mirror of https://github.com/jpillora/backoff.git
55 lines
1.3 KiB
Go
55 lines
1.3 KiB
Go
package backoff
|
|
|
|
import (
|
|
"math"
|
|
"math/rand"
|
|
"time"
|
|
)
|
|
|
|
//Backoff is a time.Duration counter. It starts at Min.
|
|
//After every call to Duration() it is multiplied by Factor.
|
|
//It is capped at Max. It returns to Min on every call to Reset().
|
|
//Used in conjunction with the time package.
|
|
type Backoff struct {
|
|
//Factor is the multiplying factor for each increment step
|
|
attempts, Factor float64
|
|
//Jitter eases contention by randomizing backoff steps
|
|
Jitter bool
|
|
//Min and Max are the minimum and maximum values of the counter
|
|
Min, Max time.Duration
|
|
}
|
|
|
|
//Returns the current value of the counter and then
|
|
//multiplies it Factor
|
|
func (b *Backoff) Duration() time.Duration {
|
|
//Zero-values are nonsensical, so we use
|
|
//them to apply defaults
|
|
if b.Min == 0 {
|
|
b.Min = 100 * time.Millisecond
|
|
}
|
|
if b.Max == 0 {
|
|
b.Max = 10 * time.Second
|
|
}
|
|
if b.Factor == 0 {
|
|
b.Factor = 2
|
|
}
|
|
//calculate this duration
|
|
dur := float64(b.Min) * math.Pow(b.Factor, b.attempts)
|
|
if b.Jitter == true {
|
|
dur = rand.Float64()*(dur-float64(b.Min)) + float64(b.Min)
|
|
}
|
|
//cap!
|
|
if dur > float64(b.Max) {
|
|
return b.Max
|
|
}
|
|
//bump attempts count
|
|
b.attempts++
|
|
//return as a time.Duration
|
|
return time.Duration(dur)
|
|
}
|
|
|
|
//Resets the current value of the counter back to Min
|
|
func (b *Backoff) Reset() {
|
|
b.attempts = 0
|
|
}
|