74 lines
1.2 KiB
Go
74 lines
1.2 KiB
Go
|
// reference: https://aws.amazon.com/vi/blogs/architecture/exponential-backoff-and-jitter/
|
||
|
|
package retry
|
||
|
|
|
||
|
|
import (
|
||
|
|
"math"
|
||
|
|
"math/rand"
|
||
|
|
"time"
|
||
|
|
)
|
||
|
|
|
||
|
|
type BackoffInterface interface {
|
||
|
|
Wait(n int) <-chan time.Time
|
||
|
|
|
||
|
|
Delay(i int) time.Duration
|
||
|
|
}
|
||
|
|
|
||
|
|
type Backoff struct {
|
||
|
|
min time.Duration // default 5ms
|
||
|
|
max time.Duration // default 5s
|
||
|
|
jitter bool // default true
|
||
|
|
}
|
||
|
|
|
||
|
|
func DefaultBackoff() *Backoff {
|
||
|
|
return &Backoff{
|
||
|
|
min: 5 * time.Millisecond,
|
||
|
|
max: 5 * time.Second,
|
||
|
|
jitter: true,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func NewBackoff(min, max time.Duration, jitter bool) *Backoff {
|
||
|
|
return &Backoff{
|
||
|
|
min: min,
|
||
|
|
max: max,
|
||
|
|
jitter: jitter,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (b *Backoff) Wait(n int) <-chan time.Time {
|
||
|
|
return time.After(b.Delay(n))
|
||
|
|
}
|
||
|
|
|
||
|
|
// Decorrelated Jitter
|
||
|
|
func (b *Backoff) Delay(i int) time.Duration {
|
||
|
|
rand.New(rand.NewSource(time.Now().UnixNano()))
|
||
|
|
base := int64(b.min)
|
||
|
|
cap := int64(b.max)
|
||
|
|
|
||
|
|
if base >= cap {
|
||
|
|
return time.Duration(cap)
|
||
|
|
}
|
||
|
|
|
||
|
|
t := int(math.Log2(float64(cap)/float64(base))) + 1
|
||
|
|
if i > t {
|
||
|
|
i = t
|
||
|
|
}
|
||
|
|
|
||
|
|
bf := base * int64(1<<i)
|
||
|
|
if bf > cap {
|
||
|
|
bf = cap
|
||
|
|
}
|
||
|
|
|
||
|
|
if !b.jitter {
|
||
|
|
return time.Duration(bf)
|
||
|
|
}
|
||
|
|
|
||
|
|
w := (bf >> 1) + rand.Int63n((bf>>1)+1)
|
||
|
|
w = base + rand.Int63n(w*3-base+1)
|
||
|
|
if w > cap {
|
||
|
|
w = cap
|
||
|
|
}
|
||
|
|
|
||
|
|
return time.Duration(w)
|
||
|
|
}
|