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50 lines
1.3 KiB
50 lines
1.3 KiB
package retry
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import (
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"math"
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"time"
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"github.com/aws/aws-sdk-go-v2/internal/rand"
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"github.com/aws/aws-sdk-go-v2/internal/timeconv"
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)
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// ExponentialJitterBackoff provides backoff delays with jitter based on the
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// number of attempts.
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type ExponentialJitterBackoff struct {
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maxBackoff time.Duration
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// precomputed number of attempts needed to reach max backoff.
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maxBackoffAttempts float64
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randFloat64 func() (float64, error)
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}
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// NewExponentialJitterBackoff returns an ExponentialJitterBackoff configured
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// for the max backoff.
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func NewExponentialJitterBackoff(maxBackoff time.Duration) *ExponentialJitterBackoff {
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return &ExponentialJitterBackoff{
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maxBackoff: maxBackoff,
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maxBackoffAttempts: math.Log2(
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float64(maxBackoff) / float64(time.Second)),
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randFloat64: rand.CryptoRandFloat64,
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}
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}
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// BackoffDelay returns the duration to wait before the next attempt should be
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// made. Returns an error if unable get a duration.
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func (j *ExponentialJitterBackoff) BackoffDelay(attempt int, err error) (time.Duration, error) {
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if attempt > int(j.maxBackoffAttempts) {
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return j.maxBackoff, nil
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}
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b, err := j.randFloat64()
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if err != nil {
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return 0, err
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}
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// [0.0, 1.0) * 2 ^ attempts
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ri := int64(1 << uint64(attempt))
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delaySeconds := b * float64(ri)
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return timeconv.FloatSecondsDur(delaySeconds), nil
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}
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