41 lines
1.2 KiB
Go
41 lines
1.2 KiB
Go
package retry
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import (
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"math"
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"math/rand"
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"time"
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)
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type BackoffFunc func(attempt int) time.Duration
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func BackoffLinearWithJitter(waitBetween time.Duration, jitterFraction float64) BackoffFunc {
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return func(attempt int) time.Duration {
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return jitterAround(waitBetween, jitterFraction)
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}
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}
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func BackoffExponentialWithJitter(base time.Duration, cap time.Duration) BackoffFunc {
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return func(attempt int) time.Duration {
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to := getExponentialTimeout(attempt, base)
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// Using float types here, because exponential time can be really big, and converting it to time.Duration may
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// result in undefined behaviour. Its safe conversion, when we have compared it to our 'cap' value.
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if to > float64(cap) {
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to = float64(cap)
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}
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return time.Duration(to/2 + to/2*rand.Float64())
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}
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}
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func getExponentialTimeout(attempt int, base time.Duration) float64 {
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// pow 3: 50ms, 150ms, 450ms, 1.35s, 4.05s, 12.15s - Now.
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// pow 2: 50ms, 100ms, 200ms, 400ms, 800ms, 1.6s - Previous.
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mult := math.Pow(3, float64(attempt))
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return float64(base) * mult
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}
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func jitterAround(duration time.Duration, jitter float64) time.Duration {
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multiplier := jitter * (rand.Float64()*2 - 1)
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return time.Duration(float64(duration) * (1 + multiplier))
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}
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