soju/rate.go

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package soju
import (
"math/rand"
"time"
)
// backoffer implements a simple exponential backoff.
type backoffer struct {
min, max, jitter time.Duration
n int64
}
func newBackoffer(min, max, jitter time.Duration) *backoffer {
return &backoffer{min: min, max: max, jitter: jitter}
}
func (b *backoffer) Reset() {
b.n = 0
}
func (b *backoffer) Next() time.Duration {
if b.n == 0 {
b.n = 1
return 0
}
d := time.Duration(b.n) * b.min
if d > b.max {
d = b.max
} else {
b.n *= 2
}
if b.jitter != 0 {
d += time.Duration(rand.Int63n(int64(b.jitter)))
}
return d
}