to wait before retrying after the first
// failure.
BaseDelay time.Duration
// factor is applied to the backoff after each retry.
Factor float64
// jitter provides a range to randomize backoff delays.
Jitter float64
}
/*
// NOTE TODO avoid use unexcept config.
func (bc *BackoffConfig) Fix() {
md := bc.MaxDelay
*bc = DefaultBackoffConfig
if md > 0 {
bc.MaxDelay = md
}
}
*/
// Backoff returns the amount of time to wait before the next retry given
// the number of consecutive failures.
func (bc *BackoffConfig) Backoff(retries int) time.Duration {
if retries == 0 {
return bc.BaseDelay
}
backoff, max := float64(bc.BaseDelay), float64(bc.MaxDelay)
for backoff < max && retries > 0 {
backoff *= bc.Factor
retries--
}
if backoff > max {
backoff = max
}
// Randomize backoff delays so that if a cluster of requests start at
// the same time, they won't operate in lockstep.
backoff *= 1 + bc.Jitter*(rand.Float64()*2-1)
if backoff < 0 {
return 0
}
return time.Duration(backoff)
}