package slack import ( "math" "math/rand" "time" ) // This one was ripped from https://github.com/jpillora/backoff/blob/master/backoff.go // 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 { attempts int //Factor is the multiplying factor for each increment step 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, float64(b.attempts)) if b.Jitter { 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 }