forked from TrueCloudLab/restic
53 lines
1.3 KiB
Go
53 lines
1.3 KiB
Go
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package minio
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import "time"
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// newRetryTimerContinous creates a timer with exponentially increasing delays forever.
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func (c Client) newRetryTimerContinous(unit time.Duration, cap time.Duration, jitter float64, doneCh chan struct{}) <-chan int {
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attemptCh := make(chan int)
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// normalize jitter to the range [0, 1.0]
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if jitter < NoJitter {
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jitter = NoJitter
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}
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if jitter > MaxJitter {
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jitter = MaxJitter
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}
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// computes the exponential backoff duration according to
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// https://www.awsarchitectureblog.com/2015/03/backoff.html
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exponentialBackoffWait := func(attempt int) time.Duration {
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// 1<<uint(attempt) below could overflow, so limit the value of attempt
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maxAttempt := 30
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if attempt > maxAttempt {
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attempt = maxAttempt
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}
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//sleep = random_between(0, min(cap, base * 2 ** attempt))
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sleep := unit * time.Duration(1<<uint(attempt))
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if sleep > cap {
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sleep = cap
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}
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if jitter != NoJitter {
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sleep -= time.Duration(c.random.Float64() * float64(sleep) * jitter)
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}
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return sleep
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}
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go func() {
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defer close(attemptCh)
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var nextBackoff int
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for {
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select {
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// Attempts starts.
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case attemptCh <- nextBackoff:
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nextBackoff++
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case <-doneCh:
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// Stop the routine.
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return
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}
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time.Sleep(exponentialBackoffWait(nextBackoff))
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}
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}()
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return attemptCh
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}
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